echnical

Activities 1985

Center for

Basic

Standards

October 1985

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
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national bureau

OF STANDARDS

library

NBSIR 85-3254

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Center for

Basic

Standards

Karl G. Kessler, Director

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory Center for Basic Standards

Gaithersburg, MD 20899

October 1985

U.S. DEPARTMENT OF COMMERCE Malcolm Baldnge, Secretary

National Bureau of Standards, Ernest Ambler. Director

ABSTRACT

This report summarizes the research and technical activities of

the Center for Basic Standards during the Fiscal Year 1985-

These activities include work in the areas of electricity,

temperature and pressure, mass and length, time and frequency,

quantum metrology, and quantum physics.

Keywords: Astrophysics; atomic and molecular physics; chemical physics;

electrical standards; fundamental constants; gravity measurements; laser

physics; length standards; mass standards; pressure and vacuum standards;

temperature standards; time and frequency standards; X-ray and gamma-ray

wavelength standards.

i
INTRODUCTION

This report is a summary of the technical activities of the NBS

Center for Basic Standards (CBS) for the period October 1, 1984 to

September 30, 1985. The Center is one of the four centers and

operating units in the National Measurement Laboratory.

The summary of activities is organized in six sections, one for

the technical activities of the Quantum Metrology Group, and one each

for the five divisions of the Center. Each division or group tells its own story in its own way. In general, there is an overview followed by

a series of short reports on current projects. Then the publications,

invited, talks, committee participation and professional interactions

during the year are listed.

More information about particular work may be desired. To obtain

this, the reader should address the individual scientists or their

division, c/o Center for Basic Standards, B160 Physics Building,

National Bureau of Standards, Gaithersburg, Maryland 20899.
TABLE OF CONTENTS

Abstract i

Introduction ii

Quantum Metrology Group 1

Electricity Division 21

Temperature and Pressure Division 76

Length and Mass Division 128

Time and Frequency Division 138

Quantum Physics Division 193

iii

QUANTUM METROLOGY GROUP

SUMMARY OF ACTIVITIES

FISCAL YEAR 1985

OVERVIEW

We are engaged in certain relatively clearly defined scientific

enterprises and at the same time concerned with development and im-’ provement of tools and measurement technology for future scientific

work. This combination of efforts is not so unusual, and for the

moment at least, appears advantageous. Indeed much of our current

scientific program benefits from earlier technical development

exercises and there are indications that this progression may continue

in the future. Evidently we benefit from an absence of externally

mandated programs and goals which makes planning and program

articulation both more difficult and more important.

In the following sub-’sections we have attempted to convey our sense

of where the work now stands and where at least some of its future may

lie. For purposes of internal management and in terms of the external

groups and facilities with which we interact, we tend to see two major

scientific thrusts: One of these concerns itself with precision

measurement, especially of the spectroscopic variety predominantly in

the x-ray and Y-ray regions, determination of fundamental constants

and tests of basic symmetries and invariances. The second concerns

itself with structure and dynamics in atoms, molecules and simple

solids perturbed by the presence of one or more inner-shell vacancies.

This work ultimately requires radiation fluxes only available at

synchrotron radiation sources to separately characterize single

vacancy and multiple vacancy processes. However, the ultimate aim is

systematic investigation of smaller molecules and other simple systems

to establish a stable basis for investigation of less well understood

systems. Lastly in this report we indicate current efforts at new technology for scientific measurements. Although it is not easy to

impose on these exercises a meaningful programmatic overlay, there are certain features which indicate an appropriateness to our presence in

these areas. These indicators include: rather challenging technical

obstacles, scientifically attractive potentiality, good local talent

and either modesty of scale or effective external collaborative

relationships

.

TECHNICAL ACTIVITIES

Precision measurements & fundamental constants

Objectives and programs :

Ongoing work in this area is primarily on spectroscopic measurements in the region of x-rays and Y-rays but includes also work on the

gravitational constant. Our spectroscopic efforts are focussed at the

1
present time on tests of QED in high Z one- and two-electron systems,

systematics of inner vacancy spectra and measurement of those Y-transitions which are directly connectable to fundamental constants and masses of elementary particles.

The overall scheme begins with optical interferometry of a crystal

(Si) lattice spacing, dissemination of this result to other diffracting crystals and their use via absolute angle measurement for

wavelength determination. Some of these wavelength determinations are

of direct importance in and of themselves, as is the case for the n-p

capture Y, while others provide markers for experiments where only

relative measurements are feasible, e.g., those involving mesic atoms

or one- and two- electron high Z systems. All aspects of this work

are currently active and in aggregate involve significant numbers of

NBS staff and visitors, as well as considerable resources both

internal to NBS and at major international centers.

NBS personnel working in this area include R.D. Deslattes 2/3, E.G.

Kessler, G.L. Greene 2/3i A. Henins 2/3, R.E. LaVilla l/3i and M. Gutkosky 1/3. We have enjoyed visits from H. Borner and T. Manning,

Institut Max Von Laue-Paul Langevin (ILL) and M. Tanaka, National

Research Laboratory of Metrology (NRLM) . Our activities take place at

NBS in lattice interferometry and x-ray spectra while Y-ray work is

carried out at ILL in Grenoble and one-and two-electron spectroscopy

has proceeded at the Max-Planck Institute for Nuclear Physics (MPIKP)

in Heidelberg and at the Gesellschaft fur Schwer ionenforschung (GSI)

outside of Darmstadt, where there are also effective collaborators

(Reinholdt Schuch, MPIKP and Heinrich Beyer, GSI).

Gravitational work carried out by Luther (2/3) aims to produce an improved value of G which has a measure of intrinsic interest, but in

addition, confronts efforts to estimate this numeric a priori

(Sternglass, 1984, Cohen, 1985). This work also aims to test

equivalence of passive and active gravitational mass for alumina,

silica and tungsten. Here there are also conflicts and questions

(Stacey, et al. 1981, Jacobson, 1983).

Current Activities - accomplishments;

The biggest challenge confronting this whole area of work is the

improbably large (lOo) apparent discrepancy between the 1975 NBS

interferometr ic determination of a Si lattice spacing and that subsequently reported by the Physikalisch-Technische Bundesanstalt (PTB).

First priority and maximum effort have been given and applied to

(respectively) this question. The experimental capabilities were re-established by last year with additional diagnostic interferometr ic

channels added to control the dominant source of systematic error. As

reported last year this system appeared to be operational and had

demonstrated sensitivity and accuracy adequate to accomplish the

needed correction factor measurements. Unfortunately, it was not

2
noticed at that time that a fundamental conceptual error prevented

these (otherwise adequate) interferometric signals from giving the

information needed to accomplish the required corrections. A revised

"path curvature" interferometer was designed, fabricated (by

Continental Optical and Perkin Elmer) and installed. This system

began to operate in September 1985 and should have yielded significant

results by the time of the Panel meeting.

Aside from the primary interferometric measurement, there is a need

for rapid and sensitive intercomparison of lattice spacings among

crystals having nearly the same lattice parameter. To address this

need, a new goniometric facility was designed and built with major

contributions from our long-term visitor Dr. M. Tanaka. Although

x-ray sources are used, the classical limits on lattice parameter

precision implied by x-ray wavelength spread are largely circumvented.

As originally planned, this new facility, the DELTA-D (6d) machine,

would have replaced the second generation x-ray interferometer

experiment. It would have made use of the same x-ray sources,

vibration isolated and temperature-controlled environment as well as computer controlled measurement apparatus. Because of the problems

already noted above, this sequential model is no longer appropriate.

We have therefore begun a process which should yield an independent 6d

machine within the month prior to the meeting of this panel. This

process involves establishing a new (and previously unplanned)

vibration isolated and temperature controlled environment. It also

involves providing dual x-ray sources not previously contemplated and

appropriate computer controlled data acquisition facilities.

The NBS-ILL precision gamma-ray wavelength facility has been

significantly up-graded during the past year. This up-grade coincided

with a one year shut down of the ILL reactor for maintenance. On the

ILL side, the reactor source tube has been replaced with a tube of a new design which will permit three sources to reside in the high flux

region simultaneously, a significant improvement for the precise but

inefficient flat crystal spectrometer. The casement in which the

spectrometer resides was removed in order to change the source tube.

During reconstruction, the casement was enlarged to accommodate a larger more stable base for the spectrometer

.

On the NBS side, the precision spectrometer was returned to the

U.S. and significantly improved. The major improvements are: 1) a larger vibration isolation platform which will permit the spectrometer

to be moved into and out of the gamma-ray beam without moving the

vibration isolation platform, 2) a positioning system for the

vibration isolation platform which allows reproducible positioning to

within a few microns, 3) improved optics for the angle interferometers, I4 ) crystal and optical polygon supports which permit angle

interferometer calibration without removal of crystals and automatic

indexing of the polygon, 5) improved collimation and detection for

better background suppression and 6) a controlled atmosphere chamber

3
for the spectometer. The target accuracy for this spectrometer is 0.1

ppm for sources of a few counts per second (2nd or 3nd order). The

spectrometer improvements are nearing completion. The vibration

isolation platform will be shipped to ILL in November or December 1985

and the precision spectrometer in January 1986.

High precision gamma-ray data recorded in 1984 were analyzed and

published during the past year. The measured wavelengths were produced in the reactions ^^Cl(n,Y) ^°C1 (517, 786, 788, 1165, 1951,

1958 keV) and H(n,Y)D (2.2 MeV). The chlorine data showed that

wavelength measurements accurate to - 0.1 ppm are possible for intense

lines up to 2 MeV. The uncertainty of the weak hydrogen line (< 0.5

counts/sec in first order) is -0.9 ppm. The deuteron binding energy

follows directly from this measurement and the neutron mass can be

derived by combining the deuteron binding energy with mass spectroscopic data. The uncertainty on the mass of the neutron has been

reduced by a factor of three.

One- and two-electron high Z studies are presently carried out at

accelerator facilities in West Germany. All such work uses focusing

crystal spectrometers and position sensitive detectors to compare

e.g., Lyman a with an otherwise determined x-ray reference line

measured on the (in-house) upgraded vacuum spectrometer. In the past

we used recoil production at 5-6 MeV/u) and x-ray standards;

although the recoil spectra are free of Doppler correction, they

remain troubled by spectator electrons. The latest generation of this

work uses acel-str ip-decel technology to produce relatively slow beams

of naked ions whose upper levels are then populated selectively by

single collision encounters with atomic H or He. A prototype of this

procedure was run at MPIKP in Heidelberg and should give results

limited by the x-ray reference line. New developments of crystal

filter markers which have now been demonstrated should overcome x-ray

line shape limitations in the future.

Gravitational activity over the past year focussed on an ultimately

disappointing study of a new fiber material (Pt/W). It turned out to

be a disaster. Even though its torsion constant and strength were

ideal, its stability and the numbers it produced were just not good

enough to generate any truly useable data, but were just good enough

to warrant continued use in the hope of eventual success. This fiber

has been abandoned and a fiber of chromium and gold-plated quartz is

currently installed and is being readied for what is fervently hoped

will be the last cut at this measurement. A hard disk has been

installed on the computer system which controls the experiment and

analyzes the data, allowing what is hoped will be easier data

reduction and analysis.

A measurement of the equivalence of the active and passive mass of

bronze and tungsten has been made. The results are consistent with

Newton. A measurement of the equivalence of the active and passive

4
mass of alumina and tungsten has been made with sufficient precision

to be interesting, as pertaining to the measurement of Stacey and

Tuck

.

Three precision spheres of borosilicate glass have been manufactured. These spheres accurately duplicate the diameter of the tungsten

spheres against which they are compared. Their sphericities are a few

parts/million rms. A manuscript is being prepared outlining their

construction.

Inner shell spectra-synchrotron radiation

Objectives and program:

Our long-standing efforts in x-ray spectroscopy have focussed on multi-vacancy and many-body effects. Aside from matters of intrinsic

interest (which are considerable) these features are ubiquitous in

both emission and absorption spectra making direct interpretation of

these spectra less robust and informative than it should be absent

these complexities. By studies of emission spectra under highly

resolved monochromatic excitation we demonstrated an unambiguous

separation of spectral features arising from-single vacancy and

multi-vacancy processes [Phys. Rev. A 27 923 0983)].

Such work is possible only with the use of an intense synchrotron

radiation source. Furthermore, extension of our original demonstration experiment, carried out on atomic argon to families of molecular

gases and simple solids and to include electrons as well as photons,

requires a dedicated and highly specialized beamline. Design,

construction and installation of such a line at the National

Synchrotron Light Source (NSLS), Brookhaven has been a major effort of

several people for more than a few years. As is well known, there

were considerable delays in the x-ray ring startup at NSLS and there

were surely problems in our development. However, as indicated in the

next paragraphs, this has been the year for full operation of the

ring, of our beamline and the beginning of its research program.

The time up to that of full operation at NSLS has not been without

issue, due to work carried out at the Stanford Synchrotron Radiation

Laboratory (SSRL) and the Hamburg Synchrotron Radiation Source

(HASYLAB). These efforts have led toward previously unanticipated

directions, some of which will fold into our ongoing program. Overall

this is a large effort, both financially and in terms of personnel.

Full time contributions come from P. Cowan, S. Brennan and B. Karlin

(a Brookhaven National Laboratory (BNL) employee supported by NBS) . Participation by T. Jach (1/2) and R. LaVilla (2/3), as well as significant contributions from R.D. Deslattes, E.G. Kessler and A. Henins rounded out the effort.

5
Current activities - accomplishments:

The past year can be divided roughly in two with regard to synchrotron radiation. On May 9, 1985 the National Synchrotron Light Source

(NSLS) began a full schedule of operational beam time. Because of the

long delay in the beginning of NSLS operation, we took advantage of

available beam time at other synchrotron sources prior to March 1985.

However, since April 1985 the principal efforts have been the installation, commissioning and operation of the X-24A beamline at NSLS.

In a collaboration with the Center for x-ray Optics of the Lawrence

Berkeley Laboratory (LBL), we obtained 8 eight-hour shifts of beamtime

February 17-20, 1985 at the Stanford Synchrotron Radiation Laboratory

(SSRL). This experimental run was at SSRL Beamline VI-2 on the

LBL/Exxon Wiggler, which is the world's brightest continuous beam

x-ray source. The intention of the experiment was to observe

photoelectron and Auger electron spectra from argon as a function of

incident photon energy near the thresholds for single and multiple-vacancy production at ~3.2 keV.

This experimental run was plagued with difficulty: The promised

eight shifts of beam were reduced to about one and one-half due to

facility-related problems. In the remaining beamtime we were able to

obtain detailed K edge absorption spectra of argon and Cl in CF

2 CI

2

. However, there was insufficient time to obtain significant electron

spectra

.

Prior to the experiment it was determined that the photon flux at

3.2 keV could be maximized by operating the wiggler in a reduced

field, undulator mode. Our observations of the performance of the

insertion device as an undulator have been accepted for publication.

Activity at the NSLS has proceeded at an accelerated pace since

April of this year. We have installed and operated all major beamline

components. The UHV compatible crystal monochromator has been

providing tuneable monochromatic x-rays since May. A focussed beam

was obtained in June despite mechanical difficulties with the grazing

incidence x-ray mirror mechanisms. Also in June, the first absorption

edge scans were taken with the monochromator. By mid-August the

performance testing of the beamline was largely completed. Due to the

UHV compatible design, beamline X-24A delivers the highest intensity

(~10^^ photons/sec-mm ) at 3*2 keV of any synchrotron beamline in the

world. The energy resolving power of the monochromator is also higher

than any previously reported. These results are in press.

A secondary x-ray spectrometer was constructed for high energy

resolution measurements of x-ray scattering and fluorescence. The

spectrometer is a tuneable curved crystal, Rowland circle instrument.

A position sensitive detector permits simultaneous data collection at

6
various wavelengths. A variable radius crystal bender was developed

to permit the crystal to detector distance to remain fixed as the

angle of the crystal is tuned.

Scientific research has begun at beamline X-24A. Both absorption

spectra and fluorescence spectra have been obtained. At this writing

it is expected that publishable results should be in hand by the time

the Committee meets.

Particularly through experiments at HASYLAB and SSRL we became

involved with x-ray surface diffraction. This is a recently emerged

facet of x-ray diffraction which had already demonstrated utility in

revealing ordered structure in overlayers but for which the diffraction process was not fully understood. Cowan formulated a dynamical

model for the case of simultaneous total external reflection and Bragg

diffraction from planes perpendicular to the surface. Interference

between these processes permits manipulation of the fields and

alteration of their spatial amplitude distributions.

We (Cowan, Brennan, Jach) obtained beam time last year at HASYLAB

to test the prediction of Cowan’s calculations. Analysis of the data

during the present year showed good agreement with the theory but the

surface conditions (Br passivated Ge operated in He) were far from

rigorously established. To confirm that the observed effects were not

due to contamination we were able to obtain both beam time and access

to a specially built surface diffraction chamber at the Stanford

Synchrotron Radiation Laboratory (SSRL) to study the predicted effects

on a Ge(111) crystal. The advantages of using this chamber were that

the surface could be prepared in the same ultra-high vacuum chamber

that was used on a goniometer for the diffraction measurements. The

data are still being analyzed but preliminary results indicate that

the dynamical effects are present on the surface and are not merely an artifact of a dirty surface.

While at SSRL we collaborated with researchers from EXXON Research

and Engineering Co. and from AT & T Bell Labs on a grazing incidence

scattering study of clean and oxygen covered Cu(110). One of the

novel effects that has been observed under grazing incidence

diffraction conditions is the presence of "forbidden reflections,"

i.e. those which would not occur from bulk diffraction due to

destructive interference from subsequent planes. Two that have been

recorded are the Cu(110) and the Cu(IOO) reflections from planes

perpendicular to the (110) surface. What is not yet settled is

whether these reflections are due to surface defects or due to the

exponentially decaying evanescent wave in the bulk, causing incomplete

cancellation of reflected waves. The strength of the copper

reflections seem to be dependent on the angle of miscut of the copper

planes from the surface. No intensity was observed from the Ge(110)

and (330) reflections; however the Ge crystal was very well oriented.

7
such that the surface normal was aligned with the (111) zone axis to

better than 30 arc seconds. Work is continuing in this area at all

three institutions.

Advanced experimental development

Objectives and program :

Partly to clarify our own thinking, several less structured efforts

are grouped here. Three areas are conspicuous at present: advanced

optical physics, fundamental physics of and using cold neutrons and

advanced x-ray optical technology. The first represents what has

emerged from J. Snyder's long involvement with laser wavelength

problems. The second is the beginning of a new long-term effort,

principally by G. Greene and R. Deslattes, to exploit the new NBS cold

neutron guide hall in the context of a national consortium. The third

simply recognizes that detector development and x-ray optical design

have become a big effort with ties to astronomy, and laser produced

plasmas, as well as to our own interests.

Activities and accomplishments:

Optical Physics

A new project has been started by J. Snyder and R. Bonanno in

collaboration with the Center for Radiation Research (Lucatorto and

Debenham) to develop a novel, ultra-sensitive instrument for isotopic

abundance analysis. This instrument will use a small racetrack

storage ring to multi-pass sample ions through an isotopically

selective process of charge neutralization, laser ionization and

magnetic mass analysis. We (Snyder and Bonanno) have begun a preliminary experiment to measure some relevant cross sections of

krypton, which has rare isotopes useful for geophysical dating and for

environmental monitoring. We hope to complete the preliminary

experiment and begin design and construction of a prototype isotope

analyzer within the next year.

The collaboration with the Physikalisch-Technische Bundesanstalt

(the West German national standards laboratory) continued with a five

week visit by J. Snyder to Braunschweig last spring. The experiment

is investigating the potential of calcium as possible future optical

frequency standard. We have made substantial technical progress, but

have not yet seen a signal from the transversely excited calcium beam.

An acousto-optic/f ibei—optic multiplexing system for the Mossbauerdrive Lambda Meter has been developed and tested.

8
x-ray Optics

After the extended period of beamline optics development, we have

focussed in the past year on spectrometers for registration of

fluorescent spectra. Actually these systems have a strong overlap

with those needed for (and already used in) accelerator experiments on one- and two- electron ions, laser produced plasmas and X-ray

astronomy. Generically these instruments combine focussing crystal

optics with position sensitive-detectors. Development work has

included new work on both the crystal optics and on detectors with an emphasis on the latter.

Crystal optics are all of the Rowland circle Johann type with a total of six "fixed function" instruments now available in several

laboratories. Realization of a wide-range general purpose instrument

is a formidable and awkward engineering development when it is noted

that 2 meter diameter Rowland circles are required to operate under

high- or ultra-high vacuum conditions. One solution implemented this

year for the NSLS work is to use variable crystal curvature to permit

a fixed crystal to detector distance. The required variable radius

design was accomplished by Henins and seems to warrant further

development and application.

Most work concentrated on detectors, which so-far all employ

cathode induction charge division ("Backgammon" detectors). Main

emphasis has been on "second-coordinate" encoding with two avenues

pursued. The first, which has already seen use in the July Heidelberg

experiment, uses charge division of the end signals of a resistive

wire "meander" pattern anode. This leads to coarse resolution in

one-dimension (binning by wires with 1-2 mm spacing) while fine

resolution (0.1 mm) is maintained in the other. A second approach,

devised by Cowan using a complex (graded density x backgammon) cathode

pattern to obtain both coordinates, is still in a preliminary phase.

Production of reliable anode frames has been a difficult technical

problem largely engaged by Luther (1/3) whose experience with fine

fibers in gravitational experiments has been of great value to this

work

.

Neutron Physics

There are a variety of investigations involving measurements on low

energy (cold neutrons) which can be fruitfully attacked using tools

and techniques developed by members of the Quantum Metrology Group.

The prospect of an in-'nouse, cold neutron facility which is proposed

to follow the NBS reactor upgrade has turned our attention (Greene

1/3) to this area of research. This work includes measurements which

have implications in particle physics, nuclear physics, astrophysics

and tests of fundamental symmetries and invariance laws.

9
These opportunities have been pursued in a variety of ways. Two of

us (R.D. Deslattes and G.L. Greene) participated in a workshop on "Scientific Opportunities with Advanced Facilities for Neutron

Scattering" at Shelter Island and one of us (G. L. Greene) has begun

preparing (with the encouragement of the editors of RMP) a major

review article on the properties of the neutron. In order to

determine an optimal program for fundamental physics with cold

neutrons, we have organized (with the Department of Energy and

National Measurement Laboratory support) an International workshop on 14-15 November 1985.

In addition, work on an experiment has begun in collaboration with

Los Alamos National Laboratory to measure the neutron lifetime, a fundamental quantity of considerable importance in nuclear, particle

and astrophysics at the NBS reactor.

FUTURE OUTLOOK

For the most part the near future can be surmised from the activity

summaries given above. In a few cases however, plans are either very

well-developed or a new direction is involved. These are summarized

below. An exception is made in the case of the synchrotron radiation

work at NSLS since at the time of preparing this document we do not

yet know how closely the experimental performance will approach our design goals. This should be clear by the time of the Committee

meeting and results will be given then on specific plans.

Precision Spectroscopy

Following reinstallation of the precision spectrometer at ILL, the

2.2 MeV gamma-ray from H(n,Y)D will be remeasured. Because of the new source tube and better positioning of the spectrometer in the

gamma-ray beam, count rates should improve by a factor of 10. The

improved statistics and the improved angle measuring capability,

suggest that a deuteron binding energy measurement near 0.1 ppm should

be possible. Measurement of high energy capture gamma-rays from the

reactions ”'^N(n,Y) and/or ^^C(n,Y) are planned for the spring of 1986.

Precision measurement of the intense lines from these reactions [4508,

5270, 5299. 5532, 5561, 6323 keV from ^^N(n,Y) and 1262, 3684, and 4946

keV from ^^C(n,Y)] will establish precision standards in a still

higher energy region. The gamipa-ray measurements when combined with

the mass differences ^^n''h 13c1h

2 -^^N^H 2

^H (0.87 ppm) or will permit a determination of the combination of constants N^h/c and

will provide a new value of the fine structure constant a which is

independent of Q.E.D. and solid state theory.

The group has had a long standing interest in precision x-ray

wavelength measurements particularly in the high Z region. E.G Kessler

has been invited to participate in "Precision Measurements of K Series

X-ray Energies, Natural Widths, and Intensities in the Actinide

10
Region" at the ILL. An ILL curved crystal spectrometer will be used

for these measurements. Because exper iraent-theory differences are

large in this region, these measurements have the potential of a significant influence on theoretical understanding of many electron

atoms

.

The long term future of high-Z one- and two-electron ion spectroscopy clearly lies with the coming generation of heavy ion cooler

rings. Ultimately all Z < 100 will become accessible but not for

several years during which there is much that can be learned even within the limitations of current sources. We plan work at two

facilities in the interim: the French nuclear center in Grenoble,

CENG, and the GSI in Darmstadt. At CENG, Geller and collaborators

have established a high performance ECR ion source; we expect to work

in collaborations with J.P. Briand's group (U. Pierre et Marie Curie,

Paris) on He-like spectra from Ne to A. The high beam currents and

low velocities available in this facility are not (to our knowledge)

equalled elsewhere. To move upward in Z so as to improve sensitivity

in regard to QED tests in H-like ions, we propose an acel-str ip-decel

experiment for the UNILAC at GSI using naked Ni. This ion has been

handled efficiently by the UNILAC accelerator and is near the upper Z limit for which there are sufficient radio frequency accelerator

sections beyond those needed for attaining stripping energies to

provide for adequate deceleration. The 1 .5 A spectral region is also

favorable in that we can realistically hope for 0.1 ppm spectroscopy.

Since the total radiative correction is 600 ppm in this case, there is an obvious potential for a sensitive measurement of the Is Lamb shift.

X-Ray Spectroscopy

As this report is being prepared in September, it is difficult to

give a precise listing of the coming year's research program at NSLS.

While a more precise picture should be available by the time the

Committee meets, it is likely that the upcoming work will include:

Threshold excitation of x-ray fluorescence of argon and molecular

gases containing chlorine and sulfur; threshold excitation of electron

spectra from gases (following the winter shutdown of NSLS); resonant

Raman and Rayleigh scattering of x-rays near threshold; and x-ray

excited fluorescence and electron emission of solids and surfaces. In

addition, the beamline monochromator will be tested with large

d-spacing crystals to permit operations at lower energies while other

beamline up-grades will include crystal cooling and pre-monochromator

energy filtering in anticipation of increased power from the source.

A proposal to study the structure of reconstructed Sn layers on Ge

(111) has been submitted to SSRL while diffraction of fluorescence

radiation at glancing take-off angles will be studied, likely at NSLS

and an attempt made to observe x-ray standing waves produced during

total reflection.
Neutron Physics

We intend to continue a vigorous program of activities in the area

of the investigation of fundamental interactions with neutrons. This

work will include further measurements of the neutron lifetime

(proposal is currently under consideration by funding agencies),

design work on the NBS cold neutron facility, feasibility studies for

long (1 m) baseline neutron interferometry, and experiments to study

nucleon-nucleon weak interaction through the investigation of parity

violating effects with polarized neutrons.

Gravitation

After the final adjustments on the new fiber and the apparatus, we hope to complete the measurements on AI2O2 and Si02 so as to

unequivocally decide either in favor of or against Stacey and so as to

obtain the precision needed to answer the conjecture of T. Jacobsen.

We hope to obtain sufficient data to shed light on the derivation of

E. Sternglass.

An improved method for measuring the equivalence or nonequivalence

of the active and passive mass has been devised, the feasibility of

which will be analyzed in detail.

12
INVITED TALKS

Quantum Metrology Group (520.06)

Sean M. Brennan, "Two Dimensional X-ray Scattering," New Directions in

X-ray Scattering Workshop, Asilomar, CA, April 1-5, 1985.

Sean M. Brennan, "Optical and Spectral Characterisitics of an Insertion Device Used Both as a Wiggler and an Undulator," International Synchrotron Radiation & Instrumentation Conference, Stanford

University, Stanford, CA, July 1985.

Paul L. Cowan, "Dynamical Diffraction of Glancing Incidence Diffraction," Universit'e P. et M. Curie, Paris, France, October 8, 1989.

Paul L. Cowan, "Recent Theoretical and Experimental Work on Diffraction of Evanescent X-rays," Lawrence Berkeley Laboratory, Berkeley,

CA, February 12, 1985.

Paul L. Cowan, "Recent Work on Diffraction of Evanescent X-rays,"

Lawrence Livermore Laboratory, Livermore, CA, February 21, 1985.

Paul L. Cowan, "A High Resolution X-ray Spectroscopy Synchrotron

Radiation Beamline for the Energy Range 800 eV," International

Synchrotron Radiation & Instrumentation Conference, Stanford

University, Stanford, CA, July 1985.

Richard D. Deslattes, "New Tales of Lamb’s Shift; How and Why to Dress

a Naked Ion," State University of New York, Stoney Brook, NY; The

University of Connecticut, Storrs, Connecticut, February 13~15, 1985.

Richard D. Deslattes, "Precision Measurements of Is Lamb Shifts in

Hydrogen-like Ions", American Physical Society Meeting, Crystal City,

Va, April 29-27, 1985.

Richard D. Deslattes, "Accurate Spectroscopy of Single-electron and

Single-vacancy Ions," Atomic Theory Workshop, NBS, Gaithersburg, MD,

May 23-29, 1985.

Geoffrey L. Greene, "The Silicon Lattice Spacing, The Neutron Mass and

the Fine Structure Constant," University of Virginia, Charlottesville,

VA, November 30, 1989.

Geoffrey L. Greene, "The Fundamental Properties of the Neutron,"

International Conference on Neutron Scattering, Santa Fe, NM, August

19, 1985.

James J. Snyder, "Ultrasensitive Laser Isotope Analysis of Krypton in an Ion Storage Ring," Argonne National Laboratory, Argonne, IL, March

1985.

13
James J. Snyder, "Resonance Ionization Mass Spectrometry; Applications in Atomic Physics and Analytical Chemistry," William Paterson

College, Department of Chemistry, April 22, 1985.

James J. Snyder, "Ultrasensitive Laser Isotope Analysis of Krypton in an Ion Storage Ring," Univeristy of Bonn, Physics Department;

University of Hamburg, Physics Department; Max-Planck Institut,

Garching, W. Germany, April-May, 1985.

James J. Snyder, "Ultrasensitive Laser Isotope Analysis of Krypton in an Ion Storage Ring," VII International Gonference on Laser Spectroscopy, Hawaii, June 24, 1985.

14
PUBLICATIONS

Quantum Metrology Group (520.06)

IN PRINT:

R.D. Deslattes, "Applications of X-Ray Interferometry," Precision

Measurement and Fundamental Constants II , 303 (198M).

R.D. Deslattes, "Precision X-Ray Wavelength Measurements in Helium-like Argon Recoil Ions," J. Phys. B.: At. Mol. Phys. J_7 L689

(198^0.

B.P. Duval, J. Barth, R.D. Deslattes, A. Henins and G.G. Luther,

"Position-Sensitive X-Ray Detector," Nucl. Inst. & Meth. in Phy. Res.

222 27A (198M).

P.L. Cowan, "Photon Energy Analysis by Reflectivity Modulation," Nucl.

Instr. & Meth. 222 46 (1984).

G.L. Greene, "Trapping of Low Energy Neutrons," Progress in Quantum

Electronics 8, 257 (1984).

B. Heckel, M. Forte, 0. Schaepf, K. Green, G.L. Greene, N.F. Ramsey,

J. Byrne, J.M. Pendlebury, "A Measurement of Parity Non-Conserving

Neutron Spin Rotation in Lanthanum," Phys. Rev. C ^ 2389 (1984).

G. G Luther and W.R. Towler, "Redetermination of the Newtonian

Gravitational Constant "G", Precision Measurement and Fundamental

Constants II , 573 (1984).

R.C.C. Perera and R.E. LaVilla, "Molecular X-ray Spectra: S-K6

Emission and K Absorption Spectra of SCO and CSp," J. Chem. Phys. ^

3375 (1984).

M.B. Morris, T.J. Mcllrath and J.J. Snyder, "Fizeau Wavemeter for

Pulsed Laser Wavelength Measurement," Applied Optics ^ 3862 (1984).

H. F. Beyer, R.D. Deslattes, F. Folkmann and R.E. LaVilla, "Determination of the Is Lamb Shift in One-Electron Argon Recoil Ions," J. Phys.

B Atom. Mol. Phys. ^8 207 (1985).

R. Bonanno, J.D. Fassett, T.B. Lucatorto, J.J. Snyder, and C.W. Clark,

"Multiphoton Excitation of Autoionlzing States of Mg," Bulletin of Am.

Phys. Soc. 30 851 (1985).

15
R. Bonanno, J.D. Fassett, T.B. Lucatorto, J.J. Snyder, and C.W. Clark,

"Stepwise Multiphoton Excitation of Autoionizing Rydberg Series in

Mg," in Electronic and Atomic Collisions abstracts of Contributed

Papers of the I4th International Conference on the Physics of

Electronic and Atomic Collisions, Palo Alto, Ca, M.D. Coggiola, et

al., (eds) p.69 (1985).

S. Brennan, "Two Dimensional X-ray Scattering," Surf. Sci. ^ 1153

(1985).

P.L. Cowan, "Dynamical Theory of Evanescent X-ray Diffraction

Stimulated by Glancing Incidence X-rays," Bull. Am. Phys. Soc. 30 310

(1985).

R.D. Deslattes, "Fundamental and Incidental Limits on the Spectroscopy

of Single Electron Ions", Nucl. Instr. & Meth. in Phy. Res. ^ 668

(1985)

.

R.D. Deslattes, R. Schuch, E. Justiniano, "Application of Decelerated

Bare Nuclei to Precision Spectroscopy of One-Electron Ions," Phy. Rev.

A, Rapid Communication ^ 1911 ( 1985 ).

G.L. Greene, E.G. Kessler, R.D. Deslattes, H. Borner, "Accurate

Determination of Gamma-Ray Energies for E ^ 2 MeV," in Capture

Gamma-Ray Spectroscopy and Related Topics ed. S. Raman, A.I.P.

Conference Series (1985).

T. Jach, S. Brennan, P.L. Cowan, "Observation of Dynamical X-ray

Diffraction from A Crystal Surface a Glancing Incidence," Bull. Am.

Phys. Soc. ^ 31 1 (1985)

.

E.G. Kessler, Jr., G.L. Greene, and R.D. Deslattes, "Gamma-ray

Energies from the Reaction ^^C1(N,Y)," Phy. Rev. C ^2 374 (1985).

R. C.C. Perera, J. Barth, R.E. LaVilla, R.D. Deslattes, A. Henins,

"Multi vacancy Effects in the X-ray Spectra of CHoGl," Phys. Rev. A 3£

1489 (1985).

J.J. Snyder, T.B. Lucatorto, P.H. Debenham, R.E. Bonanno, and C.W.

Clark "Ultrasensitive Laser Isotope Analysis of Krypton in an Ion

Storage Ring," in Laser Spectroscopy VII , Proceedings of the Seventh

International Conference (Springer-Verlag, 1985).

IN PRESS, IN REVIEW, OR NEARING COMPLETION:

S. Brennan, P.L. Cowan, T. Jach, R. Lavilla, R. Perera and H. Winick,

"Optical and Spectral Characteristics of an Insertion Device Used as Both a Wiggler and an Undulator," Nucl. Instrum, and Meth. (in press).

16
S. Brennan, P.H. Fuoss and P. Eisenberger, "X-ray Crystallographic

Studies of Pb Monolayers on Cu (110) Surfaces," Phys. Rev. B., (in

press)

.

S. Brennan, P.H. Fuoss and P. Eisenberger, "X-ray Scattering Studies:

The Structure and Melting of Pb on Cu (110) Surfaces," Proceedings of

the First International Conference on the Structure of Surfaces, (in

press)

.

P.L. Cowan, "A New Two-Dimensional Position Sensitive Proportional

Counter," Nucl. Instrum, and Meth. (in press).

P.L. Cowan, "Diffraction of Evanescent X-rays: Results from a Dynamical Theory," Phys. Rev. B _32 ( in press).

P.L. Cowan, S. Brennan, R.D. Deslattes, A. Henins, T. Jach and E.G.

Kessler, "A High Energy Resolution X-ray Spectroscopy Synchrotron

Radiation Beamline for the Energy Range 800 eV to 5000 eV," Nucl.

Instrum, and Meth. (in press).

P.L. Cowan, S. Brennan, T. Jach, M. Bedzyk and G. Materlik,

"Observation of the Diffraction of Evanescent X-ray at a Grystal

Surface," Phys. Rev. Lett, (in preparation).

R.D. Deslattes, "Accurate Spectroscopy of Single-electron and

Single-vacancy Ions," Proceedings of Atomic Theory Workshop, Am. Inst.

Phy. ( in press)

.

R.D. Deslattes, E.G. Kessler, Jr., "Experimental Evaluation of

Inner-Vacancy Level Energies and Comparison with Theory," in Atomic

Inner-Shell Physics Crasemann (ed.) (in press).

P.H. Fuoss, S. Brennan and P. Eisenberger, "Melting of Pb on Cu (110)

Studied with Grazing Incidence X-ray Scattering," Submitted to Phys.

Rev.

G.L. Greene "The Fundamental Properties of the Neutron," Physica B (in

press)

.

G.L. Greene, R.D. Deslattes, E.G. Kessler, Jr., and H. Borner, "A New

Determination of the Deuteron Binding Energy and the Neutron Mass,"

( in preparation)

.

G.G Luther, P.L. Cowan, A. Henins and S. Brennan, "New Two Dimensional

Position Sensitive Proportional Detectors Using Charge Division,"

Nuclear Instrum, and Meth. (in press).

E.S. Marmar, J.E. Rice, E. Kallne, J. Kallne and R.E. LaVilla,

"Precision Measurement of the Is Lamb Shift in Hydrogen-like Argon,"

Phys. Rev. A (in press).

17
J. Snyder, T.B. Lucatorto, P.H. Debenham, S. Geltman, "Ultra-Sensitive

Isotope Analysis by Laser Selective Multi-Stage Ion Acceleration," J.

Opt. Soc. Am. B (in press).

18
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Metrology Group (520.06)

S. Brennan, 6-GeV Ring Planning Group.

P.L. Cowan, European Synchrotron Radiation Project Beamline Instrumentation Study Group; Executive Committee, National synchrotron Light

Source Association of Users; National synchrotron Light Source

Instrumentation committee; Organizing Committee, Advanced Light source

workshop.

R.D. Deslattes, Vice Chairman, The American Physical Society, Division

of Electron and Atomic Physics.

J. J. Snyder, Co-editor of feature issue of the Journal of Optical

Society B, on the subject "Ultra-Sensitive Laser Spectroscopy."

J. J. Snyder, Editor of Academic Press book on the subject of "Laser

Characterization and Control."

19
TRIPS SPONSORED BY OTHERS

Quantum Metrology Group (520.06)

Sean Brennan; Was invited by the Tokyo Institute of Technology in

Tokyo, Japan during the month of October 1985 to discuss and lecture

on the subject of the NBS beamline at the National Synchrotron Light

Source with researchers at the Photon Factory.

Paul Cowan; Was invited by the European Synchrotron Radiation Facility

(ESRF) of Ispra, Italy (October 3~5, 1984) to be a member of the

European Synchrotron Research Project (ESRP) Beamline Study Group,

which has proposed a number of beamlines for the ESRF facility.

20
TECHNICAL ACTIVITIES

ELECTRICITY DIVISION

FISCAL YEAR 1985

Overview

The Electricity Division (ED) concerns itself with the fundamental

electrical quantities such as current, voltage, and impedance at dc and

low frequencies (to roughly 100 kHz) over many orders of magnitude and

at the highest possible levels of accuracy. Its primary mission is to

provide the central basis for a reliable and consistent system of

electrical measurement throughout the U.S., including the Nation's

scientific and defense communities as well as industry and commerce;

and to ensure that the U.S. system is consistent with those of other

countries and the internationally accepted system (i.e., the

International System of Units or SI).

The justification for all of the ED's work comes directly from the

Bureau's Organic Act, as amended, and is in its prime mission areas,

that is, the areas of responsibility for which the Bureau was originally founded in 1901. The major technical problems which benefit from

the ED'S work include fundamental physical theory; high

technology-based R&D; electrical power revenue metering, transmission,

and distribution; industrial process control; quality control in the

manufacture of electronic components and products; testing and

maintenance of electronic systems, which includes the civilian side of

defense and aerospace; and national defense requirements directly under

the Department of Defense. End user groups include scientists in

universities; electric power utilities, both public and private;

electric equipment manufacturers; process engineers who design, build,

and use industrial process control systems; manufacturers of electronic

components and consumer products; high technology civilian companies

and government agencies involved with communications, computers,

aerospace, transportation, health, and defense; and finally the armed

services

.

It is probably not an overstatement to say that the Nation's

electric power system, the cost-effective manufacture of reliable

consumer goods, the economic production of industrial materials, a viable national defense, and R&D at the cutting edge of science and

technology, would not be possible without adequate electrical

measurements; and that the basis for all such measurements within the

U.S. is the fundamental electrical units the ED maintains and

disseminates through its various services; the measurement methods and

instrumentation it develops; and the tests and calibrations of standards and instruments it performs. For example, each year well over

one thousand calibrations are carried out on primary electrical

standards of voltage, resistance, capacitance, inductance, and ac-dc

difference (i.e., thermal ac/dc voltage and current converters) that

21
belong to some of the Nation’s most important corporations, utilities,

universities and government organizations, including Hewlett-Packard,

General Motors, IBM, General Electric, Pacific Gas and Electric,

American Electric Power, Boeing, TRW, the TVA, the FAA, and the DoD.

These standards are used in turn to calibrate and otherwise support a wide range of work-horse electrical measuring instruments and systems

numbering literally in the tens of thousands, such as digital

voltmeters (DVMs), programmable voltage and current sources,

analog-to-digital and digital-to-analog converters,

resistance/inductance/capacitance (RLC) meters, impedance bridges,

electrometers, oscilloscopes, data recorders, component and printed

circuit board testers, automatic test equipment (ATE), including ATE

for weapons systems, etc. Without reliable measurement results from

such equipment, a technologically sophisticated society like that of

the U.S. could not even exist, let alone advance.

To fulfill its main responsibility of providing the central basis

for the U.S. electrical measurement system, the ED carries out work in

eight distinct but related areas with the following objectives:

1 . Realize the SI definitions of basic electrical measurement

units such as the ampere, volt, ohm, and farad, thereby ensuring that

the U.S. legal electrical units are consistent with the internationally

accepted system.

2. Develop and maintain U.S. Legal or National Reference Standards

for the basic electrical units and related quantities, thus providing a central basis for the U.S. system of electrical measurement.

3. Disseminate the basic electrical measurements units to users within the U.S. via a variety of measurement and calibration services,

and develop new means for doing so, thereby ensuring the traceability

of electrical measurements made throughout the country to National

Reference Standards.

4. Develop new methodologies and the required instrumentation and

standards which will lead to advances in the state-of-the-art of

electrical measurement, thus ensuring the availability to the technical

community of adequate measurement techniques.

5. Determine fundamental physical constants closely related to the

electrical units in order to provide the scientific community the means

to test basic physical theory.

6. Initiate and participate in international comparisons of the

basic electrical units, thus ensuring that the U.S. system of electrical measurement is consistent with those of other countries.

22
7. Participate in voluntary national and international

standardizing activities related to the electrical units, and the

fundamental physical constants, in order to foster international

compatibility of electrical measurements, eliminate and prevent

non-tariff barriers to trade, and contribute to internationally

acceptable data compilations.

8. Provide training for personnel active in the field of electrical measurements and standards, including the presentation of seminars

and workshops, and the generation of tutorial written material, thereby

elevating the overall level of competence in the field.

The objectives, current activities, FY 85 accomplishments, and

future plans of the various projects underway within the ED which

contribute to these principal areas are described in detail in the

following Project Reports. Highlights, categorized according to these

eight principal areas of work, include:

1 . Realize SI Units . Work actively continued to determine the

ratio of the NBS as-maintained ampere to the SI ampere (or

equivalently, the value of the Josephson frequency-voltage ratio 2e/h

in SI units) to an eventual accuracy of 0.1 ppm by equating electrical

to mechanical work. Extensive measurements with the new NBS

room-temperature ampere balance revealed a number of problems, most of

which have been solved. A value for the ratio accurate to 1 ppm or better should be obtained in FY 86. The redetermination of the NBS

as-maintained farad and ohm in terms of their respective SI units via

the NBS calculable cross capacitor also progressed well during the year

and a tie between the NBS bank of 10 pF capacitors and 1 resistors

used to define and maintain the NBS farad and ohm, respectively, was completed with an accuracy of 0.05 ppm. The interferometry required to use the calculable capacitor to measure the 10 pF bank itself was essentially completed and a sub-0.1 ppm determination should be

available by the end of FY 86.

2. Develop and Maintain U.S. Reference Standards . Monitoring of

the U.S. legal unit of resistance using the quantized Hall resistance

(QHR) continued and for the first time the decrease of the unit with

time (-0.05 ppm/year) was directly measured. Additionally, a new QHR

laboratory was designed, all the necessary equipment ordered (e.g., a new 15 T magnet), and its construction initiated. When completed, it

will give NBS a truly unique QHR research and measurement capability.

The collaborative effort with NBS/Boulder on the development of a Josephson array voltage standard at the 1 V level was initiated and

excellent progress was made. Equipment is now being set up at

NBS/Gaithersburg to compare an array voltage standard with the

Josephson apparatus currently used to maintain the U.S. Legal Volt and

to replace the latter with an array.

23
3. Dissemination . Although the workload this year was unusally

heavy, electrical calibration services including MAPs were generally

provided in a timely way and without serious problems. Nearly 1400

calibrations of basic standards were performed along with 24 MAP

transfers. The turnaround time decreased slightly or remained stable

in most areas but plummeted in the ac-dc difference area due to

improved operating procedures and increased use of a new automated

system. The automation of the Volt Facility moved rapidly ahead and

all measurements are now being done automatically. A new calibration

services computer (VAX 750) was ordered, received, and installed. Most

of the existing software has been converted to run on the machine and

all will be so converted by the end of FY 86. A new calibration

service for conductivity standards used in eddy current non-destructive

evaluation was formally initiated during the year.

4. New Methods, Instruments, and Standards . The dual-channel

automated electronic comparator developed for determining the ac-dc

differences of thermal converters by simultaneously measuring the

difference in converter output when nearly equal ac and dc voltages are applied to both test and standard converters was completed and incorporated into the converter calibration service for routine use. A second system is under construction. The fully automated, high

accuracy (0.01 ppm) resistance bridge for measuring quantized Hall

resistances was put into routine operation. Two cryogenic current

comparator resistance bridges for scaling between different resistance

levels with accuracies approaching 0.01 ppm were constructed and

initially tested. Some operational experience was obtained with

commercial 10 V solid-state standards as MAP transfer standards. Their

promise is considerable and based on this work one can expect a 10 V

MAP in the not too distant future and the eventual replacement of

saturated standard cells by solid-state standards, both at the 1 and

10 V levels and for both laboratory and transport standards.

5. Fundamental Constants . Since the quantum Hall effect can also

be used to determine the fine-structure constant a, the work described

above under 1 . and 2. relating to the realization of the SI ohm and

determining the quantized Hall resistance directly impacts the

determination of a via the Hall effect. Also as noted above, determining the ratio of the NBS ampere to the SI ampere is equivalent to

measuring 2e/h in SI units. An extensive analysis of previously

reported NBS fundamental constant experiments was completed and

accurate values in SI units for N^, R^, 2e/h, a, and F derived. Two

new Precision Measurement Grants were awarded, one to handle, cool, and

store antiprotons, the other to search for the electric dipole moment

of the electron. The project to laser-cool and store neutral atoms

made excellent progress during the year. A beam of Na atoms was stopped and trapped in a magnetic trap, and the results reported in two

Physical Review Letters.
6. International Comparisons . An international comparison of

conductivity standards for eddy current non-destructive evaluation was carried out with the National Physical Laboratory, U.K. Upon completion of the data analysis, a joint NBS-NPL report will be issued. A comparison of the U.S. and U.K. as-maintained unit of resistance using

a NPL 1 n resistance transfer standard was also carried out. An

international comparison of the as-maintained unit of capacitance of

East Germany, West Germany, England, France, The Netherlands, and the

International Bureau of Weights and Measures (BIPM) was completed under

the auspices of BIPM using the three NBS traveling fused silica 10 pF

capacitors.

7. Standardization . In September 1986 the Consultative Committee

on Electricity (CCE) plans to meet to consider the international

adoption of (1) a new value of 2e/h consistent with the SI for volt

maintenance purposes via the Josephson effect, and (2) a value of the

quantized Hall resistance consistent with the SI for ohm maintenance

purposes via the quantum Hall effect. In preparation for the CCE

meeting, extensive information was gathered within the U.S. on the

potential impact a change in the U.S. Legal Volt of 9 ppm and a change

in the U.S. Legal Ohm of 1.5 ppm would have on government and industry

operations. (Such changes in the U.S. legal units would occur if the

CCE adopted values consistent with the SI.) The consensus seems to be

that the international uniformity of the national practical electrical

units and having them consistent with the SI is a worthy goal and worth

the cost of implementing the changes. Draft statements of the

equivalency of the U.S. and Italian, and U.S. and Australian, practical

or as-maintained units for voltage, resistance, and capacitance were prepared and should be formally adopted in FY 86.

8. Training . In collaboration with the National Conference of

Standards Laboratories, two very well attended and received one week

courses entitled "Workshop on Electrical Measurement Assurance Programs" were given, one in Seattle WA and the other in Williamsburg VA.

During the year, a number of foreign Guest Workers were trained in

various aspects of electrical metrology, as were a number of students

including three from the metrology program at Butler Community College

outside Pittsburgh PA. There were many shorter visits (i.e., one day

to one week) by metrologists from U.S. and foreign government and

industrial standards laborator ies . The Division staff published over

25 scientific papers during the year and gave numerous presentations.

In summary, the Electricity Division has once again met its

principal electrical unit maintenance and dissemination responsibilities and at the same time made good progress on a number of important

research projects. This should continue in FY 86.

25
DISSEMINATION SERVICES: SUPPORT AND OPERATION

(N. B. Belecki, P. A. Boynton, C. B. Childers, R. F. Dziuba,

B. F. Field, G. M. Free, R. C. Fronk, J. R. Hastings,

F. L. Hermach (GW), G. R. Jones, Jr., T. E. Kiess, J. R. Kinard,

L. H. Lee, C. R. Levy, T. E. Lipe, Jr., R. E. Long,

T. P. Moore, A. Muciek (GW), E. S. Nowicki, D. D. Prather,

J. E. Sims, S. B. Tillet, A. R. Wise, E. Zdral (PSC))

Objectives

The overall objective of this project is to enable all

measurements of electrical quantities performed in the United States to

be made in terms of the U.S. legal electrical units at the required

levels of accuracy. The legal units are provided to the user community

via reimbursable calibration and MAP (measurement assurance program)

services listed in NBS Special Publication 250 and its appendices. The

timeliness and adequacy of these services must be ensured by research

and development work on new measurement techniques, standards, and

apparatus, since the quality of both MAP and calibration services

ultimately depends on the basic metrology competence of the NBS.

The outputs of this project are used directly by the metrology

community - the major standards laboratories of industry, government,

and the academic community - and indirectly through them by industry

for the quality control and maintenance of electronic products, for the

control of manufacturing processes in basic industry, for the support

of research and development aimed at the improvement of instrumentation

and in response to Federal and state regulatory requirements, such as those for traceability of voltage measurements used for the establishment of local power and energy standards and watt-hour meter testing by

power companies. In large measure, the pre-eminence of the U.S. in

high-technology areas, such as electronics, avionics, communications,

aircraft, and space vehicles, has been made possible by our country's

sophisticated measurement capability, reflected in automatic test

equipment (ATE) systems and high-quality electronic instrumentation.

Likewise, advances and progress in these areas have been rapid because

they have not been limited by measurement constraints, such as the

nonavailability of electrical instruments of adequate accuracy. This

condition can only occur if NBS maintains a strong R&D program to ensure the availability of adequate electrical standards for the

instrumentation industry.

Current Activities

The measurement services offered by NBS in the electrical area

include the calibration of primary standards of alternating current and

voltage, impedance at audio frequencies, direct (dc) voltage, and dc

resistance, as well as MAP services for capacitance, dc voltage, and dc

resistance. Some measurements are also done on ac ratio standards of

the highest accuracy. In FY 85, 24 MAP transfers and approximately

26
1398 calibrations of basic standards were performed, as detailed at the

end of this project description, for a total income of about $750 k for

the year.

During the past year the turnaround time has decreased slightly or remained stable in most areas. A noteworthy exception is the ac-dc

difference area, where the turnaround time plummeted to an average of

38 days in the second half of the FY from an average running well over

100 days in the first half. While scheduling and the queue awaiting

calibrations have not yet been eliminated, the waiting time for

individual calibrations has been shortened considerably. The improvement was caused by changes in operating procedures and increased use of

the automated system for calibration work. Elimination of the queue is

a goal for the next two years.

The majority of NBS calibration clientele is represented by the

National Conference of Standards Laboratories (NCSL), which is a major

source of information for planning future calibration activities, as well as a mechanism (through its technical committees) for disseminating NBS electrical metrology information. This past year saw extensive

interaction between the Division management and the NCSL through its

Measurement Requirements Committee and interactions at regional

meetings. The military and its defense systems contractors and the

instrumentation community are the heaviest users of electrical calibration services and it is from them that the most stringent

measurement requirements arise. We continue to maintain close ties

with the DoD via the Calibration Coordination Group (CCG) technical

subcommittees and much of the work to be described below was partially

funded by them.

Measurement services support activities fall into three broad

categories: (1) the documentation of measurement services, (2) the

development of improved measurement methods and standards, and (3) the

automation of the measurement systems used to perform both regular and

MAP calibrations.

A Division-wide effort to document all of the calibration services

according to guidelines promulgated by the NBS Calibration Advisory

Group is well under way. The guidelines require a description of the

services offered, an exposition of the theory and rationale behind the

measurement systems used, a complete analysis of the measurement

uncertainties, and detailed, written operating procedures. Despite

major changes in measurement systems in the impedance, resistance, and

ac and dc voltage areas (requiring completely new procedures and error

analyses), this work will be completed by the middle of FY 86, well in

time for meeting NBS deadlines.

Work in the second category is directed toward improvement of the

processes by which the electrical units are maintained, scaled, and

disseminated. In the ac~dc difference area, which supports ac current

and voltage measurements, the thrust of the work is to enhance the

accuracy available by investigating new and adding improved standards

27
to the set which now provides the basis for all calibrations. In the

impedance area, aged bridges are being replaced with new bridges that

take advantage of modern electronics. The thrust in the resistance

area is to improve scaling from the national standards at 1 Q, to 1 kn

and 6^53.2 for the absolute ohm and quantized Hall effect experiments

respectively, in time for NBS to contribute to a possible international

adjustment of the ohm in late 1986. Both cryogenic current-comparators

and Haraon devices are being employed in this effort. In the voltage

area, emphasis is being placed on improved dissemination, mainly

through the use of solid-state standards based on Zener diodes.

In the automation or third category, several of the hardware

systems have been completed; future activities are aimed at the

construction of complex software systems to collect and analyze

calibration data. Such activities are particularly heavy in the ac~dc

difference and voltage areas. The resistance automation activity has

been reduced in priority this year to increase the effort devoted to

scaling work in preparation for the change in the ohm mentioned above.

ACCOMPLISHMENTS

AC Current and Voltage

(J. R. Kinard, C. B. Childers, J. R. Hastings, F. L. Hermach (GW),

T. E. Lipe, Jr.)

Construction of the second automated system (System II) for ac-dc

difference calibrations has been completed. A block diagram of the

system is given in Fig. 1 . Its voltage and frequency ranges are indicated in Fig. 2 with the corresponding ranges of the manual system

given for comparison. Preliminary testing has begun using software

derived from System I, the existing system. System I is described in an article published in the June, 1985 issue of the IEEE Transactions

on Instrumentation and Measurement.

DUAL CHANNEL COMPARATOR

Fi gure 1 .

23
1000V

u

(J

z

cr

Ql

u

o

a:H

_JO

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100V

10V

IV

IV

10 100 Ik 10k

FREQUENCY (Hz)

100k ir

NBS MRNURL SYSTEM MBS RUTOMRTED SYSTEM

REGION OF LERST UNCERTRINTY OF RUTOMRTED SYSTEM

FIGURE 2.

In a further effort to facilitate ac-dc difference calibrations,

an additional commercially-manufactured, coaxial, single-range, thermal

voltage converter set has been obtained and delivery of a second new

set is expected shortly. When they are fully characterized, the new

converter sets will give us the capability for independent, parallel

operation of at least two, and perhaps three, calibration consoles.

A bilateral, international intercompari son of single junction

thermoelements at 100 Hz, 320 Hz, and 1 kHz for 5 mA has been initiated

with the National Measurement Laboratory (NML) of Australia. Stimulated

by work done at the NML by Dr. B. L. Inglis to determine ac-dc

differences at very low to zero current levels, the interchange of

thermoelements is expected to resolve differences between measurements

based on multi junction and single junction thermoelement standards.

In a related area, specially-constructed thermoelements of NBS

design intended to minimize thermoelectric errors have been ordered.

The new thermoelements will be studied to determine if their construction pattern - using thermal shunts or bridges at the heater support

junctions, Evanohm supports and heaters, and platinum leads - will

produce nearly zero ac-dc differences.

Two additional multi junction thermal converters (MJTC's) were obtained to be incorporated into the group making up the NBS primary

standards for ac-dc difference. Intercomparisons between one of the new MJTC’s, the existing NBS primary group, and the NBS reference set

29
indicate agreement to within 1 ppm from 20 Hz to 100 kHz. The agreement is particularly gratifying because the new MJTC's came from a source of manufacture not previously represented in the NBS primary

group. This work has been heavily augmented through the efforts of F.

L. Hermach (retired) who made many of the intercomparison measurements

and provided technical guidance.

Two examples of an entirely new multirange instrument

incorporating solid-state thermoelements were extensively tested.

Generally encouraging results were obtained from these prototype

commercial instruments in the range from less than 1 V to 1 kV and from

100 Hz to 1 MHz. The new instruments contain improvements over previous solid-state converter systems, but also have certain problems

requiring further study. The results have been conveyed to the Navy

Metrology Engineering Center, who sponsored the work, and to the

manufacturer, with whom liaison is being maintained.

By special prior arrangement, the reduced uncertainty of 10 ppm

for calibrations in the range of 5 to 100 V from 100 Hz to 20 kHz is

being offered to Department of Defense primary laboratories and

manufacturers of thermal transfer standards. A further special

service, offered to DoD primary laboratories only, features 5 ppm

uncertainties for measurements at 5 and 10 V over the above frequency

range. The new service involves direct comparisons with a member of

the NBS primary multi junction converter group. Calibration uncertainties at these low values require evaluation of the stability of the

converters being calibrated over several months, with a considerably

extended set of measurements being made.

Direct (DC) Voltage

(B. F. Field, T. E. Kiess, R. L. Long, J. E. Sims)

Automation of the Volt Facility is nearly complete. Two new"

automated systems for the intercomparison of standard cells have been

completed and their control software written and tested. One of the

two is in regular use making the measurements required for the operation of the Volt Transfer Program, the Division's MAP service for dc

voltage. The other, a replacement for the manual system used to measure customers' standard cell enclosures sent to NBS for calibration, is currently under test. A system of data file formats,

management and backup procedures, and computer programs to implement

necessary data-base management functions for both technical and

administrative data has been developed and is nearly fully written.

New quality control procedures for ensuring the integrity of the

measurements in the Volt Facility have been developed and implemented.

Included are both hardware and software to permit the evaluation of

both the measurement instrumentation and the working reference

standards on a daily, automatic basis. A new automated crossbar

controller has been designed and built to permit the automatic

intercomparison of primary, secondary, and working standards to

increase and enhance the information available on the performance of

these standards. The above developments have been fully documented.

30
Three commercially-available, 10 V, Zener-based voltage standards

were tested for the effects of temperature shock and power cycling on their transportability. Two of the units exhibited excellent reproducibility when subjected to a power outage and subsequent 30 C temperature change. They typically returned to their original values

to within 0.02 ppm and 0.06 ppm respectively (see Fig. 1). The other,

however, was not reproducible when power was interrupted for two days,

a common duration for shipment even by air freight. This unit also

jumped unpredictably by as much as 2^ppm when subjected to a rapid

temperature change from 23 C to 10 C.

Fig. 1 Plot of the voltage of two solid-state standards. The standards were turned off between each of the points.

Each plotted point is the mean of from 4 to 64 measurements. The error bars represent a 1 o estimate of the random uncertainty of the plotted point.

A 10 V experimental MAP transfer to the Navy Primary Standards

Laboratory in San Diego was completed. The two reproducible standards

mentioned above were shipped off power to the laboratory in two

separate experiments, one in April 1985 and the other in June. The NBS

units were compared to two commercial Navy 10 V standards using a switch box constructed by NBS. The difference between the NBS volt and

the Navy volt at 10V as defined by their two standards was found to be

0.65 ppm and 0.84 ppm in April and June respectively. This is consistent with the drift of about 1 ppm/year observed in a number of other

commercial units of the type used by the Navy as calibrated by NBS. The

two NBS standards maintained good agreement for both transfers. The

difference between the Navy volt and NBS volt determined from each of

the two NBS standards agreed to within 0.02 ppm for the first transfer

and 0.07 ppm for the second.

31
As a follow up to the Navy MAP transfer, a 10 V round-robin

transfer involving all of the DoD primary standards laboratories has

been started. The two NBS standards and one similar Army standard are being sent as a group to each of the DoD primary laboratories in turn,

with NBS calibrations at the beginning and end of the transfer. The

two NBS units are being shipped off power and the Army unit is being

shipped under battery power. The experiment has been designed to

determine the ability of each of the laboratories to make accurate 10 V

measurements as well as to evaluate the transport characteristics of

the Zener-based standards.

Precision component Zener diodes are continuously being evaluated

for suitability to be incorporated in an NBS 10 V transport standard. A

total of 200 devices have been obtained from five manufacturers and a station has been designed and built to permit the rapid testing of

devices for temperature coefficient and sensitivity to temperature

shock and power cycling. Computer programs to collect and analyze the

data automatically have been written. Eleven devices have been tested

to date for their dependence on current, temperature, and power

cycling. Based on the data, a model has been developed which partially

predicts their behavior. All necessary components (transformers,

resistors, dividers, etc.) required for building several prototype 10 V

transport standards have been ordered and it remains only to identify

suitable references for incorporation before they can be built. Several

commercial resistive dividers have also been ordered. They are intended to be used in conjunction with 10 V standards to produce

1.018 V as a possible replacement for standard cells as transport

standards. Upon their arrival, they will be tested for stability and

their sensitivity to temperature changes.

The fourth and fifth in a series of seminars on MAP’s for

electrical quantities were held in Seattle, Washington during the week

of October 20, 1984 and in Williamsburg, Virginia, during the week of

March 23, 1985. The forty attendees in each workshop participated in

five days of lectures and workshops covering statistics, voltage

metrology, quality-control techniques, and NBS MAP procedures. The

instructors for the seminars were W. G. Eicke (now retired) , M. C. Croarkin (CAM), D. Vecchia (CAM), N. B. Belecki, and A. 0. McCoubrey

(CBS), who also was responsible for logistics and administrative

support

.

Impedance

(G. M. Free, R. C. Fronk, G. R. Jones, Jr., L. Lee, C. R. Levy, S. B.

Tillet, E. Zdral (PSC))

The automatic capacitance bridges being built following a design

by R. D. Cutkosky are well underway. These bridges make threeterminal measurements comparing each of up to sixteen standard capacitors in the range from 12 pF to 1200 pF with an internal 10 pF

fused-silica dielectric capacitor at selectable audio frequencies. They

are intended as research tools and to replace the Division's Type 2

bridge, dating from the 1950' s, used for the calibration of fused-silica

and gas dielectric standards. The bridges are controlled internally by

32
a model 8085 microprocessor and can be commanded from software in a desktop computer or calculator via the IEEE 488 Standard

Instrumentation Interface. Good progress in the construction of four

bridges was made under contract, and circuit boards and transformers

for additional bridges were built by two summer Butler Community

College students. Electronics modules that can be tested outside of a completed bridge were examined to ensure that they were in good working

order and functional checks were made on transformers. The final

assembly of the first bridge has begun and will be completed in early

FY 86. Technical guidance and assistance is being provided by L. Lee

who was instrumental in the development, construction, and testing of

the original prototype bridge.

The new inductance bridge designed to replace the Maxwell-Wien

bridge (circa 1955) currently used to calibrate standard inductors has

been completed and is being calibrated. The ground circuit of the

bridge has been redesigned so that all adjustments to parameters can be

made using on-off switches to program DAC's ( digital-to-analogconverter) so that eventual automation of the bridge will be relatively

simple. A binary inductive voltage divider (IVD), whose design permits

self-calibration (with the use of an external pair of matched capacitors), has been designed by N. M. Oldham of the Electrosystems Division

and constructed for incorporation in this bridge circuit to facilitate

automation of the balancing procedure. Initial comparisons of the

binary divider with the three-winding, two-stage transformer used for

inductive voltage divider calibrations indicate ratio errors as small

or smaller than those commonly seen in commercial IVD's and quadrature

errors an order of magnitude smaller.

A new calibration service for eddy-current conductivity standards

was announced in the April 1985 issue of the SP 250 Appendix. Two sets

have been calibrated to date and the actual operating procedures for

making these calibrations a routine service are being worked out. The

measurements required for issui'ng SRM 2408 (a pure copper eddy-current

conductivity standard) were nearly completed by the end of FY 85.

An international comparison of eddy current conductivity standards

was carried out with the National Physical Laboratory (NPL) of the

U. K. ending in February 1985. At that time a set of NPL standards,

hand-carried to NBS by A. E. Drake of NPL, was compared to a similar

set using NBS apparatus. The NBS standards ranged from 29^ to 61% lACS

(International Annealed Copper Standard)

.

An investigation of the temperature-cycling properties of gas

dielectric standard capacitors has been nearly finished. The results

indicate that the instability problems with the capacitance MAP

standard that led to the curtailment of the service were due to a combination of exposure of the standard to extremes of temperature and

mechanical stress on the capacitors themselves. An experiment to

determine the feasibility of using temperature controlled fused-silica

capacitors at 10 pF and 100 pF for a MAP service at 1000 pF is nearly

complete. At issue here is the capability of existing customer

instrumentation to make the required ten-to-one ratio measurements with

sufficient accuracy to be useful; the capacitors have been long known

33
to be excellent transport standards. In the experiment, a commercial

bridge of the type used by typical MAP customers is being used to

calibrate 1000 pF NBS standards in terms of a pair of fused silica

standards. The two standards are first used to establish an accurate

10/1 ratio and then the 100 pF standard is used to calibrate the

1000 pF units. A potential problem with the quadrature balance in the

commercial bridge may force the use of auxiliary balancing networks

which NBS would have to supply for the transfer. Final results of the

investigation are expected by the end of 1985.

DC Resistance

(R. F. Dziuba, P. A. Boynton, T. P. Moore, E. S. Nowicki)

An automated, self-balancing cryogenic current comparator resistance bridge was designed and constructed with the help of Joji

Kinoshita, a guest worker from the Electro Technical Laboratory, the

national electrical metrology laboratory of Japan. Preliminary

resistance ratio measurements of 100 J2/100 10000 fi/100 and 6453.2

fJ/100 n have been completed. The random uncertainty of the

measurements is on the order of 0.02 ppm.

Two special resistance boxes were constructed in support of the

NBS absolute ampere experiment (see Realization of the SI Ampere)

.

These provide a highly accurate resistance ratio that will be used to

determine the ratio of two currents in the experiment. The resistance

boxes were calibrated against the NBS 1 reference bank via a 100:1

Hamon standard.

Two special in-house resistance transfers were completed. One

transfer involved the scaling down in resistance from the 1000-ohm

transport standard used in the absolute ohm experiment (see Realization

of t,he SI Farad and Ohm) to the NBS 1 Q reference bank. The other

transfer involved measuring a 6453.2 Q transport standard used in the

quantized Hall resistance experiment (see Quantized Hall Resistance)

against the 1 Q reference bank. Both methods utilized specially-built

Hamon standards. The uncertainty was estimated to be 0.044 ppm, one standard deviation.

A new dc current-comparator potentiometer was modified and put

into operation as the basis of the 100 Q automated measurement system.

This system is now operating on a routine basis for the calibration of

customer's 100 Q standards.

The high accuracy system used for the calibration of the best

10 kfi standard resistors was relocated and improvements made in the

system. A temperature lagging box was constructed to minimize the

effects of temperature on air-type standard and control resistors. A connector panel was constructed to provide more ready connection of

test resistors to the measurement circuit.

34
Major accomplishments in the project to automate the calibration

of standard resistors in the range from 1 00 n to 1 included the

modification of a guarded mercury stand to hold the resistors being

calibrated, and the construction of a prototype circuit to determine

the optimum detector system.

Overall Support for Calibration Services

(N. B. Belecki, R. C. Fronk, D. D. Prather, A. R. Wise)

A new Digital Equipment Corp. VAX 11/750 minicomputer, intended to

replace the Division's aging Interdata 7/32 computers, was installed

in mid-March. Software conversion was done rapidly and the VAX now supports resistance and impedance calibrations and the administrative

functions associated with the calibration services. The Interdata on

the first floor which previously provided this capability is now only

used for ac-dc difference calibrations. The degree to which the VAX

will be used to support dc voltage calibrations is not yet clear; the

Hewlett-Packard microcomputer system used to control the measurements

in the voltage laboratory may have sufficient capacity to handle data

analyses and display without resorting to use of the VAX.

A complete revision of NBS Special Publication 250, Calibration

and Related Measurement Services of the National Bureau of Standards,

has been undertaken by the Office of Measurement Services. The

descriptions of the services have been updated, reordered, and

renumbered. The management information system used in the Division to

monitor the calibration process has been modified to accomodate the new numbering system, which is expected to go into effect in April, 1986.

FUTURE PLANS

AC Current and Voltage —Reduce the queue for calibration customers by at least fifty per

cent. —Establish measurement controls and procedures to enable DoD primary

standards laboratories and those of instrumentation manufacturers to

obtain reduced uncertainties for special tests of thermal voltage

converters.

With partial OA support, study the suitability of commercial instruments for use as transport standards for ac current and voltage

measurements as a basis for providing improved support for industrial

and DoD standards laboratories.

Complete the study of new multirange solid-state converter systems,

especially investigating the effects of stray impedance loading on the

output.

35
—Make appropriate measurements to verify NBS measurement capability at

frequencies above 100 kHz and voltages above 400 V, and adjust uncertainties appropriately (it is expected that uncertainties will be

reduced in the former instance and increased somewhat in the latter.) —Complete the documentation of the calibration services.

Direct (DC) Voltage —Complete implementation of the new automated system for the

calibration of standard cells, including software and operational

systems. —Continue software development in order to move data handling and

calibration report production from the old Interdata minicomputer to

the Hewlett-Packard data system and the VAX. —Complete an analysis of the uncertainties of the measurements taken

by the new automated systems for both the calibration and MAP services. —Begin to upgrade the primary, secondary, and working groups of

standard cells by replacing bad cells in a number of enclosures as soon

as practical, consistent with maintaining laboratory operations. —Begin to investigate the use of a Zener-based transport standard at

the 1.018 V level as a replacement for the standard cell enclosures

used for the Volt Transfer Program. —Construct, test, and implement a second automated calibration system

for solid-state voltage standards with outputs up to 10 V to facilitate

development of improved standards. —Complete the documentation of the standard cell and solid-state

standards calibration and MAP services.

'—Complete an evaluation of the measurement capability of the DoD

primary laboratories at the 10 V level.

Impedance —Complete the calibration of 100 copper eddy-current SRM's, No. 2408,

101? lACS, and deliver to the Office of Standard Reference Materials

(OSRM)

.

—Calibrate and deliver to OSRM 100 titanium SRM's, one to two percent

lACS.

“Complete the investigation of an alternate approach to the recently

curtailed 1000 pF capacitance MAP, based on the use of 10 and 100 pF

fused silica capacitors in order to improve the transfer of the farad

to industry. The investigation will culminate in an interlaboratory

transfer with one or more commercial concerns.

36
—Complete the construction of four automated capacitance bridges and

begin their testing. A microcomputer to drive them via the IEEE 488

bus will be purchased and the calibration and testing software

developed by Cutkosky will be used to perform the testing. —Complete the necessary hardware and software, including optimized

balancing algorithms and special logic for controlling the grounding

circuits, for automating the new inductance bridge. —Continue development work on binary inductive voltage dividers for

automation of the main ratio balances for the new inductance bridge.

Optimum core materials and winding schemes will be determined, a final

divider constructed, and its input and output loading character istics

determined. —Complete the documentation of all measurement systems in the

impedance and eddy current conductivity area.

DC Resistance —Complete the documentation of all eight resistance areas, including

error analyses, descriptions of services, and references. —Continue development work on Hamon devices and the cryogenic direct

current comparator for scaling in the resistance area with the goals of

determining the uncertainties associated with present scaling measurements, particularly those in support of the absolute ohm and quantized

Hall effect projects, and improving these measurements to the greatest

extent feasible.

Overall Support for Calibration Services

-‘-Complete the ’Conversion of the software used to support ac-dc

difference calibrations to the VAX and retire the Interdata 7/32. —Cooperate with the NCSL to find legitimate ways to ship standard

cells. It was discovered late in FY 85 that standard cells can only be

shipped legally if they are conspicuously labelled as containing a corrosive substance (mercury) and a Class B poison (mercurous

sulphate) . Industrial experience has shown that packages so labelled

are routinely refused or delayed by the airlines and air freight

companies, thus making shipment under power difficult or impossible.

This has a deleterious effect on the NBS Volt Transfer Program, as well

as on customers' standard cell calibrations. —Explore the possibility of the use of Dataplot, an NBS

statistics/graphics program written by J. J. Filliben in the

Statistical Engineering Division, for general control charting as a quality control measure in the resistance and capacitance areas.

-“-Seek, test, and purchase a data-base management system to be used to

store and analyze historical data on customers' standards in order to

improve calibration reports and provide information on their long-term

accuracy.

37
Estimated Calibration Workload — FY 85

SP^250 #3.1 Resistance Measurements

662 Standard Resistors and Shunts

10 MAP Transfers

#3.2 Precision Apparatus

37 Inductive Voltage Dividers

#3.3 Impedance Measurements

173 Standard Inductors

260 Standard Capacitors

13 Eddy-current Conductivity Standards (2 sets)

#3.4 DC Voltage Measurements

1 40 Standard Cell Enclosures

(582 cells)

14 MAP Transfers

(24 companies)

30 Unsaturated Cells

32 Zener-diode Based Standards

#3.5 Electrical Instruments (AC-DC)

55 Standard Thermal Converter Instruments

(1241 points)

Estimated FY 85 Billing $750,000

38
JOSEPHSON VOLTAGE STANDARDS

(R. L. Steiner, R. F. Dziuba, B. F. Field, J. Toots)

Objectives

The objectives of this project are to maintain the NBS or U.S.

Legal Volt via the ac Josephson effect in superconductors to an accuracy of a few parts per 100 million, and to improve the maintenance

and dissemination of the unit of dc voltage for the U.S. through the

development of voltage standards based on the ac Josephson effect.

More specifically, the objectives are to (i) periodically maintain

the U.S. Legal Volt using the assigned value 2e/h = 483593 -420 GHz/Vj^gg

for the Josephson frequency-voltage ratio, (ii) Construct, evaluate,

and calibrate a new volt maintenance system based on the zero-crossing

step Josephson junction array. This array operates at a microwave

frequency of 70 - 95 GHz and generates voltage steps exceeding 1 volt,

allowing a one-to-one ratio calibration of standard cells at an accuracy of a few parts in 10^. (iii) Collaborate with the

Electromagnetic Technology Division's Cryoelectronics Group,

NEL-Boulder, Co. on the design, fabrication, and characterization of

these voltage standard arrays. Also included in this collaboration is

cooperation with the Physikalisch-Technische Bundesanstalt (PTB) in

West Germany on the design and characterization of similar arrays, (iv)

Upgrade the capabilities of the Electricity Division's thin film

facilities to enable local fabrication of arrays and other high quality

Josephson junctions for the existing Josephson junctions for the

existing Josephson voltage standards, (v) Use the improved thin film

facilities to investigate arrays made with NbN films. (vi) Finish

supplying Josephson junctions and system hardware for the commercial

1 ppm voltage standard developed for the Calibration Coordination Group

(CCG) of the DoD and the Korean Standards Research Institute (KSRI).

Current Activities

Objective (i) is presently the most critical. One calibration

measurement per month of the primary standard cells is necessary to

keep a close check on the drift rates of the cells. Maintenance and

repair of the cryogenic and electronic components continues, along with

new Josephson junction fabrication and testing, as necessary.

Objectives (ii) and (iii) are aimed at replacing this complex,

100:1 voltage ratio system at 8.5 GHz with a simpler, more accurate one based on the recently developed Josephson series array. Several

operational array IC chips have been tested at NBS-Boulder and the

appropriate microwave, cryogenic, and measurement equipment have been

ordered for constructing and testing the new system. Collaboration

with the Boulder Cryoelectronics Group and PTB is continuing,

especially concerning fabrication processes, design, material

composition, and characterization of these arrays.

39
The initial improvement of the Division's thin-film fabrication

facilities [objective (iv)], has begun with repairs to the rf

sputtering and electron beam evaporation machine, which has been

returned to regular use after two idle years. The vacuum pumps are being repaired and the different deposition processes are being

standardized and recorded. These activities also anticipate objective

(v), the sputtering of NbN films for the arrays.

Work on the final objective (vi) is still continuing, with the

testing and calibration of several Josephson junctions for the

commercial voltage standards.

Accomplishments

In FY 85 there were eight comparisons of the Josephson voltage

standard against NBS reference groups of Weston cells. The results of

these measurements indicate that the mean of the standard cells of the

primary reference group NBS-1 3 is drifting at the rate of -0.055

pV/month.

A new Josephson researcher (R. L. Steiner) arrived this year and

worked at NBS-Boulder for two weeks in December 1984 and over the three

month period in February-April 1985. While in Boulder, a comparison

was made at one volt between an operational Nb/Nb 2 0^/Pb-alloy array

and a calibrated Zener diode voltage reference source. The results

showed an accuracy of 0.5 ppm, limited by the transport stability of

the Zener source, and a precision of 2.5 parts in 10°, limited by null

detector drift. The array voltage was stable under test for tens of

minutes, and the array had not changed characteristics over eight

months and many thermal cycles.

The month of June 1985 was also spent at PTB participating in an experiment using Pb-alloy series arrays to demonstrate that the current

dependence of the voltage steps is less than 7 parts in 10^^.

At both NBS-Boulder and PTB, much information was obtained from

participation in the fabrication processes for both kinds of arrays,

microwave circuit design, photo-lithographic mask preparation, and

testing of the arrays. This information is essential for the

Division's future Josephson junction and array fabrication objectives.

Objective (vi) has nearly reached completion with the successful

testing and delivery of the KSRI commercial 1 ppm voltage reference. A Guest Worker from KSRI arrived in January 1985 for a three month stay

to receive training in how to use the system and to assist in its calibration. Presently the electronics for the Navy Western Standards

Laboratory system are operational, but are being kept to test junctions

for this system and replacements for the other delivered systems.

40
Future Plans

Maintenance of the U.S. Legal Volt will continue, with

construction, testing, and changeover to the one volt array system as the primary calibration standard at the earliest possible time. The

accuracy of this new system should be a few parts in 10^. Initially it

will be compared against the present system for calibration at the few

parts in 10° level.

Collaboration with Boulder and PTB will continue. The

goals are the optimization of the array design with respect to low

microwave power input and to step stability. NbN thin films used in

the array could provide even better thermal cyclability, higher

operating temperatures ( e.g., with cryorefr igerator cooling), and

generation of higher voltages.

The thin film facilities will be gradually upgraded to enable

fabrication of arrays locally. Necessary for this is the cleanup and

repair of existing vacuum systems, additional equipment for the complex

photo-lithographic techniques associated with the series arrays and for

NbN thin-film production, and the standardization of fabrication

processes for both future and present junction requirements

.

Concerning the commercial reference standards, several working

junctions are nearly calibrated. Once replacements for the existing

systems and a reserve supply of backup junctions are obtained, the WSL

system can be delivered and objective (vi) completed.

41
REALIZATION OF THE SI AMPERE

(P. T. Olsen, W. D. Phillips, E. R. Williams,)

Objectives

The objective of this research is to measure directly the NBS

as-maintained ampere in terms of the SI units of mass, length, and time

to an accuracy of at least one or two parts in ten million, or nearly

two orders of magnitude better than has ever been previously achieved.

A realization of the SI ampere with a given uncertainty is equivalent

to determining the Josephson frequency-voltage ratio 2e/h in SI units

to essentially the same uncertainty.

While the accuracy (now about 5-10 ppm) of such measurements has

not changed significantly since the turn of the century, a new technique promises dramatic improvement. This is particularly important

because measurements of other fundamental constants now indicate

serious inconsistencies between direct realizations of the ampere and

indirect determinations based on other constants. A new measurement

will help resolve these discrepancies, provide a solid contact between

SI and as-maintained electrical units, and could even lead to

artifact-independent definitions of the kilogram and mole.

Current Activities

Traditional absolute ampere experiments have measured the force

between current-carry ing coils whose dimensions were carefully detei

mined. Dimensional uncertainties have been the major limitation in

accuracy. The new approach avoids dimensional measurement by comparing

the mechanical and electrical work done as one coil is moved in the

field produced by another coil. The experiment is performed in two

parts. First, we measure the voltage induced in one coil while it moves in the magnetic field of the other, current-carrying, coil.

Second, we measure the force exerted on the movable coil by the other

when both carry current and the movable coil traverses the same path as

in the first part of the experiment. From the measured voltage and

force, along with the current, times, and displacements involved,

quantities equivalent to electrical and mechanical work are calculated

and their comparison results in an absolute ampere determination. The

difficult dimensional measurement is thus replaced with a straightforward displacement measurement.

Our plan for determining the NBS ampere in terms of the SI ampere

has three phases. The first phase, completed in early FY 82, involved

assembling and making measurements with a relatively small scale

working model to evaluate the general method described above. It was surprisingly successful considering the primitive nature of the

apparatus, yielding a statistical measurement uncertainty of about 2

42
ppm. The sytematic uncertainties were not seriously evaluated,

however, because of the unfavorable Pellat balance (rotational)

geometry used.

Phase II involves more sophisticated apparatus in a highly

favorable linear geometry. Construction of this apparatus and its

assembly and partial testing was completed in FY 83; evaluation o^ the

complete system began in early FY 8^. Figure 1 schematically

represents the essential components.

The heart of the apparatus is the system comprising coils 5 and C,

the fixed and moving coils respectively. Coils B , placed symetrically

above and below C, provide the radial magnetic field in which C moves.

The voltage induced in C and the force exerted on it are measured in

the two parts of the experiment. The balance wheel A allows C to move vertically with negligible horizontal motion. This wheel, which pivots

on a knife edge at its center, allows force determinations with a sensitivity equivalent to about 10 yg.

Fig. 1. A: Balance wheel;

B: main magnetic field

generating coil; C: movable

coil; D: reference coil;

E: balance support spider;

F: servo magnetic field

generating coil; G: servo

movable coil; H: miarble slab;

J : stone pier

.

43
The reference coil D allows us to correct for changes in the field

at C due to ambient field shifts or motion of the coils B. Coils F and

G provide the force needed to move the balance and translate C during

the voltage measurement phase of the experiment.

The displacement of coil C is measured interferometrically using a HeNe laser. Forces are measured in terras of calibrated masses and the

measured local acceleration of gravity, while voltages and currents are measured in terms of the NBS standards of voltage and resistance.

Two versions of coil system B are available. During Phase II, we are using a room-temperature version which provides a force of 20 g on

C and induces a voltage of 20 mV. In phase III, we will use superconducting coils which will provide a force equivalent to 1 kg and

an induced voltage of 1 V.

Accomplishments

Ampere measurements made during the first half of FY 85 revealed

several sources of error and noise as well as the fact that a significant measurement of the ampere can be made using the room temperature magnet. We have now corrected most of the noise and error

sources. This was accomplished in part by improved electrical

measurement and isolation and shielding of the instrument, which

reduced pick-up from various sources and improved the noise performance

of the experiment.

Other sources of error and noise were drift and noise in the

balance zero, drift in'the standard resistors, drifts and shifts in the

current source used to establish standard voltages, and excessive noise

in the voltage-velocity part of the measurement. The balance drift and

a good deal of the balance noise during the weighing part of the

experiment has been corrected by better thermal control of the balance

enclosure. This helps to eliminate changes in temperature differences

throughout the balance enclosure, which cause drifts mainly due to air

bouyancy changes. Thermal control also helps to eliminate convection

currents which cause force fluctuations. The effect of these can be

further reduced by increasing the force to be measured. We are building a new suspended coil which can carry more current and thus

increase this force by at least a factor of five.

Better thermal control of the resistor oil bath has also

eliminated drift in those standards, while a redesign of the current

source has virtually eliminated drift and shifts in the voltage

references

.

A particularly difficult source of error was related to the

peculiar type of balance which we use and was the source of

considerable noise in the velocity-voltage phase of the experiment.

44
Surface finish imperfections in the balance wheel and in the bands

which roll off the wheel were responsible for the effect. Surface

variations on the order of 0.3 micrometers produce a 1 ppm change in

the balance arm length. Because of the large dead weight carried by

the balance, this resulted in a large, fluctuating force when the

balance wheel was moved.

When the balance wheel perimeter was polished and the solid brass

band was replaced with a row of about 60 platinum-tungsten filaments,

the noise in the velocity data was reduced by about a factor of fifty.

Our progress this year was considerably aided by an exchange of

workers between our laboratory and the National Physical Laboratory of

Great Britain. NPL is engaged in a conceptually similar, but physically quite different ampere experiment. P. T. Olsen of our laboratory

spent a month at NPL, and B. P. Kibble of NPL later spent a month in our laboratory. The exchange of ideas about experimental technique and

treatment of systematic error has been quite helpful to both efforts.

Future Plans

Originally, the absolute ampere apparatus was designed to be used

with the superconducting magnet. The improvements which we have made

to the room temperature version, however, indicate that with the new suspended coil to provide a larger force, and possibly a faster coil

velocity to generate more voltage, we can achieve a significant

measurement of the ampere, at the 1 ppm level or better, sooner than

originally anticipated. Indeed, we expect to submit a value for 2e/h

in SI units with an uncertainty of 1 ppm or less, as obtained with the room temperature version of the experiment, to the Consultative

Committee on Electricity of the CIPM in time for its September 1986

meeting at which it plans to consider adopting a new value for 2e/h to

be used by all national standardizing laboratories which use the

Josephson effect to define and maintain their unit of voltage.

Ultimately, and with little additional delay, the use of the

superconducting magnet should allow a 0.2 ppm measurement or better.

45
REALIZATION OF THE SI VOLT

(F. K. Harris, L. H. Lee)

Objectives

The objective of this project is to realize the SI volt directly

by force measurements in terms of the base SI mechanical units of

length, mass, and time interval, and the assigned SI magnetic constant.

The present volt assignment is derived from absolute ohm and

ampere determinations and is uncertain to the same extent as the latter

(5 ppm or more). However, a direct volt determination should be free

from some of the systematic errors of past ampere determinations.

Furthermore, there is no conversion of electrical energy to heat, which

may have affected dimensional results and balance operation in past

ampere determinations. Thus it is hoped that a direct determination of

the volt may reduce the uncertainty in its assigned value.

Current Activities

Our volt balance consists of a vertically aligned coaxial-cylinder

electrode system with the low-voltage electrode in the annular space

between an inner and outer high-voltage electrode, and suspended from

the balance beam. The vertical electrical force on this suspended

electrode is compared by substitution to the mechanical force produced

by a known mass. The relation between electrical and mechanical

forces

,

requires that capacitance be measured against vertical electrode displacement; and the high-voltage electrode system is mounted on a carriage which can be moved vertically on three guide rails, position

being determined using a laser interferometer

.

It has been shown that horizontal electrical forces which are present if the system is not truly symmetrical about a vertical axis

may translate into a quasi-vertical force if the knife-edges of the

balance beam are not in a horizontal plane. Thus it is extremely

important that the electrode system be accurately symmetrical (within a few micrometers) about an axis that is vertical (within a few seconds

of arc) ; the carriage movement of the high-voltage electrode system

must also be vertical within the same constraint.

A mechanical disturbance to the central system can cause the

suspended electrode to oscillate as a pendulum about its central

position. When voltage is impressed on the electrometer, there is a lateral electrical force acting on the displaced suspended electrode

tending to increase its displacement during pendulous motion. This is

46
opposed by the centering force of gravity. If operational stability is

to be retained, the value of impressed voltage is limited, but can be

increased by lowering the center of gravity of the suspended electrode.

At the present time our system is stable for a 1 g force, but not for

voltages corresponding to 2-5 g forces which we would like also to

employ. Francis Hermach recently suggested the possibility of axial

stabilization of the suspended electrode by using the repulsive force

between like poles of permanent magnet pairs, one magnet fixed to the

upper rim of the suspended electrode, and its companion to the fixed

shielding ring that surrounds the upper end of the electrode. If such

a magnetic stabilization scheme can be realized, it will remove the

need to lower the center of gravity of the suspended system for force

measurements above the 1 g level. A model of the suspended electrode

system is being constructed so that we may study the possibilities of

magnetic stabilization.

Accomplishments

The grounding and shielding of the electrometer structure and the

capacitance measuring bridge have been improved in order to reduce

interference from external sources. Isolation has increased, but some intermittent disturbance of unknown origin is still present from time

to time. Determinations of 9C/9z have been made using varying 9z

intervals. The results tend to confirm the need to lap the suspended

electrode.

The model to permit the study of additional means to stabilize the

suspended electrode has been built. It contains a duplicate of the

electrometer electrode suspended from crossed knife-edges.

Future Plans

The suspended electrode will be removed and lapped in order to

reduce the variations in 9C/9z. The recently constructed model will be

used to study possible mechanisms to provide additional restoring

torque.

47
REALIZATION OF THE SI FARAD AND OHM

(J. Q. Shields, L. H. Lee, G. R. Jones, Jr.)

Objectives

The objectives of this project are to build, maintain, and operate

equipment for calibrating the NBS standards of capacitance and resistance in terms of their SI definitions to an accuracy of 1 or 2 parts

in 100 million, and to assure the compatibility of these standards with

those of other countries.

Accurate realizations of the farad and ohm are required to assure

the compatibility of instruments (via resistance, inductance, and

capacitance calibrations) that are manufactured within the U.S. and for

the determination of certain fundamental constants. The NBS absolute

farad and ohm measurements make use of a calculable cross capacitor and

a series of bridges for comparing capacitors and resistors. The result

of the measurement sequence is an absolute calibration of the NBS

reference standards of capacitance and resistance that is accurate to a few parts in 10°. These measurements can also be considered as fundamental constant determinations, with applications to questions concerning the adequacy of quantum electrodynamic theory and to the

determination of more exotic constants. For example, a reliable value

of the ratio of the NBS ohm to the SI ohm is required in order to

obtain a value for the f ine-structure constant from a measurement of

the proton gyromagnetic ratio and 2e/h as measured via the Josephson

effect; and from a measurement of the quantized Hall resistance in a two dimensional electron gas. It is also necessary for the new NBS

absolute ampere experiment.

Current Activities

The equipment was completed a number of years ago and is among the

best in the world; a value for the NBS farad and ohm in terms of the SI

farad and ohm accurate to a few parts in 10° was obtained in 197^. Work

is presently concentrated on the preparation of this equipment for a new determination of the absolute farad and ohm with slightly improved

accuracy. Other current activities include maintenance of the NBS unit

of capacitance at the 10 pF level, and participation in international

comparisons of capacitance and resistance standards.

Accomplishments

A comparison of the NBS bank of 10 pF capacitors with the NBS bank

of 1 Q resistors was completed in FY 85 with an estimated uncertainty

of ±5 X 10 ° or 0.05 ppm. The basic steps in the comparison are as follows: (1) a 10:1 ac bridge is used in two stages to compare the NBS

bank of 10 pF capacitors with a 100 pF capacitor which is in turn

compared with two 1000 pF capacitors; (2) the 1000 pF capacitors are

48
used as two arms of a special frequency-dependent bridge which measures

the ac resistances of two 10^ ohm resistors in terms of capacitance and

frequency; (3) a 100:1 ac bridge is used to measure the ac resistance

of a 1000 transportable resistor in terms of the 10^ resistors; (4)

the difference between the ac resistance and the dc resistance of the

1000 n transportable resistor is determined from ac and dc bridge

comparisons with a special resistor designed to have a negligible ac-dc

difference; and (5) the 1000 transportable resistor is carried to the

dc resistance laboratory where it is measured in terms of the NBS bank

of 1 ohm resistors which comprise the NBS ohm using Hamon dividers and

other dc techniques. In addition to the basic steps described, there

are numerous calibrations and other measurements, some very

time-consuming, which are required to assure the accuracy of the

comparisons

.

Results of the comparison show that the NBS unit of resistance has

changed with respect to the NBS unit of capacitance by 0.'48 ppm ± 0.05 ppm during the eleven year period between 1974 and 1985. If it is

assumed that the NBS unit of capacitance has remained constant since

1974, then the NBS ohm has changed from = 1 - 0.82 pfi in 1974 to

^NBS = "I ^ ~ 1.30 pQ in 1985. This is in good agreement with the

results of recent international comparisons of capacitance and

resistance, taking into account the additional uncertainties associated

with international comparisons.

The primary vehicle for international capacitance comparisons

continues to be a set of three 10 pF capacitors of NBS design and

construction which have been circulating for many years among the

major national laboratories. The capacitors were recently returned to

NBS following measurements in East Germany, West Germany, England,

France, and the Netherlands. They continue to exhibit excellent

stability while being shipped via commercial carrier. They have just

recently been sent to Australia.

Work on the computable cross capacitor itself is now underway.

All of the critical mechanical dimensions have now been measured. The

results show that no mechanical adjustments are necessary at the

present time.

The cross capacitor’s built-in Fabry-Perot interferometer with

associated laser and other equipment is now producing fringes which

appear very good to the human eye and are easily detected with a phototransistor. This is due in large part to the help provided by Dr.

Howard P. Layer of the Length and Mass Division, CBS.

Future Plans

We intend to continue work on the computable cross capacitor with

the expectation of obtaining an SI farad with an uncertainty of

±0.1 ppm or less by early 1986. A comparison of the NBS units of

49
capacitance and resistance will then be repeated while keeping the cross capacitor in operation. This should hopefully yield an SI ohm by

the middle of 1986. Subsequent work will concentrate on reducing the

uncertainties in the measurements. A comparison of the NBS unit of

capacitance with that of the Netherlands using the three 10 pF

travelling standards is also planned.

50
QUANTIZED HALL RESISTANCE

(M. E. Cage, C. T. Van Degrift, R. F. Dziuba, B. F. Field,

T. E. Kiess, W. J. Bowers)

Objectives

To develop techniques used to observe the quantum Hall effect in

semiconductors to the point where it can be used (1) to determine the

f ine-structure constant a with the unprecedented accuracy of a few

parts in 100 million, thereby allowing the unequivocal testing of

quantum electrodynamic (QED) theory; and (2) to establish a reproducible resistance standard of the same accuracy.

The quantum Hall effect has the potential of providing the most

accurate QED-independent value of the fine-structure constant as well

as an SI or absolute resistance standard based on fundamental constants

of nature rather than the present resistance artifacts. It would thus

permit definitive tests of QED as well as allow NBS to maintain the

U.S. unit of resistance continually to very high accuracy in SI units,

rather than at multi-year intervals via the very difficult calculable

cross-capacitor experiment.

Current Activities

The method for achieving these goals involves measurements of the

Hall resistance, R^^, of metal-oxide-semiconductor field effect transistors (MOSFETs) and of GaAs-AlGaAs heterojunctions at liquid helium

temperatures in large magnetic fields. The Hall resistance Rp^(i) [the

ratio between the Hall voltage V^(i) and sample current I] is given by

. V , 25,812.8

^

I 2a i i where is the permeability of vacuum (defined to be 4-rr x 10 H/m) , c is the speed of light in vacuum, and i is an exact quantum integer.

Currently we are: (1) performing quantum Hall effect experiments

on GaAs heterojunction samples using an 8 T magnet installed in a shielded room at NBS; (2) using the quantum Hall effect to monitor the

national unit of resistance; (3) constructing a new laboratory which

will allow us to continue maintaining the national unit of resistance

in one magnet system while enabling us to expand our basic research

using a second system capable of attaining magnetic fields of 1 5 T and

temperatures down to 30 mK.

51
Accomplishments

The United States unit of resistance is now being unofficially

maintained via the quantized Hall resistance R^.

In order to use the quantum Hall effect to maintain the national

resistance standard (the "NBS Ohm" or "U.S. Legal Ohm"), four

operations must be performed. First, each device is thoroughly studied

for magnetic field, temperature, and current dependence. Second, the

6453.2 ohm quantum Hall resistance [Eq. (1) with i=4] is transferred to

a room temperature resistor of nearly the same value. Third, a Hamon

series/parallel resistance network is used to transfer that value to a 100 ohm standard. Finally, another Hamon device is used to complete

the transfer to the set of five NBS one-ohm resistors which comprise

the NBS ohm.

Figure 1 (see next page) displays the latest results of these

relative comparisons between the quantum Hall resistance Rp^(4) and the

resistance of a 6453.2 ohm wire-wound reference resistor. These

measurements have typical one standard deviation total uncertainties of

± 0.02 ppm. The figure also shows that the value of this resistor is

increasing at a rate of (0.052 ± 0.005) ppm/year relative to the

quantum Hall resistance. This increase occurs even though the resistor

is hermetically sealed, is continuously temperature-controlled to

within ± 0.002 Celsius, and has not been moved.

A second 6453.2 ohm reference resistor was also calibrated in

terms of R^^(4) and then hand-carried to a basement laboratory and

calibrated in terms of the set of five one-ohm resistors which comprise

the NBS ohm (operations 3 and 4, above). The uncertainty of this

transfer is estimated to be ± 0.044 ppm — giving a total one standard

deviation uncertainty of ± 0.05 ppm for the step-down from the

quantized Hall resistance to the NBS ohm. Figure 2 (see next page)

shows this result. These data provide the first direct evidence that

the national unit of resistance is drifting; its value is apparently

decreasing at the rate of (0.052 ± 0.021) ppm/year. The uncertainty in

this drift rate is quite large, but should be further reduced as a result of our continued measurements using the quantum Hall effect.

52
AR/R

(ppm)

1983 1984 1985

TIME IN MONTHS - STARTING MAY 1983

Fig. 1 . Relative comparisons as a function of time of the quantum Hall

resistance with a room temperature reference resistor of

6,453.2 ohm nominal value. AR/R = (Rj^ - Rp)/Rp.

1983 1984 1985

TIME IN MONTHS - STARTING MAY 1983

Fig. 2. Monitoring as a function of time the value of R^ expressed as

a difference in ppm from a nominal value of 6,453.2 ohm NBS.

53
Much effort was expended this past year on performing extensive

testing of the manual and automated resistance measurement systems.

The manual system utilizes a potentiometric comparison between the

quantum Hall voltage and that developed across a room temperature

four-terminal reference resistor, whereas the fully-automated system is

a modified Wheatstone bridge. Most of the work was devoted to

calibrating the amplification factors (the gains) of the low-level dc

detectors used in both systems. In order to achieve an uncertainty

contribution of less than 0.01 ppm in the resistance comparisons, the

detector gains must be calibrated to better than Q.\%. With

considerable difficulty, we were ultimately able to calibrate each

detector sufficiently well that, for one hour of measurement, the

manual system had a precision of 0.01 ppm and an accuracy of 0.02 ppm

while the automatic system had a precision of 0.007 ppm and an accuracy

of 0.02 ppm.

During the past year R. F. Dziuba and Guest Scientist J. Kinoshita

from the Electro-Technical Laboratory (ETL), Tsukuba, Japan, designed

and assembled a cryogenic current comparator bridge to improve the

resistance scaling accuracy between resistance values of 6453.2 and 100

ohms, and between 100 and 1 ohm. Two comparators of different design

have been constructed with sufficient redundancy of discrete ratios to

provide confidence in the scaling process. A superconducting quantum

interference device (SQUID) is used to detect the bridge balance.

Initial testing of this bridge at the sub-ppm level, which is currently

underway, indicates that the basic design is sound. We expect that

work during the next year will refine this bridge to the point where we will be able to use it to reduce the resistance scaling uncertainty by

a factor of two to about 0.02 ppm. (See also the DC Resistance portion

of the Dissemination Services project description.)

Much effort was also expended this past year on designing a new quantum Hall effect research laboratory and initiating its

construction. It is described in some detail under Future Plans.

Future Plans

The new quantum Hall effect research laboratory will allow us to

expand the scope of the NBS QHE research effort to higher magnetic

fields, lower temperatures , and higher accuracy in temperature

measurement

.

Accurate temperature measurement of a sample located in a high

magnetic field can only be made by placing the thermometer outside of

the field and by providing a good thermal like to the sample. This

requires a considerable vertical extent for the apparatus. In

addition, the attainment of temperatures well below 1 K requires a dilution refrigerator and still more vertical height. The new laboratory will be located in a 13~foot-high basement room with a

54
1 4-foot-deep work area cut into the floor to accommodate a new 15 T,

persistent-current superconducting magnet. This will allow ample room

for a dilution refrigerator capable of cooling the samples to 30 mK and

having the means to measure the sample temperature within 0.5 mK of

true thermodynamic temperature.

An important feature of this system will be a vacuum interlock

arrangement which will permit the samples to be easily changed without

warming the magnet or dilution refrigerator . Because of the ease with

which we will be able to change samples, we will be able to study a large number of devices prepared by different laboratories using

different semiconductor compositions and different geometries.

In addition to this 15 T system, we will also operate in the same laboratory the present 8 T magnet system. This will allow us to

dedicate the 8 T magnet system to the monitoring of the National unit

of resistance while permitting complete freedom in the use of the 15 T

research system. Furthermore, we will be able to simultaneously

compare the quantized Hall resistances of different devices to within

0.02 ppm even though their steps might occur at different magnetic

f ields.

The new laboratory is expected to be in operation by the spring of

1986. The initial experiments planned include a precision measurement

of 8^(2) at 12906.4 Q in GaAs heterostructures and a comparison of

R^(4) as optained from Si MOSFETs and GaAs heterosturctures . We also

expect to submit a value for in SI units with an uncertainty of 0.1

ppm or less to the Consultative Committee on Electricity of the CIPM in

time for its September 1986 meeting at which it plans to consider

adopting a universal value for R^j to be used by all national

standardizing laboratories to define and maintain their unit of

resistance.

55
GAMMA-P AND THE FINE-STRUCTURE CONSTANT

(E. R. Williams, G. R. Jones, Jr., P. T. Olsen, W. D. Phillips)

Objectives

To carry out an improved determination of the gyromagnetic ratio

of the proton in H

2 O, Yp, to an accuracy of a few parts in 100 million,

thereby obtaining a value of the fine structure constant a to an accuracy of 0.02 - 0.03 ppm. This will extend the precision with which

quantum electrodynamics (QED), the Josephson effect, and the quantum

Hall effect, can be tested. It will also provide an alternate means

for monitoring and maintaining the NBS units of voltage and current.

The present approach to redetermining a is based on improving the

inductive dimensional measurement method developed in our laboratory

for determining the pitch and diameter variations of a precision

solenoid and used to carry out a 0.2 ppm determination of Y reported in

1979 . The NPL in England and the VNIIM in the USSR have reported values

of Yp that are in complete disagreement with our 1979 result (10-15

standard deviation discrepancies) . The Chinese value obtained at NIM,

Beijing, agrees with our value. We expect a new determination of Yp

will resolve this major disagreement.

Current Activities

The gyromagnetic ratio of the proton is defined as the ratio of

the angular precession frequeny (i)p,of a proton in a magnetic field B to

the magnitude of the field, Yp = cOp/B (the prime indicates the proton

is in a spherical, pure, H

2

O sample at 25 °C). The precession frequency is

measured by standard nuclear magnetic resonance methods. The magnetic

field is calculated from the measured physical dimensions of a single“layer solenoid, wound on a precision-ground quartz form, with a known (in terms of NBS standards) electric current in the turns of

wire. The location of each turn of the solenoid is found by an inductive pick-up probe and a laser interf erometer which locates the

position of the probe. We are constructing a new solenoid and

measuring apparatus that will reduce the sources of error in the

previous experiment. This new experiment will have the following

improvements: (i) a reduced sensitivity to the diameter of the solenoid; (ii) improved axial symmetry of the inductive pick-up probe;

(iii) an improved straightedge used to guide the probe; (iv) an improved laser measuring system that will allow measurement of all six

degrees of freedom; (v) increased S/N ratio for the NMR signal; (vi)

improved temperature control; (vii) improved calibrations for the

length and electrical standards; and (viii) capability for a direct

measurement of all susceptibility corrections. These advances should

produce nearly an order of magnitude improvement in our previous

56
determination. The quantum Hall effect, which provides an independent

value of a, provides additional incentive for completing the Yp

measurement in the near future.

Accomplishments

This past year began with a great deal of turmoil. One night

while the solenoid was being measured the refrigerator used to cool the

solenoid cooling fluid failed and the temperature of the fluid rose to

ilO °C. The copper windings on the solenoid expanded and went slack.

Upon cooling the distribution of tension in the wire was no longer

uniform and several turns remained slack. Rewinding the solenoid was

the only solution. The entire system was therefore disassembled and

the solenoid taken to the shop. The wire tension was increased so that

the temperature at which the solenoid goes slack is now much higher.

This extra tension squeezed the solenoid form and made it 3 Ppm longer.

Safety circuits have been installed and a new chiller system is being

installed to prevent a similar accident.

One positive result has come from the rewinding. A few gold

flakes from the gold-plated wire formerly circulated in the cooling

fluid and occassionally short-circuited a winding. We carefully washed

the wire and the solenoid while rewinding it and painted between the

turns with shellac to make shorts less likely. We have not had a shorted turn since rewinding.

Computer failures have also plagued the experiment this year. We

have had four failures each requiring a delay while factory repairs

were made. A backup for one unit that failed three times has been

ordered to reduce further delays.

In spite of these difficulties, we have improved the dimensional

measurements and tested for most systematics. Most of the improvements

have been in the control program and related servo systems. We also

reduced a major noise source when we mechanically constrained the

straightedge so that it moves ten times less when the probe is pushed

along the solenoid axis. A lower-noise amplifier improved the diameter

variation data. There still exists one unexplained shift of 0.5 ppm in

the apparent length of the solenoid between February and July. Some

further tests will be required to sort this out.

In evaluating potential systematic errors, we measured the magnetic

susceptibility of the soil in the vicinity of the nonmagnetic building

and were surprised at how large it was. Because of the unexpectedly

high iron content of the soil, the susceptibility is between 3 x 10~^

and 10 . A susceptibility this large implies a systematic shift of

the measured value of Tp of about 0.1 ppm. We have developed a new

57
method to measure susceptibility using an inductive technique similar

to that used for measuring the solenoid dimensions which we will use to

evaluate this correction directly.

Future Plans

Our goal for this year is very straightforward: We want to have a publishable value for Yp by the time of the Conference on Precision

Electromagnetic Measurements (CPEM 86) to be held at NBS in June 1986.

This result will be very important in determining the absolute or SI

value of the NBS ohm and thereby the value in SI units of the quantized

Hall resistance which will be used to define and maintain laboratory

units of resistance throughout the world. The Consultative Committee

on Electricity (CCE) of the CIPM will be meeting in September 1986 to

adopt a specific value for and we are in a very competitive position

to influence this value. We expect to have a value of Y with an accuracy of about 0.1 ppm, which will lead to values of Rj^ and alpha

accurate to 0.04 ppm.

58
LASER COOLING AND TRAPPING OF NEUTRAL ATOMS

(W. D. Phillips, A. L. Migdall, H. J. Metcalf (GW))

Objectives

The fundamental objectives of this project are to decelerate and

cool a neutral atomic beam, and to confine and further cool neutral

atoms in electromagnetic traps.

The motivation for this work is that cooling and trapping provide

solutions to the problems of 2nd order Doppler effect, residual 1st

order Doppler, transit time, and other motional effects which limit the

performance of ultra-high resolution spectroscopy. This work is

complementary to the trapped/ion cooling ion work in the Time and

Frequency Division. Both projects are directed to improved

spectroscopic resolution, but neutral atoms present different

opportunities, such as studies of atoms in electric fields. These

could test theories of the Stark effect or provide a new determination

of the fine-structure constant from Stark splittings. Spectroscopy of

very cold neutral atoms also has possible applications to frequency

standards, fundamental constants, and fundamental physics such as electric dipole moment searches. Dense, cold, trapped neutral atoms

offer the possibility of studying quantum collective effects such as Bose-Einstein condensation. Slow, cold atomic beams could be used in

collision experiments or in sensitive deflection experiments to test

statistics of photon absorption or charge neutrality of matter.

Current Activities

COLLECTION

OPTICS

Na BEAM

NaSOURCE

PROBE

LASER

BEAM MECHANICAL

SHUTTERS

MECHANICAL

SHUTTER

TAPERED

SOLENOID

UPSTREAM DOWNSTREAM

COIL COIL NEARLY MERGED

LASER BEAMS

TRAP

COOLING

LASER BEAM

MECHANICAL

CHOPPER

Figure 1 shows the apparatus used for laser cooling and magnetic

trapping of neutral atoms. Sodium atoms from the oven are collimated

to form a beam which travels along the axis of a vary ing-f ield

solenoid. The atomic beam is opposed by a laser beam which is

resonantly tuned to the yellow optical transition in sodium. As the

atoms absorb and re-radiate the laser photons, the resulting momentum

59
transfer slows the atoms down. The changing Doppler shift of the

decelerating atoms would soon take them out of resonance with the laser were it not for the vary ing-f ield solenoid which provides a compensating changing Zeeman shift. This Zeeman compensation of the

Doppler shift allows a continuous atomic beam with a thermal spread of

velocities to be brought to rest near the exit end of the solenoid.

Accomplishments

During the past year we have succeeded in demonstrating for the first

time electromagnetic trapping of neutral atoms. The trap is a magnetic

quadrupole and takes advantage of the force exerted by an inhomogeneous

magnetic field on the magnetic dipole moment of the sodium atom.

Trapping is accomplished as follows: Once an equilibrium situation is

established, with the atomic beam stopped near the end of the solenoid,

the laser is abruptly shut off. Now all the atomic velocities are

frozen, and atoms which have not yet come to rest (those closer to the oven than the stopped atoms) proceed out of the solenoid and into the

trapping region. After an appropriate delay, atoms of a specific

velocity (typically 100 m/s) are in the center of the trap region.

Here, the laser is pulsed on briefly, bringing the atoms to rest. With

the atoms at rest, the opposing coils of the quadrupole trap are energized with electric current and the atoms are trapped.

We have achieved central densities of trapped atoms greater than

10^/cm^ in a trap whose total volume is 20 cm^. The density decays

with a time constant of about 0.8 s, a rate which is determined mainly

by scattering of trapped atoms by background gas atoms. The maximum

energy of the trapped atoms is 17 mK, corresponding to a velocity of

about 3 m/s.

Future Plans

During the coming year we intend to improve the vacuum in the

trapping region so as to increase the trapping time. Ultimately the

trapping time should be limited by Majorana transitions which can change the orientation of the magnetic moments so atoms will be

expelled from the trap. Trapping times as long as a thousand seconds

may be possible. With longer trapping times it should be possible to

further reduce the energy of the trapped atoms by various cooling

techniques and to increase the density by repeated or continuous

loading of atoms into the trap.

The procedure we have developed for stopping atoms should also

allow us to load atoms into laser traps. Here, atoms are confined by

virtue of dipole or radiation pressure forces from near-resonant light

beams. We are also investigating the possibility of concentrating slow

atoms in a gas cell by three dimensional laser cooling of the gas.

60
FUNDAMENTAL CONSTANTS DATA CENTER

(B. N. Taylor)

Objectives

The principal objectives of this project are to provide an international information center within the U.S. for work in the

general area of precision measurement and fundamental constants, to

analyze the consistency of measured values of the fundamental constants

that are obtained from different experiments, and to obtain sets of

recommended values of these constants for international use.

The close relationships that exist between the fundamental

constants and precision measurements, basic measurement units such as the ampere, volt, and ohm, fundamental physics, and state-of-the-art

measurement technology, makes the subject a natural one for NBS

involvement. One of the purposes of this project is to provide

assistance and guidance in the general area of precision measurement

and fundamental constants to both NBS staff and university scientists,

in particular, to advise them on the potential impact of the various

experiments they are considering carrying out and to keep them informed

of related work currently underway in various laboratories throughout

the world.

Self-consistent sets of "best values" of the fundamental constants, obtained by means of least-squares adjustments, are required

for a variety of purposes in science and technology, for example, in

accurate calculations of the energy levels of atoms that are of

importance in nuclear fusion, or for critical comparison of theoretical

calculations with experiment. Furthermore, as the basic invariants of

nature, they can be expected to form the basis of a system of reproducible, artifact-independent measurement units. Such a system is the

ultimate long-range goal of metrology.

Current Activites

Current activities in the precision measurement-fundamental

constants (PMFC) field include (1) keeping apprised of and maintaining

a complete reprint collection of the latest accomplishments throughout

the world in PMFC; (2) carrying out new least-squares adjustments of

the fundamental constants to obtain sets of recommended values; (3)

participating in the work of national and international groups (for

example, the CODATA Task Group on Fundamental Constants and the NAS/NRC

Advisory Committee on Fundamental Constants); (4) publishing the

quarterly "Preprints on Precision Measurement and Fundamental Constants" (PPMFC) for the Office of Standard Reference Data (this

publication lists preprints as well as reprints of PMFC papers); (5)

attending and organizing national and international conferences on

PMFC, visiting laboratories carrying out work in this field, and giving

61
talks and preparing papers on the present status of the fundamental

constants; and (6) answering inquiries from both within and without NBS

relating to the PMFC field.

Accomplishments

The four issues of PPMFC were published on schedule and the

maintenance of the data Center's extensive PMFC file was continued.

In collaboration with W. D. Phillips of the Electricity Division,

oversight of the Proceedings of the Second International Conference on Precision Measurement and Fundamental Constants (PMFC-II) was continued. The volume appeared in November 198^ and has been viewed as

a significant contribution to the PMFC field.

Work was begun to ensure that PMFC papers would be strongly

represented at the forthcoming 1986 Conference on Precision

Electromagnetic Measurements to be held 23~27 June 1986 at NBS.

As part of the effort to complete the 1985 Least Squares Adjustment of the Fundamental Constants (LSAFC 85) being carried under the

guidance of the CODATA Task Group on Fundamental Constants and in

collaboration with its chairman, E. R. Cohen of Rockwell International,

three relevant papers were prepared and published. Of special interest

is "New Results From Previously Reported NBS Fundamental Constants

Determinations," J. Res. Natl. Bur. Stand. 90, 91 (1985). This paper

reports a new treatment of the previously reported results of three

electric-unit-dependent fundamental constant experiments carried out at

NBS over the last decade or so which yields accurate, indirect values

in SI units for a number of important quantities. These include the

fine-structure constant a, the Avogadro constant N^, the Josephson

frequency-voltage ratio 2e/h, and the quantized Hall resistance

R^ E h/e^.

It should be noted that originally, LSAFC 85 was to be completed

in 1984 and to be known as the 1983 Least-Squares Adjustment of the

Fundamental Constants (LSAFC 83). It was to include all the relevant

data available through 31 December 1983. However, because of delays in

finishing LSAFC 83 by the end of 1984 which was the original goal and

the completion of new, relevant work during 1984, it was decided to

extend the cut-off date for new results to early 1985 and to call the new adjustment LSAFC 85. Work aimed at finishing LSAFC 85 by the end

of 1985 is currently underway.

Future Plans

There are three major goals for FY 85: (1) Complete the data

analysis portion of LSAFC 85, prepare a summary in draft form suitable

for publication as a CODATA Bulletin, circulate it to the CODATA Task

Group on Fundamental Constants, incorporate their comments as appropriate

into a final version, and submit it for publication to CODATA by the

62
end of December 1985. (2) Review and analyze all the available data

relevant to the Consultative Committee on Electricity (CCE) September

1986 meeting at which the CCE hopes to adopt (a) a new value,

consistent with the SI, for the Josephson frequency-voltage ratio 2e/h

to be used by every national standards laboratory which employs the

Josephson effect to define and maintain its laboratory unit of voltage,

and (b) a value of the quantized Hall resistance Rj^, consistent with

the SI, to be used by every national standards laboratory which employs

the quantum Hall effect to define and maintain its laboratory unit of

resistance. (3) On the basis of the review and analysis of (2),

actively participate in the meeting.

63
PRECISION MEASUREMENT GRANTS

(NBS Precision Measurement Grants Committee; B. N. Taylor, Chairman)

Objectives

The annual objectives are to award two new Precision Measurement

Grants of $30 k (renewable for two additional years at the option of

NBS), and to renew four existing grants. The grants are awarded to

scientists in academic institutions in order to (i) promote and

encourage fundamental research in the field of measurement science in

colleges and universities and train future measurement-oriented

scientists, and (ii) foster contacts between NBS scientists and those

researchers in the academic community who are actively engaged in such

work.

The importance of research in the precision measurement-fundamental constants field has been covered in the project report entitled

FUNDAMENTAL CONSTANTS DATA CENTER. While NBS has a strong interest in

this area and much experimental work underway, it cannot do it

all - there is much expertise and relevant work in the colleges and

universities. It is the purpose of this project to tap this reservoir

and to foster the training of students who might eventually become NBS

staff by awarding grants to a selected number of outstandingly qualified, academic researchers. Only those individuals working in areas of

immediate or potential future benefit to ongoing NBS programs are chosen to receive awards. Thus, the work carried out by the grant

recipients serves to compliment the efforts of the Bureau's own staff

in closely related areas. Selection is based primarily upon the

originality of the work proposed as described in formally submitted

proposals

.

Current Activities

The research supported under the PMG program includes experimental

and theoretical studies of fundamental physical phenomena which may

lead to improved or new measurement methods and standards; the

determination of important fundamental physical constants; and general

research and development on basic measurement techniques and

instrumentation. To simplify the selection process, candidates are

first requested to submit a biographical sketch and preproposal summary

outlining the objective of their proposed research, why they believe it

to be important, and the general approach to be used, including some indication of what they expect to accomplish in the three year time

period covered by the grant. On the basis of this material, four to

eight candidates are selected by the NBS Precision Measurement Grants

Committee (consisting of four senior NBS staff) and the Outside

Advisory Committee (consisting of four senior university professors) to

submit more detailed proposals. The same committees evaluate these,

and on the basis of this evaluation, the recipients are finally

selected. The criteria used in evaluating the preproposals and full

64
proposals include the importance of the proposed research to science,

the feasibility of the research, and the past accomplishments of the

applicant

.

Accomplishments

The procedures outlined above for selecting candidates, which were

first instituted in FY 77, were again used successfully in FY 85.

Proposals were openly solicited via an advertisement in Physics Today,

announcements in appropriate trade journals and newsletters, and the

mailing of a brochure to the physics departments of all of the colleges

and universities in the U.S. which grant bachelor’s degrees in physics

(about 850). Excellent proposals were received from 29 candidates,

five of whom were chosen to submit final, full proposals. The following are the two recipients selected, their institutions, and project

titles

:

Gerald Gabrielse, University of Washington

Injection of Protons, Antiprotons, and Heavy Ions into a Penning Trap for Precision Mass Measurements

Larry R. Hunter, Amherst College

A New Method to Search for the Electric Dipole Moment of

the Electron

The aim of Gabrielse's research is to develop techniques to

handle, cool, and indefinitely store antiprotons in thermal equilibrium

at 4 K in a Penning trap in order to test the CPT theorem (charge

conjugation, parity and time reversal transformations) by comparing the mass of the antiproton and proton to one part in 10^, an improvement of

10^. The same techniques will be applied to heavy ions as a step

towards high precision heavy-ion mass spectroscopy in a Penning trap.

The aim of Hunter's research is to put an upper limit on the electric

dipole moment (edm) of the electron which is 1000 times smaller than

the current limit, thereby testing time reversal invariance (the T

transformation in CPT) and certain classes of gauge theories. The

basic principle of the experiment is to spin polarize the ground state

of the cesium atom and to search for a precession of that polarization

in an applied electric field. A limit on the edm of the cesium atom

results in a limit on the electron's edm approximately 100 times

smaller

.

For FY 85, the NBS Precision Measurement Grants Committee con- sisted of Drs. Deslattes, Hall, Taylor, and Wineland; the Outside

Advisory Committee of Professors Metcalf, Ritter, Robinson, and

Williams.

The following grants were renewed in FY 85: C. M. Caves,

California Institute of Technology, Quantum-Mechanical Analysis of

High-Precision Measurements on Harmonic Oscillators; W. N. Hardy and A.

J. Berlinsky, U. British Columbia, Development of a Cryogenic Hydrogen

65
Maser; T. E. Chuop, Harvard U. , A Test of Local Lorentz Invariance

Using Polarized ^'Ne Nuclei; M. J. Levine, Carnegie-Mellon U.,

Precision Calculation of the Anomalous Magnetic Moment of the Electron

Using a Specialized Computational Engine.

Future Plans

FY 86 plans naturally focus on renewing the four eligible current

grants and awarding two new grants. Current and past recipients will

be invited to visit NBS and to present talks as appropriate, and visits

to current and past recipients will be made by NBS staff in conjunction

with other travel.

66
Electricity Division Sponsored Seminars/Workshops

A Seminar on Electrical Measurement Assurance Programs, held October

20-2^4 198^, Harriot Sea-Tac Motel, Seattle, WA.

A Seminar on Electrical Measurement Assurance Programs, held March

25-29, 1985, Holiday Inn 1776, Williamsburg, VA.

Invited Talks

N. B. Belecki, "Automated Voltage Converter Calibrations at NBS,"

Precision Measurements Association San Diego Chapter, San Diego, CA

,

January 1985.

N. B. Belecki, Chairman of "Ask the Experts - NBS," session at the 1985

Measurement Science Conference, Santa Clara, CA, January 1985.

N. B. Belecki, "Quality Control of Voltage Measurements at NBS,"

Rochester American Society for Quality Control Annual Conference on Quality Control, Rochester, NY, March 1985.

N. B. Belecki, "Automated Resistance Calibration at NBS," NCSL Region

Three Meeting, Gaithersburg, MD, June 1985.

N. B. Belecki, invited participant in "DC-Low Frequency Requirements

Workshop," National Conference of Standards Laboratories (NCSL) Annual

Workshop and Symposium, Boulder CQ, July 1985.

M. E. Cage, "Quantized Hall Effect and the Realization of a Unit of

Electrical Resistance," Instrument Society of America Symposium for

Innovation in Measurement Science, Geneva, NY, August 1985.

M. E. Cage, "Experimental Aspects and Metrological Applications of the

Integer Quantum Hall Effect," Special Course on the Quantum Hall

Effect, University of Maryland, College Park, MD, September 1985.

R. F. Dziuba, "Resistance Calibrations in the NBS Electricity

Division," 1985 Measurement Science Conference, Santa Clara, CA,

January 1985.

B. F. Field, "Review of dc Voltage Calibration Services of the

Electricity Division," 1985 Measurement Science Conference, Santa

Clara, CA, January 1985.

B. F. Field, "New Atomic Ohm Standard and Zener Reference Monitoring

System," Precision Measurement Association San Diego Chapter, San

Diego, CA, January 1985.

67
B. F. Field, "The Impact of Physics on Electrical Metrology: Instrinsic

Standards,” American Physical Society 1985 March Meeting, Baltimore,

MD, March 1985.

B. F. Field, "Atomic Physics Based Electrical Standards,”

Government-Industry Data Exchange Program Metrology Meeting,

Gaithersburg, MD, April 1985.

B. F. Field, "Automated Voltage Calibrations,” NCSL Region Three

Meeting, Gaithereburg, MD, June 1985.

G. M. Free, "Low Frequency Impedance Measurements at NBS,” 1985

Measurement Science Conference, Santa Clara, CA, January 1985.

G. M. Free, "Recent Developments in the National Bureau of Standards

Eddy Current Calibration Program," American Society for Nondestructive

Testing, Spring Conference, Washington, DC, March 1985.

G. M. Free, "Conductivity Measurements for Material Sorting," ASTM

Symposium on Methods for the Identification and Sorting of Metal and

Metal Alloys, Los Angeles, CA, June 1985

J. R. Kinard, "Recent Developments and Future Plans for the AC-DC

Difference Calibration Service at NBS," 1985 Measurement Science

Conference, Santa Clara, CA, January 1985.

J. R. Kinard, "NBS Automated AC-DC Difference Calibration System," NCSL

Region Three Meeting, Gaithersburg , MD, June 1985.

A. L. Migdall, "Magnetic Trapping of Atoms," Center for Basic Standards

Colloquium, NBS, Gaithersburg, MD, May 1985.

A. L. Migdall, "Laser-cooling, Stopping and Trapping Atoms," Seventh

International Conference on Laser Spectroscopy Maui, Hawaii, June 1985.

W. D. Phillips, "Laser-Cooling and Trapping Neutral Atoms," Alfred

Kastler Memorial Symposium, Paris, France, January 1985.

W. D. Phillips, "Laser Cooling and Trapping of Neutral Atoms," Spring

Meeting of the American Physical Society, Crystal City, VA, April 1985.

W. D. Phillips, "Cooling, Stopping and Trapping Neutral Atoms," Physics

Department Colloquium, Yale University, New Haven, CT, September 1985.

B. N. Taylor, "Possible Changes in the U.S. Legal Units of Voltage and

Resistance," NCSL Annual Workshop and Symposium, Boulder, CO, July

1985.

68
Publications FY 85

1

. ^ Print

.

M. E. Cage, R. F. Dziuba, and B. F. Field, "A Test of the Quantum Hall

Effect as a Resistance Standard," IEEE Trans. Instrum. Meas. IM~34 , 301

(1985)

.

M. E. Cage, R. F. Dziuba, B. F. Field, C. F. Lavine, and R. J. Wagner,

"Status of the NBS-NRL Determination of the Fine-Structure Constant

Using the Quantized Hall Resistance Effect," in Precision Measurement

and Fundamental Constants II , Ed. by B. N. Taylor and W. D. Phillips,

Natl. Bur. Stand. (U.S.), Spec. Publ. 617 (USGPO, Washington, DC,

1984), p. 539.

B. F. Field, "A High-Accuracy Resistance Bridge for Measuring Quantum

Hall Devices," IEEE Trans. Instrum. Meas. IM-34 , 320 (1985).

B. F. Field, "A Sub-ppm Automated 1-10 Volt DC Measuring System," IEEE

Trans. Instrum. Meas. IM-34 , 327 (1985).

F. L. Hermach, "An Investigation of the Uncertainties of the NBS

Thermal Voltage and Current Converters," NBSIR 84-2903, April 1985.

L. B. Holdeman and J. T. Holdeman, Jr., "Support Electrode Torque on a Spherical Superconducting Gyroscope," IEEE Trans. Magn. Mag-20, 2042

(1984).

L. B. Holdeman, "Josephson Effect," in McGraw-Hill Encyclopedia of

Science and Technology , Fifth Edition, Vol. 7 (McGraw-Hill, New York,

1982), p. 438.

M. J. Littman and W. D. Phillips, "A New Method of Measuring the

Fine-Structure Constant Using Stark Spectroscopy," in Precision

Measurement and Fundamental Constants II , Ed. by B. N. Taylor and W. D.

Phillips, Natl. Bur. Stand. (U.S.), Spec. Publ. 617 (USGPO, Washington,

DC, 1984), p. 173.

H. J. Metcalf and W. D. Phillips, "Laser Cooling of Atomic Beams,"

Comments At. Mol. Phys. j_6, 79 (1985).

H. J. Metcalf, "Magnetic Trapping of Decelerated Neutral Atoms," Prog.

Quant. Electr. 8, 169 (1984).

A. L. Migdall, J. V. Prodan, W. D. Phillips, T. H. Bergeman, and H. J.

Metcalf, "First Observation of Magnetically Trapped Neutral Atoms,"

Phys. Rev. Lett. 54, 2596 (1985).

69
P. T. Olsen, V. E. Bower, W. D. Phillips, E. R. Williams, and G. R. Jones, "The NBS Absolute Ampere Experiment," IEEE Trans. Instrum. Meas.

IM-34 , 175 (1985).

P. T. Olsen, W. D. Phillips, and E. R. Williams, "Status of the

Measurement of the NBS Ampere in SI Units," in Precision Measurement

and Fundamental Constants II , Ed. by B. N. Taylor and W. D. Phillips,

Natl. Bur. Stand. (U.S.), Spec. Publ. 617 (USGPO, Washington, DC,

1984), p. 475.

W. D. Phillips and H. J. Metcalf, "Time Resolved Sub-Natural Width

Spectroscopy," in Precision Measurement and Fundamental Constants II , Ed. by B. N. Taylor and W. D. Phillips, Natl. Bur. Stand. (U.S.), Spec.

Publ. 617 (USGPO, Washington, DC, 1984), p. 177.

W. D. Phillips, J. V. Prodan, and H. J. Metcalf, "Laser-Cooled Atomic

Beams," in Atomic Physics 9 , Ed. by R. S. Van Dyck, Jr., and E. N.

Fortson (World Scientific, Singapore, 1984), p. 338.

W. D. Phillips, J. V. Prodan, and H. J. Metcalf, "Neutral Atomic Beam

Cooling Experiments at NBS," Prog. Quant. Electr. 8, 119 (1984).

W. D. Phillips, "Laser Cooling of Atomic Beams," in Physics News in

1 983 , Ed. by P. F. Schewe (American Institute of Physics, New York,

1983), p. 73.

J. Prodan, A. Migdall, W. D. Phillips, I. So, H. Metcalf, and J.

Dalibard, "Stopping Atoms with Laser Light," Phys. Rev. Lett. 992

( 1985)

.

J. V. Prodan and W. D. Phillips, "Chirping the Light-Fantastic? Recent

NBS Atom Cooling Experiments," Prog. Quant. Electr. 8, 231 (1984).

B. N. Taylor, "Electrical Units, Fundamental Constants, and the 1983

Least-Squares Adjustment," IEEE Trans. Instrum. Meas. IM-34 , 155

(1985)

.

B. N. Taylor, "New Results From Previously Reported NBS Fundamental

Constant Determinations," J. Res. Natl. Bur. Stand. 91 (1985).

B. N. Taylor, "Impact of Quantized Hall Resistance on SI Electrical

Units and Fundamental Constants," Metrologia 37 (1985).

B. N. Taylor and W. D. Phillips, Precision Measurement and Fundamental

Constants II , Natl. Bur. Stand. (U.S.), Spec. Publ. 617 (USGPC,

Washington, DC, 1984).

E. R. Williams, G. R. Jones, J. S. Song, W. D. Phillips, and P. T.

Clsen, "Report on the New NBS Determination of the Proton Gyromagnetic

Ratio," IEEE Trans. Instrum. Meas. IM-34 , 163 (1985).

70
E. R. Williams, P. T. Olsen, and W. D. Phillips, "The Proton

Gyromagnetic Ratio in H

2O - A Problem in Dimensional Metrology," in

Precision Measurement and Fundamental Constants II , Ed. by B. N. Taylor

and W. D. Phillips, Natl. Bur. Stand. (U.S.), Spec. Publ. 617 (USGPO,

Washington, DC, 1984), p. 497.

E. S. Williams and J. R. Kinard, "A Dual-Channel Automated Comparator

for AC-DC Difference Measurements," IEEE Trans. Instrum. Meas. IM-34 , 290 (1985).

2. In Press, In Review, or Nearing Completion

B. F. Field, "Metrology of Intrinsic Standards," to be submitted to

Rev. Sci. Instrum.

C. A. Hamilton, R. L. Kautz, R. L. Steiner, and F. L. Loyd, "A

Practical Josephson Voltage Standard at Cne Volt," submitted to IEEE

Trans. Electron. Device Lett.

J. R. Kinard, E. S. Williams, and T. E. Lipe, Jr., "Automated Thermal

Voltage Converter Intercomparison, " submitted to Proc. IEEE.

H. J. Metcalf and W. D. Phillips, "Laser Cooling and Magnetic Trapping

of Atoms," submitted to McGraw-Hill Yearbook of Science and Technology.

H. J. Metcalf and W. D. Phillips, "Electromagnetic Trapping of Neutral

Atoms," submitted to Metrologia.

A. Migdall, T. Bergeman, J. Dalibard, H. Metcalf, W. Phillips, J.

Prodan, and I. So, "Cooling, Stopping, and Trapping Atoms," to appear

in Laser Spectroscopy VI , Ed. by T. Hansch and Y. Shen, (Springer,

Berlin)

.

J. Niemeyer, L. Grimm, C. A. Hamilton, and R. L. Steiner, "High

Precision Measurement of the Resistive Slope of Josephson Array Voltage

Standards," submitted to IEEE Trans. Electron Device Lett.

W. D. Phillips, "Laser Cooling and Trapping Neutral Atoms," submitted

to the Proceedings of the Alfred Kastler Memorial Symposium, Paris,

January 1985.

W. D. Phillips, "Laser Cooling, Stopping, and Trapping of Neutral

Atoms," submitted to Physics News in 1985, Physics Today.

W. D. Phillips, H. J. Metcalf, and J. V. Prodan, "Laser-Cooling and

Electromagnetic Trapping of Neutral Atoms," submitted to J. Opt. Soc.

Am. B

.

N. N. Tadros and L. B. Holdeman, "Thin Film Cryogenic Resistors from

Aluminum Alloys," submitted to Cryogenics

B. N. Taylor, "Possible Changes in the U.S. Legal Units of Voltage and

Resistance," submitted to NCSL Newsletter.

71
Technical and Professional Committee Participation and Leadership

N. B. Belecki, member, ANSI S82, American National Standards

Institute Committee on Electrical Standards, Instrumentation, and

Devices

.

N. B. Belecki, member. National Conference of Standards Laboratories

Measurement Assurance Committee.

N. B. Belecki, member. National Working Group, OIML (International

Organization of Legal Metrology) Pilot Sectetariat 13. Measurement of

Electrical and Magnetic Quantities; and Co-chairman, U.S. National

Working Group, OIML (International Organization of Legal Metrology)

Reporting Secretariat 13.1, International Gompatibility of National

Primary Standards Used for Instrument Verification.

N. B. Belecki, member, TC-2, DC and LF Standards, Instrumentation and

Measurements Committee of the Instrumentation and Measurement Society,

Institute of Electrical and Electronics Engineers (IEEE).

N. B. Belecki, member. National Conference of Standards Laboratories

Measurement Requirements Committee

N. B. Belecki, member. National Conference of Standards Laboratories

Education Liaison Committee

G. M. Free, member, ASTM E7, American Society for Testing and

Materials, Nondestructive Testing; ASTM E7, SC. 7, Electrical and

Magnetic Methods (vice chairman); E7, SC. 9, Materials Inspection and

Testing Laboratories ; E7, SC. 9, Editorial Review; E7, SC7.02, Glossary

(chairman); E7, SC7.01, Nonmagnetic Applications (chairman).

G. M. Free, secretary, American Society for Nondestructive Testing, Cl

,

Research Promotion Committee.

G. M. Free, member, American Society for Nondestructive Testing, C2,

Electrical and Magnetic Methods Committee.

W. D. Phillips, member, NBS Research Advisory Committee

W. D. Phillips, member. Steering Committee for the NBS Discussion Group

on Atomic Physics

W. D. Phillips, member. Editorial Board of Progress in Quantum

Electronics

B. N. Taylor, member. Advisory Committee on Fundamental Constants of

the Division of Chemistry and Chemical Technology, Numerical Data

Advisory Board, National Academy of Sciences/National Research Council/National Academy of Engineering.
B. N. Taylor, Chairman, NBS Precision Measurement Grants Committee.

B. N. Taylor, NBS representative. Consultative Committee on Electricity

(CCE), International Committee on Weights and Measures.

B. N. Taylor, member, ANSI C-42, American National Standards Institute

Committee on Definitions of Electrical Terms.

B. N. Taylor, member CODATA (Committee on Data for Science and

Technology Task Group on Fundamental Constants.

B. N. Taylor, Technical Advisor (Chairman, U.S. National Working Group)

OIML (International Organization of Legal Metrology) Pilot Secretariat

13 . Measurement of Electrical and Magnetic Quantities; and Co-chairman,

U.S. National Working Group, Reporting Secretariat 13.1, International

Compatibility of National Primary Standards Used for Instrument Verification.

B. N. Taylor, NBS representative to Conference on Precision

Electromagnetic Measurements (CPEM) Executive Committee and Comptroller, CPEM.

73
Collaborations, Consulting, Miscellaneous Activities

N. B. Belecki and R. F. Dziuba are collaborating with metrologists from

six Southern California Companies (Beckman Instruments, Electrical

Standards Repair Service, Ford Aerospace & Communications, Lockheed of

California, Rockwell International Anaheim, and TRW) in a pilot

experiment to develop methodology for a "self-help" group MAP in

resistance. The goal is a procedure by which companies could set up

and run their own MAP, including data reduction and error analysis,

using NBS’s calibration services and their own transport standards.

Some of the equipment is being furnished by the NCSL Measurement

Assurance Committee.

N. B. Belecki and B. F. Field provided technical guidance on voltage

standards and voltage, resistance, and temperature measurements to

engineers at the Charles Stark Draper Laboratories, Cambridge, MA, in

support of a program to evaluate inertial guidance units under intense

radiation conditions.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with S. M. Girvin of the Surface Science Division (5^1) on the theoretical aspects

of the quantized Hall resistance experiment.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with D. C. Tsui of Princeton University, and A. C. Gossard and H. L. Stormer of

Bell Laboratories, on quantized Hall resistance measurements of

GaAs-AlGaAs heterojunctions.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with M. Razeghi of Thomson-CSF, France, on quantized Hall resistance

measurements of GalnAs-InP heterojunctions.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with E.

Mendez of IBM on quantized Hall resistance measurements of GaSb-InAs

he ter ojunctions

.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with J.

Gulerno, E. Sichel, and H. Sample of GTE Laboratories on quantized Hall

resistance measurements of GaAs-AlGaAs heterojunctions.

B. F. Field is collaborating with a number of companies (John Fluke

Mfg. Co., National Semiconductor, Standard Reference Labs) on the

evaluation of improved solid-state voltage standards.

B. F. Field and T. E. Kiess are collaborating with personnel from the

DoD Primary Standards Laboratories (Redstone Arsenal, North Island

Naval Air Station, Washington DC Navy Yard, Newark Air Force Station)

on the use of commercial 10 V solid-state voltage standards as MAP

transfer devices.

7^1
G. M. Free is collaborating with M. Oldham of the Electrosystems

Division, CEEE, NEL, on the design, construction, and testing of binary

inductive voltage dividers.

J. R. Kinard is collaborating with personnel from the Navy Metrology

Engineering Center, Pomona, CA, and the John Fluke Mfg. Co. on the

evaluation of solid-state thermal converters.

J. R. Kinard is collaborating with personnel from the Navy Metrology

Engineering Center, Pomona, CA , and Ballantine Laboratories on the

evaluation of automatic programmable ac to dc converter instruments.

J. R. Kinard and T. E. Lipe, Jr., are collaborating with personnel from

the Air Force Primary Standards Laboratory, Newark, Chio, on the

development of a turnkey ac-dc difference calibration system.

P. T. Clsen is collaborating with personnel of the Navy's Primary

Standards Laboratory, East (Washington Navy Yard) on the calibration of

magnetometers

.

W. D. Phillips is collaborating with M. G. Littman of Princeton

University on the spectroscopy of Rydberg atoms in electric fields and

applications to the measurement of the fine-structure constant.

W. D. Phillips is collaborating with J. Dalibard and C.

Cohen-Tannoudj i of Ecole Normale Superieur, Paris, on the laser

trapping of neutral atoms.

W. D. Phillips is collaborating with H. J. Metcalf, I. So and T.

Bergeman of S.U.N.Y at Stony Brook on laser deceleration (cooling) and

magnetic trapping of sodium atoms.

R. L. Steiner and J. Toots are collaborating with C. A. Hamilton, R. L.

Kautz, and F. L. Loyd of the Cryoelectronics Group of the

Electromagnetic Technology Division, CEEE, NEL, NBS/Boulder, and J.

Nieraeyer of the Physikalisch-Technische Bundesanstalt , West Germany, on

the development of 1 V Josephson array voltage standards.

B. N. Taylor is collaborating with E. R. Cohen, Rockwell International,

and the CO DATA Task Group on Fundamental Constants, on a new least-squares adjustment of the fundamental physical constants to be

completed in early 1986 for international adoption by CODATA.

B. N. Taylor serves as Editor with D. R. Lide of NBS' quarterly

Preprints on Precision Measurement and Fundamental Constants.

J. Toots is collaborating with D. W. Br’audaway, Sandia Laboratories;

and K. Jaeger, Lockheed Missiles & Space Co., on the implementation of

a Josephson voltage standard at their respective laboratories by

fabricating Josephson tunnel junctions.

75
TQfPERATURE AND PRESSURE DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1985

DIVISION CHIEF'S OVERVIEW

This past fiscal year has seen significant adjustments in two

Division resources; personnel and finances. As to the former, two

professionals were retired; two professionals were hired; one

postdoctoral fellow was retained under contract and new assignments were made for five professionals and one technician. As to the latter, the

Division is achieving a firmer financial basis through a significant

increase in other agency funding.

Changes as large as the ones referred to above called upon the

resourcefulness, flexibility and cooperation of all the Division staff.

They came through with a maturity that will stand them in good stead in

years to come. For the past two years I have classified the Division projects into

eight categories. I will use the same system in detailing the resource changes for the remainder of this section, leaving the technical

accomplishments for discussion in subsequent sections.

I. HIGH TEMPERATURE SCALE RESEARCH

900 K < T < 200 K

Two of the subprograms (Optical Fiber Thermometry and Gas

Thermometry) suffered no personnel changes. The major change was in the

third component - High Temperature Platinum Resistance Thermometry.

John Evans retired, but still performs services under contract. Thus,

this subprogram has not completely collapsed It proceeds, however,

under a no-frills, bare-bones mode in which absolute essentials needed

for Division health (maintenance of Al, Ag, and Au fixed points;

calibration of several Division platinum resistance thermometers at

these fixed points; characterization of special platinum resistance

thermometers) are maintained.

II. INTERNATIONAL PRACTICAL TEMPERATURE SCALE (IPTS-68)

13 K < T < 1500 K

II. A. THERMOCOUPLES

The thermocouple group assumed an extra responsibility; an other

agency contract to assist the military in improving jet engine

temperature measurements (JETCAL). M. Reilly made major contributions

76
to JETCAL this past fiscal year, preparing to turn the program over to

the thermocouple group (G. Burns and M. Scroger) in FY 86.

II. B. PLATINUM RESISTANCE THERMOMETERS

The changes in the program are profound. G. Furukawa retired and

makes contributions to the Division under contract. B. Mangum has

assumed technical management responsibility for the program. The

Division is undertaking a two-year modernization of the Platinum

Resistance Thermometry Laboratory. Thus, R. Kaeser has joined the

effort as an expert in automation; G. Evans provides technician support

part time; and E. Pfeiffer has joined to help in several areas.

H. Marshak is also assisting in design and testing of a cryogenic

triple-point (Ar) apparatus. Finally, the program has attracted some

other agency funding (CCG).

II. C. LABORATORY THERMOMETRY

J. Wise continues to run this program. It is supported entirely

from calibration fees.

II. D. SMALL TUNNEL DIODE OSCILLATOR PRESSURE SENSOR/GAS THERMOMETER

C. Van Degrift is winding down the project on Tunnel Diode

Metrology and has effectively joined Division 521 to participate in a collaboration on the Quantum Hall Effect experiment.

III. LOW-TEMPERATURE SCALE

0.001 K < T < 30 K

E. Pfeiffer has completed the establishment of a calibration

service based on EPT-76. He will continue to offer the service on a part-time basis, as he now joins the platinum resistance calibration

laboratory automation project, II. B.

A Postdoctoral Associate, W. Fogle, was retained on contract.

Otherwise, there was no change in personnel or financing in this

project

.

IV. MEDICAL THERMOMETRY

0 OC < T < 200 OC

As was discussed in II.B., B. W. Mangum assumed charge of the

Platinum Resistance Thermometry program. This has resulted in some

deemphasis of the Medical Thermometry program (Dr. Mangum ’s original,

sole responsibility). The Medical program is not finished, however, so

Dr. Mangum will keep it going with Guest Scientists, etc. The program

has attracted some other agency funding (NASA), and may attract more

this FY (OSRM; NCI).

77
V. DYNAMIC PRESSURE AND TEMPERATURE

0.2 atm < P < 10 atm; 300 K < T < 2000 K

The stalwarts of the program (G. Rosasco, W. Hurst and R. Dove)

will be joined this FY by two one-year visitors (Dr. L. Petway and Dr.

K. Smyth). Other-agency support is pending.

VI. PRESSURE

105 Pa < P < 1.2 GPa

This program has had no change in permanent personnel, but it has

attracted several Guest Scientists. An other agency contract for the

Army has assisted them in their high-pressure needs. Additional other

agency support is pending.

VII

.

VACUUM

10-6 Pa < p < io5 Pa

At the beginning of this FY, A. Filippelli joined this group. A

new laboratory was established and is being improved. Other agency

support is strong, including the Navy (new manometer); CCG (speed of

sound in Hg); DOE (properties of vacuum gages); and NBS Initiative.

R. Dove was reassigned part time to assist the group.

VIII. LEAK STANDARDS

C. Ehrlich joined the group at the beginning of the FY. This group

works closely with VII, but enjoys separate funding (Sandia).

78
I. HIGH TQCPERATURE SCALE RESEABCH

(M. Reilly, J. Schooley, R. Edsinger, W. Bowers and J. Evans)

The temperature range covered here extends from 904 K (the upper

limit of the platinum resistor scale) to approximately 2000 K (no

particular reason for this cutoff). This temperature range is presently

defined by standard thermocouples. For a variety of technical reasons,

errors in temperature measurement using these devices can become

unacceptably large (-0.5 K). Accordingly, the Division has initiated a program to address this problem. The goal is to develop a temperature

scale accurate to 10 ppm based on a comparison of two instruments based

on two physical laws; the ideal gas law and the Planck radiation law. A

further consideration is to develop transfer standards based on special

platinum resistance thermometers or on the optical fiber thermometer.

Development of the optical fiber thermometer using the Planck radiation

law is a relatively new task assumed by Division personnel with the

direct support (financial and administrative) of the Director of NBS.

It is coordinated with the other Division projects - gas thermometry and

high-temperature PRT's - as will be explained below.

I. A. OPTICAL FIBER THERMOMETER

The principal goals of the Optical Fiber Thermometer (OFT) program

are (1) to establish accurate values for the thermodynamic temperature

of the freezing points of silver (962 °C) and gold (1064 °C) relative to

that of aluminum (660 °C) and (2) to provide a means of interpolating

temperature between these fixed points with an uncertainty that does not

exceed 20 ppm. Through its development and use as a primary

thermometer, we hope that the OFT can provide the basis for the

formulation of a more accurate temperature scale over the interval 630

to 1064 oc. This program was initiated in 1983*

The OFT, as was originally conceived by R. Dils, is a selfcontained measurement system with a high-temperature probe of singlecrystal sapphire rod (nominally 1 mm diameter and 30 cm length) with a metallic blackbody cavity sputtered on its tip. The low-temperature end

of the probe is coupled directly to a silicon photodiode detector via a compound narrow-band interference filter. When the cavity is heated,

the radiant flux emitted in a narrow wavelength band can be used to

determine its temperature. Because of a high index of refraction, the

sapphire probe captures significantly more signal than does the optical

system of conventional pyrometers and, as a consequence, it has greater

sensitivity and can operate to lower temperatures than those

instruments. If the cylindrical surface of the probe is perfectly

smooth, radiant flux from the surroundings of the probe will not be

transmitted to the detector.

In principle, once the OFT is calibrated at a single temperature

within its range, it is capable of measuring thermodynamic temperatures

over its entire range (600 to 1600 oq). In practice there are three

79
major sources of error which limit the accuracy with which the OFT can measure thermodynamic temperature. These are; (1) uncertainties in the

optical properties of the probe; (2) uncertainties in the spectral

response characteristics of the optical system (particularly the

interference filter and detector); and (3) uncertainties in the

linearity of the detector and the electronic circuitry.

At present, the dominant source of error is that due to the

attenuation of the transmitted radiant flux due to absorption in the

probe plus the loss of the transmitted flux (and likely gain of unwanted

background flux) due to scattering at the cylindrical surface of the

probe. Sapphire rods tested to date all show much more absorption and

scattering than can be tolerated for the OFT program. We have also

found that the absorption and scattering tend to increase with

prolonged exposure in air of an unprotected probe in a simple tube

furnace maintained at 1000 °C.

Neutron activation analysis of samples taken from various sapphire

rods indicate that the bulk impurity content of most of the material is

quite low (less than 10 ppm). However, scanning electron microscopy has

revealed clusters of patterned formations scattered over an otherwise

featureless cylindrical surface and subsequent electron probe analysis

indicates that these formations can have localized metallic ion impurity

concentrations of up to 0.1 wt %\ The formations on the surface cause absorption as well as scattering.

We believe that these localized concentrations of impurity develop

when the rod is flame polished (the final step which fabricators use to

produce a "smooth” finish once the sapphire, which is cut from a large

boule, has been centerless ground to dimension). We are therefore

studying a number of approaches toward improving the quality of the

cylindrical surface of the probe among which are various etching,

annealing, and polishing techniques. We are also working cooperatively

with a manufacturer (who can grow sapphire rod of the required diameter

and length directly from the melt) to assist through various analytical

efforts, in upgrading the optical quality of the sapphire rod produced.

The most recent rod tested shows significant improvement over earlier

rods manufactured.

Rods of vitreous synthetic silica from several manufacturers show

about an order of magnitude less absorption and scattering than do the

best of the sapphire rods tested. Moreover, preliminary studies with

the most promising of these, Suprasil, indicate that the absorption and

scattering (near 800 °C) do not significantly increase after exposing

the rod for 16 hours at 1000 °C provided it was first sealed within a silica tube containing dry argon gas.

Thus, several OFT probes of silica-sheathed, hermetically-sealed

vitreous synthetic silica rod have been built. Also enclosed within the

sheath is a small graphite blackbody cavity which surrounds the tip of

80
tne rod. The probes are of sufficient length (an advantage of silica)

so that they can be used in the existing thermometric freezing-point

cells as well as the NBS Gas Thermometer. Their performance is

currently being tested over the range 660 to 960 °C.

In anticipation of a need to provide calibration services for

OFT's, we are now prepared to provide "special" calibrations on IPTS-68,

which will also include evaluation of the absorption and scattering

characteristics of the probe. We expect to examine several commercial

instruments in FY 86.

We expect to begin construction in January 1986 of a laboratory

committed completely to the Optical Fiber Thermometer program.

I.B. HIGH-TEMPERATURE GAS THERMOMETRY

In the FY 84 Annual Report, we reported progress in determining the

difference between the IPTS-68 and the Kelvin Thermodynamic Temperature

Scale by gas thermometry in the range above 457 °C, the highest

temperature for which results had been published by the NBS Gas

Thermometry project staff. Our FY 84 results, obtained using a new,

gas-filled furnace as a thermal environment for the Pt-Rh alloy gas

bulb, had been marked by unsuccessful efforts to duplicate the earlier,

published data. The major difficulty had appeared to be a strong timedependent decrease in the gas-bulb pressure at all temperatures above

0 °C, with a rate corresponding to as much as 6 mK/day at 660 °C.

During FY 85, we eliminated several possible causes of this drift

by checking the system for leaks and for impurities in the working gas,

and by other methods that stopped short of dismantling the gas bulb.

They were unsuccessful. Therefore, despite the substantial investment

in time and effort involved, we removed the Inconel 600 protective case from the gas bulb and made several changes designed to eliminate the

drift. These included:

• Enlargement of the inner diameter of the Inconel case, to reduce

the likelihood of a touch between the case and the gas bulb, as had

occurred in an earlier assembly;

• Removal of the oxide layer from the inside of the Inconel case,

in the hope of retarding the transport of Ni and Or impurity atoms that

we detected on the outside of all the used Pt-Rh gas bulbs;

• Increasing the thickness of the flat bottom of the gas bulb by

about a factor two, in the hope of retarding any tendency for it to

"droop" at high temperatures and thus expand slightly the volume of the

gas bulb; and

• Removal of impurity atoms from the outside of the gas bulb by

careful polishing.

81
After re-assembly of the gas bulb onto its capillary and of the

Inconel case onto the capillary cover-tube, we outgassed the apparatus

at 700 °C for about two weeks, flushing several times with clean 4-He

gas.

From the first set of measurements at 457 °C, it was clear that the

pressure decrease that had spoiled so many earlier efforts was much

reduced. While still present, the effect was now somewhat less than

half as large as it had been. To ameliorate the effect of the drift, we

instituted a modified procedure for evaluating the thermodynamic

temperature associated with a given IPTS-68 temperature:

• Each high-temperature measurement must be immediately preceded or immediately followed by a reference measurement at the ice point; and

• After one series of measurements to evaluate the magnitude of the

pressure drift was completed, no effort was made to extend the duration

of high-temperature measurements. The gas-bulb assembly was maintained

at the high temperature only long enough to minimize temperature

gradients in the furnace volume surrounding the bulb. This procedure

has the added benefit of reducing the time during which material

transport between the Inconel case and the gas bulb can occur.

The measurements that we have obtained with the re-built gas bulb

assembly, while limited in number, have shown improved precision over previous efforts. The agreement between the present results at 457 °C

and the NBS results published earlier has improved considerably,

although there remains a discrepancy of 10-20 mK as shown in Fig. 1.

During FY 85, Jung of the PTB in Berlin published preliminary

results of spectral radiation thermometry in the range 457 °C to 660

that are based upon the NBS results at 457 °C. Accordingly, we have

concentrated our own efforts on the same limited range. All of our

results to date, as well as those of Jung, are shown in Fig. 1.

The major uncertainties in our determinations arise from

uncertainties in the corrections for thermal expansion, for

thermomolecular pressure in the capillary, for the non-ideality of 4-He

gas, and for gradients in the furnace temperature. We estimate the

overall level of uncertainty as ± 20 mK. Once sufficient measurements

are complete so as to allow evaluation of our random measurement

uncertainty, it is our intention to dismantle the gas bulb assembly in

order to re-measure its thermal expansion throughout the range

0 - 660 °C, and to measure the capillary thermomolecular pressure effect

in the same range. Given the improved precision to be expected from

spectral radiation thermometry above 660 °C, it may not be necessary for

us to continue measurements above that temperature.

82
200

400

600

800

o

T-Tes

I I I o o o • • •

cn o oi

Fig. 1. IPTS-68 vs. Kelvin thermodynamic scale.

83
Our plans for the coming year also include completing publication

of the thermal expansion measurements performed in conjunction with the

earlier NBS gas thermometry.

I.C. HIGH-TEMPERATURE PLATINUM RESISTANCE THERMOMETRY

The purpose of this project is to develop high-temperature platinum

resistance thermometry as a long needed and more precise replacement for

thermocouple thermometry in defining a practical temperature scale. The

program consists of the design and testing of thermometers, electrical

measuring systems, thermometric fixed points, and interpolating

formulations, with the goal of achieving 10 mK or less uncertainty over the full range 630 to 1064 °C. Progress in these areas is outlined

below.

1. Testing new high- temperature platinum resistance

thermometers.

The Chino Company (Japan) is a commercial source of these

resistors. J. Evans (under contract) studied two of these resistors and

found them to perform as well as other candidates (made by NBS, and in

China). These results are providing an accumulating body of evidence

which suggests that special, commercially available PRT's will supplant

thermocouples for temperature scale realization.

2. NBS traceability to Ag and Au fixed points.

J. Evans calibrated several NBS PRT's at the Al, Ag and Au fixed

points in support of the other two high-temperature projects.

3. Recertification of thermocouple calibration.

Many customer thermocouple calibrations are done at the Sb, Ag and

Au fixed points. J. Evans compared his higli quality fixed points with

those used by Burns and Scroger for the thermocouple calibration

service. Evans found that the calibration laboratory fixed points were

incorrect and provided the data needed to correct them.

84
II. INTERNATIONAL PRACTICAL TEMPERATURE SCALE (IPTS-68)

(B. Mangum, G. Burns, M. Scroger, W. Bigge, J. Wise, G. Evans,

C. Van Degrift and G. Furukawa)

II. A. THERMOCOUPLES

These cover the range from 273 K to 2400 K; the thermocouple

laboratory is managed by G. W. Burns with the assistance of M. S.

Scroger. The activities generally fall into two categories: routine

calibrations and non-routine calibrations.

1. Routine calibrations.

Approximately 300 thermocouples were calibrated for 80 customers

during FY 85 producing 105 k$ in test fees.

A new computer, having several times the memory of the previous

computer, was procured and put into operation in the Thermocouple

Calibration Laboratory. The new computer will greatly simplify the

processing of calibration results and the production of emf-temperature

calibration tables for our calibration customers. Since the operating

systems and basic languages of the new and old computer differ,

existing programs must be rewritten and this lengthy task was begun.

2. Non-routine tests.

a. IMGC - NBS Collaboration on Tungsten-Rhenium Thermocouples

As part of a scientific cooperative program between the NBS and the

Istituto di Metrologia ”G. Colonnetti" (IMGC) in Torino, Italy,

Dr. Roberto Perissi spent eleven weeks at NBS working with G. Burns on the calibration of tungsten-rhenium type thermocouples. A group of

sixteen W-3%Re versus W-25^Re thermocouples (thirteen NBS thermocouples

and three IMGC thermocouples) were calibrated in the range 1000 to

2000 OC by direct comparison with a new transfer standard optical

pyrometer developed and calibrated by Dr. R. Righini and others at the

IMGC. The thermocouple calibrations were conducted in a UHV high

temperature furnace where the measuring junctions of the thermocouples

were located within a hollow, cylindrical blackbody cavity formed from

tantalum tubing.

With the exception of one calibration run, the repeatability of the

measurements was very good. However, a systematic difference, ranging

from about 2 °C at 1000 °C to 3 °C at 1600 °C, was observed between

calibration results obtained in this work and previous calibration

results for similar thermocouples (taken from the same spools of wire)

that were calibrated by comparison with Type S and Type B reference

thermocouples. This difference was thought to have been caused by the

lack of true blackbody conditions in the cavity. A calibration check of

the IGMC pyrometer performed by the NBS Radiometric Physics Division at

85
about 1064 °C agreed with the earlier calibration of the instrument made

at the IGMC within 0.1 °C.

The joint IGMC-NBS program will be continued during FY 86. Another

blackbody cavity of improved design will be fabricated for use in the

NBS furnace. Dr. Righini will construct a transfer standard optical

pyrometer at IMGC for the NBS Temperature and Pressure Division.

G. Bussolino of IGMC will come to NBS to assist G. Burns with the

initial setup and operation of the pyrometer. Additional calibrations

of IGMC and NBS thermocouples will be carried out in the 1000 to 2100 °C

range. This effort is aimed at achieving improved thermocouple

standards in the 1600 to 2100 °C range to enable more accurate

thermocouple calibrations to be provided for NBS calibration customers.

b. ASTM and ISA Committee Work

To assist ASTM Committee E20.04 with the preparation of a new

document giving temperature-emf tables for some non-standard

thermocouple systems, temperature-emf tables were computed using

existing polynomials for the following thermocouples;

1) W versus W-26%Re

2) Platinel II

3) Type KP versus Au-0.07at./6Fe

4) Pt-55^Mo versus Pt-0.1^Mo

5) Pt-40/&Rh versus Pt-20^&Rh

6) Ir-40^Rh versus Ir

Tables (in both °C and °F) for the above thermocouples were

provided to the Committee in the appropriate format for inclusion in the

document, which is to be published in the ASTM Annual Book of Standards,

Vol. 14.01.

Since the nicrosil versus nisil thermocouple was recently assigned

a letter designation. Type N, by the SP-1 Committee of the Insturaent

Society of America (ISA), emf- temperature tables for the thermocouple

were prepared for inclusion in ISA standard MC96.1 and sent to the

Chairman of the SP-1 Committee.

Temperature-emf tables for the Type N thermocouple (in both °F and

°C) and for its thermoelements versus platinum (Pt-67) were also

prepared in the appropriate format for inclusion in the next revision of

ASTM Standard E-230 and sent to the Chairman of Committee E20.04.

c. Thermometry for Jet Engines (G. Burns and M. Reilly)

This project, initiated in May of 1984 with support from the U.S.

Navy, is now sponsored by all members of the Armed Forces Combined

Calibration Group (CCG). The overall objectives are to (1) investigate

and evaluate present DOD calibration support of jet engine temperature

86
measurements; (2) provide a comprehensive report that details the

present system and demonstrates several alternative methods to provide

the calibration support required; and (3) develop the support system

that is mutually agreed upon to optimize performance by means of

automation

.

In each jet aircraft engine, groups of thermocouple sensors are

located at various zones within the engine so that the junctions will

accurately sense conditions which are critical to the safe and proper

operation of the aircraft. The average dynamic state sensed by the

thermocouple array is characterized as a temperature which, through

experience obtained during the design and testing stages of engine

development, can be related to engine performance. A primary zone of

interest is that of the exhaust gas temperature (EGT) just downstream

from the turbine. Readings above the normal limit for this zone

indicate conditions which can cause significant reduction of engine life

and make engine operation extremely hazardous. Readings below the

normal limit indicate a condition of reduced engine efficiency with

consequent loss of thrust.

For most types of jet engine thermocouples, the active element is

Type K wire which meets ASTM/ISA special calibration tolerances. The

thermocouple is usually enclosed within a specially designed metal

housing (unique to each engine zone) which provides protection for the

junction as well as correct aerodynamic flow of the hot gas stream in

order to minimize the error in the reading. Each assembly is mounted on

the outer surface of the engine wall with the junction penetrating into

the engine to a fixed depth. The calibration of the engine thermocouple

is known to degrade with use; the useful lifetime depends upon its

particular thermal history and environment within the jet engine.

For many military aircraft, particularly those in the Navy, the

performance of the EGT system is routinely tested situ without

running the engine by using instrumentation called a JETCAL Analyzer

System. This is dons by simulating a known engine operating temperature

and verifying that the instrumentation of the aircraft indicates that

temperature to within the specified tolerance. To achieve this, each

thermocouple of the EGT array is simultaneously heated by a JETCAL

heater probe (a small furnace of special design which is clamped onto

the thermocouple housing). The JETCAL Analyzer controls the average

temperature of the probes at the specified test temperature (usually

near 600 °C) by matching the signal produced by the thermocouple

embedded in each probe to a known voltage generated within the Analyzer.

When the temperature of the EGT thermocouples has stabilized, the

aircraft instrumentation should indicate the test temperature within a specified tolerance, generally ilO °C.

The JETCAL Analyzer is also used "at the bench" to test all

unmounted engine thermocouples during engine overhaul and as well as at

87
the test stands where the performance of the overhauled engine is tested

and "trimmed”.

The JETCAL heater probes are electrically heated using an internal

wire-wound resistance with power supplied by the Analyzer. A

calibrated, special tolerance Type K thermocouple, embedded in the probe

core, is used to sense its temperature. Each model of JETCAL probe is

specially designed to test one particular type of engine thermocouple

assembly. The heater probes are required to be calibrated to i 4 °C or better.

Several studies by the Navy indicate that the present system used

to provide calibration support for JETCAL/TEMPCAL heater probe has been

inadequate for a number of years. The principal reason is because

adequate standards have not been available to the calibration

laboratories. (Because of their unusual geometry, most jet engine

thermocouples cannot be reliably calibrated and therefore do not make

suitable standards by themselves.) It was concluded in 1983 that, due

to the limitations of the current procedures being used by the Navy for

the calibration of the JETCAL probes, realistic calibration

uncertainties were more likely to be 18 °C.

At the request of the CCG, the Temperature and Pressure Division

(TPD) has undertaken the task of assisting the DOD calibration

laboratories to develop improved standards and procedures for the

calibration of the JETCAL heater probes. In April I 985 we submitted an initial report in which we recommended both long- and short-range goals

for upgrading procedures and improving the accuracy of the calibration

of JETCAL heater probes.

The most important long-range goal is for Navy land-based standards

laboratories responsible for the JETCAL heater probe calibration to use

the tin, zinc and aluminum freezing-point cells for direct calibration

of their working standards rather than the current method which is to

compare the working standards with a calibrated Type S thermocouple in a horizontal tube furnace. In support of this goal, we propose to work

together with the Naval Metrology Engineering Center to develop

procurement specifications for the required freezing-point cells and

associated furnaces, the Navy Primary Standards Laboratories to

establish calibration protocols, and the Type II Standards Laboratories

to help set up the calibration facilities and to train their personnel

in the use of the freezing-point apparatus.

In support of the principal short-range goal, to resolve known

problems associated with the calibration of specific JETCAL heater

probes, we propose to develop several new working standards which will

correctly simulate the thermal loading characteristics of the jet engine

thermocouple when it is placed inside the heater probe during

calibration. To do this we expect to devise suitable adapters (specific

for each engine thermocouple) which can be attached to the standard

88
thermocouple after its calibration. The standard thermocouples will be

of sufficient length so that they can be calibrated in thermometric

freezing-point cells (tin, zinc and aluminum) without immersion errors.

II. B. PLATINUM RESISTANCE THERMOMETERS (PRT’s)

The objectives of this program are (1) to maintain the IPTS-68(75)

in the range 13 K to 904 K (the region of the scale in which the

standard instrument is the SPRT); (2) to make improvements in the

realization of that scale; (3) to disseminate the scale (through

calibrations, precision measurement seminars, MAP’s, lectures,

publications, interactions with standards-writing organizations, etc.);

and (4) to prepare for a new IPTS.

The following table outlines the SPRT calibration procedure.

SPRT CALIBRATION PROCEDURE

13 K to 500 K Capsule SPRT’s Calibrations by comparison

against reference standards

78 K to 904 K Long-stem SPRT’s Calibrations by comparison

against reference standards

at 90 K and by use of fixed

points (TP H 2O, Sn, and

Zn)

.

For the capsule PRT’s we are re-evaluating the calibration

procedure. The old system, although having a fast turnaround time, is

largely manual. E. Pfeiffer has studied the feasibility of performing

capsule PRT calibrations on his EPT-76 automated laboratory. That

successful result is reported in III.A.

In the case of the long-stem PRT’s, a new automated laboratory is

under construction. Specific accomplishments this FY include:

(1) Dr. G. T. Furukawa has been analyzing data obtained on the

triple point of oxygen and a paper on the results is in progress.

(2) A draft of the documentation of the platinum resistance

thermometer calibration service was written and given to J. Simmons.

This turned out to be a rather massive volume.

89
(3) A set of lecture notes on platinum resistance thermometry was prepared for the lectures to be presented at the Precision Thermometry

Seminar in October 1985.

(4) A new set of posters detailing the SPRT calibration procedure

and the IPTS-68(75) was prepared.

(5) Modernization and semi-automation of the SPRT Calibration

Laboratory were planned with the help of Drs. R. Soulen and G. Furukawa

and Messrs. R. Kaeser, E. Pfeiffer and W. Bigge.

(6) Apparatus and electronic equipment required for item (5) were

ordered. Most, but not all, of these have been received.

(7) Tin and zinc fixed-point cells are used in the calibration of

SPRT's and since there is a critical shortage of these in the PRT

Laboratory, materials required for the preparation of several new cells

of each were ordered. With the exception of some samples of pure tin

and pure zinc, the materials (graphite crucibles, precision bore glass

tubing, rubber stoppers, etc.) are now in hand and ready for use in the

preparation of the new cells.

(8) Dr. G. Furukawa (under contract) is testing a new 3-zone

furnace (to be used for the zinc point) that he designed. He supervised

the construction of the various parts of the furnace by the NBS

Instrument Shops, and when that was completed he assembled the furnace.

(9) Three new SPRT's suitable for use to the silver point were

purchased from Chino Works America, Inc.

(10) Drs. G. Furukawa and H. Marshak, with some advice from Drs.

B. Mangum and R. Soulen, designed an apparatus, incorporating an argon

triple-point cell, to be used in the calibration of long-stem SPRT's.

Dr. Furukawa provided the principal design information for the system.

This apparatus will accommodate 7 long-stem SPRT's and 6 capsule SPRT's.

Construction has begun on this apparatus and when it is complete, it

will replace the comparison apparatus currently used at the oxygen

point.

(11) We have a continuing MAP on calibration of SPRT's. The MAP

with the U. S. Army Test, Measurement, and Diagnostic Support Group,

Redstone, was completed and the MAP SPRT's are now at Boeing Aerospace

Company.

(12) Since the zinc-point furnace was burned out last year, there

is only one operating furnace left for both the tin and zinc cells.

Nevertheless, during this past FY 62 SPRT's were calibrated. In

addition, data have been taken but not analyzed and reports prepared for

8 additional SPRT's, giving a grand total of 70 SPRT's calibrated.

90
During the calibrations of these SPRT's, further comparisons were

made between the manually operated Guildline dc current comparator

bridge and the automatic Cutkosky dc-pulse bridge in preparation for

automation of the measurement and analysis processes in the calibration

of SPRT's.

(13) The SPRT Calibration Report has been revised significantly so that, when the automation is completed, the customer will get

substantially more information about his thermometer and the calibration

process and its attendant uncertainties. Also, the SPRT will be

routinely calibrated at two currents, with tables provided for zeropower dissipation in the SPRT and for a continuous current of 1 mA

flowing through the SPRT.

(14) The data and results maintained on computer cards for all of

the SPRT's calibrated at the NBS on the IPTS-68 were transferred to

files which can be read and manipulated by the new NBS computer.

(15) Planned organization of the PRT Laboratory for the new IPTS

being proposed.

(16) We began a contract with CCG for the NBS to evaluate the

"best" commercial IPRT's (i.e., non-SPRT) up to 650 °C. As part of this

contract, we selected the "best", i.e., most stable, IPRTs commercially

available and ordered 11 of them - 4 from Minco, 2 from Hy-Cal, 3 from

RDF, and 2 from Burns Engineering.

We have located a furnace to use in this project but we must adapt

it for testing the IPRT's at 650 °C. Following the preparation of the

furnace and testing it, we will begin tests on the IPRT's.

II. C. LABORATORY THERMOMETERS

Approximately 520 liquid-in-glass thermometers and 10 thermocouples

were calibrated by Ms. J. Wise. The number of additional thermometers

calibrated as special tests, including thermistors, industrial platinum

resistance thermometers and digital thermometers, remained at

approximately 100, indicating that the public still has a need for these

special calibrations.

R. Soulen and J. Wise completed a monograph entitled. Thermometer

Calibration: A Model For the State Calibration Laboratory, that will be

printed next month. With the help of this monograph, a state or industrial organization should be able to establish a laboratory to

calibrate temperature measuring instruments in the range of 0 °C to

+200 °C with an accuracy of 0.1 °C.

The computer has been put on the NBSNET, which saves a great deal

of time in processing the data and producing reports of calibration.

Generating reports of calibration in this way enables any errors to be

91
corrected through the word processing program on the computer, and a new

report generated immediately. Conversion of computer programs from the

UNIVAC 1100 to the Cyber 205 has been completed.

J. Wise completed approximately one-half of the Documentation

Project for laboratory thermometers.

J. Wise participated in the biannual Precision Thermometry Seminar

and continued to work with ASTM as Secretary of E-20, Thermometry. She

is also Secretary of Subcommittees E-20.90, Advisory, and E-20. 05,

Liquid-in-Glass Thermometers and Hydrometers. J. Wise serves as a member of ASTM Subcommittees E-20.91, Editorial and Nomenclature and

E-20.08, Medical Thermometry.

II. D. SMALL TUNNEL DIODE OSCILLATOR PRESSURE SENSOR/GAS THERMOMETER

C. Van Degrift continued his transition to the Quantum Hall Effect

project with 65/t of his time spent helping M. Cage with proposal and

report writing, major procurements, and the design of the new

research laboratory. His experience with the low-temperature

refrigeration and thermometry in high field solid helium-3 research is an excellent complement to the existing capabilities of the Electricity

Division (521) in that project.

The remainder of Dr. Van Degrift's time was directed toward the

completion of the Solid He-3 and the Tunnel Diode Oscillator Transducer

projects. Calibrations of the two germanium resistance thermometers

used in the solid helium-3 research against the melting curve, proceeded

with difficulty. The lack of an situ valve at the sample may prevent

the calibration from being more accurate than ± 0.5 mK. Calibrations of

the tunnel diode oscillator pressure sensor against a piston gage are

nearly complete, although it was found necessary to spin the piston by

hand since the drive motor introduced instabilities at the 10-ppm level.

An apparatus, constructed by visiting Italian scientist,

Dr. F. Pavese of Istituto di Metrologia ”G. Colonnetti", has been

maintained to within 100 mK of 0 °C since January to study the

reproducibility and long-term stability of the small tunnel diode

pressure sensors. The results are not very encouraging, as we can

easily see some relaxation processes which have a time scale of hundreds

of hours. We will continue this study on a low priority basis in order

to fully understand the fundamental physics of the relaxation. It

tentatively appears that the diaphragm relaxation follows the nonexponential behavior proposed by P. W. Anderson, et al., for relaxation

of "heirarchically constrained systems”.

92
III. LOW TQIPERATURE SCALE

(E. Pfeiffer, J. Schooley, J. Colwell, H. Marshak, W. Bowers,

W. Fogle)

This project is divided into two parts: (1) the temperature region

covered by the EPT-76 (0.5 K - 30 K) and (2) the region below 0.5 K

covered by the temperature scale NBS-CTS-1 (0.010 K - 0.5 K).

III. A. EPT-76: temperature SCALE

Goal t The primary goal of the EPT-76 laboratory has been to

establish at NBS the Provisional 0.5 K to 30 K Temperature Scale (EPT76) and to provide a calibration service based on that scale. Secondary

goals include a thermometric evaluation of the various resistance

thermometers which presently serve, or may be candidates to serve in the

future, as secondary reference standards in the EPT-76 region. Such

evaluations would address such factors as sensivity, stability,

durability, and smoothing or interpolation methods. Another secondary

goal is the development of automated calibration procedures for transfer

to other temperature calibration laboratories. An added goal in 1985

was evaluating the feasibility of performing automated calibrations of

capsule platinum resistance thermometers (PRT's) on IPTS-68 between

13.81 K and 273*15 K in the EPT-76 comparison cryostat, with a view

toward transferring such calibrations out of the PRT calibration lab.

Progress during FY 1985 : A major accomplishment during FY 85 was

the completion of a three month experimental run during which up to 19

resistance thermometers were variously compared at temperatures between

0.30 K and 295 K. Starting on May 2 and ending August 3» the

experiment, for the most part, ran around-the-clock seven days a week,

attended to by only one person. Some specific accomplishments from the run include:

a) Calibrated three germanium resistance thermometers (GRT's) and

one rhodium-iron resistance thermometer (RIRT) over the range 0.5 K to

30 K against EPT-76 for outside customers. This reduced the EPT-76

customer backload to zero.

b) Calibrated three CRT's over the range 0.3 K to 100 K for

another research project within the Division. An RIRT for the same

project was found to be unsatisfactory for calibration due to excessive

self-heating in vacuum, apparently as a result of leakage of the filling

gas from the enclosing capsule. Also calibrated four additional CRT's

from 1 K to above 90 K for general use at NBS.

c) Transferred EPT-76 from the two NPL-calibrated RIRT's which

serve as main secondary reference thermometers for the scale at NBS to a third RIRT to serve as a backup reference thermometer. The backup RIRT was compared against both reference RIRT's at 43 temperatures over the

range 0.45 K to 27.5 K. The resultant 86 calibration points were

93
smoothed to a standard deviation of 0.12 mK by fitting the R values to a 12th order polynomial in T. This compares with a s.d. of about 0.15 mK

for the smoothed NPL reference calibrations.

d) Measured the self-heating of four RIRT's (the three NBS 100-ohm

RIRT's mentioned above plus a customer's 50-ohm device) over the range

0.5 K to 30 K. The results agree with earlier measurements done below

10 K.

e) Recalibrated a stable CRT which has been in continuous use at

NBS for more than 20 years and which presently serves as a check

thermometer for CRT calibrations in the range 1.5 K to 30 K. A

preliminary analysis indicates that the latest calibration agrees with a 1983 calibration within 0.2 mK below 15 K and within 0.5 mK between 15 K

and 30 K. This seems adequately within the claimed accuracy of ^

1 mK

for NBS calibrations on EPT-76.

f) Realized the transitions of Superconductive Fixed Point Device

SRM -767 (Delta). The transitions of this SRM constitute five of the 11 defining reference points of EPT-76. This particular device (Delta) is

monitored during each EPT-76 calibration run as a check on the stability

of the reference RIRT measurements for the range 0.52 K to 7*2 K. The

results indicate a long-term stability and/or reproducibility of the

combined SRM-767/RIRT measurement system of about t 0*1 mK. This

SRM -767 device also is periodically loaned to the SRM-767 production

laboratory of J.F. Schooley to serve as an inter-laboratory check

standard on EPT-76 temperatures disseminated by the EPT-76 calibration

laboratory and by the SRM-767 production laboratory. A comparison of

the two laboratories' results indicate an inter-laboratory agreement of

i 0.2 mK.

g)

Compared three PRT's between 13*81 K and I 8 I .7 K and at room

temperature to assess the performance of the EPT-76 calibration cryostat

above 30 K with respect to future automated PRT comparisons and to

assess the non-uniqueness of present NBS IPTS-68 PRT calibrations in

that region. Not suprisingly the largest disagreement of 1.2 mK

occurred at I 8 I .669 K, midway between the IPTS-68 calibration points of

90.188 K and 273*15 K. Between 100 K and 21 K the disagreement reduced

to 0.3 mK or less, while between 21 K and 13*8 K it was as much as

0.7 mK.

h) Coincident with the PRT comparisons described above, the three

RIRT's discussed in c) above were calibrated against IPTS-68 from the

PRT's up to 94 K using the Cutkowsky automatic resistance bridge, and up

to 181 K using the dc measurement system. Such calibrations should

reveal any irregularities in the smooth merging of EPT-76 with NBS

IPTS-68 at 30 K and, furthermore, might even reveal any "fine-structure"

deviations of NBS IPTS-68 with respect to thermodynamic temperatures. A

preliminary analysis of the data between 20 K and 9^ K for one RIRT

94
indicates that such merged calibrations are smooth to no better than

about t 0.6 mK.

Plans for FY 1985 ?

a) Although the final documentation of the EPT-76 research was not

completed in FY 85 as previously planned, it is currently estimated to

be 80 - 90 percent completed and the completed portion has undergone a preliminary division review. Selected results from the 1985

experimental run will be incorporated into the document, which is

expected to be completed during the first quarter of FY-86. At that

time the evolution of the EPT-76 laboratory will be considered complete

and the calibration service completely documented. Thereafter, the

calibrations based on EPT-76 will probably be conducted over a 3-month

period once per year by E. Pfeiffer.

b) Limiting the EPT-76 calibration to a once per year event will

free Pfeiffer to work on several projects in the new PRT laboratory.

III.B. EPT-76: SUPERCONDUCTING FIXED POINTS

SRM 767a contains six metallic samples (Nb, Pb, In, Zn and Cd) that

are reproducible to within t 0.3 mK. SRM 767a is in regular production

(6 units supplied to the NBS Office of Standard Reference Materials this

past fiscal year). The units are calibrated in a laboratory maintained

by J. Schooley.

The major effort during FY 85 was given to evaluations of both the

long-term and short-term temperature reproducibility attainable through

the use of SRM 767a. Concerning the long-term drift, the first set of

data comes from a study by E. Pfeiffer in his EPT-76 laboratory.

Pfeiffer re-measured the Tq values of the samples contained in the

SRM 767a device, code-named ’’Delta". The data that he has obtained over

a three-year period in this study are summarized in the following Table.

Evidence of an apparent long-term drift of 0.3 mK in Schooley’s

laboratory is under study. Evidence indicates that the observed "drift"

in the Tq is not an actual variation in the superconductive transitions,

but due to a measurement error induced by a change in laboratory

procedure.

The short-term precision of a Tq measurement was studied in

Schooley' s laboratory. Experiments show that apparently it is possible

to repeatedly measure temperatures that are uniform within ten

microkelvins by the use of the SRM 767a devices.

During FY 86, Schooley plans a direct re-calibration of his RIRT

against Pfeiffer’s standards to test directly the possibility of

thermometer drift. He also plans to complete measurements of the

95
dependence of Tq upon magnetic field. A further experiment planned for

the coming year involves evaluating the stability of paramagnetic

thermometers by use of the SRM 76?a device.

Tc VALUES OF SAMPLES IN THE SRM 767a DEVICE "Deltal"

Element Tc,K 1982 Tc,K 1983 Tc,K 1985

Pb 7.199 95 (dc) 7.200 02 (ac) 7.200 05 (dc)

7.199 90 (ac)

Range = 0.000 15 K

In 3.414 40 (dc) 3.414 46 (ac) 3.414 43 (dc)

Range = 0.000 06 K

A1 1.179 75 (dc) 1.179 75' (ac) 1.179 86 (dc)

Range = 0.000 11 K

Zn 0.850 35 (dc) 0.850 20 (dc) 0.850 32 (dc)

0.850 15 (ac)

Range = 0.000 20 K

Cd 0.519 95 (dc) 0.519 95 (dc) 0.519 93 (dc)

Range = 0.000 02 K

Note that the ranges of the measured temperature variations

occurring in the Tq values listed in the table are no larger

than 0.2 mK, and average about one-half that amount. Barring

coincidental, simultaneous drifts of the reference thermometer

calibrations and the sample transitions, these results place an upper limit of 0.1-0. 2 mK on the long-term drift of for the

"Delta" samples.

III.C. NBS-CTS-1

This scale, developed at NBS and distributed wordwide via SRM 768,

does not have international sanction. Research along parallel lines at

other national standards laboratories (KOL; PTB-Berlin; Helsinki)

should bring confirmation and the possibility of adoption of a provisional temperature scale from 1 mK to 500 mK by the CCT when the

next scale is formulated.

The scale is based on a comparison of two absolute thermometers;

noise and nuclear orientation. Research in both of these areas this

96
past year has been directed at understanding all systematics so that

ultimately a scale accurate to O.IJ will evolve. To these two primary

thermometers are added two secondary thermometers: the melting curve of

He-3 and the paramagnetism of cerium magnesium nitrate.

1

.

New apparatus

The keystone to the low-temperature scale is the establishment

of a new apparatus which can be used to extend the measurements to

temperatures as low as 1 mK. A new dilution refrigerator was installed

this past FY. Leaks delayed the successful operation by 4 months.

Retrofitting the apparatus with filtered, high-quality leads; upgrading

the resistance bridge; improvements in the plumbing and numerous other

upgrading projects took another 4 months. The apparatus has been

successfully operated to temperatures as low as 4.5 mK three times and

the performance of the system well documented. The thermometry

experiments to be conducted on the new apparatus may now commence in

FY 86.

2. Auxiliary thermometry

A SQUID system has been added to the cryostat and tested in

situ in preparation for the paramagnetic measurements. A gas handling

system has been built for the He-3 melting curve thermometer.

3. Noise thermometry

Improvements in noise thermometry have been made at the PTBBerlin, which suggest that the performance of the NBS noise thermometer

could by significantly improved by a radical redesign. Such are design

was done and a new noise thermometer constructed. Tests will proceed in

FY 86.

4.

Nuclear Orientation Thermometry

objectives of the nuclear orientation thermometry program

60p^r^ crystal) T-ray anisotropy thermometer

b) Investigate rare

The

are: a) Recompare the ^^CoCo (single

and the Josephson junction noise thermometer to '0.1

earth systems for their possible use as Y-ray anisotropy thermometers in the

temperature region above that defined by the ^OcqCo (single crystal'

thermometer, namely above '50 mK. c) Investigate the use of Y-ray anisotropy

thermometers for absolute thermometry in magnetic fields.

a) The recomparison of the 60 qo59co (single crystal) Y-ray

anisotropy thermometer and the Josephson junction noise thermometer is

awaiting final test and modifications to the new 3He/^He dilution

refreigerator in R. Soulen’s lab. Preliminary data on the performance of

thermometer has been taken on the Marshak dilution refrigerator using both

Nal(Tl) and Ge(Li) detectors. The agreement between the temperatures deduced

using each detector is fairly good; however, since this refrigerator can only

97
cool to ~15 mK, the results are not that conclusive (the peak of the ^^^Co

thermometer’s sensitivity is at 6.9 mK).

New 59co single crystals have been prepared and are ready to be

irradiated to produce the required ^^Co activity so that they can be

used on the new dilution refrigerator discussed in item 1 above.

b) The collaborative (NBS-Freie Universitat-Bonn Universitat)

research work on the low-temperature magnetic properties of the rare

earth system ^ 1 59xb (single crystal) is proceeding very nicely.

Here at NBS we have measured the anisotropies of some of the more

intense Y-rays as a function of magnetic field and temperature. These

measurements were done on a bulk ^^0Tb^59x5 (single crystal) sample;

i.e., one produced by irradiating the ^59xp single crystal in a reactor

- thus the "I ^^Tb activity is produced uniformly throughout the entire

sample volume. Although the shape of our sample was not favorable to

achieve magnetic saturation at the field that we used (IT) for these

measurements, we were still able to deduce an approximate value for the

quadrupole interacat ion. The latter enabled us to reduce the search

region for the NMR-ON (nuclear magnetic resonance on oriented nuclei)

experiment which was attempted again this past August in Berlin. (These

measurements must be done on an implanted sample rather then a bulk one since the rf skin depth is only on the order of a few hundred angstroms.

The radioactive ^^^Tb is implanted in the surface of the ^59xp single

crystal sample using the isotope separator at Bonn Universitat.) The

attempt in the summer of 1984 was unsuccessful since we had to search a large frequency range (-200 to -1000 MHz) in small steps (2 MHz). The

results of our latest search (the measurements are still going on in

Berlin) indicated that the first resonance (transitions between the spin

substates m = +3 and +2) is about 480 MHz. These results are very

preliminary. If our measurements are successful (and we also find the resonance for m = +2<^ +1) then the "'^0Tb^59xb (single crystal) system

(either implanted or bulk samples) can be used for absolute thermometry

in the temperature region from -30 to 200 mK, complimenting the region

defined by the ^^Co^^co (single crystal) thermometer. Some of these

results will be written up shortly for a publication.

c) One of the problems often encountered in low-temperature

experiments is that of being able to make accurate temperature

measurements in a magnetic field. The only thermometers presently able

to make absolute temperature measurements in a magnetic field are Y-ray

anisotropy ther mometers. Although some Y-ray anisotropy thermometers

can operate without a magnetic field, e.g., the ^Oqo59co (single

crystal) thermometer, most of them require magnetic fields. Any field

greater than that needed to achieve magnetic saturation simply adds to

the hyperfine field already present at the nucleus. Thus the effect of

the magnetic field can be accounted for exactly.

98
In order to demonstrate the usefulness of T-ray anistropy

thermometers (in a magnetic field) in fundamental metrology, we (Dr. G. Eska, Walter-Meissner Institute, Munich, West Germany; Prof. B. G. Turrell, University of British Columbia, Vancouver, Canada; Dr. R. M.

Mueller, I.F.F. der KFA, Julich, West Germany; and H. Marshak) plan to

measure the ^He superfluid transitions. These measurements will be

started this winter on Dr. Eska’s nuclear demagnetization refrigerator

in Munich.

99
IV. MEDICAL THEHMOMETRY

(B. W. Mangum and G. Evans)

The goal of this program is to develop a set of temperature fixed

points and a means of using them to calibrate transfer standards for the

temperature region of interest (0 - 200 °C) to the medical community.

The program is the responsibility of Dr. B. .W. Mangum who is assisted

part-time by G. A. Evans.

The following table outlines the temperature fixed point program.

MEDICAL TEMPERATURE FIXED POINTS

Material Tf (°C) Status

Indium 156.63 Under study.

Succinonitrile 58.0805 i 0.0015 SRM 1970

115 cells tested.

NBS J. Res. paper

written.

SP-260 publication

prepared

.

Phenol 40.92 Under study.

n-Lauric acid 43.95 Under study.

n-Docosane 44.4 Under study.

Rubidium 39.303 i 0.005 SRM 1969

SP-260 publication

completed.

Ethylene carbonate 36.32 Alternative to Rb

under study.

Gallium 29.772 t 0.001 SRM 1968

Several papers

published

.

100
Specific accomplishments this FY include:

(1) Seventy-six triple-point cells of zone-refined succinonitrile

were investigated this year (39 were tested last year) for their

suitability to serve as SRM 1970, a new temperature reference standard

at 58.080 °C. Since three cells (in some cases only two) are prepared

from each zone-refined lot, the cells of each lot generally have

slightly different freezing points due to the presence of different

(small) amounts of impurities. Conseequently , it is necessary to test

each cell for its suitability as SRM 1970. A total of 109 of the 115

cells prepared were deemed suitable to be used as SRM 1970 (their

triple-point temperatures were not lower than 58.0785 ®C). One of the

115 cells broke during tests. A histogram of the freezing-point

temperatures of the 109 cells accepted , plus two of the cells rejected,

as SRM 1970 is shown in Fig. 2. Figure 3 show how the cells of each lot

were distributed. The mean value of the freezing points of the 109

cells accepted for SRM 1970 is 58.0796 °C, with an estimated uncertainty

of 10.0015 °C relative to the International Practical Temperature Scale

of 1968. The total spread in the freezing-point temperatures of the 109

cells was 2.1 mK. The data on the 114 cells of succinonitrile were

analyzed and a paper, entitled "SRM 1970: Succinonitrile Triple-Point

Standard - A Temperature Reference Standard Near 58.08 °C" was written

for the NBS Journal of Research and for the SP-260 series. This gives

not only the results on the 114 cells, but also how the cells were

prepared, and how the user of the SRM should proceed in realizing the

temperature of this fixed point.

(2) We believe that an organic material, sealed in glass cells,

with a fairly large heat of fusion would probably be easier for clinical

laboratory personnel to use than the rubidium triple-point standard

which by its nature must be sealed in stainless steel. With this in

mind, some melting/freezing experiments on 2 large cell and several

small cells of ethylene carbonate (melting point of 36.324 °C) were

conducted to evaluate the suitability of this material to serve as a temperature fixed point near body temperature (37 °C). It appears that

ethylene carbonate can be sufficiently purified that it can be used as a temperature reference point. Both melting and freezing experiments have

been conducted on both the large and the small cells and from these

preliminary experiments it appears that the freezing method, using the

mush technique, yields results which are more reproducible than those

obtained by the melting method. The material can probably be

sufficiently purified that either method may be used for realizing the

fixed point but the freezing method may be the simpler to use. In

collaboration with Dr. John Cox of NPL, a study was made on the 2 large

cells with SPRT’s and also with thermistors. Both groups determined the

triple-point temperature [we obtained the result that T(NBS) - T(NPL) = 0.3 t 0.2 mK, maximum, using 3 SPRT's at NBS and 8 SPRT*s at NPL], the

purity, and melting/freezing behavior. In addition, B. Mangum

investigated the time dependence of the approach to equilibrium after

creating a mush condition following supercooling of the ethylene

101
Freezing Point Temperature (°C)

Fig. 2. Histogram of the triple-point temperatures obtained by freezing

of all of the SRM 1970 cells. The histogram at the bottom of

the figure is for cells designated -1/X; that in the middle of

the figure is for cells designated -2/X; and that at the top of

the figure is for cells designated -3/3*

102
14

w

o5 O

o

0> Si

E

3

12

10

8

6

4

2

0

1/3

F~1 2/3

EH 3/3

t(°C)

Fig. 3* Histogram of the triple-point temperatures of the 109 cells of

SON accepted as SRM 1970, plus those of two cells with

temperatures below 58.0785 °C, which, consequently, were

rejected as being unsuitable for SRM 1970.

103
carbonate, and showed that the technique being used by NPL was flawed.

A compilation of our data has been made and a paper to Metrologia will

be written shortly. We plan to investigate the melting and freezing

behavior of some more small cells of this material next year to

ascertain not only the agreement among the cells of a given lot but also

that among the cells of different lots. The amount of purification

necessary to produce cells with freezing points within a sufficiently

narrow range of temperatures to make this material suitable as an SRM

must be determined also.

(3) Just as there is a special need for a temperature fixed point

near body temperature, so there is a special (even critical) need for

two fixed points bracketing the hyperthermia range used in cancer

therapy. Those two points should be at about 41 or 42 °C and 44 or

45 °C. Several materials have been selected as possibile candidates for

those temperatures, and one small cell of phenol and 3 small cells of

n-lauric acid, have been obtained. More cells of these materials have

been ordered, as has cells for one other material, n-docosane. We made

some preliminary studies of the small triple-point cells of phenol and

n-lauric acid during the year and these materials look promising. Since

hyperthermia is used in cancer therapy, some discussion with personnel

of the National Cancer Institute has already taken place regarding their

funding some of this work. The funding by the NCI, if successful, would

not be available until mid-1986.

(4) The investigation of the melting/freezing behavior of highpurity indium in small Teflon cells has continued in order to further

test the feasibility of using this point (and realized in such small

cells) as a temperature fixed point, and to develop it into an SRM. A

collection of cells of different sizes, different immersion depths and

constructed with different kinds of high-temperature epoxy has now been

prepared and tested. Based on the results of that work, a design of

cells appropriate for SRM’s has been made and an order for the

construction of 100 cells has been put into the NBS instrument shops.

In addition to the possible use of indium as an SRM temperature fixed

point, there is the possibility of using it as a temperature fixed point

for the International Practical Temperature Scale. In fact, a fixed

point at about the melting point of indium is urgently needed for the

calibration of capsule SPRT's, to provide a more accurate calibration

for the most accurate and precise work needed in research, and to

provide a check on the routine calibration of SPRT*s. With this in

mind, we are proceeding to make a thorough investigation of the indium

melting/freezing behavior and of the reproducibility of the

melting/freezing-point temperature. We have begun testing of our two

cells of indium, filled with 99.9999^ pure indium, the cells being of

sizes sufficient for use with long-stem SPRT's and capsule SPRT's. We

have had a lot of trouble with the oil bath being used in investigating

the melting/freezing behavior of the indium in the two cells, but the

problems have been solved now. Some preliminary results on the large

cells indicate the pressure dependence of indium to be

104
4.95 t 0.04 mK/std. atm. A preliminary value of the freezing-point

temperature of one of the cells is 156.635 °C. We plan to continue

measurements on the cells during the coming year.

(5) We have begun an investigation of the quality of diode

thermometers at temperatures below about 400 K. The equipment required

for this investigation was acquired and the computer program for

controlling the experiments and acquiring the data has been written and,

for the high temperature part, i.e., 77 K to 400 K, has been tested. A

selection of 30 of "the best” diode thermometers were purchased and 10

of them were installed in the cryostat. In order to gain experience

with the diodes, we have started the investigation by studying their

and our equipment’s behavior at temperatures above 77 K. Following

completion of this aspect of the study, we will begin the investigation

at temperatures below 78 K. Also, an investigation for NASA of 10 very

small diodes designed for surface temperature measurements has begun in

the range 77 K to 335 K. These also will be investigated at cryogenic

temperatures during the next phase of the NASA project.

105
V. DYNAMIC PRESSURE AND TEMPERATURE

(G. Rosasco, W. Hurst and R. Dove)

Goal ; The goal of this project is to develop the means of

measuring P and T with high temporal response (10 ns) and high spatial

resolution (mm3). a laser diagnostic technique based on nonlinear

optical spectroscopy is used. Specifically the project is designed to

develop the algorithms for inferring P and T from spectral lineshapes

and intensities. A second goal is to accumulate reference data and

develop predictive theory for selected gases of importance in diagnostic

applications.

Accomplishments in FY 85 : We have completed measurements of the

electronic contribution to the nonresonant third order nonlinear

susceptibility of H 2

. As discussed in earlier reports, the nonresonant

electronic term in the third order susceptibility is important in CARS

(coherent anti-Stokes Raman spectroscopy) diagnostics of temperature and

pressure because the CARS signal depends on the squared magnitude of the

third order susceptibility. Thus, there are terms in the response

which are interferences between the (real) nonresonant contributions and

the (complex) resonant contributions. These interference terms

dramatically alter the shapes of the spectral bands and thereby can lead

to uncertainties in the determination of temperature and pressure. (The

values of these quantities are strongly dependent on fitting spectral

shapes.

)

Our measurements of the H 2 susceptibility generally followed the

approach used previously for Ar and N 2

* The experimental procedures and

data analyses were improved and better precision achieved. The data and

best fit model for the density dependence of the observed nonresonant

signal normalized by the amplitude of the resonant susceptibility of the

D 2 internal standard are shown in Fig. 4. The points labelled

are the pressure dependent response of the optical system which was

determined from two separate experimental runs (1-6 atm) on D 2 :He

reference samples. The best value for the ratio of the total

nonresonant background of H 2 to the amplitude of the internal standard

AqNq has an uncertainty of +0.0003 and -0.0005, i.e., approximately

i This level of precision is approximately 3 times better than that

achieved in our earlier measurements. From this ratio we calculate the

electronic contibution (3CJ/24) (approximately 1/2 the total) to be

0.445 X 10“^^ esu with an uncertainty (not including the uncertainty of

the reference standard) of ± 6 %.

In order to more accurately interrelate the values of the

electronic susceptibility measured by other nonlinear optical techniques

(see Table from last year's report) and thereby assess the accuracy of

our knowledge of this quantity, we have used a simple model for the

frequency dependence of the electronic term in the third order

susceptibility. This quantity is a function of the four frequencies

involved in the experiment, and the simple dispersion relation we have

106
Rati

0

(5%) : (95%)

10

8

C\Jo

4

M

Best

2

0

0 2 4

p (atm)

6

Fig. 4. Measured pressure dependence of the nonresonant signal

normalized by the amplitude of the resonant susceptibility of

D 2 j obtained in determination of the nonresonant

susceptibility of H 2 (top curve). The lower curve indicates

the pressure dependent response of the optical system, a contribution included in the data analysis. The "best" value

obtained for the normalized nonresonant background of H

2 is

indicated.

107
used is based on approximating the electronic term as the product of

four first order susceptibilities. This leads to a dispersion formula

which depends on an effective squared frequency equal to the sum of the

squares of these four frequencies. We applied this formula to the data

compiled and measured in our earlier work, to recent measurements by

Shelton of the dispersion of the susceptibility in field induced second

harmonic generation (FISHG), and to the theoretical calculations of the

susceptibility of He which is the (absolute) reference standard for the

FISHG measurements. The results of this analysis are displayed in

Fig. 5. Remarkably, all the data can be accounted for by this simple

dispersion formula. Our analysis is the first demonstration of a unifying dispersion relation for all nonlinear optical techniques. We

now feel confident that gas phase susceptibilities can be accurately

(better than 5J) predicted for any technique of interest if a reliable

value is available from any other technique or at some other wavelength.

Work also has continued on modelling the spectral lineshape under

conditions where both velocity- and phase-changing collisions are

important. The importance of accurate predictions of spectra under

these conditions increases with increasing temperature, as discussed in

last year’s report. We have now developed a fast, rapidly convergent

computer program for fitting experimental lineshapes to the two

’’standard" models which apply under these conditions. The standard

models are the hard and soft collision models. Data for five systems

(D 2sX, X=D2 , H 2 , He, N 2 > Ar) have been acquired and/or analysed over the

past year.

The development of a (Raman) pump laser of high peak-power and

narrow bandwidth also has been in progress during the past year. The

requirements for the pump laser in the context of our work and some

alternatives for providing the necessary performance were discussed in

last year’s report. We have pursued the development of an injectionseeded (also termed, somewhat inaccurately, injection-locked) high power

flash lamp pumped dye laser (FLPL). Using a number of FLPLs, which we assembled from parts loaned to us by other groups at MBS, we have

succeeded in building a system which produces -10 mJ in a 1 ys pulse

(10 pps) with a full bandwidth of under 8 MHz. The spectral purity of

this laser is quite high in that the power at the peak of the 8 MHz

component is of the order of 1000 times that at the peak of any residual

broadband component in the output of the laser. We note that the nonseeded, free-running FLPLs typically produce outputs with bandwidths of

lO’s-IOO’s of cm~^ (1 cm“^ = 30 GHz). The spatial mode of this laser

also is very good, being essentially TEMqq. The bandwidth of our system

is at least 2-5 times more narrow than that of lasers based on (doubled)

Nd:YAG pumped dye laser amplifiers. However, for our experimental needs

the peak power of this laser is too low. We now are investigating a two

stage FLPL system to increase the peak power by a factor of 5-10. We

are confident that we can achieve the power requirements, but must

determine if the spectral purity and spatial mode quality are sufficient

for our needs. If successful, the two-stage FLPL system will be

108
10^9

(3o/24)

(esu)

o

X

HL.

0) w Ch

cr cr 0 < < 0 0

L_ J

Fig. 5. Electronic hyperpolarizabilities of Ar, H 2 and He at 1 amagat,

296 K, measured by various workers using the labelled

experimental techniques versus the square of the effective

frequency obtained from the dispersion relation.

109
superior to any existing alternative for the needs of our experimental

program.

Plans ; In the coming year we have a number of projects planned

which will be pursued in collaboration with scientists who will be

joining our effort on a temporary basis. A postdoctoral trainee from

Howard University, Dr. Larry Petway, will be working with us over the

next year on the problem of the effects of velocity-changing collisions

in diagnostic spectra. He will be exploring both experimentally and

theoretically the prediction of line shapes for both heavy and light

collision partners over a large range of temperature (to 1800 K). A

guest worker collaboration has been established with Prof. David May of

the University of Toronto, Physics Department. The experiments to be

conducted at NBS with Prof. May involve line broadening and shifting of

the Q-branch spectrum of HD. Our facilities are uniquely suited for

these measurements and Prof. May's expertise in problems of pressure

dependence of Q-branch spectra will be very helpful in our work.

Dr. Kermit Smyth of the NBS Center for Fire Research will be joining us for an NBS Internal Sabbatical in October 1985. His interests are in

learning more about the techniques of nonlinear Raman optical

diagnostics and in determining a predictive basis for diagnostic

spectra. The emphasis of this collaboration will be on experimental

studies of foreign gas broadening and the temperature dependence of line

widths.

The first few months of the experimental program for the coming

year will be centered on the final stages of development of the high

peak-power Raman pump laser, the variable T and P furnace, the gas

mixing system, and the data acquisition system. The latter three

systems are close to completion but do require final assembly and

testing. Since there are still major questions to be resolved in the

case of the performance the Raman pump laser, we have begun more serious

planning for the development of the system based on a single

longitudinal mode, injection-seeded Nd:YAG laser (see last year’s

report). Clearly, the laser systems remain a major challenge for our

experimental program.

110
VI . PISTON GAGES

(V. Bean, G. Driver, W. Markus, B. Welch, and J. Houck)

Goal ; The piston gage is the instrument of choice for precise

pressure measurements in the range above the limits of manometry. The

instrument consists of a carefully made piston fitted into a matching

cylinder which is, in turn, connected to a pressure generating system.

The piston is loaded with known weights, floated by adjusting the

pressure using a transmitting fluid, and rotated to relieve friction and

to assure concentricity. The pressure is calculated as the ratio of the

downward force due to the weights loaded on the piston to the effective

area of the piston-cylinder combination. Our goal is to determine the

effective area at atmospheric pressure Aq, and the change in the

effective area with pressure, in order to; (A) equal or surpass the

other national standards laboratories; (B) provide American piston gage

manufacturers with the needed calibration services to keep their

products competitive in the world market; (C) meet the need for

increased accuracy requested by our calibration service customers, such

as the DoE and DoD laboratories.

Commercially available gages span the range from 2 kPa to 1.4 GPa

and may be designed for use with gases or fluids in appropriate parts of

the range.

Progress in FY 85 ; During FY 85 we have conducted a systematic

search for those factors that can affect the accuracy of three special

piston gages at the part-per-million level. We have demonstrated that;

A . Aq

1. In the absolute mode, gas molecules escaping out of the annular

space between the piston and the cylinder and colliding with the

underside of the weight hanger can change the pressure at one atmosphere

by about 2 ppm. There is no effect in the gage mode since the meanfree path of the gas molecules is so short compared to gage dimensions.

2. When two gages having areas differing by a factor of 4 are

balanced in the gage mode and then the space around the weights

evacuated (the absolute mode), we find that the air bouyancy correction

for the weights does not fully account for the resulting out-of-balance

condition. The effect is a function of the gas used as the pressure

medium. For example, for helium at one atmosphere it amounts to about

1 ppm, for nitrogen, it is 23 ppm. The effect is also a function of

pressure and the width of the gap between the piston and the cylinder.

There are two possible mechanisms by which gas molecules could exert a vertical force on the piston and create this effect. The first is

momentum transfer due to molecular collisions with the piston; the

second is electrostatic force due to the charge on the molecules. When

the measured differences were plotted for six gases, the correlation

with molecular weight was poor, while the plot versus the electrostatic

111
force term for the Van der Waals equation of state is rather monotonic

(Fig. 6). This suggests that electrostatic force rather than momentum

is the more likely explanation.

Fig. 6. Pressure differences between gage and absolute mode for several

gases plotted as a function of the Van der Waals electrostatic

term.

112
The next step in this investigation is to determine the gas density

along the length of the annular space between the piston and cylinder

while the gage is operating in both the absolute and gage modes. This

density distribution will be studied as a function of pressure using

several gases. Current practice in piston gages assumes that a calibration done in the gage mode is valid in the absolute mode.

Clearly, in light of these new results, that is a poor assumption. We

are now in a position to provide emperical corrections for the effect,

but understanding of the underlying physics requires more work.

B. Distortion

1. Pressure coefficient. Work continues on improving methods to

determine piston gage pressure coefficients. We have designed and built

an apparatus to measure the change of the outer diameter of the cylinder

of a piston gage as a function of pressure and length along the

cylinder. The essential feature is a guarded capacitor electrode in the

form of a thin ring surrounding the cylinder and mounted such that it

can be moved with a micrometer head along the length of the cylinder.

The instrument has nanometer sensitivity. Figure 7 shows the change in

cylinder outer diameter at 25 MPa plotted as a function of length along

the cylinder. When this preliminary data is confirmed with other

measurements, then the results will be compared with calculations based

on a rigorous solution of the biharmonic equation as a test of the

suitability of the equation for calculating the distortion coefficient.

2. Controlled-clearange gages. At higher pressures, the only

appropriate way to deal with the distortion problem is to use a controlled-clearance piston gage. We have begun the design of a new

280-MPa controlled-clearance gage which incorporates a commercially

available piston and cylinder assembly. This gage is intended to become

a new primary standard in that range.

113
Fig. 7. The change of outer diameter of the cylinder of a piston gage

at 25 MPa plotted as a function of length along the cylinder.

114
VII . VACUUM

(C. Tilford, D. Martin, S. Wood, R. Hyland, C. Ehrlich,

A. Filippelli F. Long, and K. McCulloh)

VI I. A. MANOMETRY

The cornerstone to this program is the ultrasonic interferometer

manometer (UIM). It is used for calibrations, as a prototype for other

manometers, and as a research tool. In the first category, the UIM has

continued to serve as a workhorse for low pressure and vacuum

calibrations, including those required to support in-house activities.

The number of "for fee" calibrations of capacitance diaphragm gages

increased only slightly to 14. However, a like number were performed to

maintain the gages used in the leak and high vacuum flowmeters, and to

verify the continued stability of the gages used in the BIPM-sponsored

low-pressure round robin, for which NBS is the pilot laboratory. An

increasing number of ball gages, widely used for low range differential

pressure measurements, have been received for calibration on the UIM.

This has required a considerable amount of time as we attempt to

understand the low range performance of this type of gage.

The accuracy of the pressure measured by the UIM is currently

limited by one major factor - the uncertainty in the speed of sound in

mercury. A separate apparatus has been built to measure this quantity.

The instabilities in these measurements are two to three times larger

than expected, but the temperature uniformity and stability are somewhat

better than expected. Some difficulty has been experienced in

controlling the mercury levels, but the main problem at this time is the

failure of an infrared detector and its backup spare, used to stabilize

the CO 2 laser. Delivery of a replacement unit is expected shortly.

The precision of the UIM may be inferred from a comparison with

another type of a gage (a piston gage, PG14). The precision is 2-4 ppm

with comparable long-term stability.

Several design changes in the UIM have been developed, to the point

that they can be implemented. They are intended to enhance the "high"

pressure performance of this instrument. These include a better

temperature control system, direct coupling of the ultrasonic transducer

to the mercury, and improved RF electronics and microcomputer control

systems. These will be implemented and tried out in instruments to be

built for the Navy Engineering Metrology Center and the Sandia Primary

Standards Laboratory. The Navy has requested a 2-3/4 meter manometer,

2-1/2 times the range of our present instrument. This will present

significant fabrication and assembly problems, but will allow us to

explore the upper limit to the range of this type of instrument.

A measurement survey of the accuracy of aircraft altimeter

calibration facilities at 57 locations throughout the country was

conducted with the assistance of A. McCoubrey and G. Driver under the
sponsorship of the Federal Aviation Administration. The results are

still being analyzed but it is clear that the accuracy varies greatly

between facilities.

VII. B. HIGH VACUUM STANDARDS

The major effort has been in the extension of our vacuum standards

to lower pressures and the development of leak rate standards.

Concurrent with this has been a rapid increase in our high vacuum

calibration work load, participation in an international vacuum

standards comparison, and continuing investigations of the properties of vacuum transfer standards, most notably the spinning rotor gage. This

has generated an intolerable overload on existing equipment,

particularly our primary high vacuum standard. Thus, much of the past

year has been spent building custom equipment, getting it into service,

and finding the space to accomodate it. In February the high vacuum lab was shut down for three months and was doubled in size. The new space

allowed us to install part of a vacuum system which we had obtained as surplus from NASA and modified to serve as part of an interim leak rate

standard. We have also installed and are presently testing a new

’’bellows" flowmeter that will supplement our existing "piston" flowmeter

and be used with both the leak standard and the vacuum pressure

standard. A second part of the NASA system has been more extensively

modified and intial testing begun. This sytem will initially be used

for tests related to the development of ultra-high vacuum standards, but

our intent is that it will ultimately become part of an improved leak

standard. A third, entirely new, system has been designed and is nearly

half fabricated in the NBS shops. It is intended to operate at lower

pressures and take some of the overload from the primary high vacuum

standard. It has also been designed to permit the experimental

investigation of certain systematic errors that are difficult to

theoretically model.

In spite of the disruption of the laboratory and the substantial

effort expended on getting the new equipment designed and into service,

there has been considerable progress made with available equipment. By

refinement of our operating procedures and small modifications to the

equipment we have been able to extend the range of the existing primary

high vacuum standards two decades down, and confirm that we can make

reliable measurements at 10~^ Pa (10~8 Torr), although with an increase

in the uncertainty to 55&. An extensive series of measurements have been

conducted on a group of spinning rotor gages as part of an international

high vacuum round robin conducted under the auspices of the BIPM. These

data (for our lab only) have been combined with other data as part of an error assessment that will appear, along with a description of the

apparatus, in an archival journal publication. We also managed to

perform 24 high vacuum "for fee" calibrations during the year, up from

12 the year before, but apparently a record soon to be surpassed, as 14

calibrations have already been scheduled for FY 86 as of the end of

September.
Characterization of vacuum transfer standards continued at a somewhat reduced pace. The main activity was the investigation of the

behavior of hot filament ionization gages in magnetic fields, a problem

of particular interest to the magnetic fusion research program. The

results were quite complicated, but did establish that radical changes

in gage behaviour can occur at fields as low as a few hundred Gauss.

The most dramatic changes are negative collector currents and

oscillations within the gage structure in the 100 to 600 MHz range.

Work on the spinning rotor gage has continued as an integral part of our high vacuum standards and calibration work. We have been attempting to

correlate gage performance and signal characteristics, understand the

frequency dependence of the residual drag, and accumulate a body of

historical calibration data to assist in evaluating the long term

stability of this type of gage. Most of our results to date have been

published in archival journals. Bernd Lindenau, one of the codevelopers of the spinning rotor gage, joined us in July as a guest

worker, and has started a research program to address the factors

limiting the low pressure range of the gage.

In spite of the pleasing success this last year in reducing the

lower limit of our high vacuum standard it is apparent that future gains

will be harder to make. We are now at pressures where we can no longer

rely on the types of gages that we understand as a result of the

previous year's work, and both lower range leak and pressure standards

will require better understanding of UHV gages. Limited

characterization work will soon start on UHV nude BA gages, modulated BA

gages, and extractor gages. We will also begin preliminary work towards

better understanding quadrupole mass spectrometers. We are further

limited by the hydrogen background in our vacuum systems. One of the

experiments scheduled for the second modified NASA vacuum chamber is a "low" temperature (450 °C) bake in a nitrogen atmosphere to determine if we can significantly deplete the interstitial hydrogen. If this fails

we will have to pursue high temperature vacuum baking, or use of

aluminum vessels. A broader concern is that, as we go lower in

pressure, certain assumptions in the design of the standard become more

critical and there is little or nothing in the way of other standards

with which to make comparisons. Therefore, in the interest of

developing an alternative measurement technique employing different

physics, we have entered into and are providing financial support for a collaborative research program with Bruce Kendall of Penn State

University to investigate a Brownian Motion gage. As an absolute

standard the Brownian motion gage should in theory improve as the

pressure is reduced, but there are several practical problems that must

first be solved. Kendall's experience in this area should be very

valuable in making a start in addressing these problems.

Last February two more training courses were held on the use of the

spinning rotor gage. In spite of the time of year and limited publicity

we quickly had capacity attendance, and the demand continues. The

additional equipment and laboratory space now available will allow us to
expand the class size, and, most importantly, avoid the complete shut

down and removal of some experiments during the classes. We also had

larger than expected attendance at a workshop cosponsored last spring

with the Fusion Technology Division of the American Vacuum Society on the Calibration of Residual Gas Analyzers. A doubling of expected

attendance to 80 necessitated a more formal format than we had desired.

Workshops are being organized for the fall of 1986 on ultra high vacuum gaging and for the spring of 198? on leak standards and calibrations.

It is expected that a followup to the RGA Workshop will be held in I 987 .
VIII. LEAK STANDARDS

(C. Tilford, R. Hyland, C. Ehrlich, S. Wood, F. Long, D. Martin)

The leak rate standards program has benefited greatly from the high

vacuum standards development and is off to a fast start. A series of

measurements were performed using the high vacuum primary standard and

the piston flowmeter on two sintered metal transfer leaks calibrated by

the Sandia Primary Standards Laboratory (SPSL). It became apparent that

one of the leaks was not stable but measurements on the other leak, and

subsequent recalibration by SPSL, indicate agreement between the two

laboratories to within a few percent between 4 x 10“^^ and

3 X 10”® moles/sec (10”® and 7 x 10”^ std cc/sec). A second series of

measurements have been performed using the modified NASA vacuum chamber,

using both the piston and the new bellows flowmeter, and a sintered

silicon carbide transfer leak. These measurements have shown agreement

between the two flowmeters at the low end to better than a percent and

have been combined with the earlier measurements to establish a lower

limit of our present measurement capability of at 10”^"' moles/sec

(2 X 10””^ std. cc/sec). These results will appear in an archival

publication.

The helium leak comparator contributed by the SPSL has been

modified to broaden its temperature range. It has been used to

investigate the temperature dependence and equilibration times of helium

diffusion leaks. It is expected that it will be an integral part of the

leak special test service that we plan to offer in the near future.

At the moment the primary technical problem preventing the early

introduction of a leak calibration service is the lack of reliable

transfer standards. The results with the sintered metal leak were

disappointing. The results for the one SiC leak tested to date has been

encouraging and several other transfer leaks have been fabricated, and

will be tested.

An article was written which was chiefly educational in nature.

The tradition of characterizing flow (leak) rates in terms of a "throughput” rather than a true flow rate has evolved over the years.

This article addresses this problem and attempts to encourage users to use the more properly defined physical unit.
INVITED TALKS

Temperature and Pressure Division (522)

Venn E. Bean, "Pressure Metrology; Primary Standard Piston Gages",

Proceedings of the 10th Conference of the International Association for

the Advancement of High Pressure Science and Technology, Amsterdam,

8-11 July 1985.

George T. Furukawa, "Fixed Points of Thermometry" ASTM Committee E20

Technical Talk, Los Angeles, CA, 22 May 1985.

Richard W. Hyland, "Some Characteristics of Transfer Leaks", 14th Annual

Symposium Applied Vacuum Science and Technology/Florida Chapter,

American Vacuum Society, Clearwater, FL, February 4, 1985.

G. J. Rosasco, "Dispersion in the third-order nonresonant

susceptibility", Gordon Research Conference on the Laser Diagnostics in

Combustion, New London, NH, July 1985.

Robert J. Soulen, Jr., "Recent Advances in Pressure and Temperature

Metrology at NBS", Physikalisch-Technische Bundesanstalt (PTB), Berlin,

West Germany, 19 June 1985.

Robert J. Soulen, Jr., "Recent Developments in NBS Cryothermometry",

Freie University of Berlin, Berlin, West Germany, 24 June 1985.

Sherry D. Hood, "Things Your Mother Never Told You About the Spinning

Rotor Gage", Tennessee Valley Chapter, AVS, Knoxville, TN, April 30,

1985.

120
PUBLICATIONS

Temperature and Pressure Division (522)

IN PRINT;

1. J. C. Legras, V. E. Bean, J. Jager, S. L. Lewis, and G. F. Molinar,

"Note on the results of the first phase of an international

comparison in the pressure range 20-100 MPa organized by the High

Pressure Working Group of the Comite Consultatif Pour la Masse, J. Phy. E: Sci. Instrum. J_8, 361 (1985).

2. J. C. Legras, V. E. Bean, J. Jager, S. L. Lewis, and G. F. Molinar,

"International comparison in the pressure range 20-100 MPa

organized by the High Pressure Working Group of the Comite

Consultatif Pour la Masse," BIPM Technical Report 84/2.

3. J. H. Colwell, W. E. Fogle, and R. J. Soulen, Jr."The NBS

Temperature Scale in the Range 15 to 200 mK", Proceedings of the

17th International Conference on Low Temperature Physics , Karlsruhe, FRG, August 15-22, 1984; (North-Holland, Amsterdam, 1984)

p. 385.

4. C. D. Ehrlich, A. Deforge and R. Kiebert, "A Technique for

Optimizing the Disc Uniformity of a Magnetic Scanning High Current

Implanter", Nucl. Instrum, and Methods 228 (1985).

5. R. Liebert, B. Pedgers, C. Ehrlich and W. Callahan, "Performance

Characteristics of the Extrion 160-10 Ion Implantation System",

Nucl. Instrum, and Methods 16 (1985).

I 6. J. P. Evans, "Evaluation of Some High-Temperature Platinum

Resistance Thermometers", NBS J. Res. No. 5, Sept. /Oct. 1984.

7. W. E. Fogle, J. H. Colwell, and H. J. Soulen, Jr., "Determination

of the Superconductive Transition Temperatures of Cd, Zn, and A1

Using a Josephson Junction Noise Thermometer,", Proceedings of the

17th International Conference on Low Temperature Physics , Karlsruhe, FRG, August 15-22, 1984; (North-Holland, Amsterdam,

1984), p. 1149.

8. R. W. Hyland, "A Comparison of Some Thermodynamic Properties of HpO

from 273.15 to 473.15 K as Formulated in the I 983 ASHRAE Tables and

the 1983 NBS/NRC Steam Tables", Moisture and Humidity I 985 - Measurement and Control in Science and Industry (1985) pp. 29-35.

Proceedings of the 1985 International Symposium on Moisture and

Humidity, Washington, DC, April 15-18, I 985 .

121
9. R. W. Hyland and C. R. Tilford, "Zero Stability and Calibration

Results for a Group of Capacitance Diaphragm Gages", J. Vac. Sci.

and Tech. ^

(3), 1731 (1985).

10. Robert L. Berger, Thomas R. Clem, Victoria A. Harden, and B. W.

Mangum, "Historical Development and Newer Means of Temperature

Measurement in Biochemistry", chapter in Methods of Biochemical

Analysis, Vol. 30, edited by David Glick, (John Wiley & Sons, New

York, 1984), pp. 269-331.

11. B. W. Mangum, "Stability of Small Industrial Platinum Resistance

Thermometers", NBS J. Res. 305-316 (1984).

12. H. Marshak and C. H. Spiegelman, "Determining Multipole Mixing

Ratios from Nuclear Orientation Experiments," Nucl. Instrum, and

Methods A234 , pp. 455-467 (1985).

13. H. Marshak, "Gamma-Ray Multipole Mixing Ratios Using Nuclear

Orientation; *’°°Er", Hyperfine Interactions pp. 413-422 (1985).

14. K. E. McCulloh, S. D. ¥ood and C. R. Tilford, "Zero Stability of

Spinning Rotor Vacuum Gages", J. Vac. Sci. Tech A, _3 (3)>

May/ June 1985.

15. W. Lempert, G. J. Rosasco, and H. S. Hurst, "Rotational collisional

narrowing in the NO fundamental Q-branch, studied with CW

stimulated Raman spectroscopy," J. Chem. Phys. 4241 (1984).

16. G. J. Rosasco and M. S. Hurst, "Measurement of resonant and

nonresonant third-order nonlinear susceptibilities by coherent

Raman spectroscopy", Phys. Rev. A 3^, 28l ( 1985).

17. Go J, Rosasco and W. S. Hurst, "Phase-modulated stimulated Raman

spectroscopy", J. Opt. Soc. B 2, 1485 (1985).

18. James F. Schooley, Thermometry , NBSIR 85-3133; also to be published

as a CRC book.

19. J. F. Schooley and J. H. Colwell, "Superconductive Temperature

Reference Points Above 0.5", Proceedings of the 17th International

Conference on Low Temperature Physics , Karlsruhe, FRG, August 15-

22, 1984; (North-Holland, Amsterdam, 1984), p. 409.

20. Robert J. Soulen, Jr., "Status of the International Temperature

Scale", Proceedings of Measurement Science Conference, Santa Clara,

CA, Jan. 17-18, 1985. (Tied for best paper of the conference.)

21. C. R. Tilford, "Sensitivity of Hot Cathode Ionization Gages", J. Vac. Sci. Tech. 546 (1985).

122
22 . C. R. Tilford, "Characteristics of Ion Gages", in the Proceedings

of the Int'l Symposium on Vacuum Technology and Nuclear

Applications, edited by R. Krishnan, Ch. Verkate Swarlu, and S. P. Mhaskar (Indian Vacuum Society, Bombay, 1984), p. 139*

23. C. T. Van Degrift, "The Use of Tunnel Diode Oscillators as High

Precision Transducers from 0.02 K to Room Temperature", in

Proceedings of the Tenth International Cryogenic Engineering

Conference , Helsinki, Finland, 31 July - 3 August 1984, ICEC10,

edited by Dr. H. Collan, Dr. P. Berglund and Prof. M. Krusius

(Butterworth & Co., England, 1984), pp. 349-352.

24. C. T. Van Degrift, "A Progress Report on the Development of a Small

High Precision Pressure/Temperature Sensor For use at Low

Temperatures," in Proceedings of the Tenth International Cryogenic

Engineering Conference , Helsinki, Finland, 31 July - 3 August 1984,

ICEC10, edited by Dr. H. Collan, Dr. P. Berglund and Prof. M.

Krusius (Butterworth & Co., England, 1984), pp. 353-356.

25. B. E. Welch and Vern E. Bean, "Pressure and temperature

measurements in the annulus between the piston and cylinder of a simple dead-weight gauge," Rev. Sci. Instrum. 1091 (1984).

26. S. D. Wood and C. R. Tilford, "Long-term Stability of Two Types of

Hot Cathode Ionization Gages", J. Vac. Sci. Tech. A 3, (3)> May/June

1985.

APPROVED FOR PUBLICATION:

B. E. Welch, L. A. Guildner, and Vern E. Bean, "Factors Affecting the

Precision of Gas-Operated Piston Gages at the Part per Million Level,"

Proceedings of the 31st International Instrumentation Symposium, San

Diego, CA, 6-9 May 1985.

Ruben J. Lazos-Martinez and Vern E. Bean, "Elastic Distortion in Piston

Gages", Proceedings of the Xth Conference of the International

Association for the Advancement of High Pressure Science and Technology,

Amsterdam, 8-11 July 1985.

V. E. Bean (Chairman), S. Akimoto, P. M. Bell, S. Block, W. B.

Holzopfel, M. H. Manghnani, M. F. Nicol, and S. M. Stishov, "Another

Step Toward an International Practical Pressure Scale; 2nd AIRAPT IPPS

Task Group Report," Proceedings of the Xth Conference of the

International Association for the Advancement of High Pressure Science

and Technology, Amsterdam, 8-11 July 1985.

Vern E. Bean, "Pressure Metrology; Primary Standard Piston Gages",

Proceedings of the 10th Conference of the International Association for

the Advancement of High Pressure Science and Technology, Amsterdam,

8-11 July 1985.

123
Charles D. Ehrlich, "A Note on Flow Rate and Leak Rate Units", Journal

of Vacuum Science and Technology A.

Richard W. Hyland, Charles D. Ehrlich, Charles R. Tilford and Steve

Thornberg, "Transfer Leak Studies and Comparisons of Primary Leak

Standards at NBS and SNL", Journal of Vacuum Science and Technology A.

B. W. Mangum, "Temperature and Thermometry", The Encyclopedia of

Physics, 3rd Edition, edited by Robert M. Basancon, Van Nostrand and

Reinhold Co., New York, 1985.

B. W. Mangum and S. El-Sabban, "SRM 1970: Succinonitrile Triple-Point

Standard - A Temperature Reference Standard Near 58.08 °C", NBS Journal

of Research, 1985 or 1986.

B. W. Mangum and S. El-Sabban, "SRM 1970 : Succinonitrile Triple-Point

Standard - A Temperature Reference Standard Near 58.08 ®C", NBS

Special Publication SR 260-101, 1986.

E. E. McCulloh, C. R. Tilford, C. D. Ehrlich, and F. G. Long, "Low Range

Flowmeter for Use with Vacuum and Leak Standards", to be published in J. Vac. Sci. Tech. A.

J. Tapping and M. L. Reilly, "The Index of Refraction of Sapphire

Between 24 and 1060 °C for Wavelangths of 633 and 799 nm, to be

published in J. Opt. Soc. America.

C. R. Tilford, K. E. McCulloh and S. D. Wood, "NBS Primary High Vacuum

Standard", Journal of Vacuum Science and Technology A.

J. A. Wise and R. J, Soulen, Jr., "Thermometer Calibration: A Model for

State Calibration Laboratories, to be published as NBS Monograph 174.

124
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Temperature and Pressure Division (522)

V. E. Bean, Chairman, AIRAPT (International Association for the

Advancement of High Pressure Science and Technology) Task Group on the

International Practical Pressure Scale,

V. E. Bean, Member, BIPM (International Bureau of Weights and Measures)

Consultative Committee for Mass and Related Quantities, Working Group on Medium Pressure.

V. E. Bean, Member, BIPM (International Bureau of Weights and Measures)

Consultative Committee for Mass and Related Quantities, Working Group on High Pressure.

V. E. Bean, Member, ICSU (International Council of Scientific Unions)

Committee on Data for Science and Technology, Task Group on Critical

Interdisciplinary Survey of Property Data on High Pressure Phases.

G. H. Burns, Member, ANSI SP-1, American National Standards Institute

Committee on Temperature Measurement Thermocouples.

G. H. Burns, Member, ASTM E-20, American Society for Testing and

Materials Committee on Temperature Measurement, Subcommittee E-20. 04,

Thermocouples

.

C. D. Ehrlich, Member, ASTM E-7, American Society for Testing and

Materials Committee on Nondestructive Testing; Member, Subcommittee

E7.08, Leak Detection Testing.

G. T. Furukawa, Member, ASTM E-20, American Society for Testing and

Materials Temperature Measurement Committee; Subcommittee E-20. 03,

Resistance Thermometers; Subcommittee E-20. 04, Thermocouples; Secretary,

Subcommittee E-20. 06, New Thermometers; Member, Subcommittee E-20. 07,

Fundamentals in Thermometry; and Subcommittee E-20. 94, Publications.

H. S. Hurst, Member, ANSI MC088, American National Standards Institute

Committee on Calibration of Instruments, Subcommittee SC.03,

Temperature.

B. W. Mangum, Member, NCCLS C002, National Committee for Clinical Laboratory Standards, Area Committee on Clinical Chemistry, Subcommittee

SC.01, Enzyme Assay Condition, Working Group WG.01, Temperature Measurement and Control; and Member, NCCLS C010, Area Committee on Instrumentation; Secretary, Subcommittee SC.01, Temperature.

125
B. W. Mangum, Vice Chairman, ASTM E-20, American Society for Testing and

Materials, Temperature Measurement Committee; Member, Subcommittee E20.03> Resistance Thermometers; Chairman, Subcommittee E-20.06, New

Thermometers; Member, Subcommittee E-20. 07, Fundamentals in Thermometry;

Subcommittee E-20.08, Medical Thermometry, Working Group WG.02, Fever

Thermometers; Working Group WG.02A, Electronic Fever Thermometers;

Working Group WG.02B, Mercury-In-Glass Fever Thermometers; Working Group

WG.02C, Disposable Fever Thermometers; Working Group WG.03, Continuous

Clinical Temperature Monitoring Systems; Working Group WG.04, Clinical

Laboratory Temperature Measurement; and Member, Subcommittee E-20.90,

Executive Subcommittee.

B. W. Mangum, Member, OIML PS12, International Organization of Legal

Metrology, Measurement of Temperature and Calorific Energy Committee,

RS4, Electrical Thermistor Thermometers.

J. F. Schooley, Chairman, ANSI MC88, American National Standards Institute Committee on Calibration of Instruments.

J. F. Schooley, Delegate, 15th Meeting of International Committee on Weights and Measures (CIPM), Consultative Committee on Thermometry

(CCT); and Delegate, Subcommittee WG3, Replacement of IPTS-68.

J. F. Schooley, Delegate, OIML PS 12, International Organization of Legal

Metrology Committee on Measurement of Temperature and Calorific Energy.

J. F. Schooley, Editorial Board, Metrologia .

J. F. Schooley, Member, Organizing Committee for 1986 Applied

Superconductivity Conference, Baltimore, MD.

R. J. Soulen, Jr., Member, ASTM E-20, American Society for Testing and

Materials Temperature Measurement Committee.

R, J. Soulen, Jr., Member, ASTM B001, American Society for Testing and

Materials Committee Electrical Conductors, Subcommittee SC. 08,

Superconductors

.

R. J. Soulen, Jr., Member, International Committee on Weights and

Measures (CIPM), Consultative Committee on Thermometry (CCT), WG4.

C. R. Tilford, Member, ASTM E021, American Society for Testing and

Materials Space Simulation and Applications of Space Technology Committee, Subcommittee SC. 04, Space Simulation Test Methods, Working Group

WG.01, Revision of Standards E296-70 and E297-70.

C. R. Tilford, Chairman, AVC C004, American Vacuum Society Standards

Committee; Member, Subcommittee SC. 01, Gaging.

126
C. R. Tilford, Chairman, BIPM C002, International Bureau of Weights and

Measures Consultative Committee on Mass and Related Quantities, Working

Group WG.02, Working Group on Low Pressures.

C. R. Tilford, Chairman, RTCA SCI 50, Radio Technical Commission for

Aeronautics, Special Committee for Minimum Performance Standards for

(Aircraft) Vertical Separation Above Flight Level 290.

C. R, Tilford, Member, Board of Directors, Vacuum Technology Division of

the American Vacuum Society.

J. A. Wise, Secretary, ASTM E-20, American Society for Testing and

Materials, Temperature and Measurement Committee; Member, Subcommittee

E-20. 05, Liquid-in-Glass Thermometers and Hydrometers; Secretary,

Subcommittee E-20. 90, Executive Subcommittee; and Member, Subcommittee

E§20.91, Editorial and Nomenclature.

127
LENGTH AND MASS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1985

I. Overview

The Length and Mass Division (LMD) has the responsibility to; maintain

the U.S. primary standards for length, mass, and density; provide the first

level of transfer to secondary standards; and improve the standards and

measurement instrumentation through basic and applied ressearch. As of

October, 1985, the Division has responsibility for the NBS mass calibration

service.

Many activities occur in support of these responsibilities. Comparisons of the U.S. standards are made with the International Bureau of Weights

and Measures (BIPM) and with other national laboratories to ensure international compatibility. A close working relationship is maintained with the

divisions in the National Engineering Laboratory which provide length and

force calibration services to the public. This cooperation not only

concerns the first level of transfer of dimensional quantities but also

includes the transfer of measurement techniques and instruments, such as the

portable laser length standard, the submersible balance, and the load cell mass comparator, which were developed in the LMD. Cooperative projects with

outside institutions, such as state metrology laboratories, universities,

and private corporations , ensure that our activities are revelant to the

problems of the measurement community. The Division is frequently requested

to provide information and assistance to public and private organizations

which need state-of-the-art length and mass measurements and cannot obtain

adequate support from the private sector.

Length activities this year involved: use of the NBS Portable Laser

Length Standard in several experiments at NBS and other laboratories to

measure fundamental constants and base units; and the development of a servo-system for the NBS Scanning Tunneling Microscope.

Activities in the mass program focussed on: development of servo-controlled kilogram balances for primary mass comparisons; development of

retro-fitted servo-systems and automated weight changers for commercial

balances used in the calibration program; analysis and publication of the

results of the BIPM calibration of the U.S. mass standards; initiation of an international round-robin to measure solid density artifacts; and completion

of the new transportable mass measurement package and liquid densimeter.

Two theoreticians in the Division, John Cooper and Helen Holt, are developing methods to treat field effects on atomic processes and the

time-dependence of excitation processes under varying field conditions. In

addition to his theoretical work. Cooper collaborates with scientists in the

Center for Radiation Research on experimental spectroscopic measurements.

128
Robert Cutkosky transferred into the Division in October, 1984.

He has collaborated with Randy Schoonover on several projects in the mass program to automate the commercial balances in the calibration laboratory and to develop a servo-controlled flexure kilogram balance. He has

also continued his DoD sponsored work on the development of the automated

NBS Type 3 Capacitance Bridge and related standards in collaboration with

Lai Lee of the Electricity Division. Cutkosky and Lee earned a 1985 I-R 100

award for the design of the automated capacitance bridge.

II. Technical Activities

1 . Length Measurements and Standards

The length activities this year included the usual responsibilities of

realizing and disseminating the length standard to industrial and scientific

laboratories and also included new ventures into other fields which involve

high precision length measurements.

A. NBS Portable Laser Length Standard

The interest in the NBS portable laser length standard continues

to be high, not only from domestic sources, but also from foreign countries

which are in the process of building metrology laboratories to support

industrialization. Activities this year involved promoting the use of the

length standard in measurements of fundamental units and atomic constants

for programs at NBS and other laboratories . Howard Layer also visited the

national laboratories of India and Egypt to present a series of lectures on length standards and related metrology and to work with the metrologists in

the laboratories to transfer technology which can be used to fulfill present

measurement needs in these countries.

ACCOMPLISHMENTS: The NBS portable laser length standard is currently

being used in two new measurements of the ohm by means of the calculable

capacitor: one in the Van Swinden Laboratory in Delft, the Netherlands, and

the other in the NBS Electricity Division. These measurements are part of

the effort by the electrical standards community to establish the quantized

Hall effect as the primary standard of resistance. A meeting of the CCE has

been scheduled for the summer of 1986 to compare the results of national

laboratories worldwide. Howard Layer has also helped the NBS Electricity

Division make several changes in the existing calculable capacitor to

improve its precision and accuracy by relating the measurements directly to

the length standard, providing better isolation between the laser and the

interferometer, and by improving the servo-system.

The Division is also providing length measurement support to the

Ele.(5tricity Division's experiment to measure garama-p and to the Quantum

Metrology Group’s experiment to measure the silicon lattice spacing.

The collaboration with Dr. William Lichten of Yale Univeristy on

the measurement of the Rydberg constant is continuing. This effort, to

date, has resulted in a value which has a precision of one part in 10^
using crossed atomic and optical beams. Several modifications to the

apparatus are now being implemented which should allow further improvement

in the accuracy of the Rydberg value and reduce its uncertainty to a value

which is very near the limit set by the uncertainty of the length standard.

PLANS FOR FY 86: Work involving the NBS laser length standard will

continue at approximately the same level as in FY 85. Emphasis will again

be placed on encouraging the application of the NBS system when other length

measuring instruments do not provide sufficient accuracy.

B. Servo-system for the NBS Scanning Tunneling Microscope

In the course of developing a capacitance motor and highly stabilized electronic driver for the electrostatically servoed mass comparator,

the Electron Physics Group in the Radiation Physics Division of CRR inquired

about the suitability of these devices as a servo-system for a new scanning

tunneling microscope (STM) which they had just started to develop. Results

at IBM in Zurich indicated that such an instrument was capable of making

high quality pictures of surfaces with atomic resolution. However, the

length measuring capability of instruments built up to that time only

provided information about atomic surface symmetries but was insufficient

to provide reliable dimensional information. The new STM provided an excellent opportunity to test the balance servo electronics and to provide

an extension of length measurements to the atomic domain in a direct way

that had not been done before.

ACCOMPLISHMENTS: The initial application of the high voltage amplifier

to the STM uncovered several deficiencies which were subsequently corrected

by a completely revised design. The new amplifier, which can be designed to

have an output voltage range as large as 4000 volts, has a low noise level

and a stability that is better than one part per million. This level of

stability enables one to servo distance measuring probes to about one picometer in a system with a bandwidth of several hundred Hz. Using the new amplifier in the STM servo circuit, the Electron Physics Group has been able

to obtain topographs of metalic surfaces with vertical resolution better

than 10 picometers. This level of performance is sufficient to resolve

atomic steps on crystal surfaces. The NBS Surface Characterization Group

has used the STM to examine gratings and optical surfaces produced by

diamond turning machines with unprecedented resolution. The STM will

provide NBS with a new measurement technology for scientific studies as well as a wide range of metrology applications.

With the completion of his collaboration on the servo-system for

the STM, Howard Layer will redirect his efforts toward completion of

the electrostatically-servoed kilogram comparator.

2. Mass Measurements and Standards

A. Servo-controlled Primary Kilogram Comparators

The Division’s efforts to improve the operational Voland balance and

develop new automated primary kilogram comparators involved three activities

130
this past year. The Voland balance was retrofitted with the electromagnetic

beam servo-system developed by Schoonover and Cutkosky. Two parallel

projects are underway to develop a completely new type of automated mass

comparator. Both use the same basic structural design: cast aluminum

base plates, symmetrical cast beam, etc. They differ in that one will use laser sensing of the beam position, an electrostatic servo-motor to restore

the beam, and knife-edge pivots while the other will use the simpler

electromagnetic beam servo-system and commercial flexure pivots.

ACCOMPLISHMENTS: The Voland balance is now operating under servo

control. Enough experience has been gained to compare its operation

under servo control to that in the free-swinging mode. The most striking

improvement is that the balance sensitivity is now constant from day to day

and throughout a complete set of mesurements. The sensitivity has also been

shown to be linear over the full 20 mg range of the balance.

The overall standard deviation of a set of measurements did not improve

under servo control. A careful study of thermal gradients within the

balance has shown that thermal effects do not contribute significantly

to the standard deviation. The Voland is operating sufficiently well

to serve as our present primary kilogram comparator and no futher major

modifications are anticipated.

All of the major components, except for the electrostatic beam servo

motor, have been completed and assembled for the new laserservoed knife-edge

balance. A capacitance motor has been chosen for this balance because it

does not require the use of magnetic materials even though a magnetic system

would be advantageous from many other points of view. A very highly

stabilized, low noise, high voltage (4000V) electronic driver for the

capacitance motor has been developed and successfully tested on the Scanning

Tunneling Microscope. The capacitance motor is now under development.

A new project was initiated this year by Schoonover and Cutkosky to

construct a automated kilogram comparator with flexure pivots, the simpler

electromagnetic servo system, and the same cast beam and structural com- ponents designed for the balance discussed above. This project is divided

into the following four steps:

1 ) Servo a beam with flexure pivots and demonstrate the required

sensitivity.

2) Demonstrate precision by repeated weighings of a 1 kg weight.

3) If precision is adequate, develop a weight changing mechanism

for intercomparing six 1 kg masses.

4) Investigate vacuum weighing.

The first step has been completed and the construction for the second

step is well underway.

PLANS FOR FY86 : Development of the new kilogram comparators will

continue. Working prototypes of both designs should be complete by the

end of FY86.

131
B. Recalibration of the U.S. Kilograms

The goal of this project is to ensure that the mass calibrations

performed by NBS are compatible with the international system of mass measurements. The first step in this process — the recalibration of

the U.S. national protoptye kilograms, K20 and K4, and two stainless

steel kilograms at BIPM — has now been completed and documented. Work

is now underway to develop and calibrate an group of stainless steel

check standards and working standards for the calibration service. A new set of quality control procedures will be developed and implemented

in the calibration laboratory to monitor the working standards.

ACCOMPLISHMENTS; The results of the BIPM recalibration have been

analyzed and published. The major conclusions from that work can be

briefly summarized in the following comments. The Pt-Ir standards must

be cleaned in exactly the same manner as that used by BIPM in order to

achieve comparable results. When the cleaning is properly done, repeated

mass measurements agree to within 5 micrograms. After cleaning, the U.S.

national prototype K20 was found to be only 1 microgram below its 1948 value

-- a difference that is well within experimental uncertainties. The

cleaning process removed approximately 20 micrograms. Repeated calibrations

of the two stainless steel weights, both at NBS and BIPM, indicate a repeatability better than 30 micrograms. The majority of the non-reproducibility seems to be due to the difficulties associated with the air buoyancy

correction.

The six stainless steel kilograms which will be used as check standards

and working standards in the calibration service are now being monitored for

stability. Their densities have been determined to high accuracy by

hydrostatic weighing against our silicon transfer standards. Their masses

have been measured against the stainless steel standards which were calibrated by the BIPM.

PLANS FOR FY86 : We will continue to monitor the stability of the

new stainless steel standards and recalibrate N1 and N2, the present

working standards of the calibration service, to carefully document any

differences between the recalibrated and presently assigned mass values.

C. Retro-fitted Automation of Commercial Balances in the

Calibration Program

There is a growing need in the NBS mass calibration laboratory and

in the outside mass metrology community for automated mass comparators

which perform as well as or preferably better than the mechanical balances

now in common use. Modern electronic balances lack the combination of range

and, most importantly, the precision required in the NBS mass calibration

program. This deficiency has been overcome with the development of beam

servo system that has been installed on existing high-precision mechanical

balances.
The initial goal of the project was to automate the data acquisition of the balance observations and then to examine the possibility of

automating the total calibration process.

ACCOMPLISHMENTS: A successful electromagnetic beam servo system

has beeji developed. It has been installed on the Voland kilogram comparator

and on a Mettler model H31 5 balance used to calibrate the kilograms for the

portable mass measurement package.

The servo system has enabled us to examine several ways to avoid the

systematic errors that are known to be caused by thermal effects and arise

from the presence of the balance operator. One method would replace the

operator with a mechanical weight changer. A second approach goes one step

further and forces thermal equilibrium between the weights being calibrated

and the air in the balance chamber. Both approaches have been successfully

tested and can be adapted to some of the mechanical balances used in the mass calibration program.

The remotely operated mechanical weight changers developed and tested

on the Mettler balance so far have been manually operated systems with

limited applications. A fully automatic robotic arm which is capable of

loading the balance with weights in various combinations from a preloaded

matrix is now being developed.

PLANS FOR FY86 : Research and testing will continue on all of these

automated components until adequate performance has been demonstrated. They

will then be adapted to the mechanical balances in the calibration program.

D. Density of Solids

Working Group 5 of the Consultative Committee for Mass and Related

Quantities (COM) has organized an international round robin of solid

density intercomparisons. NBS is serving as the pilot laboratory for

these measurements.

ACCOMPLISHMENTS: The Working Group 5 met in Japan in September, 1984

to formulate its final plans. The round robin has begun. NBS has made

initial measurements of the artifacts and shipped them to the next participating laboratory. The artifacts include two stainless steel kilograms and

two 800 g silicon crystals.

PLANS FOR FY86 : NBS will remeasure the density artifacts at the end of

the seven-laboratory round robin. As the pilot laboratory, we will also

analyze the data obtained by all participating laboratories and write the

preliminary report.

E. Liquid Densimeter

The objective of this project is to develop a new type of liquid

densimeter for the Standard Reference Materials Program to be used in

the certification of liquid density SRMs in the NBS Chemical Process

Metrology Division. The SRMs are designed to satisfy the need in metrology

133
for a family of liquid density standards in the range from 0.6 g/cm^ to 2.0

g/cm3 for calibrating hydrometers to 100 ppm and the most precise vibrating

tube densimeters to 100 ppm or better.

ACCOMPLISffliENTS : The densimeter has been constructed and tested to

determine its precision and linearity. As soon as the internal density

standard, a gold plated aluminum sphere, has been calibrated hydrostatically, the instrument will be turned over to the Chemical Process Metrology

Division.

F. Portable Mass Measurement Package

This project, sponsored in part by the NBS Office of Weights and

Measures, is developing a transportable mass measurement package to assist

State and industrial metrology laboratories in assigning mass values to

kilograms, particularly those which have unusual shapes and densities and

require significant air buoyancy corrections. Most laboratories have

adequate balances but some lack the necessary auxiliary equipment and

experience to make accurate air buoyancy corrections. This package will

help to overcome these deficiencies. The package includes:

1 . Calibrated kilogram masses of various geometries and densities,

2. Fractional mass standards for trimming mass differences at

various altitudes,

3. Computer hardware and software for standardized data reduction

and statistical control,

4. Air density instrumentation to measure temperature, barometric

pressure, and relative humidity, and

5. Automatic data acquisition system for those laboratories

equipped to use it.

ACCOMPLISHMENTS: The complete package has now been assembled and

calibrated. It will be shipped to the California State Metrology Laboratory

to begin the first round robin which will include several other state labs

and two industrial labs, Sandla and the 3M Company.

PLANS FOR FY86 : The Division will monitor the results of the round

robin and make any further modifications that are required. One of the most

important long-term objectives of this project is the training that participants will receive by using the package. Many participants will be exposed

for the first time ot state-of-the-art weighing techniques and laboratory

automation. It may be desirable later to develop a formal training seminar

baaed on the instrumentation and techniques used in this package. A second

objective is to extend the mass calibration capability of the package from

the 1 kilogram level down to 1 mg.

G. Other Service Projects

The Division collaborated with the piston gage calibration group

of the Temperature and Pressure Division to improve the uncertainties

of mass values assigned to piston gage weights. A new weighing station

was designed with an insulated weighing enclosure to minimize the systematic

13 ^
errors due to thercal effects that normally occur when weight s or surface to mass ratio are calibrated.

The Division also made some special measurements for the

Division which is conducting experiments to measure the ideal

Their experiment measures acoustic resonances in a large spher

The internal volume of the cavity must be determined to 1 ppm

picnometry. The Division's activities included: weighing the

designing 20 kg of stainless steel counterweights, and determi

masses and volumes of the counterweights against laboratory st

Preliminary picnometer measurements have been successfully con final measurements should be completed in November.

using mercury

p' cr'cn!0ps’^ ) ring the

andards

.

oleted

3 . Atomic Theory

Work during the past year has focused on completion of the experiments

on field effects of autoionizing states and preparation to make high

resolution measurements of field perturbed absorption spectra using the 6.5

m V'JV spectrometer recently installed at the N3S storage ring (SURF-II) by

the University of Maryland.

The experimental work on field effects on barium autoionizing states,

condusted in collaboration with D. Kelleher and E. Salomon of the Center f

Hasiation Research, has been completed. All of the experimental data have

been transferred to computer storage and a detailed analysis of the result

is underway. Two papers describing some of the work have already been

published. One of the papers (Phys. Rev. Letters (1 955)) describes an interesting interference effect caused by field mixing and the second pape

contains a general description of the work and a sample of the results

obtained. At least one additional paper will be prepared based on the dao now available.

In preparation for measurements on SURF-II, a gas handling system has

been built, tested, and used to measure the degree of polarization of the

light entering the spectrometer slit. Light from the storage ring was focused on the entrance slit via a three-mirror system designed to produce

nearly 100c polarized light. Our measurements indicated that the light was

at least 96% polarized and, in addition, provided information about the flux

levels to be expected when spectra are recorded.

Plans for the next year include completing the analysis of the barium

data and beginning work on the high resolution absorption spectra as soon as the spectrometer is operational.

P'JBLICATICNS

1. E.3. Salomon, J.W. Cooper, and D.E. Kelleher, "Electric-f ield

interferences in autoionizing resonances," Phvs. Rev. Letters

(1985).

^ r» a H
2 E.B. Salomon, J.E. Cooper, and D.E. Kelleher, "Studies of Electric

Field Effects on Barium Autoionizing Resonances," Atomic Excitation and

Recombination in External Fields , M.H. Nayteh and C.W. Clark, editors,

Gordon & Breach, N.Y., p. 325 (1985).

3 E.B. Salomon, J.W. Cooper, and G. Mehlman, "Photoabsorption Cross

Section of Barium from 237.9 to 120 nm," Phys. Rev. A 1 878 (1 985).

4. C.W. Clark and J.W. Cooper, Conference Report on "Field Effects in

Rydberg Atoms," to appear in July-August issue of NBS Journal of

Research.

5. V.I. Mishin, G. Lombardi, D.E. Kelleher, and J.W. Cooper, "FieldEnhanced Autoionization in Gadolinium," (to be submitted to JOSA)

.

6. A. Peuto and R.S. Davis, "Comparison of Solid Density Standards

Between IMGC and NBS," J. Res. NBS 90(3), 217-227 (1985).

7. J.B. Patterson and R.S. Davis, "A Density Comparison of Silicon

Artifacts Between NML (Australia) and NBS (U.S.)," J. Res. NBS 90(4),

( 1 985) . In press.

8. R.S. Davis, "Recalibration of the U.S. National Prototype Kilograms,"

J. Res. NBS 90(4), (1985). In press.

9. P. Carre and R.S. Davis, "Note on Weighings Carried Out on the NBS-2

Balance," J. Res. NBS. Accepted for publication.

10. R.S. Davis and G. Girard, "Rapport sur la comparason d'etalons de masse de 1 kg en platine iridie et an acier inoxydable entre le

National Bureau of Standards et la Bureau International des Poids

Mesures," Recueil de Travaux de BIPM. In press.

11. T.J. Quinn, C.C. Speake, and R.S. Davis, "A 1 kg Comparator using

Flexure-strip Suspensions; Preliminary Results," Metrologia. To be

submitted.

12. R.S. Davis, "Note on the new formulations of f, Psv» Document

CCM/ 85 - 10 , Consultative Committee for Mass and Related Quantities.

13 . R.M. Schoonover, "A Large Capacity High Precision Electronic Mass

Comparator," Proceedings of the 10th Conference of IMEKO TC-3 on Measurement of Force and Mass, Kobe, Japan, p. 101 (1984).

14. R.M. Schoonover, "A Force Balance Liquid Densimeter," Proceedings

of the 10th Conference of IMEKO TC-3 on Measurement of Force and

Mass, Kobe, Japan, p. 107 (1984).

15 . R.M. Schoonover, "Mass Comparator for In-Situ Calibration of Large

Mass Standards," J. Res. NBS 90(4), (1985). In press.

136
16. T.F. Scrivener and R.M. Schoonover, U.S. Patent No. 4,523,653, "Load

Cell Mass Comparator," June 18, 1985.

17. R.D. Cutkosky, "An Automatic High-Precision Audiofrequency Capacitance Bridge," IEEE Trans. Instr. & Meas., IM-34 (3) . 383 (1985).

INVITED TALKS

Richard S. Davis, "Romancing the Kilogram," An After Dinner Talk to the

Regional Conference of Deans of Engineering, Hartford Graduate Center,

Hartford, CT, May 3, 1985.

Richard S. Davis, "Recalibration of the U.S. Prototype Kilogram," National

Conference of Wseights and Measures, Washington, DC, July 15, 1985.

Howard Layer, Presented a Series of Lectures on Length Metrology at the

Advanced Metrology Conference, National Physical Laboratory, New Delhi,

India, February 1985.

Howard Layer, Presented a Series of Lectures on Length Metrology at the

National Institute of Standards, Cairo, Egypt, March 1985.

Howard Layer, "Servo Systems Using PZTs," 3rd International Precision

Engineering Seminar, Interlaken, Switzerland, May 1985.

Randall M. Schoonover, Presented a Series of Lectures on Mass and Density

Metrology at the Advanced Metrology Conference, National Phycical

Laboratory, New Dehli, India, February 1985.

Randall M. Schoonover, "Mass Comparator for the In-Situ Calibration of

Large Mass Standards," OIML Seminar on Testing of Bulk Weighing

Installations, Paris, France, April 1985.

Randall M. Schoonover, Lectured at the George Washington University Standards Laboratory Course, October 1984 and April 1985.

137
TIME AND FREQUENCY DIVISION

FISCAL YEAR 1985

I. INTRODUCTION

The National Bureau of Standards (NBS) is responsible for the

development and maintenance of a system of measurements required to

support science and industry. The specific functions of NBS were assigned

to the Department of Commerce by the Bureau's enabling legislation (15

U.S.C. 272). Portions of this legislation state:

"The Secretary of Commerce is authorized to undertake the following

functions

:

(a) The custody, maintenance, and development of the national

standards of measurement, and the provision of means and methods for

making measurements consistent with those standards,...

(e) Advisory service to Government agencies on scientific and

technical problems.

(f) Invention and development of devices to serve special needs of

the Government."

In carrying out these functions, the Secretary has authorized specific

activities including:

"(1) the construction of physical standards;

(2) the testing, calibration and certification of standards and

standard measuring apparatus;

(3) the study and improvement of instruments and methods of

measurements, . .

.

(11) the broadcasting of radio signals of standard frequency;"

The Time and Frequency Division located in Boulder, Colorado is

primarily responsible for the standards of time and frequency. The

standard of length is based on the frequency standard and the division has

worked on the realization of the meter as well. However, primary

responsibility for the meter resides in the Length and Mass Division. The

most important product of the division is the service provided to science,

industry, and other government agencies. There is no sense in establishing and maintaining standards of measurement unless they are efficien-tly

disseminated. Standards operation, research on new standards, and

development of methods of measurement all closely support the services of

the division. The extension of standards and methods in range and

accuracy and into new fields should receive sufficient emphasis to keep

NBS prepared to satisfy the demands for improved services. Basic research

related to standards is performed to challenge the talents of the staff

and to stimulate the development of new ideas. Advisory service to

138
Government agencies and the development of devices to serve the special

needs of Government are important NBS roles which increase the efficiency

of government by applying the special expertise of NBS to significant

Government problems. The expertise needed to provide this advice to other

agencies is derived from involvement in both basic research and goaloriented research and development.

The division is organized into seven groups which meet different

aspects of the division’s responsibilities. These groups are:

• Time and Frequency Services (Section II)

• Time Scale and Time and Frequency Coordination (Section III)

• Hydrogen Masers (Section IV)

• Atomic Beam Standards (Section V)

• Ion Storage (Section VI)

• Optical Frequency Metrology and Devices (Section VII)

• Geophysical Measurements (Section VIII)

In order to more clearly show the program emphasis, this report will

be presented with these group names as section titles, and the staff

working in each area will be listed at the beginning of each section.

There is considerable overlap between the work of several of the groups,

but no attempt is made to separate the work into clean categories since

this would add confusion.

Each section of the report begins with a short description of the

general program and objectives of the group. This is followed by a list

of specific FY 1985 accomplishments and the plans for FY 1986. The accomplishments are keyed to the plans outlined in last years report, but

tracking between the two will be difficult because the arrangement of this

years report has been significantly altered. Nevertheless, every

specific planning item described last year can be located in this report.

In an effort to relate the division’s work to the division’s mission,

a set of objectives have been used. Any one of the objectives which are

listed below may appear in the description of the work of several groups

since there is heavy overlap and collaboration between a number of the

groups.

139
OBJECTIVES

• G-enerate NBS time scales, UTC(N3S) and TA(NBS)

• Broadcast time and frequency signals from radio stations WWV,

WWVH and WVB and the GOES satellites.

• Provide seminars, calibrations and measurement assurance on a fully reimbursable basis.

• Maintain international coordination of time scales and frequency

standards using the Global Positioning System

• Develop advanced methods for time transfer using communication

satellites.

• Provide reference frequencies from the microwave to the

visible region of the spectrum.

• Establish the units of the International System for the

"second” and the "meter".

• Make fundamental improvements in atomic spectroscopy for

future application to primary frequency standards.

• Develop metrology for precise time, frequency and length

measurements.

• Perform basic studies in program areas related to future time

and frequency standards.

• Advise and work with other governmental agencies and industry to

incorporate advanced time and frequency metrology into their

programs

.

• Measure far infrared frequencies of atoms and molecules (especially

transient species) for radio astronomy and upper atmospheric science.

140
II. Time and Frequency Services

The Time and Frequency Services Group has the primary focus of direct

industry and other agency support. The division broadcast services, the

new Frequency Measurement Service, and the Time and Frequency Bulletin all

fall within their responsibility. In addition to these on-going services

the group is working on four other projects: coordination of clocks using

two-way satellite time transfer, development of time transfer techniques

approp’^iate to a tactical (military) communication environment, synchronization of space-borne communications nodes, and a broad study of timing

methods useful to the electric power industry. At a later date the

two-way time coordination function will be transferred to the Time Scale

and Coordination Group. The group's work is described in more detail

below.

Staff: D. W. Hanson, Project Leader

W. J. Bonner (Part-time)

D. A. Howe

J. L. Jespersen

G. Kamas

M. A. Lombardi

D. L. Real

R. E. Beehler (Broadcast Manager)

WWV

,

WWVB, Ft. Collins WWVH, Hawaii

J. E. Folley (Part-time) A. Fabro (Part-time)

J. M. Max ton E. F. Farro

J. B. Milton, Chief Eng. Ferguson (Part-time)

c. S. Snider N. Hironaka

A. R. Trevarton C. L. Trembath, Chief

In order to have useful standards of time, frequency, and length it

is essential to provide convenient access to these standards. This is

accomplished primarily via the radio broadcasts of stations WWV, WWVH , and

WWVB and a time code broadcast by the GOES satellites. NBS also provides

telephone tirae-of-day services, publications of time and frequency values

of other radio stations as received at NBS, portable clock comparisons and

calibrations. The meter is now defined in terms of a fixed value for the

speed of light and the standard of frequency (time). The very accurate

measurements needed to implement this definition are largely complete and

the practical dissemination of the meter is handled by the Length and Mass

Division. Seminars concerning time and frequency metrology are regularly

scheduled to educate new entrants to the field.

The division's services are important in many applications involving

commercial, government, and scientific activities. These include:

141
Navigation

Celestial navigators need time to determine their precise location.

An error of 2 seconds could cause a ship to miss its destination by about

one kilometer. Thus military and commercial shipping and small boat

owners depend in a life and death sense on the availability of the signals

from WWV and WWVH.

More sophisticated electronic navigation systems such as LORAN-C and

the Global Positioning System (GPS) must maintain time much more accurately. An error of only 3 microseconds could produce the same one kilometer error for the navigator.

Systems Control and Synchronization

The electric power industry uses both frequency and time information

in the management of generation and distribution of electric power.

Frequency measurement has been fundamental to the industry for many years

and is satisfied by signals from WWVB and GOES. Time is becoming

increasingly important in the recording of fast occurring events (faults),

system control, measurement of power flow, avoiding outages caused by

exceeding stability limits, and for fault location on long transmission

lines.

Radio and TV stations need accurate frequency to broadcast signals at

exactly their assigned frequencies. They need accurate time to set

station clocks so they can join the network at the right instant.

The aviation/aerospace industry needs accurate time for aircraft

traffic control systems and for synchronization at satellite and missile

tracking stations.

The telecommunications industry needs time accurate to one microsecond and better to synchronize communication's nodes spread over wide

geographical areas.

Data Acquisition

The FAA records accurate time on its audio tapes along with the

air-to-ground communications from airplanes. Having an accurate record of

when particular events happened can be an important factor in determining

the cause of a plane crash or equipment malfunction.

Geophysicists/seismologists studying lightning, earthquakes,

weather, and other geophysical disturbances need time to enable them to

obtain data synchronously and automatically over wide geographical areas. They use it for labeling geophysical events. Other scientists use time

for controlling the duration of physical and chemical processes.

142
Astronomers use time for observing astronomical events, such as lunar

occultations, eclipses, and pulsars.

Science and Metrology

Manufacturers need time and frequency to calibrate counters,

frequency meters and test equipment.

Accurate spectra of molecules are needed to measure atmospheric

concentrations.

Laser frequency measurements provide accurate calibration frequencies

for spectroscopists and for radio astronomy as well as the means for

realization of the meter.

*********ih********************************^**^^^^*^*^**********^**^***^^**

OBJECTIVE: Broadcast time and frequency signals from radio stations WWV,

WWVH and WWVB and the GOES satellites.

»*»»»»************^**************if*******************it********5t***********

NBS offers several around-the-clock time and frequency dissemination

services to the general public. In 1923i radio station WWV was

established by NBS and has been operated since that time. A sister

station, WWVH was established in 1948, on the Hawaiian Island of Maui,

and relocated to Kauai in 1971. In 1956, WWVB began low frequency

broadcasts. WWV’s signal is also offered by a telephone service, not

toll-free, by dialing (303) 499-7111. A similar service from WWVH is

available by dialing (808) 335-4363 in Hawaii.

Broadcasts from WWV and WWVH can be received on conventional

shortwave receivers nearly anywhere in the world. Broadcast frequencies

include 2.5, 5, 10, and 15 megahertz for both stations and 20 megahertz

from WWV only. Accuracies within one millisecond can be obtained from

these broadcasts if one corrects for the station's distance from the

receiver. These services also provide standard frequencies, a BCD time

code, astronomical time corrections, and certain public service announcements from other government agencies. The telephone service offers to

individuals without receivers, the capability of obtaining NBS time and

audio frequency signals. The caller can receive a time signal accurate to

30 milliseconds or better, about the maximum delay in cross-country

telephone lines. WWVB offers a direct path signal of greater accuracy

than WWV or WWVH, but a special 60-kilohertz low frequency receiver is

required. WI^VB's signal includes a binary coded system, needing special

decoding equipment. WWVB's coverage area is shown in Figure 1. These

broadcast services are coordinated with similar operations in other

countries through active participation in the international CCIR

organization.

NBS time and frequency signals covering about 40 percent of the earth

have been relayed via geostationary satellites since 1975. The coverage

143
area is shown in Figure 2. More than 10 years of experience has shown

that such a system does provide continuous time and frequency reception

that is much more dependable than ground-based AM and FM radio stations,

is free from propagation anomalies, and has a 100-microsecond accuracy.

Table I summarizes the principal NBS time and frequency dissemination

services. Table II gives some details of the HF radio broadcasts.

FY 1985 Plans

Plan - Conduct a major survey of users of the NBS time and frequency

dissemination services.

Accomplishment - The performance of this survey has been delayed

until the first half of FY86 due to higher priority tasks. Approval

for the survey has been obtained and a preliminary design of the

survey has been completed.

Plan - Study the needs and alternatives for replacing the WWV transmitters

with more energy-efficient units.

Accomplishment - The energy and economic analysis was completed on schedule. Replacement of the three main transmitters should reduce

our power requirement by 100 kW with a resultant energy saving of

73,000 kWH/month. The projected cost recovery period for purchase

and installation of the transmitters is three to four years. A

budget request for these transmitters was included for FY 1987, but

this was rejected by DoC. Further efforts to find funding for the

transmitter replaoement are underway.

Plan - Develop a capability to monitor and control selected functions at

the NBS radio stations from remote locations. The goal is to reduce the

number and cost of out-of-hour visits made to the station sites.

Accomplishment - The system was completed on schedule and the station

status and diagnostic information is now available remotely. This

should reduce some unnecessary trips to the station during non-work

periods.

Plan - Complete improved software and hardware documentation for the GOES

satellite time code systems.

Accomplishment - A large part of the documentation has already been

done and completion is scheduled for 11-30-85. This is a major

effort covering all facets of the GOES operation.

FY 1986 Plans

Complete a major survey of the users of the NBS time and frequency

dissemination services and document the results.

144
Figure 1

Figure 2

145
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146
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147
Upgrade W¥VH data acquisition system for more convenient data transfer

operations to NBS/3oulder.

Transfer operational GTDS satellite orbit determination program and

related operations from Boulder Cyber 750 to appropriate components of the new NBS Cyber 840/855/205 computer system. Investigate alternative links

to new NOAA/Suitland computer facility.

Develop an upgraded operational software package of GOES procedures that

combines separate programs into a menu-driven, fully integrated program.

Update related documentation accordingly.

Maintain reliable operations from WWV, WWVB, W\7VH, and the GOES

satellites

.

*^^*^^^*^**********¥;*¥:*******^*************^********^*)h***^******^********

OBJECTIVE: Provide seminars, calibrations and frequency measurement

assurance on a fully reimbursable basis.

Frequency Measurement Service

This new frequency measurement service is highly automated, modest

in cost, and provides traceability to NBS at a level of one part in 10^",

although even applications which do not require this level of performance

can be readily supported. The service is based on common-view reception

of low frequency signals from stations such as WWVB or Loran-C. The NBS

service consists of assisting the user to set up a low frequency receiver

and data logger system which is the most appropriate for his needs and his

location. A typical system contains a receiver, microcomputer , disc units

and printer-plotter . The user's responsibility is to provide a dedicated

phone line and modem so that his data can be compared with data recorded

at NBS, thus providing assurance that the measurements are valid. The user

also receives a bulletin which reports the performance of many of the

accurate signal sources. To assist the user in getting the most out of

this system NBS provides specific training using the actual equipment.

Time and Frequency Bulletin

The Division has continued the distribution of its Time and Frequency

Bulletin to over 1200 users of NBS services. The preparation and mailing

of this bulletin has been constantly improved to reduce costs and to

increase its usefulness. The bulletin has been expanded to support our new calibration services and will continue to be improved.

Seminars

The Division seminars provide industry, calibration labs and the

military with information and training on the use of frequency standards.

One seminar was offered in 1985 and it was well attended. This will be

148
continued as long as the demand is there. A special effort is made to

have the seminar support the introduction of new services and to be of

particular interest to the nations ’s calibration laboratories.

FY 1985 Plans

Plan - Continue Measurement Assurance for frequency calibrations. Provide

information on service through published articles and the NCSL

newsletters.

Accomplishment - A paper describing the Frequency Measurement Service

was presented at the 1985 Workshop and Symposium of the National

Conference of Standards Laboratories (NCSL), July 15~18, 1985. A

working system, demonstrated at a booth during the four days of the

meeting, attracted a great deal of attention. This interaction has

resulted in a number of new customers for the service.

Plan - As demand dictates, provide a comprehensive Time and Frequency

Seminar on a fully reimbursable basis.

Accomplishment - A seminar on Time and Frequency was held August 1

3

through 15, 1985. Paid attendance was 45 and and the seminar was favorably received by most of the attendees. A waiting list

developed well before the conference started, since a maximum

practical attendance of 45 has been set. Consideration is now being

given to an offering of the seminar during the spring.

Plan - Achieve an income level of $36,000 per year for the Frequency

Measurement Service.

Accomplishment - Income level for the service has recently exceeded

$50,000 per year. It may be a little early to conclusively determine

the growth rate, but it seems to be accelerating. Twenty-one systems

are in place with important industrial and government customers. All

comments from these users are highly favorable.

FY 1986 Plans

Continue operation of Frequency Measurement Service. Provide information

on service through published articles. Develop training on disk for

system users..

As demand dictates, provide a comprehensive Time and Frequency seminar on

a fully reimbursable basis.

149
OBJECTIVE: Develop advanced methods for time transfer using communication

satellites

.

The use of communications satellites for time transfer at all levels

of performance appears to be widely accepted in light of the success of

several efforts during the last few years. Much of this is also due to a number of favorable changes in the available technology, economics, and

demand. At the higher levels of performance, work reported by Japan and

unpublished tests involving MBS, USNO, and COMSAT Laboratories have

demonstrated one-half nanosecond time comparison precisions using two-way

time exchanges through a communications satellite. Additional laboratory

tests have indicated that 20 picosecond comparisons are possible using the same techniques with higher transmission poweri levels. The tests were encouraging and resulted in an informal agreement between MBS, USNO and

the NRC in Canada to work together to develop a permanent network to serve these three laboratories . All of the necessary equipment has been

acquired and tests will begin next year.

The use of communication satellites for the delivery of time and

frequency information on a subscription basis also appears feasible with

the application of technology originally developed and used by the DoD.

The integration of this technology with careful baseband design (representation of the time and frequency information) could yield a viable (and

fully reimbursable) delivery system serving important industrial and

government needs in a very economical and reliable fashion. Preliminary

system examination by calculation and consultation with satellite industry

engineers and scientists have confirmed feasibility. Potential industrial

consumers of such a service have strongly urged MBS to further develop

these concepts.

FY 1985 Plans

Plan - Install and bring into operation at Boulder the equipment for

two-way time transfers using communication satellites and spread spectrum

techniques

.

Accomplishment - A 6.1 -meter, parabolic antenna has been installed on the main NBS-Boulder facility. Final integration of electrical and

electronic systems must be completed before full operation can begin.

This is expected to occur just after the start of calendar year

1986.

Plan - Perform preliminary evaluation of the two-way time transfer

technique for international time coordination.

Accomplishment - Longer than anticipated design time for the roof

installation of the antenna has caused a delay in evaluation of the

150
system. The design work started in March 1985 with installation

projected for May, but that was delayed until the last week of

August, 1985.

FY 1986 Plans

Complete two-way time transfer system and, using the system, begin

coordination with the US Naval Observatory (USNO) and the National

Research Council (NRC) in Canada.

»*»»***»*************)tit**5t ^t** 5t**************Jt**********^t^tit*****^*it****

OBJECTIVE: Advise and work with other governmental agencies and

industry to incorporate advanced time and frequency metrology into their

programs.

FY 1985 Plans

Plan - Pending outside funding, conduct a study on how a fully reimbursable, one-microsecond time service might be implemented. The study

will stress low cost and reliability using available leased telecommunication services.

Accomplishment - Funding for a one-year study was received from the

Department of Energy in December 1984. Preliminary results suggest

that a reimbursable service is realistic. Several alternate

approaches are still under consideration. The study is on schedule

and will be completed in December 1985.

Plan - Pending outside funding, develop time transfer techniques and

systesms to initiate and maintain mission timing in a tactical communication environment.

Accomplishment - Funding for this work was received for FY85 and work

is in progress. The program is to continue in FY36 with a change in

emphasis to space-borne communication platforms.

FY 1986 Plans

Pending other agency funding, conduct studies on the synchronization of

space-borne communication nodes.

Complete study of a one-microsecond reimbursable time service. Pending

additional funding, continue work on this topic in the direction indicated

by the study conclusions.

151
III. Time Scale and Time and Frequency Coordination

This group has the responsibility for the operation and further

development of the NBS time scales and for coordination of these time

scales with other standards laboratories and the Bureau International de

L'Heure (BIH). The time scale is, of course, a key responsibility since

it not only provides the basis for all services, but also serves as the

stable reference against which much of the division gauges its' research.

The group has developed a coordination scheme based on common view of the

Global Positioning System (GPS) satellites which has become the de facto

coordination approach for the world.

Staff; D. W. Allan, Project Leader

A. J. D. Clements

D. D. Davis

J. E. Gray

H. E. Machlan

T. K. Peppier

M. A. Weiss (Part-time)

J. Levine (1/2 time)

L. Erdosh (Guest Worker)

******************************)f**Jt»***************3f**********Jt************

OBJECTIVE: Generate NBS time scales, UTC(NBS) and TA(NBS)

**********^**:^**^************^*******************************^***ii***^***^

NBS atomic time is generated from an ensemble of approximately twelve

commercial and one laboratory cesium beam frequency standard and two

laboratory hydrogen masers. The time of all the clocks is automatically

measured every two hours with a precision of a few picoseconds. The

UTC(NBS) time scale is computed immediately following a measurement cycle

using a weighted-average algorithm. The small dispersion of the clocks

during the two hour interval between measurements makes it possible for

NBS to provide UTC(NBS) to users with 1 ns precision at all times.

Coordinating with the Bureau Internationale de L'Heure, UTC(NBS) is

steered toward and kept within a few microseconds of UTC.

At the end of each month, the TA(NBS) time scale is computed using a Kalman algorithm. This computation is optimum in the statistical sense

for clocks having both white frequency noise and random walk frequency

noise, a good model for the clocks in the NBS ensemble. The

second of TA(NBS) is steered toward NBS's best estimate of the SI second

based on yearly calibrations of the ensemble by NBS-6.

FY 1985 Plans

Plan - Establish policies and procedures for the routine operations of the

time scale and fix responsibilities for their implementation.

152
Accomplishment - Considerable attention has been given to the time

scale during FY85. Howard Machlan was moved from WV in Fort Collins

to assist with the effort. Remodeling of part of the time-scale

space is underway and power back-up systems are now in operation.

Redundancy has been added to several systenis to increase reliability.

Documentation is in progress. The time scale has been shown to be

operating at the theoretical performance level, that is, the scale

performance is limited only by the individual clocks in the ensemble

and the algorithm which combines them. The major concern is the

long-term reliability and adequate management of the large data base

associated with the time-scale. This includes not only data on clocks

in the NBS ensemble, but also data on the many clocks (and primary

standards) which are transferred in through the GPS system.

Plan - Use the system with receivers at WWV and WVH to relate the

performance of the clocks at those sites to (UTC)NBS and study the

possibility of including them in the time scale.

Accomplishment - NBS/GPS receivers have been installed at both sites.

Data from these receivers is now routinely filed in the time-scale

computer giving back-up redundancy at the level of performance of the

clocks at the radio stations. Time transfer accuracy is better than

10 nanoseconds. Because of the non-independent method of operation

of these cesium standards, they are not useful as independent

additions to the time-scale ensemble. The GPS receivers assure that

UTC(NBS) is accurately available at the station sites.

Plan - Complete and put into operation the new emergency power backup

system and the measurement backup system.

Accomplishment - System has been completed and is in operation. It

performed well during a scheduled, 10-hour power outage. A few

additional problems were identified during this outage and solutions

for these have been developed.

Plan - Develop the appropriate interface between environmental monitoring

equipment (recently ordered) and the time scale computer (PDP 11/70), and

begin study of the influence of environmental parameters on clock behavior.

Accomplishment - All equipment for environmental monitoring has been

received and tested. Most of it is fully installed and operating,

but completion of the system is awaiting remodeling of part of’ the

time-scale space and computer interfacing of some of the equipment.

This monitoring equipment proved to be especially useful during the

recent scheduled power outage.

FY 1986 Plans

Complete modifications and improvements of emergency power backup systems

and develop procedures for their routine testing to assure reliability.

153
study alternatives for acquisition of a backup computer for the time

scale. Consider long-term needs for replacement of current computer.

Pending outside funding, initiate development of a "best research clock"

as a reference for study of the millisecond pulsar. This work would be

collaborative with Arecibo Observatory, Princeton, Berkeley, etc.

Complete implementation of time-scale environmental monitoring systems.

System will trip alarm to alert staff when environmental parameters go out

of operating range.

*******i(**¥**************it************5t^eee***^t********it*********jt**jti(*jt**it*

OBJECTIVE: Maintain international coordination of time scales and

frequency standards using the Global Positioning System.

A satellite based time transfer system which technique was developed

in the Time and Frequency Division between 1979 and 1982 is now operational. Based on this approach a number of receivers are operating;

e.g., at PTB in Braunschweig, West Germany; at OP in Paris, France;

Goldstone, California; Madrid, Spain; Canberra, Australia; at NRC in

Ottawa, Canada; at lEN in Torino, Italy; at RRL in Tokyo, Japan; at VSL in

Delft, The Netherlands; at USNO in Washington, D.C.; as well as at NBS in

Boulder, Colorado. A computer based automatic data collection network

acquires the data from the receivers. This data is combined with the data

from the NBS Atomic Time Scale so that the time of the remote clock is

known with respect to UTC(NBS) to a precision better than 10 nanoseconds

after one day of averaging.

JPL employs three receivers in the same mode used by NBS for

international coordination to provide frequency calibrations between the

sites of the NASA Deep Space Network at a few parts in 10^^. In fact, JPL

funded part of the receiver development at NBS. The receivers at Boulder,

Paris, Ottawa, Torino, Tokyo and Braunschweig, are being used to transfer

clock data from NBS, OP, NRC, lEN, RRL, VSL and the PTB to the International Time Bureau in Paris. This new system has replaced Loran-C as the

principal time and time interval transfer link for the SI second and the

International Atomic Time Scale (TAI) for all major national standards

laboratories.

FY 1985 Plans

Plan - Vtork through CCDS to establish responsibilities, cost sharing, and

limits of coverage for NBS supported GPS time coordination.

Accomplishment - The CCDS has fully endorsed use of the NBS/GPS

Common-View Technique for international coordination. It is now the

de facto coordination method for all of the primary standards and 50^

of all other clocks in TAI. BIH plans to send a guest worker to NBS

154
to learn more about the technique. NBS is currently handling the

tracking schedules for the system, but 3IH will take over that

responsibility in the future.

FY 1986 Plans

Cooperate with BIH guest worker to transfer GPS coordination methods and

tracking procedures to this international organization. This is, of

course, contingent upon the visit of this guest worker.

Publish paper summarizing procedures used in GPS time and frequency

coordination.

OBJECTIVE: Develop metrology for precise time, frequency and length

measurements.

******^*^*^*****^^*^ik**ik^*******^^********^******^************************

Techniques for characterization and measurement of frequency and frequency

stability

The need for frequency measurements range from sub-audio to the

ultraviolet. NBS has been a world leader in developing and disseminating

the measures of frequency stability, their practical implementation, and

accuracy. For example articles in the Feb. 1966 issue of Proc. of IEEE and

the 1971 IEEE I&M laid the foundation for specifying a practical way of

defining frequency stability, which has become the defacto international

standard in the field. The dual mixer concept of measuring time,

frequency, and frequency stability makes it possible to easily measure the

difference between state-of-the-art frequency standards even if they are nominally the same frequency. This concept was introduced in 1975 by NBS

and NRG (Ottawa, Canada), and is used in the new NBS time scale

measurement system. Now, picosecond precision time difference

measurements can be made automatically on virtually any number of

state-of-the-art clocks. Work in 1975 illuminated the limitations on frequency multiplication due to the phase noise in the standard or the

multiplier chain, explaining numerous previous failures at precision

infrared synthesis. This new understanding of the multiplication process

then stimulated considerable improvement in the phase noise of crystal

oscillators and signal processing equipment. In the rf region, the lowest

noise crystal oscillators, buffer amplifiers, isolation amplifiers, and

frequency multipliers presently available are a direct outgrowth of

prototype designs and analysis developed at NBS. These new low noise

devices have numerous applications in precision metrology as well as in

the development of new frequency standards such as the passive hydrogen

maser, stored ions, and cesium.

155
Techniques for characterizing noise in clocks

As part of the generation and dissemination of the SI second it is

necessary to have an ensemble of clocks as a memory of the rate given by

the primary frequency standard. This is accomplished by running a set of

clocks based on commercial frequency standards which, in general, don’t

have the accuracy of the primary standard but have very good frequency

stability. These clocks, when properly characterized, act as a good

flywheel for the rate of NBS-6 . The memory accuracy of the clock ensemble

can be improved by either increasing the number of clocks or by wisely

utilizing the clocks available. NBS has chosen to use a modest number of

clocks with sufficient reliability, redundancy and variety (to avoid

systematics from a particular manufacturer) from the available vendors

making clocks, but then to characterize the clocks with enough care so that optimum time and frequency can be generated from the ensemble as memory of the rate given by the NBS primary frequency standard.

One of the current time scale algorithms had its philosophical basis

in 1968 and has evolved into different programs with different computers.

It became important to know how well this algorithm was approaching

optimal performance given the set of clocks at hand. A cooperative effort

was engaged in with the Statistical Engineering Group and out of that work

came some very important contributions. First, a method was developed

using Kalman filters to model atomic clocks and obtain maximum likelihood

estimates of the model parameters from data on the ensemble of clocks.

Tests for the validity of the model and confidence intervals for the

parameter estimates were made and shown to be statistically significant.

Techniques were also developed on the statistical significance of

frequency drift and yielded some very important insights. In addition, a Kalman or recursive algorithm for estimating time from the ensemble of

atomic clocks was developed. The algorithm allows for the addition or deletion of clocks and provides for automatic error detection and

correction. Because of the success of this program, this Kalman

algorithm is now used to generate the time scale TA(NBS) and the previous

algorithm mentioned is still used to generate UTC(NBS). With this effort

also came the conclusion that the past algorithm was very near optimum in

its performance.

FY 1985 Plans

Plan - Initiate examination of the systematics in clock behavior through

improvement of the statistical software routines.

Accomplishment - Performed some preliminary experiments on the effect

of environmental changes on clock performance. More complete studies

will require completion of environmental monitoring system and

automated recording of selected environmental parameters on the

time-scale computer.

156
FY 1986 Plans

Continue study of correlations between clock performance and environmental

parameters

.

OBJECTIVE: Provide seminars, calibrations and measurement assurance on a fully reimbursable basis.

Global Time Service

The division now offers a service, based upon the NBS designed

receiver, which provides for extremely high precision time and frequency

data at the users site. A receiver which is located at the users facility

communicates its data automatically to an NBS computer which stores the

raw data, determines which data elements are suitable for time transfer

calculations and provides an optimally filtered value for the time and

frequency of the user’s clock with respect to the NBS Atomic Time Scales.

The user is given an account on one of the NBS computers through which he

may access the results of the NBS analysis. Tests between receivers in

Colorado and Canada, Germany, France, Spain, Wyoming, Louisiana,

Washington, DC and California have demonstrated an ability to perform time

comparisons with a precision of a few nanoseconds using an averaging time

of 13 minutes and frequency comparisons with a precision of 1 part in 10^

for averaging times of four days and longer.

Calibration of Atomic Standards

In conjunction with its new time scale algorithms NBS has developed

a time and frequency measurement system which is unsurpassed in many of

its capabilities. This new system has vastly improved capability of

calibrating any clock that might be sent to NBS. The full accuracy of

the NBS time scale and primary frequency standard is readily available and

measurements are made automatically every two hours on a clock being

calibrated. These data are logged in the NBS time scale computer and the

standards characteristics and performance are readily documentable

.

Similarly, the person for whom the clock is being calibrated can be given

an account in one of the NBS computers through which he may access the

data as taken in real time.

FY 1985 Plans

Plan - Achieve an income level of $150,000 per year for the GPS Service.

Accomplishment - Net income for the service in FY85 was $1^0,000.

The purchase of 21 receivers of the NBS design effectively

transferred the receiver design to industry. The NBS purchase

resulted in announcement by the company of a commercially available

157
product with a price tag which is very attractive. As a result, new

users of the NBS service will purchase their own receiver (ie. NBS is no longer involved with providing receivers for the service).

FY 1986 Plans

Finish remodeling of calibration facility (room 2047).

Shift staff responsibility for Global Time Service to more effectively

distribute work load within the group.

OBJECTIVE: Advise and work with other governmental agencies and

industry to incorporate advanced time, frequency and length metrology into

their programs.

FY 1985 Plans

Plan - Advise Air Force Space Division on time and frequency aspects of

operation of Global Positioning System.

Accomplishment - NBS characterization of GPS clocks and the Kalman

filter parameters has continued to enhance the performance of the GPS

system. The NBS/GPS Time Service was installed at Rockwell

International to support calibration of GPS clocks.

FY 1986 Plans

Continue to advise Air Force Space Division on operation o'f Global

Positioning System. Pending outside funding, develop time-scale system

for GPS ground control.

Pending JPL funding, develop methods for remote steering of a clock using

GPS.

158
IV. Hydrogen Masers

The primary goal of this effort has been to develop a passive

hydrogen maser with good medium-terra to long-term stability for DoD requirements and for use in the MBS clock ensemble. The project, which has

been funded by the Navy, has been quite successful. Two masers are currently operating in the ensemble and they have been out-performing the

commercial cesium standards by a wide margin. The maser technology has

been transferred to industry through the Industrial Research Associate

Program. The project has also addressed a number of issues which are of

importance to the division. These include: line-center errors in high

performance servo systems and phase noise in frequency multipliers and

synthesizers.

Staff: F. L. Walls, Project Leader

K. B. Persson

L. L. Lewis (Industrial Research Associate)

T. E. Smith (Industrial Research Associate)

S. R. Stein (Industrial Research Associate)

OBJECTIVE: Generate MBS time scales, UTC(NBS) and TA(NBS).

»*******^t****************************************9t***********************»

Active hydrogen masers have long been touted for their excellent

short-term stability, but long-term stability has generally been poor.

The MBS maser project has focussed on improving long-term stability in a passive maser which is relatively simple and small. The goal has been a system which will fit into a package equivalent to ' that of a commercial

cesium standard.

The results obtained to date have been impressive. The best of these

masers provides medium-to- long -term stability equivalent to that of a cesium ensemble of approximately 25 high performance tubes. The

fundamental design advance has been the servo locking of the physical

cavity resonance to the hydrogen reference. The system also locks the

slave oscillator to the same atomic resonance. The obvious conclusion is

that the long-term stability of active hydrogen masers has been severely

degraded by cavity pulling effects and that variations in the wall shift

are extremely small relative to the present accuracy of primary standards.

FY 1985 Plans

Plan - Add hydrogen masers to MBS ensemble to improve its stability.

Accomplishment - Two masers, PHM-4 and MPH-14, are now part of the

time scale. Both are performing extremely well out to at least

several weeks. Moreover, in evaluating their frequencies, we have

shown that MPH-14 is reproducible to better than 3x10”^^ exclusive of

the wall shift. Since the wall shift has been shown to be stable to

159
-1 ^ better than 1x10 -* per year, this represents a major advance for

portable clocks. This work generated an extensive study of servo

errors reported at a recent meeting and scheduled for submission to

IEEE Transactions on Instrumentation and Measurement. The servo

work provides a useful guide for development of NBS-7.

FY 1986 Plans

Add a third NBS passive hydrogen maser to the NBS ensemble.

Pending available funding, purchase a commercial version of the passive

hydrogen maser to improve reliability of the NBS ensemble.

Study correlation between frequency noise in the passive masers and

environmental parameters (e.g. humidity, pressure, and temperature).

Complete study of servo errors and begin transfer of servo technology to

primary standard project.

OBJECTIVE: Provide seminars, calibrations and measurement assurance on a fully reimbursable basis.

jt*************************************************************************

Measurement of Phase Noise

The improved phase stability of components developed for the passive

maser have enhanced the division capability to provide special calibrations of phase noise in oscillators, amplifiers, frequency multipliers and

synthesizers from 5 MHz to 700 MHz. The present level of precision and

accuracy for the NBS systems exceeds the performance of any commercial

device over this frequency range.

FY 1985 Plans

Plan - Establish policies and procedures for the routine operation of

calibration services and fix responsibility for their implementation.

Accomplishment - Calibration systems were upgraded to handle a broader range of frequencies. The descriptions of NBS calibrations

in the central NBS catalogue of services (SP250) were completely

rewritten. A room adjacent to the time scale has been set aside for

calibration activities and renovation of that space has started.

Once all systems are in place in this space, the procedures and

policies for their operation will be finalized.

Plan - Determine user needs and upgrade calibration capability as appropriate (e.g., for signals at 10 MHz or stability at one-second

averaging time)

.

160
Accomplishment - Ultra-low-noise multiplier chains were developed and

tested. New circuits providing references at 10 MHz and 100 MHz have

been fabricated and tested. The new systems improve resolution for

- 12 - 1/2 measuring OyCt) at three seconds from - 3x10 x to

- 1 x1 0~^ New computer hardware will be needed to automate

measurements at one second.

FY 1986 Plans

Extend capability for phase noise measurement to 18 GHz.

Extend calibration capability for Oy(x) down to a one-second averaging

period.

OBJECTIVE: Establish the units of the International System for the

"second" and the "meter".

FY 1985 Plans

Plan - Complete low phase noise synthesis chain for multiplication to 10

GHz in support of both the optically pumped cesium standard and as a candidate element of a future chain for synthesis into the visible region.

Accomplishment - A new 5 MHz to 100 MHz multiplier was designed,

fabricated and tested. Four printed circuit versions of this circuit

have been assembled and final • testing will be completed shortly.

Three low-noise, x-band oscillators have been acquired and circuits

are ready for locking them to the multiplied 100 MHz systems.

FY 1986 Plans

Renovate and "recalibrate" electronics for NBS-4 and NBS-6.

Finish synthesis to x-band. Multiply x-band signal to 70 GHz and phase

lock the two systems.

**5t**********^t*******************Jt**5(**it*if^t**************^fit )t** if*»if*»»*

OBJECTIVE: Advise and work with other governmental agencies and

industry to incorporate advanced time and frequency metrology into their

programs.

Hydrogen maser technology

The passive hydrogen maser developed at NBS with partial military

funding has demonstrated exceptional frequency stability from a few

seconds to a few weeks. Based on 2 months of data, the stability is - 5 x 10 at 1 day and - 2 x 10~^^ at 8 days. At a level of resolution of ±

161
3 X 10 ^^/day, the drift is unobservable. The time dispersion per day is a factor of 4 to 5 times better than the best available commercial cesium

frequency standards.

Several Industrial Research Associates have worked with NBS for three

years on this program. This cooperation continues and the first passive

hydrogen maser to be constructed in this program is now in operation.

Low acceleration sensitivity quartz crystal resonators

Vibration sensitivity is presently one of the most severe difficulties encountered when using a frequency standard in non-laboratory

environments. Although NBS no longer has an experimental quartz crystal

research program, consulting support is being provided to the U.S. Army

and its industrial contractors.

FY 1985 Plans

Plan - Continue collaboration with Industrial Research Associates in the

development of a passive hydrogen maser field standard.

Accomplishment - The collaboration with Industrial Research

Associates has resulted in successful transfer of the

passive-hydrogen-maser technology to industry. NBS's industrial

partner is now close to testing an engineering design model of a commercial version of the NBS miniature passive hydrogen maser. This

unit should achieve performance equal to or better than MPH-1 4 with

the reliability characteristics of a 3rd -generation system.

FY 1986 Plans

Continue collaboration With Industrial Research Associates on the passive

hydrogen maser.

162
V. Atomic Beam Standards

This program has just received sufficient additional MBS funding to

allow construction of NBS-7, the next generation primary frequency

standard which will be based on optically pumped cesium. The objective is

a standard which can be easily operated in a nearly continuous mode with

semi-automatic assessment of systematic errors at an accuracy level of 1 part in 10^^. The project is built upon successful tests of the concept

on field-size standards pumped by laser diodes.

Staff: R. E. Drullinger, Project Leader

D. J. Glaze

D. L. Hilliard

L. Holberg

J . P . Lowe

A. De Marchi (Guest Worker)

J. Yoder (Industrial Research Associate)

«»»*»»»i(****jt»*******»**jt******************************jtit**************it**

OBJECTIVE: Establish the units of the International System for the

"second" and the "meter".

Operate NBS-6, the U.S. primary frequency standard

Since 1968 NBS has designed and developed three new cesium devices:

NBS-4, NBS-5, and NBS-6. NBS-4 has a medium-length cavity of 50 cm, and

was built to test new ideas for improving the stability of cesium devices.

This standard is one of the most stable cesium clocks in the world,

-1 B achieving a stability of 7 x 10 . It should be noted here that no previous NBS cesium frequency standards directly drove a clock; instead,

they were used periodically to calibrate the frequency of an ensemble of

commercial cesium beam clocks that ran continuously. NBS-4, because of

its excellent stability, has served as a working clock in the time-scale

ensemble.

NBS-5 was built on the framework of NBS-3 and in turn served as the

basis for NBS-6, completed in 1975. The refinements incorporated over the

years include greatly improved components to provide narrower resonance

lines (25 hertz), the ability to reverse the direction of the atomic beam

(which allows errors due to asymmetries in the cavity to be diagnosed),

and other features aiding analysis of performance. It can also undergo

routine maintenance without being completely turned off. NBS-6 has an accuracy of 3 x 10~^ ; more accurate but not quite as stable as NBS-4.

Used together, these two standards generate the U.S. standard second. A clock ensemble is used to carry the second forward in real time so that it

is continuously available.

163
FY 1985 Plans

Plan - Evaluate NBS-6 by the end of FY 1985.

Accomplishment - Major modifications to the vacuum system and

refurbishing of the electronic components are in progress. The

evaluation will begin when these are completed. It now appears that

the evaluation will be delayed approximately three months.

Plan - Use NBS-6 to calibrate TA(NBS).

Accomplishment - The last calibration of TA(NBS), completed in late

1984, showed no shift in TA(NBS) within the stated systematic errors

of NBS-6, that is, within eight parts in lo”'^. This again confirms

that the time-scale stability is sufficient to continue evaluations

with an interval of one year. When and if the systematic errors of

the primary standard are reduced, a shorter calibration interval may

be required.

Plan - Continue work on field-size optically pumped cesium standards in

collaboration with an Industrial Research Associate. Focus on those

elements which directly affect the development of a primary standard

(e.g., laser stability requirements, laser stabilization schemes, and the

Majorana effect)

.

Accomplishment - Studies of the laser noise and clock stability have

resulted in the development of a model which relates laser noise to

clock performance. This has helped clarify the requirements for

laser diode performance. Simple methods for stabilization,

line-narrowing, and tuning of the laser diodes are now under study.

A third-generation, field-size standard has been designed and

incorporates the ideas generated by theoretical study of Rabi line

pulling and Majorana transitions. This new tube will allow for study

of a number of systematic effects.

Plan - As appropriate, modify and upgrade components of NBS-4 and NBS-6 to

alleviate operational difficulties associated with aging and damaged

components.

Accomplishment - Major modifications and rework of the vacuum system

and electronics of NBS-6 are nearing completion. The ion pumps are being replaced, new pumping and vacuum monitoring parts are being

added, and a system for relieving the sliding seal problems is under

construction. New connectors, cabling, and grounding have been added

to improve reliability and reduce instabilities in the electronic

subsystems. Modifications to NBS-4 have been delayed until the work

on NBS-6 is complete.

164
FY 1936 Plans

Conplete modifications and rework of NBS-6.

Complete evaluation of NBS-6 by Jan. 31, 1986. Use evaluation of NBS-6 to

calibrate TA(NBS).

Continue study of the field-size standard with emphasis on development of

design information for NBS-7.

Initiate upgrade and modification of NBS-4 to bring it up to its earlier

performance level.

OBJECTIVE: Make fundamental improvements in atomic spectroscopy for

future application to primary frequency standards.

Primary cesium standard development

The known limitations to the accuracy of NBS-6 lie with the microwave

cavity phase shifts, exacerbated by the dispersive nature of the state

selection magnets. In addition, there are unknown shifts of the cesium

clock frequency associated with systematic effects which cannot be readily

studied in conventional systems. Replacing the magnets in a cesium

standard with optical pumping and detection using laser diodes should

allow the reduction of cavity phase shift uncertainties, and permit a better understanding of the limitations of cesium standards. A small

laboratory version of the optically pumped cesium atomic beam frequency

standard has been constructed and performance demonstrated at o,,(x) < _i p _i /p ^ y 7x10 T . Long-term data showing the ’’flicker" floor has not yet

obtained.

been

FY 1985 Plans

Plan - Develop detailed plans for a test bed to evaluate the potential for an optically pumped primary standard and initiate construction of the

system.

Accomplishment - A detailed study of the Ramsey-cavity design has

been completed. The optical pumping concept allows excellent control

of end-to-end cavity phase shift, so the new cavity has been designed

to minimize the distributed cavity phase shift. The design selected

is relatively radical and considerable outside review is planned

before an irreversible commitment is made to it. This review will run parallel to testing of a prototype cavity which is now being

fabricated. The cavity geometry and dimensions have set the stage for

completion of the system design from the inside outward. The

performance requirements for the laser diodes have been established

165
and techniques for achieving required performance have been

demonstrated. Considerable work on electronic subsystems has also

been initiated. This includes:

1 . A new frequency synthesis concept has been developed and

tested.

2. A model for the phase modulator has been developed and

character ization of a test system is near completion.

3 . A major study of servo errors has been undertaken and is near completion.

4. A new staff member is addressing the demodulator and

integrator circuits.

FY 1986 Plans

Complete design of a frequency standard (test bed) based on optically

pumped cesium, and initiate construction of the system.

OBJECTIVE: Advise and work with other governmental agencies and industry

to incorporate advanced time and frequency metrology into their programs.

^e**5t***jt^t it** ie****it*********5^****9t*^t**********************»***jt*jt******

Cesium beam technology

Recent advances in cesium beam technology which have come from Division

studies of optically pumped cesium clocks could improve the performance of

commercial devices which are used in military applications. For example,

this research could improve both the long-term stability and the

reproducibility after turn-on of satellite based cesium clocks. These

improvements involve the use of laser diodes, cesium heat pipe ovens,

optical pumping, and fluorescence detection of atoms.

Much of this work is performed under contract for other governmental

agencies. In addition, the Division has formed two Industrial Research

Agreements with manufacturers of cesium clocks. These agreements permit

the transfer of NBS research results to the private sector, and also

bring guest scientists from industry to the governmental laboratory.

FY 1985 Plans

Plan - Complete testing of cesium heat pipe ovens and publish the results.

Accomplishment - A detailed, quantitative model for these ovens was developed and measurements confirm that it is reasonably accurate.

The model suggests a design modification which should substantially

improve performance. Oven-life testing continues and results of the

work have been submitted for publication. This work has been funded

by another agency and has potential for large benefits for commercial

cesium standards.

166
Plan - Continue collaboration with an Industrial Research Associate (IRA)

in the development of an optically pumped cesium field standard.

Accomplishment - This IRA agreement involves a commitment on the part

of NBS’s collaborator to fabricate field-size cesium tubes modified

for optical pumping. Two such tubes have already been fabricated and

tested and a third has been designed. The collaborative work has

resulted in clear demonstration of the optical-pumping concept. The

measured performance of o (t) < 7x1 0~^ is still above the

flicker floor for the system.

FY 1986 Plans

Fabricate modified recirculating (heat-pipe) cesium oven and compare its’

performance with the model.

Continue collaboration with an Industrial Research Associate on the

development of an optically pumped cesium standard.

167
VI. ION STORAGE

The long term plans for primary frequency standards for the division

involve an eventual shift to ion storage and radiative cooling. For the

present the effort of this group is being directed toward development of

the physics of the concepts. The group has already demonstrated a Be"^ ion

clock which operates at a performance level equal to that of NBS-6, the

present NBS primary standard. While the focus of this work is ion

standards, the techniques are also applied to other problems of

fundamental interest.

Staff: D. J. Wineland, Project Leader

E. C. Beaty

J. C. Bergquist

J. J. Bollinger

W. M. Itano

C. H. Manney

F. Ascarrunz (Work Study)

L. R. Brewer (Postdoc)

H.-U. Daniel (Guest Worker)

A. Derbyshire (Guest Worker)

S. L. Gilbert (Postdoc)

R. G. Hulet (Postdoc)

D. J. Larson (Guest Worker)

G. Leuchs (Guest Worker)

J. D. Prestage (Postdoc)

OBJECTIVE: Make fundamental improvements in atomic spectroscopy for

future application to primary frequency standards.

******»»*******^t*************^t**i(**9t*)t*****»***********5t;^*»****9t*****je****

Atomic clock based on stored ions

As a step towards realizing a primary frequency standard based on stored ions, the Division has made a clock based on a ground state

hyperfine transition in ^Be'''. The combined uncertainties in all

systematic frequency shifts (such as those due to Doppler effects) are at

the same level as those of the present U.S. primary time standard,

NBS-6 which has an uncertainty of about One part in 10^^.

In these experiments, a few hundred ^Be ions were confined in a Penning trap and laser cooled to temperatures less than IK. An

oscillator was locked to a magnetic field independent hyperfine transition

(- 300 MHz) using an optical pumping, double resonance technique.

Measured stabilities were about equal to a commercial cesium clock. The

hyperfine transition was driven for 20 s on each cycle which produced a linewidth of 0.025 Hz. During this time, the laser was shut off to avoid

light shifts; this also allowed the ions to heat slightly from background

gas collisions causing a second order Doppler shift of about 2 x 10

168
Other systematic effects are below this level. Frequency stability and

accuracy performance can be improved in the future by using an ion with a higher hyperfine frequency. For this reason, mercury ions with hyperfine

transitions at around 30 GHz are now being studied. The heating problem

is discussed below.

Farther in the future, it appears that the most accurate clocks will

be based on optical transitions in atoms or molecules. The main reason

for this conjecture is that the Q's for such transitions can be extremely

high 10^^). With this in mind, the two-photon S^D transition in Hg

has been studied. The transition was observed for the first time in a miniature rf trap. The present linewidth is limited by the laser

bandwidth, but this transition has a fundamental Q of about 0.5x10''^

(radiatively limited).

lon-cloud/trapped-ion studies

Studies are made of ion dynamics and the relation of these dynamics

to trap design. It appears that the principle limitation to accuracy of a frequency standard based on stored ions will be the uncertainty in the

second-order-Doppler (time-dilation) frequency shift due to the rotation

of the ion cloud. This rotation is a non-thermal effect and is independent

of the internal temperature of the cloud. Tnerefore detailed studies of

ion-cloud temperature, density and rotation are being made using a two-laser, optical-optical double resonance technique.

A new concept for a frequency standard based on "sympathetic cooling"

is being studied theoretically and experimentally. In sympathetic

cooling, one ion species is cooled by Coulomb coupling with another ion

species which is laser cooled. Tnis was proposed and demonstrated (on the

Mg isotopes) a few years ago at NBS and is now being considered for use

in the mercury standard. The advantage is that the "clock" ions can be

continuously cooled, but ac Stark shifts from the cooling radiation can be

made negligibly small. Tnis should result in substantially narrower

linewidth (less than t millihertz) and reduction of errors due to the

second-order Doppler shift.

FY 1985 Plans

Plan - Continue investigation of laser cooling of Kg"^ in Penning and rf

traps with emphasis on improved vacuum and increased laser power.

Accomplishment - Direct laser cooling (A = 19^ nm) of Hg"^ ions in an rf

trap has been observed. The best cooling and largest signals were

obtained for single ions. For the near term, this result indicates

that there is no fundamental limitation in achieving direct laser

cooling in the Penning trap experiments. For the longer terra, the

result demonstrates feasibility for the trapping and cooling aspects

of a Hg optical frequency standard.

169
Plan - Further investigate (theoretically and experimentally) "sympathetic

cooling", that is, cooling of one ion of spectroscooic interest by another

ion which is laser cooled. Upon completion of the ^Be'*’ experiments, begin

construction of two-ion traps for this investigation.

Accomplishment - A computer solution for spatial shapes of

two-component ion clouds has been accomplished. At T=0, the species

separate, but cooling is maintained by the long-range Coulomb

coupling. A Be'’’/Hg'^ trap has been fabricated and tested for Be'*’ and

Hg separately. Sympathetic cooling experiments will be initiated in

the near future. A Mg /Be trap is in the final design stages.

This apparatus will allow a more complete evaluation of the concept.

Plan - Initiate fabrication of "array" detector to facilitate studies of

cloud shape and size.

Accomplishment - The position-sensitive, photon-multiplier tube, the

"array", was received in June, 1985. The electronic interface is

nearing completion and testing of the entire system will take place

in the near future.

FY 1986 Plans

Continue investigation of laser cooling of Hg"^ in rf traps. Study

mechanisms which limit the linewidth of the two-photon transition in Hg"^

and develop methods for reducing this linewidth.

Complete fabrication of array detector and use it to observe single Hg"^

ions

.

Conduct experimental studies of sympathetic cooling. Correlate results

with computer solutions and study alternatives for using the concept as a basis for a primary frequency standard.

********»**>***it*******»it**********)t»**********9t*»*»*jt»»***it**)t***»*5^»**»*

OBJECTIVE; Perform basic studies in program areas related to future time

and frequency standards.

As an outgrowth of studies on ion clouds stored in Penning traps for

possible frequency standard application, several closely related basic

studies have been undertaken.

Search for Spatial Anisotropy

Frequency standards, including those based on atomic or nuclear

(Mossbauer) transitions, have traditionally played an important role in

testing gravitational theories. One example is measurements of the

gravitational red shift. In addition, the very high resolution attained

in trapped ion spectroscopy enables other sensitive tests of the Einstein

170
Equivalence Principle (EEP). All metric theories of gravity (including

General Relativity) are founded on the EEP, according to which, any

nongravitational physics experiment done in a local freely falling frame

near a strongly gravitating mass will have the same outcome when done in a freely falling frame far away from all such masses. Also included in the

EEP is local Lorentz invariance which states that the outcome of the

experiment is independent of the velocity of the freely falling frame. In

particular, two different atomic clocks (i.e., clocks based on transitions

in two different kinds of atoms) located at the same point in space-time

will have relative rates which are independent of (1) the velocity of the

freely falling lab, and (2) the position and mass of strongly gravitating

bodies. As a test of the EEP the frequency of the ^Be"^ "clock” transition

(Mj = 1/2, Mj = -

3 / 2 ) (Mj = 1/2, Mj = -1/2) has been compared to the

frequency of a passive hydrogen maser to see if a correlation can be found

with orientation in space. Two gravitational interactions have been

proposed which violate the EEP and shift the ^Be"^ "clock" transition

relative to the hydrogen transition. Our experiments have searched for

sidereal variations of the ^Be'*’ "clock" transitions relative to the

hydrogen transition. These experiments have achieved resolution better

than 0.1 mHz and see no such variation. These results decrease previous

experimental limits by a factor of 300 and in the future we expect to gain

a further increase of two orders of magnitude in resolution.

Non-neutral plasmas

In the language of plasma physics, the ion clouds in a Penning or rf

trap comprise a one component, non-neutral ion plasma. In a small plasma

of laser cooled ^Be^ ions stored in a Penning trap we have observed

behavior which is indicative of the liquid state. In this case the

Coulomb coupling constant I was as high as 10. Calculations predict that

at r = 2 , the pair correlation function should begin to show oscillations

characteristic of a liquid, and at much larger values of r (F = 170)

crystallization may take place. In our experiment a second laser was used

to probe the ion plasma and measure the temperature of the ions from the

Doppler broadening of the optical probe transition. The ion number

density was determined by measuring the (SxS) cloud rotation frequency.

Because the trap electric field and magnetic field were known, the space

charge electric field was extracted from the cloud rotation frequency and

used to determine the ion number density. Ion number densities of - 2 x

1 o'^/cm^ and temperatures of < 100 mK produced values of F = 10. Values of

F large enough to observe a liquid-solid phase transition should be

accessible in future versions of this experiment. If the theoretical

cooling and density limits can be obtained, values of F as large as 15,000

are perhaps possible for Be'*’ ions. Because experimental information on three-dimensional, strongly coupled plasmas is almost non-existent, these

experiments can provide some useful tests of the theoretical calculations.

171
FY 1985 Plans

Plan - Initiate study of magnetic susceptability perturbations to

hyperfine structure in ^Be''’ (success will rely upon how many field

independent transitions it is possible to measure).

Accomplishment - Attempts were made to study all of the

field-independent transitions in ^Be'*', however the low-field

transitions (B=1.6 T) were not accessible due to parasitic heating

(apparently caused by trap asymmetries) . To circumvent this problem

a new trap with a high degree of axial symmetry has been designed.

Q + Plan - Continue search for spatial anisotropy in ^Be .

Accomplishment - A first experiment has been completed and reported

in the Physical Review Letters. The result shows no anisotropy at a level which is 300 times lower than the limit set by Hughes, et al.

and Drever in 1 96l

.

Q + Plan - Study three-dimensional cooling of ^Be . Look for liquid-solid

phase transition.

Accomplishment - Three-dimensional cooling (that is, simultaneous,

direct laser cooling of the cyclotron, magnetron and axial degrees of

freedom) has been done. .P's as high as 100 were observed indicating

"fluid" behavior very near the transition to a "solid" (the solid

should appear at P = 170). Future efforts will be devoted to

diffusion and interference experiments aimed at directly observing

order in the plasma.

FY 1986 Plans

Complete fabrication of a highly symmetric (axially) ion trap and use it

to conduct a study of the magnetic susceptibility perturbations to

hyperfine structure in ^Be"*” or

Using the trap described above, improve sensitivity of system for studying

anisotropy of space.

Q + Continue study of phase transitions in ^Be plasmas using

three-dimensional cooling. Initiate design of system for study of

low-angle (Bragg) scattering in these plasmas.

Study statistics of fluorescence from a single ion.

Study stimulated Raman technique for measuring plasma temperature.

172
VII. OPTICAL FREQUENCY METROLOGY AND DEVICES

This group retains the expertise and facilities which were used in

earlier measurements of the speed of light and the subsequent work which

led to the redefinition of the meter in terms of the second. More

recently, this frequency synthesis has proven to be extremely useful as a basis for spectroscopic standards in the infrared and far infrared. Of

particular note is the generation of tunable far infrared radiation

(TuFIR) using either second or third order mixing. The radiation

generated completely spans that part of the spectrum. The group continues

to improve devices and concepts for frequency synthesis. This will prove

to be especially valuable should the stored ion work move to an optical

frequency.

Staff: K. M. Evenson, Project Leader

D. A. Jennings

J; S. Wells

M. D. Vanek

J. H. Brown (Guest Worker)

A. Hinz (Guest Worker)

K. R. Leopold (Postdoc)

E. C. C. Vasconcellos (Guest Worker)

L. R. Zink (Res. Assistant - CU)

OBJECTIVE: Provide reference frequencies from the microwave to the

visible region of the spectrum.

Spectroscopic frequency references (measured with respect to the cesium

standard)

The pioneering work done by the laser frequency synthesis group in

extending direct frequency measurements from the microwave to the visible

portion of the electromagnetic spectrum is now being used to measure the

frequencies of atomic and molecular transitions which are of importance to

spectroscopists, astronomers, and atmospheric scientists. Before the

advent of heterodyne optical spectroscopy (in which the frequency is

measured with respect to cesium) the wavelengths of spectral features were measured. These measurements were hundreds of times less accurate than

the new direct frequency measurements. The knowledge of the frequencies

of selected species allows the spectroscopist, astronomer or atmospheric

scientist to carefully calibrate spectrometers and receivers to the

appropriate frequencies (or wavelengths).

The generation of reference frequencies with requisite accuracy

involves accurate heterodyne frequency measurements and the reliable

fitting and analysis of the spectral data. Coordinated activity at NBS

(between the Time and Frequency Division in Boulder and the Molecular

Spectroscopy Division in Gaithersburg) involves selection of suitable

173
molecular calibration candidates, measurement of their frequencies, and

the analysis, and dissemination of the results in the form of reference

frequency tables.

To meet current needs absorption frequency calibration standards must

be readily obtained and easily handled with at least one calibration point

every few gigahertz. The reference lines must be well resolved and

free of accuracy-limiting fine structure each to an accuracy of one part

in 10®.

The far infrared (0.1 to 5 THz, 3 mm to 60 urni)

The frequencies of several hundred optically pumped lasers have been

measured and are used by laboratory spectroscopists to measure absorption

features. Laser Magnetic Resonance (LMR) spectroscopy has been developed

into one of the world's most sensitive techniques for observing and

measuring frequencies of molecules. Laser magnetic resonance

spectroscopy uses these known frequencies to predict the frequencies of

free radicals used by astronomers and upper atmospheric researchers. The

new technique of tunable far infrared spectroscopy (Tuf ir) , developed by

NBS, promises a much more general technique for measuring frequencies in

this region. Further mention of this concept is made later in this

section.

The CO 2 laser which is stabilized to CO 2 itself furnishes the main

frequency grid for all of our measurements and is widely used for reference

purposes

.

The infrared region (25 to 200 THz, 1.5 to 12 lam)

The frequencies of hundreds of lines of OCS, DBr, CO, N

2 O, and NO now

furnish reference grids for this region. The methane line used to

stabilized the He-Ne laser is especially noteworthy. It serves as a particularly accurate reference for both metrology and spectroscopy. Work

on a number of the other molecules has been funded for a number of years

by NASA in support of the Clean Air Act Amendments of 1977. Accurate

spectroscopic measurements of molecules which are important in upper

atmospheric chemistry provide the basis for heterodyne studies of the

upper atmosphere. This work is thus helpful in resolving questions about

pollution issues (e.g. acid rain).

Carbonyl Sulphide, 815-2140 cm"^

Tables of OCS absorption lines have been provided for use as frequency calibration standards in the following regions of the

infrared: 815-892 cm^"' , 1008-1092 cm"\ 1649-1738 cm~^ , 1850-1921

cm~^ and 2013-2140 cm \ The absorption line frequencies and

approximate intensities are calculated from spectroscopic constants

which have been determined by fitting selected data from the

literature. This data includes NBS heterodyne frequency measurements

174
for all except the 2013-21 40 cm""' region. The uncertainties of most

of the recommended frequency standards are on the order of 1 to 1

0

MHz. Hot band transitions and transitions for some of the less

abundant isotopic species are included in the tables in order to

provide patterns for the unambiguous identification of the lines as well as to provide additional calibration standards in some cases.

The calibrations atlas contains over 6600 entries.

Deuterium bromide (1-0 band), 1630-1985 cm

^

Heterodyne frequency measurements have been made on selected

deuterium bromide 1-0 band transitions ranging from P(20) to R(17).

The measurements include electric quadrupole split triplets

comprising the R(0) and P(1) transitions in the D'^Br isotope. New

DBr constants have been determined and a table of frequencies,

believed to be accurate to 3 MHz, is available.^ Separation between

cm”"' at 1980 cm to 1 1 cm ' at 1630

It does however, span

line pairs ranges from about 6

cm”"' hence this molecule has limited utility.

the OCS gap between 1 738 and 1 850 cra~"' and partially covers another

OCS gap between 1921 and 2013 cm .

Nitrous and Nitric Acids (Tunable Diode Laser)

Heterodyne frequency measurements on N

2 O at 5.3 ym and 9.0 pm have

been completed and measurements at 7.7 ym are partially complete.

Two papers describing this work present calibration tables covering

the following regions; 21 35-2268 cm”"' , 181 6-1 930 cm"”' and 1 207-1 304

cm”"' . The nitric oxide fundamental spans the 1 741-1 980 cm region

for calibration purposes and is also of intrinsic interest for the

atmospheric scientists as well.

Carbon monoxide (2-0), 4120-4350 cm”

The 2-0 ro-vibronic band of has been studied extensively by

Fourier Transform Spectroscopy techniques and has become a widely

accepted calibration standard. Current developments with a color

center laser spectrometer have permitted use of an alternate

technique not only to confirm these results, but also to lead to an improved set of molecular constants. The data were combined in a

1 least squares fit with seven unpublished microwave results to

determine new constants which are an order of magnitude improved over

prior results. A new frequency calibration table with some entries

differing by as much as 15 MHz from Fourier Transform technique

results has been published.

Nitrous oxide (color-center laser)

The absolute frequencies of 39 lines in the 00^2-00^0, 20^1-00^0, and

12^1-00^0 bands of N

2

O in the 4300 - 4800 cm range have been

measured by heterodyne frequency techniques. The lines were each

175
measured in Doppler-limited absorption with a color-center laser as a tunable probe of the N2O and two stabilized CO2 lasers as reference

frequencies. New ro-vibrational constants have been fitted to these

measurements. Tables of calculated transition frequencies are given

with estimated absolute uncertainties as small as 10”^ cm~^ . The

pressure shifts of four lines have been measured, and the values fall

within the range of 0 to -2 MHz/kPA (0 to -0.2 MHz/Torr)

.

Visible Region

Measurements in the visible region are described in the next section.

FY 1985 Plans

Plan - Publish results of frequency measurements in -*CH2F2 and CD^OH.

Accomplishment - The paper on CD^OH was submitted and has been

accepted for publication. The paper on ^^CH2F2 is in preparation.

Plan - Initiate measurements with LN2-cooled CO laser and TDL spectrometer

on N2O bands at 7.7 and 8 ym.

Accomplishment - Approximately half of the measurements in these

bands have been completed and a paper on them has been accepted by

the Journal of Molecular Spectroscopy. These are the first

heterodyne measurements in this region which are traceable to the

cesium frequency. The CO laser used in these studies performed

exceptionally well with operation at the highest vibrational

transition ever reported.

Plan - Measure NO band at 5 ym.

Accomplishment - Measurements on NO in this region are complete and a paper reporting them is in preparation. This molecule is important

for spectrometer calibration as well as for studies of the upper

atmosphere.

FY 1986 Plans

Compete measurements on N2O bands in the 7.7 ym region. Initiate

measurements on N2O at 10 ym.

Use N2O calibration frequencies for tunable-diode-laser spectroscopic

studies of HNO^ at 7.7 ym.

Measure the OCS band at 5 ym.

176
OBJECTIVE: Establish the units of the International System for the

"second" and the "meter".

Provide frequency measurements of lasers suitable for realizing the new

definition of the meter

IN 1982 the Comite Consultatif pour la Definition du Metre

(CCDM) proposed a new definition for the meter, namely that: "The meter is

the length of the path travelled by light in vacuum during a time interval

of 1/299 792 458 of a second." In October of 1983 the General Conference

of Weights and Measures approved this change which is based to a large

extent on both pioneering work and exacting measurements made by NBS.

Wiuh this definition the meter can be realized from the wavelength of any

laser which is stabilized to a narrow atomic or molecular absorption for

which the frequency is known. The wavelength X is determined from the

relation A=c/v, where c is the fixed value of the speed of light and v is

the measured frequency of the laser. Thus, the realization of the meter

will require the measurement of the absolute frequency of suitable

spectral lines in the visible spectral region. To this end, the Division

has performed two highly accurate frequency measurements of hyperfine

transitions in molecular iodine used for laser stabilization. One is in

the yellow spectral region, and the other, red.

The absolute frequency of a dye laser stabilized on the o hyperfine

component of the 17~1 P(62) transition at 520 THz (576 nm) in iodine was measured with respect to the CH^ stabilized . 88 THZ (576 nm) . A 26

THz CO

2 laser, a color center laser at 1 30 THz, and a He-Ne laser at 260

THz, were used as transfer oscillators. The measured I 2 freauency was 520

206 808.547 MHz with a total uncertainty of 1.6 parts in 10^*^.

The absolute frequency of the 473 THz

stabilized on the i hyperfine component of

transition, was measured by comparing its

synthesized by summing the radiation from

The three lasers were an 88 THZ CH^ stabil

125 THz coloc center laser (2.39 pm) with

a 260 THz He-Ne

at 520 THz (576

the i hyperfine

10

He-Ne laser (633 nm)

,

the 127

I 5 11-5 R(127)

Rll( 26 ) 13c“J ;i 02 l^ser, and

an I^ stabilized dye laser

is 473 612 214.789 MHz for

uncertainty of 1.6 parts in

frequency with a known frequency

three lasers in a He-Ne plasma,

ized He-Ne laser (3-39 pm), a its frequency referenced to the

laser (1.15 pm) referenced to

nm) . The measured frequency

component with a total

10

These frequencies, when used to realize

25 -fold improvement over the present Krypton

the new meter, represent a length standard.

177
OBJECTIVE: Develop metrology for precise time, frequency and length

measurements.

Techniques for characterization and measurement of frequency and frequency

stability.

Frequency metrology from the far infrared to the visible has been

greatly stimulated by the work at NBS . The early work on W-Ni point

contact metal-insulator-metal (MIM) diodes, carried out simultaneously and

independently by MIT and NBS, laid the groundwork for precision frequency

synthesis in this spectral laser region.

An extremely important outgrowth of this work was the first frequency

measurement of the 3*39 micron line of CH21 followed by the wavelength

measurement of the same line. The product of the frequency and wavelength

produced a value for the speed of light nearly 100 times more accurate

than the previously accepted value. This work coupled with recent

frequency measurements of visible spectral lines has led to the

replacement of the Krypton lamp as the length standard and the assignment

of an exact value for the speed of light.

Recent work on the MIM diode has expanded the frequency difference

range over which measurements can be made by a factor of 100 (in the

visible) . This is expected to greatly simplify frequency metrology

because of the reduction in the number of frequency markers to reference

lines necessary to fully cover this spectral region.

Techniques for laser frequency synthesis

Frequency synthesis is usually 'achieved in some non-linear device

which adds, subtracts and multiplies the frequencies of the radiations

incident on it. In the Time and Frequency Division we have used W-Ni

metal-insulator-metal (MIM) point contact diodes as detectors, harmonic

generators, and mixers of coherent radiation from the microwave to the

visible region of the electromagnetic spectrum. The MIM diode plays a major roll in the Laser Frequency Synthesis Chain which connects the cesium

clock to the visible l 2 -stabilized lasers and hence provides the

realization of the meter from the new definition.

The MIM diode has been used for the past 15 years and the mechanical

and electrical engineering improvements have been steady. Recent use of

conical coupling along with off-axis parabolic focusing mirrors has led to an exciting new technique of generating tunable far infrared radiation.

Tunable coherent radiation can be generated in the uv, visible and near infrared regions of the electromagnetic spectrum with the use of

tunable lasers and non-linear optics. Only recently have tunable sources been available in the far infrared and these did not allow complete

178
coverage since the technique involved the addition of microwave sidebands

to several of the stronger far infrared lasers. Division scientists have

now succeeded in generating tunable cw far-infrared radiation via CO 2

difference frequency mixing in a tungsten-nickel, (MIM) diode.

Previously, the MIM diode had been used mainly to make direct frequency

measurements from O .3 to 200 THz.

Six tenths of a microwatt of tunable, cw far infrared radiation has

been generated by mixing 130 mW of radiation from each of two CO

2 lasers

in a MIM diode. The difference frequency was radiated from the MIM diode,

and was detected in a calibrated germanium bolometer. The use of

a waveguide CO 2 laser with its greater frequency tunability as one of the

lasers used to generate the difference frequency promises a complete

coverage of tunable cw radiation in the entire far infrared band from 100

to 6000 GHz with the additional advantages of simplicity and high

accuracy. Using this technique, it has been possible to readily detect

the J=5^-J = 4 transition of CO (576 GHz) and the J=1-^J=0 transition of HF

( 1.23 THz). Just recently the HCl spectrum from 0.5 to 5.5 THz has

been measured and this simple molecule now provides for ah excellent

calibration standard in that frequency range.

FY 1985 Plans

Plan - Perform analysis of entire TuFIR spectrometer in order to determine

relative importance of the performance of each component. Look for

methods to further improve sensitivity.

Accomplishment - An analysis of the TuFIR spectrometer was completed

and the key limit to sensitivity was found to arise from inadequate

CO 2 laser feedback isolation. When this problem was rectified, the

system sensitivity improved by an order of magnitude. Considerable

study of the low-frequency properties of the MIM mixers was carried

out in FY 1985 . It was found that different diode characteristics

are required for second-order and third-order mixing. Second-order

mixing is best where the diode exhibits the traditional rectification

in its I-V characteristic. Third-order mixing is best when the I-V

characteristic is anti-symmetric about the origin. Some empirical

rules regarding the electrode work functions were developed.

Plan - Complete study of the range of application of TuFIR spectroscopy by

making measurements in the range of 5 to 7 THz.

Accompli shment - Completion of this study has been delayed by

difficulty in obtaining an appropriate detector. The detector is now

on order and scheduled to arrive shortly.

FY 1986 Plans

Bring second TuFIR spectrometer (using third-order FIR generation) into

operation

179
Increase TuFIR sensitivity through use of a ^He bolometer and a cooled

grating prefilter.

Study properties of diodes for second-order and third-order mixing.

Search for diodes with improved mixing properties

OBJECTIVE: Measure far infrared frequencies of atoms and molecules

(especially transient species) for radio astronomy and upper atmospheric

science.

High resolution spectroscopic measurements in the far infrared have

been advanced significantly through development (at NBS) of two

measurement techniques. These techniques are used to make unique

laboratory measurements, previously inaccessible, which have bearing on difficult atmospheric and astronomical studies.

Laser Magnetic Resonance (LMR) spectroscopy has been developed into an ultrasensitive technique (i.e., several orders of magnitude more sensitive than microwave spectroscopy) for observing and measuring

reactions involving molecules. LMR techniques are singularly effective in

measuring parameters necessary to model the effects of pollutants (e.g.,

fluorocarbons, nitric oxide, etc.) in the atmosphere.

Subsequently LMR was used to make the first laboratory observation of

the CH

2 spectra. The CH2 radical is an important building block for all

organic molecules and is present as a free radical intermediary in many

chemical reactions. Measurements of CH, CD

2 and CD were completed and the

spectra of GeH^, GeH, SiH, and Si were identified.

The new techniques of Tunable Far Infrared (TuFIR) spectroscopy

promises to enhance the LMR technique by measuring some of the same free

radicals at zero field. Zero field measurements will have a greater

accuracy. The technique, an outgrowth of NBS frequency synthesis work

involving MIM diodes, also allows the measurement of all far infrared

active molecules, not just paramagnetic ones. Measurements of OH

frequencies have been completed. Tables of far infrared transition

frequencies for the molecule are now available.

FY 1985 Plans

Plan - Remeasure rotational frequencies of CH using TuFIR spectroscopy.

Accomplishment - These measurements have been deferred to FY 1986 in

order to meet higher priority objectives.

Plan - Study LMR spectra of ^"^OH and complete analysis of LMR data on GeH.

180
Accomplishment - These studies have been completed and a paper is in

preparation. An atlas of frequencies is now available to the radio

astronomy community.

Plan - Search for LMR spectra of molecular ions.

Accomplishment - Using LMR, the OH"^ ion was observed only to find

that the Berkeley group had observed it two weeks earlier. HCO

lines in the FIR were observed and measured for the first time using

TuFIR methods.

Plan - Publish paper on tunable far-infrared spectroscopy of OH.

Accomplishment - Paper has been completed and submitted.

FY 1986 Plans

Using TuFIR methods, search for spectra of molecular ions.

Perform OH line-broadening measurements for use in upper atmospheric

studies

.

181
VIII. GEOPHYSICAL MEASUREMENTS

This is a small program conducted in JILA by Time and Frequency

Division staff. One of the projects involves construction and demonstration of an apparatus for measuring intermediate baselines (25 km to 50 km)

with an uncertainty of 1/2 cm or less. The multiple-wavelength technique

that is used is closely related to satellite navigation and timing

problems which also require a complete accounting for atmospheric

dispersion. A second project involves use of an array of tilt detectors

to study properties of the earth’s mantle and core-mantle boundary. A third program which is just starting, is a feasibility study for using GPS

timing signals for very accurate geodesy.

Staff: J. Levine, Project Leader

J . A . Magyar

J. Allison (Res. Assistant - CU)

B. Busby (Res. Assistant - CU)

K. Hurst (Res. Assistant - Columbia U.)

D. Livigni (Work Study)

H. Matsumoto (Guest Worker)

C. Meertens (Res. Assistant - CU)

C. Rocken (Res. Assistant - CU)

OBJECTIVE: Develop metrology for precise time, frequency and length

measurements

.

Distance measurement techniques

The need to accurately determine the lengths of baselines on the

surface of the earth arises in many different contexts, ranging from the

calibration of tracks used for rocket tests to estimation of the relative

motions of large geographical regions in seismically active zones. This

work is particularly timely, since the use of timing techniques for such

distance measurement is expected to grow and a key roadblock to improved

resolution involves the dispersion of the atmosphere.

FY 1985 Plans

Plan - Continue field and laboratory evaluations of the system and

evaluate systematic errors.

Accomplishment - Tests of the com.plete system uncovered a systematic

variation of the apparent refractivity with wind speed. The

refractivity changed by several percent on windy days, an unreasonably large effect. We believe the effect is produced by a coupling of phase shift with entrance angle in the primary optical

chain and we are in the process of constructing new input optics in

order to resolve the difficulty.

182
FY 1986 Plans

Complete field and laboratory evaluation of the system.

OBJECTIVE: Evaluate the utility of nano-radian level tilt measurements

in studying earth structure.

FY 1985 Plans

Plan - Complete analysis of the remaining data and finish work on the

theoretical model of the Yellowstone Caldera.

Accomplishment - The preliminary analysis of the measurements is

complete. The construction of the model is finished, but a final

comparison between theory and experiment has been delayed for few

months by the change in computing systems (to the 205 in

Gaithersburg)

.

FY 1986 Plans

Complete comparison between theory and experiment on the model of the

Yellowstone Caldera.

183
INVITED TALKS

Time and Frequency Division (524)

D. W. Allan, "How and When to Perform Allan Variance Calculation or Phase

Noise Measurements, Measurement Science Conference, January 18, 1985.

D. W. Allan, "NBS Time and Frequency MAP Program, Measurement Science

Conference, January 18, 1985.

D. W. Allan, "Relativity in Celestial Mechanics and Astrometry, lAU

Symposium, May 28, 1985 in Liningrad, Russia.

D. W. Allan, "Status of Time and Frequency Program at NBS", Consultative

Committee for the Definition of the Second (CCDS), June 5, 1985 in Paris,

France.

D. W. Allan, A Review of International Time and Frequency Comparisons Via

the NBS/GPS Common View Technique, 1985 North American Radio Science

Meeting and International lEEE/AP-S Symposium, June 19, 1985 in Vancouver,

Canada.

J. C. Bergquist, "Fluorescence Detection of Trapped Ions," Federation of

Analytical Chemistry and Spectroscopy Societies, September, Philadelphia,

PA, 1984.

J. C. Bergquist, "Two-Photon Optical Spectroscopy in Hgll," Frequency

Control Symposium, Philadelphia, PA, May 1985.

J. C. Bergquist, "Two-Photon Optical Spectroscopy in Hgll," Seventh

Internet ional Conference on Laser Spectroscopy (SEICOLS), Maui, Hawaii,

June 1985.

J. J. Bollinger, "Generation of Strongly Coupled Ion Plasmas," 26th Annual

Meeting of the Division of Plasma Physics, Boston, MA , October 29, 1984.

J. J. Bollinger, "Strongly Coupled Non-Neutral Ion Plasma," Institute of

Theoretical Physics, Workshop on Strongly Coupled Plasmas, Santa Barbara,

CA, February 1985.

R. E. Drullinger, "On the Fluorescent Light Shift in Optically Pumped

Cesium Standards," 39th Annual Symposium on Frequency Control,

Philadelphia, PA, May 1985.

R. E. Drullinger, "Optically Pumped Small Cesium Beam Standards: A Status Report," 39th Annual Symposium on Frequency Control, Philadelphia,

PA, May 1985.

184
K. M. Evenson, "Advances in Far-Infrared Spectroscopy", NASA Headquarters,

November 1984.

K. M. Evenson, "Tunable Far-Infrared Spectroscopy," NBS Gaithersburg,

November 1984.

K. M. Evenson, "The New Meter," Physics Department, University of Wyoming,

Laramie, WY, October 23“24, 1984.

K. M. Evenson, "Tunable Far-Infrared Spectroscopy," University of

Michigan, Ann Arbor, MI, February 1985.

K. M. Evenson, "Tunable Far-Infrared Spectroscopy," Ford Motor Company,

Detroit, MI, February 1985.

K. M. Evenson, "Tunable Far-Infrared Spectroscopy," Seventh International

Conference of Laser Spectroscopy (SEICOLS), Maui, Hawaii, June 1985.

K. M. Evenson, "Frequency Spectroscopy: The Last Measurement of the Speed

of Light: And The New Meter," the Sculoa Normale, Pisa, Italy, September

1985.

K. M. Evenson, "Tunable Far-Infrared Spectroscopy ,", High Resolution

Spectroscopy Meeting, Riccioni, Italy, September 1985.

p + W. M. Itano, "Radiative Lifetime of the Metastable State in Hg ,"

Annual Meeting of the Division of Electron and Atomic Physics, May 1985.

J. Levine, "Techniques for Computing Fourier Transforms," Computational

Physics Seminar," University of Colorado, Boulder, CO, November 1984.

J. Levine, "Tiltmeters, ” Amoco Oil Company, Tulsa, OK, June 1985.

J. D. Prestage, "Limits on Spatial Anisotropy By Use of ^Be"'' Ions," Gordon

Research Conference, Wolfboro, NH, July 1985.

D. B. Sullivan, "Time," Precision Measurement Association, February 1985.

D. B. Sullivan, "A Recirculating Oven for Atomic Beam Frequency

Standards," 39th Annual Frequency Symposium, Philadelphia, PA, May 1985.

F. L. Walls, "Errors in Sinusoidal Frequency (Phase) Modulation Derived

Servo System," 39th Annual Frequency Control Symposium, Philadelphia, PA,

May 1985.

F. L. Walls, "Noise in Resonators, Filters and Oscillators," 39th Annual

Frequency Control Symposium, Philadelphia, PA, May 1985.

185
F. L. Walls, "Precise Phase Noise Measurements of Oscillators,"

Proceedings of rf Technology Expo ’85, Anaheim, CA, January 1985.

D. J. Wineland, "Laser Cooled Ions, Rice University, November 15, 1984.

D. J. Wineland, "Optical Pumping of Stored Atomic Ions," Symposium Alfred

Kastler, Paris, France, January 1985.

D. J. Wineland, "High Precision Spectra of Laser Cooled Ions," California

Institute of Technology, February 1985.

D. J. Wineland, "Laser Cooled Ion," University of Georgia, April 15, 1985.

D. J. Wineland, "Laser Cooled, Trapped Ions," University of Hamburg, West

Germany, January 1985.

D. J. Wineland, "Laser Cooled, Trapped Ions," Max Plank Institute,

Garching, West Germany, January, 1985.

D. J. Wineland, "Laser Cooled, Trapped Ions," M. A. Ferst Symposium

honoring Prof. Norman Ramsey, Georgia Tech, June 1985.

PUBLICATICNS

Time and Frequency Division

The Direct Measurement of the 3 ^^1 PiriS“Structure Interval and the

gj-Factor of Atomic Silicon by Laser Magnetic Resonance, M. Inguscio, K. M. Evenson, V. Beltran-Lopez , and E. Ley-Koo, Astrophysical Journal,

278:L127-L130, (1984).

Cptical Frequency Synthesis Spectroscopy, K. M. Evenson, D. A. Jennings,

F. R. Petersen, J. S. Wells, and R. E. Drullinger, Prog. Quant. Electr.

Vol. 8, 143-151 (1984).

Infrared and Far-Infrared Transition Frequencies for the CH

2 Radical, T.

J. Sears, A. R. W. McKellar, P. R. Bunker, K. M. Evenson, and J. M.

Brown, Astrophysical Journal 276:399-402, (1984).

New Time and Frequency Services at the National Bureau of Standards, S. R. Stein, G. Kamas, and D. W. Allan, Proceedings or the l6th Annual Precise

Time and Time Interval Planning and Applications Meeting, December 1984.

A Wideband Frequency-Cf fset Locked Dye Laser Spectrometer Using a Schottky

Barrier Mixer, J. C. Bergquist and H.-U. Daniel, Cptics Communications,

48, 327-334 (1984).

186
Efficient Single Mode Operation of a cw Ring Dye Laser with a Mach-Zehnder

Interferometer , J. C. Bergquist and L. Burkins, Optics Communications, 50 , 379-385 ( 198^0.

A New Miniaturized Passive Hydrogen Maser, F. L. Walls and K. B.

Persson, Proc. of the 38th Ann. Freq. Control Symposium, 1984.

Position Location with the NBS/GPS Time-Transfer System, M. Weiss, PLANS

'84 Conference Proceedings, 1984.

Test of Wall Coatings for Controlled Moist Air Experiments, H. J. Liebe,

V. L. Wolfe, and D. A. Howe, Rev. Sci. Instrum. 55(10), 1702-1705, 1984.

A Simplified GPS C/A Receiver Front End with Low Noise Performance, D. D.

Davis and A. D. J. Clements, Proceedings of the I6th Annual Precise Time

and Time Interval Planning and Applications Meeting, December 1984.

Spectroscopy of Stored Ions, D. J. Wineland, in Precision Measurement and

Fundamental Constants II , B. N. Taylor and W. D. Phillips, eds. National

Bureau of Standards (US) Spec. Publ. 617, 83“92 (1984).

Progress Toward a Stored Ion Frequency Standard at the National Bureau of

Standards, W. M. Itano, D. J. Wineland, J. C. Bergquist, and F. L. Walls,

in Precision Measurement and Fundamental Constants II , B. N. Taylor and W.

D. Phillips, eds. National Bureau of Standards (US) Spec. Publ. 617, 83-92

(1984).

A Consistent Coordinate Time On and Near the Earth, N. Ashby and D. W.

Allan, Phys. Rev. Lett. (1984).

High Resolution Spectrum of the Band of Nitric Acid (HNOo) Near 880 cm \ A. G. Maki and J. S. Wells, J. Mol. Spectrosc. 108, 17-30 (1984).

Frequency Standard Research Using Stored Ions, D. J. Wineland, Wayne M.

Itano, J. C. Bergquist, J. J. Bollinger, and H. Hemmati , Prog. Quant.

Electr. _8, 139-1 42 (1984).

Pressure Effects on the Frequency of Continuous-Wave Optically Pumped

Far-Infrared Lasers, M. Inguscio and K. M. Evenson, Opt. Lett. 9_, 443-444

(1984).

Strongly Coupled Nonneutral Ion Plasma, J. J. Bollinger and D. J.

Wineland, Phys. Rev. Lett. 348-351 (1984).

Rotational Structure of ”*^02, ”’^o'’'^0, and ^o”’ ®0( from Laser

Magnetic Resonance Spectra, J. Mol. Spectrosc. 1 07 , 395-404 (1984).

Laser-Magnetic-Resonance Detection of Magnesium Atoms in

^Pq

1 2 States, M. Inguscio, K. R. Leopold, J. M. Murray

Evensong J. Opt. Soc. Am. B/Vol. 2 (1985).

the Metastable

, and K. M.

187
Accuracy of International Time and Frequency Comparisons Via Global

Positioning System Satellites in Common-View, D. W. Allan, D. D. Davis, M.

Weiss, A. Clements, B. Guinot, M. Granveaud, K. ' Dorenwendt , B. Fischer, D. Hetzel, S. Aoki, and M. -K. Fujimoto, L. Charron, and N. Ashby, Conference

on Precision Electromagnetic Measurement, IEEE Trans, on Instrumentation

and Measurement, IM~3^ » 118 (1985).

P Q 4- Hyperfine Structure of the 2p P^/o State in ^Be , J. J. Bollinger, J. S.

Wells, D. J. Wineland, and W. M. Itano, Phys. Rev. A 271 1 -271 4 (T985).

Trapped Ions, Laser cooling, and Better Clocks, D. J. Wineland, Science

226, 395-400 (1984).

Heterodyne Frequency Measurements on N

2 O at 5.3 and 9.0 pm, J. S. Wells,

D. A. Jennings, A. Hinz, J. S. Murray and A. G. Maki, JOSAB Vol.'2,

857-861 (1985).

Spectroscopy of Stored Atomic Ions, D. J. Wineland, W. M. Itano, J. C. Bergquist, J. J. Bollinger and J. D. Prestage, in Atomic Physics 9 , R. S.

Van Dyck, Jr., and E. N. Fortson, Eds., (World Scientific, Singapore,

1985), p. 3-27.

Laser Cooled Atomic Frequency Standard, J. J. Bollinger, J. D. Prestage,

W. M. Itano, and D. J. Wineland, Phys. Rev. Lett. 1000-1003 (1985).

Q + Limits for Spatial Anisotropy by Use of Nucelar-Spin-Polarized ^Be Ions,

J. D. Prestage, J. J. Bollinger, W. M. Itano, and D. J. Wineland, Phys.

Rev. Lett. 54, 2387-2390 (1985).

New Time and Frequency Services at the National Bureau of Standards, S. R.

Stein, G. Kamas, and D. W. Allan, published in the Proceedings of

the Measurement Science Conference, 1985.

The Microwave and Far-Infrared Spectra of the SiH Radical, (J. M. Brown),

(R. F. Curl), and K. M. Evenson, Astrophysical Journal, 292, 188-191

(1985)

.

Clock Character ization Tutorial, D. W. Allan, published in the

Proceedings of the Measurement Science Conference, 1985.

Measurements of the gj-Factors of the 6s ^]/2 ^ 1/2 States in

”'°°Hg''’, W. M. Itano, J. C. Bergquist, and D. J. Wineland, J. Optical Soc.

Am. B, 1392-1394 (1985)

.

188
?u3l::at:c}js in phccess

Recent Irenes in N5S line =ne Frecuency listri’Duticr; Services, H.

^ *3” Li o /7 ^’^300031.’"^" ~Z*ITT ’an. ‘936.

Frecuency Staniares Based cn Optically P'onpsd Cesi’ur:

De putlisnec in Proceedings of IFZF Special Issue, "!

wi —

.

Measurements of Frequency otaoi_ity,

ouolisned in Proceedings of the IZFF

' • -j • ae s Er.c • /I ip0ClE— — 5 SLi S j o En • . * ^ 2

-cng .ern r:er.avior or ^avity rr.ase Jirrerence

Z. Orullinger, to oe published in Metrclcgia, '935

^ r* —

•

Separating ^cme

Va^^^n^*^ a^d I'*

r.rror sources in tne <--j.ooa_ .-'ositicning

Analysis, D. W,

lub-ication in .-.acio ici‘

Aj._an anc M. ^'eiss, acc:

Frequency Standards Based on Stored Ions, 0. J. Wineland,

in IZZZ Special Issue on Radio Measurements and Standards,

ce puc-isnec

tical Purging of Stored Atomic Ions, 0. J. Wineland, ^1 sergquist !l-inger, ana ^ oe ouD-isnec in tne

Proceedings Symp . Alfred Kastler, r

A ’.'ew Way to Measure Frecuency, n-r^r V

.o-i rtor-c sr.

5Uw ^

^COPG ' PEO0 ' ni0 bs ou*D I.r sb 0 i1 pp 0 Vic ini oy of

‘0 ?'^CC00C'^ftS f th^

in CeLeso eI. cs E’^c •^sb’^c^crnv> ^

-arth, D. W. Allan and N' . Ashby, : nu oy

c

w —Li i*. .«o* n — '_^y

Tine Scale Soabilioies oasec cn Tine anc Frecuency Kalnan Fillers, T. A.

Cannes anc ft. A_-an, oo oe puo-isnec -a one

A.nnual Frequency Control Symposium, 1935

a ^ m /-t ceecinsrs ^ ^ or one :^9tn

P’^ecise ^'"'ase MPIz to 2C »1E-._S ) nr -ecnnc_ogy r.xpc. 955.

- requenev Standards Basse on A.tomic rr/d’^oger.

Special Issue, Jan. '986.

-. =^a S, -roc. of _r.r.r

requenev ana .ime

V

tandards Based on Stored Ions, J rtine^ana, .i. M. ^tano, u Prestage, Proc. '5th Ann,

Precise . ime anc Tine 1'^ oerva " l I'^o^o'cn^ ^l^r^"'n<

Naval Research laboratory, Washington, 00, Oec. '93^, to be puolished.

189

n.

(y)
New Far Infrared Laser Lines Obtained By Optically Pumping "'^CD^OD, by K. M. Evenson and E. C. C. Vasconcellos , submitted to International Journal

of Infrared and Millimeter Waves, July 1985.

Frequency Measurement of the Solitary Ethyl Alcohol Laser Line, by E. C. C. "Vasconcellos and K. M. Evenson, submitted to the Journal of Infrared

and Millimieter Waves.

Far Infrared Spectrooscopy of NH(D) (a'A) and NaH(X'Z'^), K. R. Leopold, L.

R. Zink, D. M. Evenson, and D. A. Jennings, to be published in the

Proceedings of the 17th International Symposium on Free Radicals.

Measurement of Optical Frequencies, D. A. Jennings, K. M. Evenson, D. J.

Knight, Special Issue of IEEE, 1985.

Two-Photon Optical Spectroscopy of Trapped Hgll, J. C. Bergquist, D. J.

Wineland, W. M. Itano, and H. Hemmati, submitted to the Proceedings of the

Seventh International Conference on Laser Spectroscopy, 1985.

1 s The Microwave and Far-Infrared Spectra of the OH Radical, E. R. Coraben,

J. M. Brown, T. C. Steimle, K. R. Leopold and K. M. Evenson, submitted to

Astrophysical Journal, September 1985.

q p p Energy and Radiative Lifetime of the 5d^ os State in Hgll by

Doppler-Free Two-Photon Laser Spectroscopy, J. C. Bergquist, D. J.

Wineland, W. M. Itano, H.-U. Daniel, and G. Leuchs, to be published in

Phys. Rev. Lett.

New FIR Laser Lines and Frequency Measurements for Optically Pumped CD^OH,

R. J. Saykally, K. M. Evenson, D. A. Jennings, and F. R. Petersen,

submitted to International Journal of Infrared and Millimeter Waves, 1985.

Tunable Far Infrared Spectroscopy, K. M. Evenson, D. A. Jennings, K. R.

Leopold, and L. R. Zink, submitted to Proceedings of the Laser

Spectroscopy Conference, 1985.

Infrared and Far-Infrared Laser Magnetic Resonance Spectroscopy of the GeH

Radical: Determination of Ground State Parameters, J. M. Brown, K. M.

Evenson, and T. J. Sears, submitted to the Journal of Chemical Physics,

1985.

Errors in Servo Systems Using Sinusoidal Frequency (Phase) Modulation,

to be published in the Proceedings of the 39th Annual Frequency Control

Symposium, 1985.

On the Fluorescent Light Shift in Optically Pumped Cesium Standards, J. H.

Shirley, to be published in the Proceedings of the 39th Annual Symposium

on Frequency Control, 1985.

190
optically Pumped Small Cesium Beam Standards: A Status Report, A.

Derbyshire, R. E. Drullinger, M. Feldman, D. J. Glaze, D. Hilliard, D. A.

Howe, L. L. Lewis, J. H. Shirley, I. Pascaru and D. Stanciulescu, to be

published in the Proceedings of the 39th Annual Symposium on Frequency

Control, 1985.

Doppler-Free Two-Photon Laser Spectroscopy of Hgll, J. C. Bergquist, D. J.

Wineland, Wayne M. Itano, H. Hemmati, to be published in the Proceedings

of the 39th Annual Frequency Control Symposium, 1985.

Recovering Files from a Damaged Files-11 Disk, J. Levine, submitted to RSX

Multitasker, 1985.

A Beam Reversal Experiment on NBS-6 Primary Cs Standard Including Rabi

Pulling Evaluation, A. DeMarchi, G. D. Rovera, R. E. Drullinger, and D. A. Howe, to be published in the 39th Annual Frequency Control Symposium,

1985.

A Recirculating Oven for Atomic Beam Frequency Standards, R. E.

Drullinger, D. J. Glaze, and D. B. Sullivan, to be published in the 39th

Annual Frequency Control Symposium, 1985.

Angular Momentum of Trapped Atomic Particles, D. J. Wineland, J. J.

Bollinger, W. M. Itano, J. D. Prestage, to be published in J. Opt. Soc.

Am. B.

SEMINARS ORGANIZED

NBS Time and Frequency Seminar, August 13~15, 1985, Boulder, Colorado.

SPECIAL REPORTS

’’NAVSTAR" Global Positioning System, Air Force Space Division Final

Report, 1984.

"NBS Industrial Time Service Phase II Study for Bonneville Power

Administration," July 15, 1985.

TECHNICAL AND PROFESSIONAL COMMITTEE

PARTICIPATION AND LEADERSHIP

D. W. Allan, Study Group VII, International Radio Consultative Committee

(CCIR)

.

D. W. Allan, IEEE IM TC-3 Frequency and Time.

D. W. Allan, NASA Team Member for Shuttle Timing Experiment.

191
D. W. Allan, member and US delegate, Commission A International Radio

Scientific Union.

R. E. Beehler, CCIR Study Group 7; International Chairman of Interim

Working Party 7/'4 on "Improved Time Coordination and Dissemination Using

Satellites".

K. M. Evenson, URSI Commission D.

D. A. Jennings, Member CCDM

J. L. Jespersen, Chairman IRIG Timing Committee.

D. W. Hanson, Member Technical Advisory Committee for TDRSS , NASA

Satellite Program.

G. Kamas, Measurement Assurance Subcommittee, National Conference of

Standards Laboratories.

J. Levine, Chairman, Electronic Shops

J. Levine, Computing Allocation Committee, Colorado University

J. Levine, National Academy of Sciences, Committee on Geodesy

J. Levine, Board of Review of Science Institute

J. Levine, NBS Computer Users Committee

D. B. Sullivan, member. Commission A International Radio Scientific Union.

D. J. Wineland, Committee for NBS Precision Measurements Grants

D. J. Wineland, Program Committee of the Division of Electron and Atomic

Physics, American Physical Society

192
QUANTUM PHYSICS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1985

Page

Overview 194

Summaries of QPD Research Programs 197

Publications of QPD scientists, their graduate students

and Post-docs, and Visiting Fellows 240

JILA Visiting Fellows for 1984-85 264

JILA Visiting Fellows for 1985-86 266

Scientists working at JILA on sabbatical or other leave

(other than Visiting Fellows) 268

Conferences Sponsored at JILA 273

Seminars and colloquia given at JILA 274

Invited talks given by QPD scientists 282

Technical and professional committee participation and

leadership by QPD Scientists » 287

Consulting by QPD scientists 291

Other agency research undertaken by QPD scientists 293

Trips sponsored by others for QPD scientists 297

University and department committee memberships

of QPD scientists 313

Graduate students and postdoctoral research associates

supervised by QPD scientists 318

Courses taught at the University of Colorado by QPD

scientists 320

Background on JILA 321

193
OVERVIEW

The Joint Institute for Laboratory Astrophysics-'- (JILA) has had another

exciting and productive year:

o David Norcross' energetic term as Chairman of JILA came to an end

on December 31; Carl Lineberger graciously agreed to succeed him

and will be serving as Chairman until 1987.

o After eight years as Chief of Quantum Physics Division, Gordon Dunn

has been liberated from his bureaucratic responsibilities and

allowed to return full time to more rewarding pursuits in his laboratory. He is succeeded as Division Chief by Katharine Gebbie.

o David Hummer has spent the past year at the Institute of Astronomy

and Astrophysics, University of Munich, as the recipient of a Senior U.S. Scientist Award from the Alexander von Humboldt Foundation.

o Stephen Leone received the Department of Commerce Gold Medal Award

for his contributions to the field of chemical dynamics.

o David Nesbitt received a Dreyfus Fellowship: This prestigious

award, of which only ten are given annually, is designed to help

launch the research programs of young scientists in all areas of

chemistry.

o The Visiting Fellows Program continues to thrive. In 1985 JILA had

13 Visiting Fellows and 1 Research Fellow for Teachers; as part of

the same program, Arthur Phelps spent six months in Gaithersburg as the JILA/NBS Exchange Fellow. In 1986 there will be 12 Visiting

Fellows, 1 Research Fellow for Teachers, and 1 JILA/NBS Exchange

Fellow

.

o The University's plans for an addition to the JILA building are progressing famously: the current schedule calls for construction

to begin late in the second quarter of 1986. This will provide an additional 15,000 square feet of desperately needed office and laboratory space.

^ Quantum Physics is the division through which NBS participates in

the Joint Institute for Laboratory Astrophysics, a cooperative enterprise between the NBS and the University of Colorado. More background

on the Institute in included as the last section in this report.

194
o JILA's computing capability has been substantially increased with

the installation in August of a VAX/8600 with color graphics and

hardwired communication to offices and laboratories. In addition,

hardware will soon be installed to allow communication, both interactively and in batch mode, with the Cyber 205 in Gaithersburg.

o During the past year, Quantxjim Physics Division scientists:

Obtained high resolution infrared spectra of a weakly bound

Van der Waals molecule in a planar supersonic jet.

Contributed to an international comparison of absolute gravity

meters at the BIPM in Paris

.

Developed a powerful technique to stabilize the laser frequency of any cw laser with transducers located external to

the laser.

Demonstrated experimentally that extrinsic electric fields can

have a profound effect in enhancing dielectronic recombination

of electrons and ions.

Found that the expected energy density of gravitational radiation from binaries is about 10”^ of the energy density of

light in the Universe.

Developed an equation of state for moderately dense plasmas

that exhibits dramatically improved agreement with experiment.

\ Made the first measurements of the magnetic fields of dwarf

flare stars.

Carried out for HCN the first reliable calculations of electron collisions with a triatomic polar molecule.

Demonstrated that heavy silanes and radicals produced by

silane discharges (used to produce photovoltaics) are made by

surface reactions.

Determined that the If'’ -I- O2 ion reaction can contribute substantially to the red emission of the Aurora Borealis.

Provided theoretical understanding of the anomalously large

measured probabilities in the multiple ionization of atoms by

ultra- intense laser pulses.

195
Demonstrated that in the competition between two decay channels from highly excited atomic states, the Raman process

becomes competitive with direct photoionization at high laser

power densities.

Measured the very rapid collisional quenching of a rotational

level of the H2(c^II^^) metastable state by thermal -energy H2

molecules

.

196
RESEARCH PROGRAMS

FUNDAMENTAL AND PRECISE MEASUREMENTS

Laser Stabilization and Stopped Atoms - J. L. Hall

The application of stable laser techniques to fundamental spectroscopic problems requires the availability of stable -- but widely

tunable - - cw dye lasers. The apriori incompatibility of high stability

with wide tunability (not to mention with the rap idly- flowing intracavity free dye stream) has greatly prolonged the development of such

lasers. Industry is also interested in these problems. At present

there are something like 550 commercially produced, actively- stabilized,

cw dye laser systems in service worldwide, all based on a fundamental

stabilization technique published and developed by Hall's group. With

linewidths of about 1 or 2 MHz, these commercial lasers are in part

responsible for the explosion of tunable -laser spectroscopic techniques

over the past five years. Dramatically higher levels of dye laser frequency stability have now been demonstrated in Hall's laboratories, var- iously 50 kHz, 1 kHz and 200 Hz. A high power dye laser has even been

phase-locked to a stable low-power He-Ne source. Now that sufficient

transducer bandwidth can be obtained to suppress intrinsic laser instability using feedback techniques, the next major challenge is to develop

refined methods of tuning/guiding/offsetting the laser's frequency and

of controlling it to an appropriate reference in order to enhance the

mid- and long-term stability. Hall's group is now developing an interferometric scan technique for wide scans < 10%) and moderate accu- racy (< 1 MHz) . The accurate tuning problem has been addressed for

modest scans (± 3.5 GHz) by the development here of a broadband traveling wave electro-optic phase modulator (based on a miniature LiTa03

crystal), which produces a tunable optical sideband with the full sub-Hz

accuracy of the rf source and with the full 34% efficiency available in

the phase modulation process. Using this system, augmented by computer

control. Hall has recently studied isotope shifts and hyperfine structure in Hg with an accuracy in the 20 kHz range, limited principally by

the 24 MHz natural linewidth of the transition.

Another interesting application of the tunable sideband technique

is the conversion of an atomic beam to a static gas sample at millikelvin equivalent temperature. The velocity deceleration of the atomic

beam is provided by the directed momentum transfer from the laser to the

counter -running atomic beam, about 30,000 absorption/random-emission

events being required to suppress the initial thermal velocity and stop

a beam of sodium atoms dead in their tracks. During this process, the

changing velocity- induced Doppler shift sweeps through about 100 resolvable natural linewidths. The availability of the inertia- free sideband

frequency sweeping capability (using a swept frequency oscillator to

feed the broadband electro-optic modulator) has been fundamentally use- ful in this work, enormously simplifying the interpretation of these

197
atom- cooling experiments. Hall's group has obtained a three-dimensional

residual velocity distribution of 3 m/s RMS, equivalent to a kinetic

temperature of about 8 mK, which is in quantitative agreement with the

fundamental limit imposed by the natural linewidth. Hall is now preparing to follow this stage with a period of post-cooling, pumping a 20 -fold weaker line (which happens to be in the uv for Na) . This work

will open qualitatively new regimes of "atomic beam" physics, including

gravity-effects as a first-order consideration, atom bouncing, and atom

aggregation with "atom mirrors" formed by pulsed, reversing curved wavefronts . One of the most exciting prospects for spectroscopy implicit in

this work is the availability of long perturbation- free coherent interaction times, certainly 10 's to 100 's of milliseconds. Hall's computer

simulations suggest that an average atom may spend a few 10 's of seconds

in this bounce trap. Thus, a high density buildup factor may be

expected given the typical 2 ms "recharging" cycle repetition rate.

Strong optical cooperative effects (super radiant emission and soliton

modes) are expected, while high density collisional effects (such as Bose condensation) may be accessible with a suitably chosen atomic system and/or still stronger cooling. The immediate payoff of this stablelaser and cold-atom technology will be for the laser stabilization problem itself -- to provide a super-narrow (in view of the increased interaction time) transition for the laser frequency reference.

As an adjunct to this work. Hall and his group are pressing the

limits of laser stabilization to a passive material optical reference

cavity. Lowering the noise and drift rate of such a locked source will

allow slower servo loops in guiding on to an atomic resonance. The

lower bandwidth there will thus lead to lower frequency noise of the

system. In addition, the cavity locking techniques are interesting in

their own right because of possible application in inertial guidance

(passive laser-driven ring resonator gyroscopes) , local oscillator stabilization for space satellite communication, and as the optical refer- ence source for gravity wave detectors based on interferometry. The dye

laser experiments up to now have used servo bandwidths of a few

(< 5) MHz. If the frequency servo bandwidths can be pushed into the

30-40 MHz domain, it will be possible to lock the exciting -- and now

widely available -- single frequency solid state laser diode to produce

kilohertz linewidths or perhaps less. Hall's preliminary experiments

in this direction are very promising. On the other side, driving toward

the ultimate stability/lock accuracy limit with conventional gas laser

sources is also very exciting. While the increase in space and improved

environmental control planned for the new JILA addition will certainly

help the laser stability experiments described above, these cavity stabilization experiments will require drastic improvements in environmental stability if they are to begin to reach their full potential. In

the meantime, the scientists in Hall's group are investing considerable

effort and occasional cleverness in overcoming the thermal changes,

acoustic noise level, floor-borne vibrational noise level, 60 Hz magnetic fields, elevator- induced changes in the Earth's magnetic field,

tilting of the laboratory floor driven by wind forces on the JILA tower.

198
etc. Ac present they have generated and measured beat stability of two

independent lasers well below the 100 mHz level (see Figure 1) , which

would correspond to laser linewidths of the same value if the cavity

used for the locking were equivalently stable. Unfortunately, it is

easy to demonstrate by heterodyne techniques with a laser stabilized on

an I

2 reference line that the previous reference cavity was profoundly

influenced by temperature rates of change, barometric changes, and

floor -tilt effects. A new cavity support/isolation structure should

help such problems, but to work effectively in the mHz domain of interest for laser gyros, and ultimately for laser cooled ion spectroscopy, a laboratory with isolated piers reaching bedrock is essential. Modern

control systems for temperature and electric service will also be

required in these labs.

At various stages in these developments, techniques have been in

hand to allow precision measurements of high physical interest. Representative experiments include the measurement of the relativistic Doppler shift, observation of Ramsey fringes, an improved test of the isotropy of space, measurement of Rydberg atom levels using a travelingcarriage Lambdameter, development of optical sideband techniques for

high precision and ultra- sensitive spectroscopy, measurements of statedependent hyperfine coupling in HF, observation of Rydberg energy level

shifts due to thermal radiation, and the stopped atom work described

above. In addition to the 100-plus publications, the program has

developed four patents -- two issued and two pending.

A description of the JILA stable laser program would be seriously

incomplete without mention of the collaborative experiments undertaken

jointly with other labs. One collaboration with S. Chu and A. P. Mills

of Bell Labs led to precise measurement of the 1S-2S transition frequency of triplet positronium. Such a precise measurement is of great

interest as a definitive input to the QED testing business, since no limits are imposed by nuclear form factor corrections. On the other

hand, since both leptons e~ and e"^ have the same mass, additional theoretical effort is required to obtain the equivalent Dirac energy levels

without access to the central potential approximation. Further, a great

deal more effort is required to calculate all the QED terms in positronium than in the hydrogen. Hall's contributions to the positronium

experiment were mainly in frequency stabilization and wavelength metrology. Much the same ingredients are present in the JILA- Stanford collaboration (Professor T. W. Hansch) on the precision measurements in hydrogen. Hydrogen transitions are to be measured at Stanford relative to

reference transitions -- for example in Te2 -- that will ultimately be

measured with extreme accuracy at JILA using advanced interferometric

techniques now under development. Another by-product of this cooperation with Stanford is the development of a novel and universal laser

stabilization technique. The method can work with the output of any cw laser since the active transducer is located outside the laser cavity.

The technique uses both an electro -optic phase modulator and an acoustooptic frequency shifter. In addition to frequency correction, the

199
10.24 see H

PHASE STABILITY OF LASER BEAT

Figure 1. Two commercial HeNe lasers intended for the supermarket scanner market have been modified to have effective tuning capability. To evaluate the

accuracy of the locking techniques, both lasers have been locked to a single

optical reference Fabry Perot Cavity. Independence of the locks is assured by

a plurality of optical isolators, acousto-optic frequency shifters etc, so that

the inter-laser beat frquency will give pure information about the precision of

the two locks. In the upper plot (Fig. la), the beat frequency of the two

lasers (i^beat “

‘^/^^ef-eav “ MHz) has been further heterodyned down to 2 Hz

using a stable rf frequency synthesizer. A further shift of 2 Hz (Fig. lb)

brings the beat essentially to zero. Any momentary phase jump of either source

(u - 473 X 10^^ Hz) would appear directly in this doubly heterodyned optical

phase picture. Thus the laser phase is stable over about eight seconds, representing a drastically sub-Hz optical linewidth!

200
system provides optical isolation against optical feedback to the laser

source and can be configured to provide effective intensity control as well. There is strong commercial interest in this device, and a patent

application has been filed jointly with Stanford.

Laser Gravitational-Wave Observations in Space - P. L. Bender and

J. E. Faller

Work has continued on determining the practicality of a laser

experiment to detect gravitation waves in space with periods of about

0.1 seconds or longer. The basic concept for the experiment has been

described in earlier annual reports: Laser heterodyne techniques are to

be used to measure variations in the roughly million-kilometer separations of three masses in Earth- like orbits around the Sun.

D. Mils, Bender and R. F. Webb ink (JILA Visiting Fellow) have made

major progress this year in understanding the sources of the continuous

gravitational radiation that can be observed in space. Mironovskii had

shown in 1966 that WUMa binary stars, for which the Roche lobes of the

two stars touch, would give a strong but narrow peak of gravitational

waves at about 10”^ Hz frequency. The peak strain spectral amplitude

expected is about 10“^^/Hz^^^, made up of contributions from the roughly

10^ to 10® WUMa binaries in the Galaxy. Then in 1984, Iben and Smart

estimated that there should be several hundred close white dwarf

binaries giving strain amplitudes at the Earth of 10"^^ or greater.

Hils, Bender and Webbink have investigated the expected spectrum of

gravitational radiation from the close white-dwarf binaries in much more

detail and also determined the probable spectrum of radiation from three

other types of binaries in the Galaxy. In each case, they found that

the spectrum contains contributions from so many binaries that the signals from individual binaries usually cannot be resolved, even for a year of observations. Exceptions are for very nearby binaries, particularly those at the high-frequency end of the observable spectrum. For

the close white-dwarf binaries, the calculated strain spectral amplitude

ranges from about lO'^^/Hz^^^ at 10'^ Hz to the expected detection sensitivity limit of about 10“^^/Hz^^^ at 10"^ Hz. Bender and his colleagues

showed that the expected energy density in the Universe from such gravitational radiation is about 10"^ of the energy density necessary to

close the Universe, a result that had not been realized earlier! They

also calculated the spectral amplitudes for non-contact classical

binaries, neutron-star binaries, and cataclysmic variable binaries. The

resulting amplitudes are large enough to be observable, but the shape of

the spectrum for neutron-star binaries may not be sifficiently different

from that for close white-dwarf binaries to distinguish their contributions .

The gravitational radiation spectrum from binaries is of considerable interest for its own sake, but it also is of major importance in

201
terms of the design of a laser gravitational wave antenna in space. One

of the primary objectives of the antenna will be to search for pulses of

gravitational radiation due to the formation or interaction of black

holes with masses of a few thousand solar masses or more. The detection

of such pulses seems reasonably likely if black holes in this mass range

played a substantial role in the early history of the galaxies. It now

appears that the sensitivity limit at frequencies of about 10'^ Hz will

be determined more by the binary radiation confusion limit than by the

interferometer sensitivity. Bender and Faller will thus consider

whether an antenna arm length of about 10^ km rather than the 10® km

proposed earlier may be desirable in order to improve the sensitivity at

frequencies of up to 1 Hz . The possibility of using higher laser power

than the 1 mW assumed previously also will be investigated.

Mercury Orbiter Relativity Subsatellite - P. L. Bender

M. A. Vincent and Bender have investigated the accuracy with which

the orbit of a relativity subsatellite around Mercury could be determined from a number of roughly 8 -hour periods of high- accuracy tracking

data from the Earth. The purpose of this work is to support earlier

investigations by N. Ashby, Bender, and J. M. Wahr on how well gravitational theory could be tested in a Mercury Orbiter Mission if the

center-of -mass distance between Earth and Mercury were determined within

a given systematic error limit over a period of one to eight years. In

order to convert the measured distance from the Earth to the subsatellite into the desired center- to-center distance, the component in the

direction toward the Earth of the satellite position vector with respect

to the center-of-mass of Mercury has to be determined.

The orbit calculations assumed that the relativity subsatellite

would be in a high inclination orbit at roughly 2500 km altitude. Doppler tracking data plus range data were assumed to have been taken for

32 8 -hour periods covering about a year. The data periods were chosen

to correspond to two different orientations of the Earth-Mercury vector

with respect to the plane of the satellite orbit for each of 16 different orientations of Mercury with respect to the satellite orbit plane.

The gravity field coefficients for Mercury up through degree and order

6, 8, or 10 were then solved for, along with range biases and initial

orbit elements for each of the 32 periods. The main errors allowed for

were radial and off-axis biases in the calculated solar radiation pres- sure on the satellite plus uncertainties in the higher degree gravitational field terms that were not solved for. For a Doppler tracking

precision of 5 x lO"’-® and a ranging accuracy of 3 cm, the apparent

uncertainty in the center- to-center distance is about 15 cm.

During the next year, Vincent and Bender plan to improve the modeling of the solar radiation pressure effects. This is expected to

improve the accuracy for determining the center- to-center distance.

However, even the present 15 cm uncertainty would permit excellent

202
checks on gravitational theory. The possibility of a Mercury Orbiter

Mission with a relativity subsatellite now seems considerably higher

than during the last five years, since Chen-wan L. Yen at the Jet

Propulsion Laboratory has found new trajectories that would permit

larger payloads to be put in orbit around Mercury than for previously

considered trajectories.

Edtvos Experiment - J. E. Faller

The weak equivalence principle tested by the Edtvos experiment is

the hypothesis that all test bodies fall with the same acceleration in

the same gravitational field. This principle provides the experimental

foundation on which the geometrization of space-time in Einstein's

General Theory of Relativity is based. The central position of the

principle in Einstein's and other metric theories of gravity emphasizes

the importance of testing it to the best possible accuracy. Any failure

of the universality of free fall would necessitate a theoretical revolution.

Though in concept this principle is testable by dropping different

masses and observing whether or not they fall at the same rate, torsion

balances have been used since the experiments of Baron R. von Edtvos

and his colleagues in the late 19th and early 20th centuries. Accordingly, since that time, experiments designed to test this equivalence of

gravitational and inertial mass have been referred to as Edtvds experiments .

The approach to the experiment that Faller has adopted arises from

the observation that in the traditional torsion pendulum, the fiber

serves both to support the masses and to determine the torsion coefficient. In Faller' s approach, the suspension is provided entirely by a liquid, and the restoring and centering functions of the fiber are achieved by an appropriate electrode array subject to adjustable voltages .

P. Keyser and Faller have moved their new large Edtvds float to

the center of the spectroscopy laboratory in order to avoid the dynesized gravity gradient forces present in the corner of the laboratory,

which were causing millimeter-sized offsets in the centering. They then

proceeded to install active temperature control. This proved to be no easy task (given the room's oftentimes ±1 °C per few hours excursions).

In order to increase the rate of progress (understanding of these systems) during the latter part of this year, work on the large float (with

its several week's response time to any changes made for test purposes)

was temporarily halted so that the available manpower energies could be

focused on the functionally identical (but easier to make) changes on small gradiometer based floats. In part this was dictated by the need

for the graduate student (Keyser) to complete his Ph.D. thesis this year

or else be subject to the University statute of limitations requiring

203
that he retake (and pass) the comprehensive examinations again. Therefore Faller and Keyser have temporarily refocused their efforts on this

useful, but not necessarily as fundamental, application of fluid- fiber

torsion pendulums.

GEOPHYSICAL MEASUREMENT METHODS

Gravity Gradiometer - J. E. Faller

Faller and Keyser are proceeding with the testing of two 0.25-m

diameter fluid- supported pendulum apparatus as gradiometers . This

development -- in addition to its importance for the Eotvos work -- has

application to tunnel and intrusion detection as well as security for

nuclear stockpiles. Commercial applications of these devices for sink

holes etc. are being explored. During the past year, Faller and Keyser

have been testing these two floats under differing temperature control

conditions, both near room temperature and at 4 °C . They have also run

one of these floats as a "non-gradiometer" (using a cylindrically symmetric mass distribution) in an attempt to separate out gravitational

(gradient) noise from instrumental noise. One curious and perplexing

thing did occur on one occasion. One of the floats "locked" up, and as far as they can tell this lock-up was not related to any surface con- taminants, nor was it apparently related to any bulk contaminant. An

ordered structuring of the (pure) water has been occasionally suggested

in the literature, but to see such a thing (if indeed that is what they

saw) on such a macroscopic system, is both suspect and mind boggling.

Faller and Keyser are continuing to explore this aspect in an attempt to

pin it down, if at all possible.

Absolute Gravimeter (g) - J. E. Faller

Over the past year Faller and T. Niebauer, with assistance from

J. Gschwind and A. Joll of the Defense Mapping Agency (both assigned

to work in JILA) , are completing development of a new absolute gravimeter. The value of g continues to play a significant role in the

determination of certain physical constants and standards. With the

accuracies obtainable today, its measurement also has broad application

to geophysics and geodesy.

The JILA absolute gravimeter is based on the free-fall interferometric method: a freely falling mass that contains a corner cube serves

as a mirror in one arm of a Michelson interferometer. The times at

which selected interferometric fringes occur are used to calculate the

acceleration of the mass by the Earth's gravity. A stabilized laser,

used as a light source in the interferometer, provides the standard of

length, while an atomic frequency standard provides the standard of

time. A new dropping mechanism eliminates several sources of systematic

204
errors, and a long period isolation device greatly decreases the instrument's sensitivity to ground vibrations.

The construction of six such instrximents is now almost complete.

The which- laser issue has been resolved by going to a commercially

available intensity-stabilized laser. Nevertheless, Faller and his colleagues have spent the order of one -half a man-year studying the various

error sources inherent in these lasers, some of which were not known to

the manufacturer. The particular question of interest is how various

error sources affect the accuracy of the lasers and what can be done to

minimize and/or eliminate them. The discriminator development during

the past year appears to have been successful in meeting the critical

experimental requirements. Further, Faller and his colleagues have

found a way to perform a self -calibration on their timing electronics.

Functionally the overall design that has evolved appears to be an excellent one -- both in terms of convenience and field usability.

A major focus during the past year involved finishing the first of

these units so that it could be taken to Paris last June and July to

contribute to the Absolute Gravity Meter Campaign held at the International Bureau of Pounds and Measurements (BIPM) June 24 through July 5.

Also participating in this intercomparison was a Chinese (Beijing)

instrument, an Italian (Torino) instrument, and a Russian (Novosibirsk)

instrument. Although Sakuma's new BIPM instrument was not working at

that time, it was expected that it would be again shortly. The first of

the new JILA instruments was demonstrated to work and to work very well.

The only problem of any substance was the spongy (mattress like) floor

at the place the BIPM had designated Gravity Point A^, where the mea- surements were made.

Over the next months Faller and his colleagues expect to finish

their "production" of absolute gravity instruments. Over the next

several years their intention is to see absolute gravity measurements

become both usable and used in the field. With the new instruments,

they expect to improve on the 6-10 gal (2 cm height sensitivity) accu- racy of their earlier prototype instruments. If these instruments are reasonably successful in the field, the last years of this century

should see absolute gravity measurement mature both as a new geodetic

data type and as a useful geophysical tool.

Water Vapor Calibrator Development - P. L. Bender

The accuracy of a nijmber of geophysical and astronomical studies

based on microwave distance measurements is limited mainly by uncertainty in the propagation correction due to water vapor in the atmosphere. Measurements of tectonic plate motions by Very Long Baseline

Interferometry are among those affected, as will be the tectonic studies

soon to be made with dual- frequency Global Positioning System

receivers. Water vapor radiometers that measure radiated power in the

205
22 GHz water vapor emission line are likely to be used with increasing

frequency to measure the integrated water vapor content along the line

of sight to the sources of the microwave signals. However the accuracy

of these results is currently checked only against radiosonde data.

S. J. Walter and Bender have obtained funds from the Jet Propulsion

Laboratory to develop a microwave -optical system to improve the accuracy

in the correction to the microwave distance measurements due to the

atmospheric water vapor. Since optical distance measurements are affected much less by water vapor, the difference between microwave and

optical measurements to an aircraft at about 6,000 meters would serve to

determine the microwave distance correction. Such an aircraft would be

above about 95% of the atmospheric water vapor, and meteorological

measurements at the aircraft would permit correction for the remaining

water vapor. The resulting measurements of the total amount of water

vapor integrated through the atmosphere would be compared with estimates

from a dual frequency water vapor radiometer looking along the same line

of sight. Such comparisons are expected to give a valuable calibration

of the water vapor radiometers used in geophysical and astronomical

applications. The comparisons of results also may aid in improving the

algorithms used in analyzing the water vapor radiometer results.

During the past year, Walter and Bender have completed a thorough

design review for the transmitter and receiver of the water vapor calibrator and have purchased most of the parts for a ground-to-ground test

of the instrument. The various components have been mounted on base

plates and are now being prepared for initial laboratory tests. Subsystems that still need to be designed and constructed or purchased

include a relative phase measurement system for the two output 15 kHz

signals from the microwave and optical channels plus a data recording

system. The instrumental sensitivity is 18° in relative phase for each

1 cm of microwave path delay due to the atmospheric water vapor. The

required overall measurement accuracy is 0.5 cm or better.

Walter and Bender expect to complete the basic instrument and

ground testing during the next year and also to carry out some airborne

tests. Comparisons against other sources of information on the atmospheric water vapor content along the ground test path cannot be made

because of the difficulty of obtaining the other information with sufficient accuracy. Thus the ground-to-ground tests will be limited to

determining the instrument stability over short paths and to checking

the reasonableness of the observed variations over longer paths. The same is true for the initial airborne tests, which will be made in the

Boulder area.

206
ASTROPHYSICAL MEASUREMENT

Sobolev Method with Continuous Absorption - D . G . Hummer

G. B. Rybicki (Center for Astrophysics) and Hummer have generalized

the Sobolev method for radiative transfer in spectral lines in flowing

gases to include the effects of continuous opacity. They have given the

generalization in detail for plane parallel geometry and in outline for

general geometry. With a student in Munich, Hummer has also worked out

the spherical case in detail. Although this work involves an extremely

difficult mathematical analysis, the results are simple and give excellent agreement with accurate numerical calculations requiring powerful

computers. These results are required for work on the winds of WolfRayet stars and for modeling absorption lines in quasars.

Winds of Wolf-Ravet Stars - D. G. Hummer

With collaborators J. Puls, A. Pauldrach and R. P. Kudritzki in

Munich, Hummer has carried out calculations of radiation- driven stellar

winds of Wolf-Rayet stars in which the generalization of the Sobolev

method mentioned above plays an Important role. They have produced

detailed structural models of the atmosphere and wind of the eclipsing

Wolf-Rayet binary system V444 Cygni, which reproduce well the empirical

model for this object obtained by Cherepashchuk et al. from the inversion of light curves covering UV, visual and IR wavelengths. The agreement of their theoretical results with the empirical model provides

strong evidence that: 1) The effective temperatures of Wolf-Rayet stars

are two to three times larger than currently believed; and 2) The winds

are driven by the force of radiation from the underlying star. Hummer

has realized for at least five years that the accepted effective temperatures of Wolf-Rayet stars were much too low because they were being

inferred by comparing observed spectra with inappropriate models. He

has also long suspected that when the correct temperatures were used,

the radiation field would be found to carry enough momentum to drive the

wind -- contrary to popular opinion.

Determination of Atmospheric Parameters of Hot Stars - D. G. Hiimmer

The existing methods of determining the effective temperature, sur- face gravity and helium to hydrogen abundance ratio of hot stars have

been analyzed by D. Abbott and Htammer, who find that all methods of

determining temperature from continuum measures are in principle grossly

unreliable. In collaboration with B. Bohannan, they have undertaken a program to redetermine stellar parameters for hot stars from observations of line profiles observed with CCD detectors at signal- to-noise

ratios of several hundred. By fitting a large number of different line

profiles to state-of-the-art stellar models that include the effects of

blanketing by stellar winds, they can determine accurate values of the

207
basic parameters. The fact that a large number of lines are fit in

detail demonstrates the internal consistency of their models. A systematic redetermination of the stellar parameters for hot stars in the

Northern Hemisphere is underway as the thesis project of graduate student S. Voels. Hummer and Kudritzki are working on a similar analysis

of stars in the Magellanic Clouds, using observational material obtained

in December 1984 at the ESO Observatory by a member of the Munich group.

Results for six stars have been presented at lAU Symposiiam 116 on "Stars

and Associations in Galaxies" held in Porto Helu, Greece May 26-31,

1985. Further observations are scheduled for this winter.

In their recent review of Intrinsic Parameters of Hot Blue Stars,

Kudritzki and Hummer have shown that their determination of stellar

parameters is sufficiently accurate to provide, for the first time,

observational tests of stellar evolution theory that can discriminate

between various alternative treatments of mass loss and convective over- shooting as well as check on other approximations. They have planned a joint Munich- Boulder project to obtain high precision spectra of about

twenty 0- stars in our Galaxy and in each of the Magellanic Clouds to be

analyzed as described above.

Hummer has also proposed a program based on the refined theory of

stellar winds of 0- stars that he developed in Munich in collaboration

with Kudritzki and Puls, using his recent generalization of the Sobolev

method. They plan to use the maximum wind velocity as determined from

UV line profiles, together with the effective temperature and surface

gravity as found from their method of analyzing line profiles, to determine the mass, radius, and luminosity of individual hot stars. This

provides in principle a purely spectroscopic method, without calibrations, of determining the distances of hot stars. For four stars for

which data are available, their distance determinations agree well with

those obtained by membership in associations.

Rotational Non-LTE in the Atmospheres of Mars and Venus D. G. Hummer

Three years ago A. Kutepov (University of Leningrad) , who spent

nine months at JILA, and B. Moore (JILA Visiting Fellow) joined Hummer

in carrying out the first calculation of rotational band radiative

transfer in which rotational LTE was not assumed. They found significant deviations from rotational LTE in the atmospheres of Mars and Venus

which, if ignored in the interpretations of the observed CO2 bands,

would lead to major errors in the determination of the temperature

structure of the atmospheres of these planets. The near- impossibility

of sending manuscripts out of the USSR caused a long delay in completing

this paper, which has now been published.

208
Coll is lonal -Radiative Recombination D . G . Hummer

For the past several years, P. J. Storey (University College

London) and Hummer have been working on improved and extended calculations of radiative recombination line intensities and total recombination rates, taking into account the effects of electron collisions,

which become crucial at high densities. They have also extended the

theory to two- and three -electron systems and have obtained preliminary

results. Hummer has recently shown that the effect of collisional transitions from the ground and first excited states, which are ignored in

the classical "Case B" theory, become important for hydrogen at densities of 10® cm'® and for He"^ at 10^ cm'®, thus invalidating the theory

for these cases. He and Storey have developed an "Extended Case B" that

accounts for these collisions, and they are calculating the appropriate

recombination data in this approximation. One important conclusion

already apparent is that collisions from the n=2 levels at higher densities quickly force the upper levels into LTE, which will probably

explain the piozzling results obtained recently by K. J. Barlow (University College London) and Hummer in their analysis of the infrared

spectra of Wolf-Rayet stars. The calculations of recombination line

intensities for H and He'*’ in Case B are now complete. The bulk of the

calculations for the Extended Case B covering a higher density range

are in hand, and much of the material on the hydrogenic ions of C, N,

and 0 has also been computed. Much work remains to be done on the twoand three-electron systems, which are important for the interpretation

of IR lines in a variety of stellar winds.

Hydrogen Line Spectrum of Accretion Disks - D . G . Hummer

D. Carroll, a graduate student, has been constructing models of the

accretion disks of dwarf novae in order to compute the profiles of

hydrogen lines formed in disks, using the generalization of escape probability theory to axisymmetric flows developed by Rybicki and Hummer a few years ago . The goal of this work is to determine the energy input

in the disk from the dissipation of the circular motion, which causes

the material to fall inward towards the white dwarf. They hope to

obtain observational constraints on the dissipative mechanism, the

nature of which is still not understood and remains a major puzzle.

Carroll's Ph.D thesis on this work will be submitted in November 1985.

The Q-pacitv Project - D . G . Hximiner

In recent years evidence has accumulated that predictions of the

theory of pulsating stars are not in accord either with observation or with the theoiry of stellar evolution for stars with significant amounts

of elements heavier than hydrogen and helium. However for stars with

very small abundances of the heavier elements, both theories are in

accord with observation, and the theory for stellar evolution itself has

209
generally been in agreement with observation. Evolutionary calculations

depend primarily on the opacity of material at very high temperatures

and densities, characteristic of the centers of stars, while pulsation

calculations involve much lower temperatures and densities because the

pulsationally unstable regions of stars are much closer to the visible

atmospheres. These circumstances have led Hummer and his colleagues to

question the accuracy of the opacities of elements heavier than helium

and hydrogen, at moderate temperatures and densities, 3.5 < log T < 7.0

and -12 < log p < -2. An examination of the methods used to calculate

opacities in this region discloses that the approximations now in use

are quite crude and far inferior in accuracy to what is now possible

with the computational techniques of present-day atomic theory. For

this reason, D. Mihalas (NCAR) , M. J. Seaton (London) and Hummer decided

to undertake an entirely new and independent calculation of the stellar

opacities for the relevant temperatures and densities (so-called "envelope conditions"). This work is now well underway, with Seaton and

P. G. Burke (Belfast) leading the calculation of the atomic cross sec- tions, radiative transition probabilities and line -broadening parameters, and Mihalas and Hummer taking responsibility for the equation of

state (i.e. specifying the level populations for each species of atom

and ion as a function of temperature and density) and the ultimate processing of the individual atomic cross sections etc. into the total

opacity.

The benefits to be expected from this work are considerable.

(1) The resulting opacity tables (or rather computer fits to bi-cubic

splines) will be of known accuracy. (2) In addition to the standard

mean opacities (Rosseland, Planck), a variety of group means, opacity

distribution functions, and other representations more fine-grained than

the gross mean opacities will be computed, as well as various thermodynamic functions for the gas. All of this material is necessary for the

solution of radiative-gas dynamical calculations in a variety of astrophysical and terrestrial applications. (3) A vastly improved and much

more detailed theory of stellar pulsation will be possible, including

the calculation of spectral line profiles as a function of phase. This

should yield a much more accurate relation between stellar luminosity

and other observable properties such as period, abundance, line profiles, etc. If this turns out as expected, the old period-luminosity

relation, which is only highly approximate, could be replaced by a much

more reliable method of determining the cosmic distance scale. (4) As

a by-product, this project will yield radiative data accurate to about

10%, and electron excitation cross sections of slightly lower accuracy,

for all transitions of interest in all atoms and ions up to and ultimately including iron. (5) The equation of state and resulting thermodynamic functions will be the most accurate yet derived for a range of

temperatures and conditions that include those of almost all terrestrial

laboratory, fusion and industrial plasmas and electrical discharges.

210
Equation of State D . G . Hummer

In connection with the opacity project, Hummer has devoted a con- siderable amount of attention in the past year to the question of an improved equation of state for non- ideal plasmas with densities up to

10'^ gm cm‘^. The general approach is to derive an expression for the

Helmholtz free energy as a function of all atomic populations and then

to minimize with respect to these populations. This work is being done

in collaboration with Mihalas.

Hummer's particular responsibility is the evaluation of finite

atomic partition functions. As has been known for many years, the partition function for an isolated atom diverges, and convergence is

obtained by accounting for the perturbations of the atom or ion by the

surrounding plasma. In view of the difficulty of this problem and the

diversity and lack of agreement of existing theories. Hummer decided to

take a simple physical approach aiming for a correct physical picture

and accepting that quantitative accuracy was probably not possible at

present. In the course of this work, he discovered that a number of

accepted models were either partially or completely wrong. For example,

much work has been done in which the effect of the plasma on the atom is

represented by a screened coulomb potential (SCP) . Solutions of Schrodinger's equation with the SCP give only a finite number of bound

states, which removes the divergence problem in the partition function.

However, Hummer has shown that the SCP is completely inappropriate as an atomic potential and that results obtained in this way are utterly

wrong. Quite a large number of papers based on this model are now

worthless. Similarly, a well-known model developed by Unsold is also

wrong.

Hiimmer has derived results based on the quantum theory of Stark

ionization and detailed plasma microfield distributions, which appear to

explain in detail accurate laboratory spectra of hydrogen arcs . He and

Mihalas have recently completed the first paper of a series on the

improved equation of state. Results for two additional papers (one on numerical results for the equation of state and the other on thermodynamic functions in plasmas) are in hand. Hummer has also completed a paper giving rational approximations permitting the rapid computer evaluation of the Holtzmark distribution, its integral and derivative, which

enter the evaluation of the truncated partition function.

Measurements of Magnetic Fields in Cool Dwarf Stars - J. L. Linsky

Linsky and his Ph.D. thesis student, S. Saar, are pursuing a major

program to measure surface magnetic fields on stars cooler than the Sun.

They have already succeeded in making magnetic field measurements on stars much cooler than was heretofore possible; they have also developed

an analysis technique to take into account for the first time the saturation of optically thick absorption lines.

211
Figure 2. Comparison of apodized 4m FTS spectra of AD Leo (crosses), similar

spectra of the dX5 magnetically inactive star 61 Cyg A, and a sunspot umbra/

photosphere ratio spectrum from Hall's atlas. (The ratio spectrum removes telluric Lines without affecting Ti I, which is absent at solar photospheric

temperatures.) The solid line model fit to the AD Leo data is for the magnetic

parameters indicated. All data are on the wavenumber scale of AD Leo. The

spectra have been displaced vertically for clarity, and positions where the

noise is enhanced because of the approximate removal of strong telluric lines

from the AD Leo spectrum are marked with arrows.

212
Magnetic fields broaden spectral lines by the Zeeman effect.

Attempts to measure such fields in cool stars using standard Zeeman

analysis techniques with circular polarization optics have been unsuccessful, presumably because highly turbulent and oppositely directed

fields cancel the circular polarization signal. To get around this

problem, astronomers in the last few years have followed a different

approach in which they measure the magnetic field by the increased

broadening of unpolarized profiles of absorption lines with large

Lande g factors (large Zeeman splitting) compared to lines with small

Lande g factors.

Linsky and Saar have extended this work in two important ways

.

First, they have developed a radiative transfer computer code that simulates the formation of spectral lines in a stellar atmosphere, including

Zeeman broadening and saturation due to large opacity at line center.

They have then used this code to derive stellar magnetic fields and sur- face coverage factors by comparing high quality observed line profiles

with their computed profiles. Second, they have acquired a large number

of high spectral resolution and high signal- to-noise profiles from different observatories. For example, they obtained spectra of the cool

flare star EQ Virginis using the Multimirror Telescope and of AD Leo

using the Fourier Transfer Spectrometer (FTS) on the Kitt Peak 4 m telescope. They measured fields of 2500 ±300 Gauss covering 80 ±15% of the

surface of EQ Virginis and 3800 ±260 Gauss covering 73 ±6% of the sur- face of AD Leo. These are the first field measurements for any dwarf

flare stars. Figure 2 shows the data (pluses) and theoretical fit

(solid line) for line profiles of AD Leo and, for comparison, the spectra of a sunspot (2900 Gauss) and the star 61 Cygni A, which is likely

to have only a weak field. Linsky and Saar are presently analyzing

additional observations from Kitt Peak and the Multimirror Telescope,

which indicate fields on about a dozen additional stars.

Planning for Future Space Observatories to Obtain Ultraviolet and X-Ray

Astrophvsical Data - J. L. Linsky

Linsky is participating in the detailed planning of a number of

astronomical missions. The most immediate mission is the Hubble Space

Telescope to be launched in 1986/87. Linsky has been a Co- Investigator

on the High Resolution Spectrograph (HRS) since 1978 and has participated in the major decisions that have led to the design and construction of this instrument. As a part of the commissioning and calibration

of the instrument after launch, the Co-Investigators will be making the

first observations of stars with this instrument. The HRS will obtain

spectra with resolution up to 10^ covering the spectral region

110-320 nm. Linsky is also a Co-Investigator on a proposed imaging

spectrograph that will hopefully replace the HRS five years after

launch. During the last year, Linsky was appointed an Interdisciplinary Scientist and member of the Science Working Group for the proposed

Advanced X-Ray Astrophysical Facility (AXAF) . This is a proposed

213
1.2-m grazing incidence telescope that will obtain high resolution X-ray

spectra in the mid-1990's. During the next ten years or so, he will

advise the AXAF project. His specific interests are high-throughput

spectroscopic observations of stars to measure stellar coronal temperatures, densities, and flow velocities.

Linsky is also a member of the Science Working Group that is studying various possible designs for a Far Ultraviolet Spectroscopic

Explorer (FUSE) satellite. This will likely be a grazing incidence

telescope and spectrograph to cover the 10 - 200 nm spectral range at

both low and high spectral resolution. This is a particular change both

instrumentally and scientifically because the 10 - 120 nm spectral

region is unexplored except for the Sun.

Microwave Measurements of Stellar Mass Loss Rates - J. L. Linsky

Linsky and his postdoctoral research associate, S. Drake, have

completed a survey of microwave emission from 39 of the closest stars

that are more luminous and cooler than the Sun. This survey at 5 and

15 GHz was made using the National Radio Astronomy Observatory Very

Large Array (VLA) . The purpose of the survey was to measure mass loss

rates for a class of stars (giants and supergiants of spectral types G,

K, and early M) for which there was very little data heretofore. Micro

wave emission from these stars is thermal bremsstrahlung from the ionized component of the circvimstellar gas that is leaving the star, a phenomena called "mass loss", which is of great interest in astrophysics.

In their survey they detected six stars, five of which are wind sources,

and one is a hot coronal source (Capella) . For these five sources, the

microwave spectral indices are consistent with optically thick emission

from a stellar wind. The inferred mass loss rates for the ionized com- ponents of these winds indicate that the gas is partially ionized (one

to five percent) and that the mass loss rates can be used to constrain

different theories proposed to explain the acceleration of stellar

winds. Drake and Linsky are now writing up their survey of microwave

emission from close binary stars. These are all synchrotron sources and

show an interesting dependence of microwave luminosity on period and

thus on proximity and rotational velocity.

Modeling of Extended. Expanding Stellar Chromospheres - J. L. Linsky

Linsky and Drake, are computing models for the extended outer atmosphere of the prototype cool giant star, Arcturus. To accomplish this,

they have written a computer code that solves the radiative transfer

equation in spherical geometry including the effects of partial redistribution (PRD) and mass flux conservative outflow. The equations are solved in the co -moving frame of the fluid. PRD means that photons are scattered noncoherently in the line core and nearly coherently in the

wings, where the only important noncoherent term is radiation damping.

214
Using this code, Linsky and Drake have determined a model for Arcturus

that predicts an accurate profile of the resonance line and is con- sistent with the observed microwave flux. This model specifies the mass

loss rate and radial dependence of the electron density, total density,

expansion velocity, and turbulent velocity.

Linsky and Drake intend to check the validity of the model by using

it to predict other line profiles observed in Arcturus and other stars.

Linsky has published a detailed review of PRD radiative transfer and

its use in computing stellar line profiles.

X-Ray Bright Points on the Quiet Sun - K. B. Gebbie

J. Toomre and Gebbie are conducting two major observational studies

as Guest Investigator Programs on the repaired Solar Maximum Mission

(SMM) satellite. The first is a program of coordinated observations of

X-ray bright points using the Ultraviolet Spectrometer and Polar imeter

(UVSP) Instriament and the Soft X-ray Polychrometer (XRP) . This work is

carried out in collaboration with A. Gabriel of Rutherford Laboratory,

J. Gurman of the UVSP team, and L. November and F. Hill of the National

Solar Observatory. X-ray bright points, which have so far been seen

only in broad-band X-ray images, were one of the significant findings

of Skylab. They appear to be formed where small concentrations of magnetic flux emerge through the photosphere. Their discovery has made

it possible to follow the emergence of flux on scales much smaller than

those of active regions and to identify patterns of behavior quite different from those associated with the normal solar cycle. But apart

from Skylab, these results have been derived from a total of only six

rocket flights. SMM has not been able to observe X-ray bright points,

largely because the X-ray Polychrometer instrument is not sensitive

enough to identify them in the usual raster mode.

Fortunately, Toomre 's and Gebbie 's earlier study of persistent

flows in the lower transition region suggests that C IV Doppler observations can be used to provide coordinates for likely sites of X-ray

bright points. Near-real- time UVSP data are analyzed to predict coordinates at which to obtain soft X-ray spectral line profiles with XRP during subsequent orbits. Such closely coupled observations with UVSP and

XRP may yield the first spectra of X-ray bright points and thus the

first quantitative measurements of the plasma producing these soft

X-rays

.

Rapid UV Brlghtenings in Active Regions - K. B. Gebbie

As a second Guest Investigator Program on the SMM satellite, Toomre

and Gebbie, in collaboration with J. Porter of Marshall Space Flight

Center, are pursuing their discovery of rapid changes in the ultraviolet

emission from bright sites in active regions. Their recent analysis of

215
C IV and Si IV line emission observed with high spatial and temporal

resolution suggests that heating events of modest amplitude occur almost

continually at many sites in active regions. Such heating events suggest that magnetic field reconnection in an active region is proceeding

almost stochastically, with modest events occurring far more frequently

than those with large amplitudes. This may be evidence in the transition region for the "magnetic burning" or "topological dissipation"

advocated by Parker as a means of heating the corona.

Toomre and Gebbie are using the UVSP instrument on SMM to conduct a survey of these brightenings in order to obtain better statistics on their spatial distribution and frequency. This should yield estimates

of their contribution to the total energy balance of the transition

region and their relation to flare activity

ATOMIC AND MOLECULAR PHYSICS

Electron Collisions with Polar Molecules - D. W. Norcross

A. Jain and Norcross have been carrying out large scale computational studies of rotationally and vibrationally elastic and inelastic

scattering of electrons and positrons by a variety of molecules, and

developing and extending numerical techniques to treat more complicated

molecules and processes.' Results will find application in studies of

many practical and fundamental processes (e.g. laser modeling, physics

of the interstellar medium) and in studies of chemical reaction dynamics

(e.g. flow of energy from electron kinetic energy to molecular dissociation via excitation of molecular nuclear motion)

.

Recent progress includes detailed calculations of cross sections

for vibrationally elastic scattering by (linear) HCN, HF, and CO, and

for vibrational excitation of HF, and a study of resonance (autoionizing) states of HCN" as a function of internuclear distance. HCN is of

particular interest for several reasons: It is a prototypical triatomic polar molecule with the simplicity of linearity in the ground

electronic state; it shares characteristics in electron scattering with

nonpolar N2 (a prominent Pi resonance) and polar HCl (a diffuse Sigma

resonance) ; it exists in diffuse interstellar clouds and in CN laser

systems; and it has been considered a candidate for a gaseous high-power

switch. Code development leading to a capability for full vibrational

close-coupling calculations with an exact treatment of the electronelectron exchange interaction has been outlined and initiated (work to

date uses an approximate treatment of nuclear dynamics that necessarily

fails near vibrational excitation thresholds) . Work is also underway to

extend the code to calculate negative ion states of molecules, a novel

application of scattering theory.

Future work will include application of the vibrational close

coupling code to previously studied molecules (HF and HCl) in order to

216
provide the first, definitive, near- threshold results; extension of the

work to vibrational excitation of CO; and production of accurate results

for the lowest bound states of HCl”, HF“, and HCN” . This latter work

will be the first to provide a systematic connection between negative

ion resonances and true bound s'tates in these molecules as a function of

nuclear geometry. S. V. ONeil, P. Rosmus (JILA. ex-Visiting Fellow), and

Norcross plan to complete an elaborate calculation of the lowest bound

states of HCl” using Rosmus' molecular structure code for comparison

with results to be obtained from the scattering code -- there are very

large and unexplained differences between previous molecular structure

results, none of which seems to be consistent with the resonance

results

.

Electron Impact Excitation of Atoms and Atomic Ions - D, W. Norcross

Norcross' group is pursuing several fundamental and applied problems in the theory and computational physics of this process. F. Parpia

has nearly completed a new attack on one of the most perplexing discrepancies in electron- ion collisions work -- the difference between mea- surements (by Dunn and coworkers) and calculations (by Norcross, coworkers, and others) for excitation of the resonance line in the simple

"one -electron" ion Be"^. A. K. Pradhan is making systematic progress

towards completing the work on excitation of Mg- like ions, for application to fusion diagnostics and plasma modeling, and in application of

the theory of dielectronic recombination (DR) in practical calculations

incorporating field effects. D. A. Harmin is developing an extension of

the quantum- defect theory of DR to include the influence of arbitrary

electric fields. F. de Paixao is working on an elaborate seven-state

close -coupling calculation of electron scattering by the ground and

excited states of sodium, looking towards analysis of a variety of

experiments using mixtures of laser oriented atoms in excited states and

spin polarized electron projectiles.

Results for the excitation cross section of Be"^ differ surprisingly

little from those of the earlier calculations, even though much more

attention was paid to effects arising from virtual excitation of the core of the ion. Calculations of the polarization of the resonance line

radiation excited by electron impact are in progress; this is a much

easier quantity to measure, and a serious discrepancy with theory was

also observed. The calculations for Fe XV were the first for excitation

of the Mg-like ions . to be completed; the important 3s^-3s3p ^Pj^ transition was found to be subject to large resonance enhancement. Progress

has been made in the development of a general program for calculating DR cross sections for any ion, in intermediate coupling, and including

external field effects in the Stark broadening formulation developed by

Harmin. Preliminary results for 3s - 3d and 3p - 3d excitation in Na

are in excellent agreement with the measurements of Stumpf and Gallagher; they identify the resonances responsible for the puzzling sharp

threshold onset of these cross sections.

217
The detailed studies of electron Impact excitation of singly

charged ions will be extended to the first ions of the Na, K, and Mg

isoelectronic sequences. The production-mode calculations of the

Mg- like ions will continue with work on S V, Ar VII, Ca IX, Cr XIII, and

Ni XVII. A new program of calculations on little understood metastable

states of atomic negative ions will begin with an attempt to identify an observed long-lived state of Ca' . The Na calculations will be extended

to produce results with higher resolution (e.g. angular distributions)

and for more transitions (3s - 4s, 3s - 4p, and 3p - 4s). The first

application of the new formalism and program for field effects in DR

will be to the case of Mg'*" currently being measured by Dunn's group.

Electron-Atom and Atom-Atom Collision Processes - A. C. Gallagher

The electric breakdown and conduction of a gas and the radiation

from the resultant plasma are of importance in lasers and area lighting,

in switching and power generation, and in the diagnostics of man-made

and astrophysical plasmas. The radiative and electrical properties of

these hot gases depend on electron-atom and atom-atom collision

processes, which couple the kinetic energies of the particles into radiative transitions and visa versa. During this year Gallagher, in collaboration with postdoctoral research associate J. Kelly and graduate

students X. Hahn, M. 0' Callaghan, and G. Schinn, has been studying

several kinds of collision processes that occur in these hot gases. As

it is neither practical nor economical to investigate all specific

species and processes of current or potential interest, these investigations are designed to obtain highly detailed diagnostics of a few specific processes, thereby guiding and testing basic understanding applicable to all similar processes. Specifically, Gallagher and his colleagues are carrying out the following experiments.

An experiment to measure fully differential electron excitation of

Na atoms from the 3S to 3P state has been constructed and tested. This

experiment will use a completely new approach, the detection of differential cross sections by recoil Doppler shift to allow measurements that

are fully differential in M., M and 9 . This experiment will test

theories in the critical thre^ol^ region with orders of magnitude more detail than has previously been available.

Inelastic atom-atom collisions are also being measured differentially using the recoil Doppler shift. Here Na atoms are excited to the

3P3^2 state with a single velocity in the laser direction (v^,) , and a small fraction of these atoms are inelastically transferred to the 3P^^2

state by collision with an inert gas atom. The v^ distribution of these

post-collision atoms is then measured from the laser induced fluores- cence (LIF) spectrum of the 3P^^^2 transition. The results of this

gas -cell experiment involve a collisional velocity average that somewhat

dilutes its diagnostic power. A crossed atomic beam apparatus has

therefore been constructed to remove this averaging and allow direct

218
measurement of differential (in angle) inelastic atom-atom collision

cross sections and very precisely delineate the theoretical understanding of the interactions and the energy transfer process. Initial experiments in the atomic beam apparatus will study collisions between equivalent and dissimilar alkali atoms in the excited state.

The pair of atoms undergoing a collision can absorb and emit radiation at wavelengths far from the atomic transitions. The spectrum of

this continuum radiation provides a powerful diagnostic of the interaction energies of the collision complex. The spectrum has been studied

in this and other laboratories for many years to study collisional

interactions. These studies have been restricted to radiative transitions between isolated electronic states of the collision complex, or in

other words to elastic collisions. This year in collaboration with

T. Holstein, Gallagher's group has extended the lineshape theory to

include inelastic collisions and particularly the absorption and emission of radiation in the voided level-crossing region responsible for

most inelastic atom-atom energy transfer. This theoretical result is

now published, and experiments have been designed to use and test this

theory in the laboratory.

A new experiment has been started this year to study collisional

and stimulated radiation processes in Sr and Sr-alkali vapor mixtures.

Fluorescence transients following pulsed radiative excitation of Sr are being diagnosed to establish radiative and collisional pathways and

cross sections in this highly excited vapor.

Silane Neutral Chemistry - A. G. Gallagher

The quality and utility of hydrogenated amorphous silicon (a-Si:H)

film photovoltaics has increased every year since their initial production in 1976. Efficiencies of 8-10% are now routinely achieved compared

with crystal silicon cell efficiencies that are now 14-18%. Because

a-Si:H can be deposited inexpensively from a discharge as a thin layer

on large areas, it is a leading contender for solar power generating

systems. In spite of this impressive progress, major improvements in

deposition rate, large-area reliability, stability, and efficiency are still feasible.

Since 1979 Gallagher and his group have been studying the discharge

and surface processes that lead to the film production in order to

assist this progress with improved understanding of the microscopic pro- cesses. During the last year, they have concentrated on understanding

the neutral radical gas chemistry, using their unique and sensitive radical detector (based on threshold ionization mass spectrometry) . They

were able to measure the mixture of mono and disilane radicals, which

are primarily responsible for film deposition, and have modeled the

sources of these radicals. By analyzing their data, they have shown

that much of the discharged neutral chemistry occurs on surfaces, and

219
they have delineated several of the dominant surface processes using

measurements and diagnosis of silane surface pyrolysis. With this

increased understanding of the surface processes, they are now devising

experimental tests of their models for the surface process of greatest

interest; the silicon incorporation and film growth. During the last

year, R. Robertson has completed his thesis under this project.

Dielectronic Recombination - G . H . Dunn

In 1964 dielectronic recombination (DR) was hypothesized to be the

dominant recombination process in very hot plasmas. On the basis of its

success in rationalizing a discrepancy in temperature measurements of

the Sun, the mechanism has since been routinely incorporated into models

of astrophysical , fusion, and other hot plasmas. Nevertheless, it was not until 1983 that experimental breakthroughs in JILA and three other

laboratories resulted in the first successful laboratory measurements of

the cross section for this process. All the experiments gave cross sec- tions significantly greater than theoretically predicted. To explain

the discrepancies, the hypothesis was advanced that extrinsic fields of

modest size in the collision region mix angular momentum states,

increasing the number of states through which DR can occur. The extrinsic field thus becomes a "knob" by which the cross section can be turned

up or down. The next step was obviously to test this bizarre but important concept under controlled conditions.

The experiments at JILA were performed using crossed beams of ions

and electrons to study the process e + MgCSs)"^ Mg(3p,ni)** -*• Mg(3s,nl)* + hi/ . In the 1983 experiments, the stabilizing photon and

product Rydberg atom were detected in coincidence and the total cross section measured. In the more recent measurements, the Rydberg atoms

were detected and cross sections measured both as a function of the

principal quantum number of the final Rydberg atom (Mg(3p,nl)) for

fixed electron energy and as a function of electron energy for fixed

principal quantum number. For this work, Dunn and his collaborators

developed a novel and versatile new Rydberg state analyzer/detector

,

which uses a wedge field and position sensitive detector. Figure 3 illustrates results obtained by Dunn, A. Muller (JILA Visiting Fellow),

D. Belid, B. DePaola, N. Djurid, D. Mueller, and C. Timmer for

versus n^ for three values of electric field in the collision region.

Recent theoretical work by groups in Connecticut, Oak Ridge, and' JILA

are in qualitative agreement with these results, though some work

remains to be done.

It is predicted that DR involving ions with transitions An=l and

larger radiative stabilization rates will be less subject to the

observed field effects. Work is underway to make measurements on the

helium-like ion Li^ using the Rydberg state detection method.

220
>

Figure 3. Cross section x width AE, of electron energy distribution versus

field ionization quantum nxmber n^. Solid circles, E^. - 23.5 V cm'^; open

circles, E^ - 7.24 V cm"^; triangles, E^ - 3.62 cm"^. Uncertainties are one statistical standard deviation. For - 33, the relative uncertainties are also indicated. Absolute uncertainties at n^ - 33 are within 10%.

Figure 4, Measurements on electron- impact ionization of S*"^. The excitationautoionization feature beginning around 170 eV is clear. The solid curve through the points is a theoretical calculation that agrees well with the

data.

221
Electron- Impact Ionization of Ions G . H . Dtinn

Dunn and his colleagues have found during the past few years that

electron- impact ionization of ions is affected to varying degrees by

"secondary" processes such as excitation-autoionization and

dielectronic-capture double autoionization. Indeed, these indirect

mechanisms may dominate the ionization process by more than an order of

magnitude. Since these cross sections are important for modeling

fusion, astrophysical , and high-power laser plasmas, Dunn and his

colleagues have been trying to gain a systematic understanding so that

the cross sections can be predicted and incorporated into modeling

codes

.

Using the electron-cyclotron-resonance (ECR) ion source at Oak

Ridge National Laboratory (ORNL) for the first time, A. Howald,

D. Gregory, F. Meyer, R. Phaneux, Muller, Djurid and Dunn made measurements on electron- impact ionization of Mg- like ions, and

Ar®'*’, where excitation of a 2p electron followed by autoionization plays

an important role. Figure 4 shows results for S^'^, where the excitation-autoionization feature beginning around 170 eV is clear. The solid

curve through the points is a theoretical calculation that agrees with

the data. The X-ray laser breakthrough at Livermore using Ne-like selenium is beset with an anomaly that 2p - 3p excitations are apparently

not as large as theoretically predicted. Dunn's previous data on excitation-autoionization of Na-like ions also shows this same anomaly, but

the data on Mg- like ions agrees with theory. Repeat measurements were

also made on which had previously shown an anomalously high excitation-autoionization cross section compared with other Li- like ions. The

new experiment is in line with others and with theory.

The ECR source at ORNL is prolific in producing multiply- charged

ions. Charge states of ions not previously available (e.g., iron ions

up to Fe^'*') permit measurements on species and charge states of

particular importance to the fusion program. These measurements are being pursued.

Merged Electron- Ion Beams - G . H . Dunn

Dunn and his colleagues have, for more than ten years, been

involved in making measurements on electron- impact excitation of ions.

The approach has been to use crossed beams of ions and electrons and to

observe and measure the fluorescence in the third orthogonal direction.

Using this approach, they measured excitation of Be^, C^"*”, N^"^ (Li-likes), Mg'*", Al^'*’ (Na-likes), Ca"^, Ba"^, Hg"^, Li"^, Zn"^ and Ga'*’. With

a few exceptions, this constitutes the extent of cross section measure- ments for electron- ion excitation. For most (but not all) of the above

cases, An=0 and A>2=1 for the excitation. A few years ago, it became

clear that the fluorescence technique would not yield good measurements

for many of the most important cases (e.g., high-z ions, An?^0 , A2t^1) .

222
To cope with this, Dunn and his colleagues are developing an entirely

new measurement concept to obtain electron- ion excitation cross sections. The method involves merged beams of electrons and ions and the

detection of the inelastically scattered electrons with trochoidal ana- lyzers fore and aft. The profound advantage is that the collection

efficiency is 100% compared with 10'^ or so for the fluorescence and

other methods of detecting inelastically scattered electrons. The

method overcomes all the limitations mentioned above and can yield good

measurements for high z, Aru^O and Air^l

.

Timmer, DePaola, and Dunn have been designing and building the

equipment necessary to realize these concepts. This new apparatus will

soon be together, and they plan to be doing first experiments with it

this coming year. At JIIA they will make measurements on singly charged

ions, since their ion source is limited. This will shake down the

methodology as well as yield some interesting measurements. They will

then take the apparatus to the ECR ion source at ORNL for measurements

using multiply-charged ions. Some of the first measurements will

undoubtedly involve looking at excitations of the type 2p - 3p in

Ne-like ions, since there appears to be such an anomaly involving these

excitations in the X-ray laser work at Livermore.

Low Temperature Ion-Molecule Reactions - G . H . Dunn

Dunn and his colleagues have developed the Penning ion- trap as a tool for investigating ion-molecule reactions in a heretofore inaccessible temperature range (4 K - 30 K) . A number of reactions have been

studied, including the first observations and measurements of radiative

association involving small nonpolar molecules. In all cases, the reactant neutral molecule has been H2 (or D2

) , and conditions are such that

there is (probably) a normal mix (3:1) of ortho/parahydrogen. To gain a more complete understanding of these mechanisms and to obtain data more

directly applicable to the modeling of molecule formation in the interstellar medium, the measurements should be done with pure parahydrogen.

M. Schauer, S. Jefferts, and Dunn are modifying the apparatus to make

these experiments possible.

Dielectronic Recombination - S . Geltman

At high temperatures, dielectronic recombination becomes the most

important electron- ion recombination process in a plasma. It dominates

over one-electron radiative recombination because there are many doublyexcited Rydberg states into which the free electron may resonantly

enter. Geltman has been working with a group at the Lawrence Livermore

National Laboratory in the preparation of a computer package for dielectronic recombination to be incorporated into their dense -plasma modeling

codes. The needed branching rates between radiative decay and autoionization are being calculated in a hydrogenic approximation for

223
arbitrary Z, which is determined by the instantaneous plasma conditions.

Programs for the needed rates have been prepared, and they are in the

process of being tested in the Livermore codes.

Multiple Ionization by Intense Laser Pulses - S. Geltman

A number of experiments have been done in recent years in which

high states of ionization have been seen when atoms are irradiated by

intense laser pulses. Typically these measurements are done on rare gases with photons from Nd:YAG (1.17 eV) and ArF (6.42 eV) lasers, the

pulse lengths are in the picosecond range, and intensities are ~ 10^^ - 10^^ W/cm^. The general process may be represented as X + Nqhi/ + qe, where ions have been detected for Nq and q values

as large as 99 and 10, respectively. It has not been possible to obtain

a correlation between the numbers of multiply charged ions produced at

intensity I and the expected theoretical form, 1^*^.

Geltman has been re-examining the theory on the basis of a Hartree

atom model in which the outer shell electrons are independent of one another and interact only with an effective central field. The one- electron ejection probability p may be computed in the normal quantum

perturbation theory manner and has the expected where Ni is a photon

number much smaller than Nq. Geltman has been able to construct products of these (with appropriate statistical factors) to represent P^*^\

the approximate probability for multiple electron ejection. His results

for the relative abundance of charge states Xe'^ give much improved

agreement with the data of Rhodes et al. than was possible to obtain

with the form. For low- intensities , his new theory gives the dependence and a time -dependence of t*^, rather than t. There is also

good general agreement of the theory with multiple ionization measurements using CO2 laser pulses, which of course involve much higher photon

numbers

.

Geltman is planning to apply the present theory to other measurements as they become available and also to extend it to cases where

multiphoton ionizations may occur via autoionizing states, such as in

Sr. The latter processes are highly resonant and pair correlations

become important.

Model Study of Above-Threshold Ionization - S. Geltman

In analyzing the energy spectrum of electrons that are ejected in

a multiphoton ionization process, it has been found that not only is

there a peak at the expected = Nj^hi^ - IP, but at sufficiently high

laser intensities additional peaks appear at E2

=- Ej^ + 2hi/

,

E3 = E^ + 2hi/, etc. Thus electrons are absorbing more photons than the

minimum required for ionization. A number of approximate theories have

had varying degrees of success in explaining these measurements

.

224
Geltman has started an investigation of this process using very simple

atomic and field models, so that an exact solution of the time -dependent

Schrodinger equation can be found. He has taken the model in which the

atomic potential is a one -dimensional 5-function and the laser field is an oscillating square wave. The fact that this model laser field is a constant between alternations of direction allows one to use the wellknown mathematics of the d.c. Stark effect, i.e., to express exact wave

functions in terms of Airy functions. This should allow the development

of a step-by-step exact numerical solution, from which one has the population of all continuum states, i.e., the ejected electron distribution.

Geltman plans to examine the electron energy peak structure under various conditions of frequency, intensity, and pulse length.

Stark Effects in Laser Isotope Separation - S. Geltman

Geltman has been continuing his cooperation with T. Lucatorto and

J. Snyder of NBS/Gaithersburg in their program of using sharply tuned

lasers in multiphoton ionization to obtain highly efficient isotope

separations. The prototype system of separating the rare isotopic ^°Sr

from the common one ®®Sr has been treated by means of a system of two cw

lasers tuned to 460.8 and 428.3 nm, which pump the ground state Sr to

the 5sl3d state via the 5s5p intermediate resonance. It is then photo

ionized by an intense CO2 laser. The Stark shifts in this two-step

excitation are critical in optimizing the efficiency of the isotope

separation. These shifts and the needed photoionization cross section

were calculated as a function of laser intensities. This led to a resulting sensitivity of the overall scheme of better than 10”^^ with a throughput of 10^^ atoms/sec. The next phase of this project will

involve the Kr isotopes of atomic weights 81 and 84, which are very

important in the analysis of ground water for radioactive traces. In

addition to Stark shift theory, this project will involve calculating

charge transfer cross sections. The cooperation between Boulder and

Gaithersburg on this work will continue.

Kinetics of Metastable - A. V. Phelps

Phelps and his colleagues are making measurements of the colli

sional process responsible for the production and loss of H2 (c^n^) metastable molecules in electrical discharges in H2

. Such discharges are important in devices such as hydrogen thyatrons and negative ion sources.

The present phase of this work is concerned with the measurement of

the rate coefficients for collisional destruction of the metastables.

H. Tischer (CU) and Phelps have published a letter describing these

measurements for the N=1 rotational level and the v=2 vibrational level

of the c^IIy state of H2

. A. B. Wedding (CU) and Phelps are extending

the measurements to other rotational and vibrational levels of the

225
metastable state. The experimental technique involves the measurement

of the transient absorption of a cw dye laser by the metastables following perturbation of the metastable population by a pulsed dye laser.

After completing the measurements of the H2 metastable destruction,

Phelps and his colleagues plan a brief look at D2 metastables. They

then plan to determine experimental rate coefficients for the excitation

of these metastables by electron Impact from ground state H2.

Noneguilibrium Electron Experiment and Theory - A. V. Phelps

Phelps and his colleagues are making experimental tests of models

of the behavior of electrons in gases at very high electric fields and

low gas densities. The current experiment yields absolute values of

the emission of radiation as a function of position from a low pressure,

high voltage discharge in a spatially uniform electric field. Comparison of these results with the predictions of theory provides tests of

the accuracy of various approximate theories . The data and theories

derived from this study are important for the modeling of plasma reactors, charged particle beam propagation and high power switches.

In collaboration with B. Jelenkovid (CU) , Phelps has made a number

of measurements of the spatial distribution of emitted light from these

low current discharges for a variety of gases, electrode materials, and

electric-field- to-gas-density (E/n) ratios. The measurements are made

absolute by comparison with previous experiment and theory at low E/n.

At present, the agreement with theoretical calculations made in collaboration with L. C. Pitchford (GTE Laboratories) is poor, and an explanation is being sought.

The future of this project is uncertain because of the difficulties

in getting other agency funding. The immediate plan is to pulse the

current through the discharge on a time scale that will separate electron and ion induced emission. After this, Phelps and his colleagues

propose to make energy analyses of the electrons and to compare theory

and experiment for nonuniform electric fields.

JILA-NBS /Gaithersburg Exchange - A. V. Phelps

During the second half of FY- 85 , Phelps participated in the NBS

program to exchange scientists between JILA and NBS/Gaithersburg. While

in Gaithersburg, he worked with the Applied Electrical Measurements

Group of the Electrosystems Division of the National Engineering Laboratory. The research project was to model electron behavior in the corona

discharges being studied experimentally by R. J. Van Brunt. Initially,

it involved developing a set of collision cross sections for electrons

and SFg. They then used these data in their recently developed electron

Boltzmann code for gases for which electron attachment is important and

226
applied them to SFg and SFg mixed with other gases to predict SFg dissociation rate coefficients for modeling the measured decomposition rates.

This collaboration is expected to continue as the need arises in Van

Brunt's research and may be part of a proposed project on computer

modeling of plasma-chemical reactors used for processing of materials.

Angular Distributions of Photoelectrons from High Excited Atomic States

S. J. Smith

The (angular momentum) properties of highly excited aligned states

reached by stepwise excitation with polarized pulsed laser beams can be

studied by measuring and analyzing angular distributions of photoelectrons, since these are determined in part by the angular part of the

excited state wave function. Smith and G. Leuchs (Max Planck Institute

for Quantum Optics, Munich) have used this method in the past to study

Rydberg series in barium, a system with two valence electrons in which

the single electron Rydberg series is perturbed by the presence of

states in which both valence electrons are simultaneously excited.

During FY-85, Smith and Leuchs completed a study of the 6sns ^Sg Rydberg

series in barium in the energy range around a 5d7d (J=0) doubly excited

state. The results were particularly interesting for two reasons:

(1) The interaction with the 5d7d (J=0) state is a pure quadrupole

interaction with direct uncomplicated interpretation, and (2) This type

of measurement was shown to be unique among measurements of series perturbations in that it contains information about the sign of the interaction.

Smith and Leuchs continued or initiated two additional studies during FY-85. One was a study of the competition between two decay channels from highly excited states: (1) Direct photoionization, and (2) A

Raman redistribution to nearby states. The effect of the latter process

appears in the angular distribution from a subsequent photoionization

process, which then differs from that of (1). These studies show that

the Raman process, negligible at low power densities of the photoionizing laser, becomes competitive with direct photoionization at high laser

power densities. This is in direct contradiction to the commonly

accepted view of theoreticians that the first order (direct photoionization) process should always dominate over the second order (Raman redistribution process) . Revised theories of this competition have been

worked out by K. Rzazewski (JILA Visiting Fellow) and by G. Alber.

Of continuing interest is the possibility of observing some manifestation of the limits of validity of dipole selection rules in

photoionization of electrons from Rydberg atoms, since the phase of the

optical field may vary appreciably from one side of the atomic system to

the other. A departure from the dipole selection rule would appear in

the photoelectron angular distribution as the introduction of a higher

spherical harmonic in the distribution. More specifically, one could

expect a front- to-back asymmetry with respect to a plane transverse to

227
the laser beam. An exhaustive study of the photoelectron flux from the

13 state of sodium by Nd:YAG second harmonic radiation at 55° forward and backward with respect to the plane shows four percent asymmetry

to about four standard deviations. The effect is an order of magnitude

larger than the estimate based on a classical picture of the electron

orbit. The experimental result for the ratio of electric quadrupole and

electric dipole matrix elements, Q=0. 035(8), is a good check on the

bound- free matrix element of r^, not available in other experiments.

Further measurements in two -electron perturbed systems are being

planned with a view to obtaining more quantitative (accurate) measurements of perturbations and to exploiting the photoelectron angular

distribution method as an unique spectroscopic tool.

The Role of Fluctuations in Non-Linear Optical Absorption in Atoms

S. J. Smith

D. S. Elliott, M. Hamilton, K. Arnett and Smith have developed a system based on the use of fast frequency and phase modulators for

imposing statistically well characterized fluctuations with a bandwidth

of about ±1 GHz onto the external beam of a highly stabilized ring

laser. Furthermore, by driving the system with Gaussian (random,

statistically stationary) noise, they can achieve prescribed laser lineshapes ranging from Lorentzian to Gaussian. They are fully characterized statistically by the laser lineshape and linewidth, both of which

can be measured directly. The objective is to study experimentally and

fully quantitatively the effect of different laser lineshapes and linewidths on a variety of nonlinear optical absorption processes in atoms.

The results of the first studies, addressed to one of the conceptually simplest nonlinear processes, unsaturated Doppler- free two-photon

absorption (3S-5S transition in atomic sodium), were completed in FY-85.

The results clearly demonstrate the limitations of intuition, and/or

experience with monochromatic lasers, in dealing with nonlinear effects.

During FY-85 a major effort was made to study effects associated

sodium). The double -optical -resonance technique was used. A weak probe

laser sampled the structure of the 3P3^2 level, which is split and

shifted in an intense laser field, by coupling it (by scanning) to the

4D5^2 Figure 5 shows examples of probe scans (a) with a nearly

monochromatic laser, and (b) with a wideband laser of measured power

spectrum (c)

.

The most dramatic feature in the results of this work is

the behavior of the symmetry of the double -peaked probe scan. The

asymmetry can take different signs with different laser lineshapes and

linewidths. This phenomenon provides a strong handle on the role of

fluctuations in a nonlinear process and is of great interest to the

theoreticians (such as former JILA Visiting Fellows P. Lambropoulos

(use) and J. Eberly (Rochester)).

228
INCREASING PROBE FREQUENCY

Figure 5. The probe laser absorption spectrxun for (a) a "monochromatic" saturating laser and (b) a saturating laser with a nearly Lorentzian shaped power

spectrum (c) with HWHM of 7 MHz. In (c) the subsidiary peaks on the left are frequency components on the local oscillator beam used in the heterodyne detection of this spectrum. Thus they can be ignored. Note that the vertical scale

is logarithmic. The Lorentzian and Gaussian curves drawn for comparison also

have HWHM of 7 MHz.

2

229
Finally, during FY-85 Smith started a study of the effect of lineshape, linewidth, and intensity on the so-called Hanle effect (zero magnetic field level crossing resonances), in collaboration with H. Metcalf

and T. Bergmann (both of SUNY Stony Brook) and J. Brandenberger

(Lawrence University). The object is to provide a quantitative check of

theoretical predictions of P. Avan and C. Cohen- Tannoudj i , which depend

on lineshape properties.

A thesis project (K. Arnett) will continue this effort as well as initiating studies using amplitude noise on the laser. Preliminary

efforts have been made to observe the resonance fluorescence spectrum in

sodium using optical heterodyne techniques (a collaboration with

D. Elliott, Purdue). This effort will continue.

JILA ATOMIC COLLISION CROSS SECTION DATA CENTER - J. W. Gallagher

FY 1985 Accomplishments

The JILA Data Center under the direction of J . Gallagher has

carried on an active program to compile and evaluate data in the areas

of electron and photon collisions with atoms, ions, and simple molecules. Several projects entailed collaboration with Data Center

visitors who participated in the review and evaluation of data in their

fields of expertise. The following projects were completed in FY 1985;

journal references may be found in the list of QPD publications elsewhere in this report.

o Charge transfer of hydrogen atoms and ions in metal vapors.

T. J. Morgan, R. E. Olsen, A. S. Schlachter, and J. W. Gallagher

o Electron production in proton collisions : Total Cross Sections

.

M. E. Rudd, Y.-K. Kim, D. Madison and J. W. Gallagher

o Anisotropic scattering of electrons by and its effects on electron transport : Tabulations of cross section and results.

A. V. Phelps and L. C. Pitchford

o Tabulations of collision cross sections and calculated transport

and reaction coefficients for electrons in and D2

. S. J. Buckman and A. V. Phelps

o Tabulations of collision cross sections and calculated transport

and reaction coefficients for electron collisions with O2

. A. V. Phelps

230
o An evaluated compilation of data for electron- impact excitation

of atomic ions. J. W. Gallagher and A. K. Pradhan

o Atomic data for electron- impact excitation of ions.

A. K. Pradhan and J. W. Gallagher

o Alignment and orientation of collision processes - What we have

learned so far. N. A. Anderson, J. W. Gallagher, I. V. Hertel

o Analysis of orientation and alignment in electron impact excitation of heavy rare gases

.

The Ar 4s ^P and ^P Case

.

N. Anderson, J. W. Gallagher, I. V, Hertel, and F. J. da Paixao

Work In Progress

Collisional Alignment and Orientation of Atomic Outer Shells. I. Direct

Excitation by Electron and Ion Impact. N. 0. Andersen, J. W. Gallagher,

and I. V, Hertel

To describe these processes, the authors have determined new parameters that have more physical meaning than those usually published and

which can be derived from published data in most cases. Data have been

collected and reformatted from approximately two hundred papers on alignment and orientation in electron collisions with H, He Ne , Ar, Kr,

Xe , Li, and Na. Measured and calculated data for each incident energy

and final target state are being compared to evaluate the quality of the

work and identify the influence of competing physical processes such as radiation trapping in experimental work and the accuracy of theoretical

descriptions. A manuscript describing this work is being prepared for

submission to "Physics Reports" and an Information Center Report will

give a comprehensive presentation of the data.

A Review of Measured Electron Impact Excitation of Atoms and Atomic

Ions. D. W. 0. Heddle

Professor Heddle of Royal Holloway College, University of London,

spent a month at JILA in the stimmer of 1985 continuing work on this

review. Last year he reviewed data on the alkalis, alkaline earths,

cadmium and zinc. This year he concentrated on helium, a substantial

topic in itself, and a detailed analysis of the associated data. The

data on the other rare gases were also collected and reviewed. Heddle

will continue to work on the review at his home institution and plans to

complete a first draft of the manuscript for "Reviews of Modern Physics"

in 1986.

231
Absolute Partial Cross Sections for Molecular Photoionization Processes

.

J. W. Gallagher, C. E. Brion, P. W. Langhoff and J. A. R. Samson

The authors had collected and compared all data on total photoionization, partial channel photoionization, and dissociative ionization of

twenty- one common small molecules by the fall of 1984. Preparation of

the manuscript lagged, however, and virtually no progress has been made

on the project during FY-85. Efforts are currently being renewed to

complete this project and to submit a manuscript to the "Journal of

Physical and Chemical Reference Data" in 1986.

The Atomic Collisions Data Base.

In addition to the Data Center's bibliographic collection, approximately nine hundred numerical data files have been entered into the Data

Base. These are being used to prepare figures supporting the Center's

review activities. Programs have been developed to produce listings and

indices of the material in the Data Base. Work is currently ongoing to

provide on-line enquiry capability.

The Digital Equipment Pro 380 data-capture system was acquired to

replace the outdated Tektronix 4051 and peripherals. Purchased software

is being studied and tailored to meet specific needs of the Data Center.

FY 1986 Plans

Gallagher and her colleagues will be making a major effort to com- plete the three reviews currently underway. In addition, they will con- tinue the modification and improvement of procedures through full incorporation of the Atomic Collisions Data Base and the DEC Pro 380.

Work will begin on "Atomic Data for Fusion, Volume II. Collisions

of Electrons with Atoms and Molecules", which is part of the five-volume

series to be published by the Controlled Fusion Atomic Data Center of

Oak Ridge National Laboratory.

A second new project, a review of properties and reaction rates of

atmospheric ozone, will be started with J. I. Steinfeld of M.I.T.

232
CHEMICAL PHYSICS

State-Resolved Dynamics via Laser Absorption Spectroscopy - D. Nesbitt

Nesbitt is pursuing four new areas of research into molecular spectra and dynamics using ultrahigh sensitivity infrared absorption techniques: (1) Spectroscopy, intramolecular energy transfer, and vibrational predissociation of weakly bound clusters in a supersonic molecular beam, by direct absorption of a tunable difference frequency

laser, (2) Gas -solid interactions by monitoring the nascent quantum

state distributions of sublimation from simple molecular solids into a vacuum, (3) Molecular properties (such as dipole moments) of vibrationally excited species by coherent transients, (4) Spectra of ultracold

radicals in a supersonic jet excited by a weak Corona discharge.

Although Nesbitt joined the Division only a year ago, he and

C. Lovejoy and M. Schuder have already obtained high quality spectra of

small Van der Waals and hydrogen bonded molecules. Study of these prototypic, weakly bound species provides new information on the nature of

bonding, collisional energy transfer in the gas phase, and the extremely

important issue of the time scale for intramolecular vibrational relaxation. Their novel technique uses time resolved, direct infrared absorption of a high resolution tunable difference -frequency laser in a supersonic jet expansion. This source of tunable laser light (2.2/x — 4.2/x)

covers a strategically rich portion of the spectrum where -OH, -CH, -NH,

-SH, -PH, XH (X=halogen) stretches and their deuterated analogs occur. By dynamically subtracting laser amplitude noise, Nesbitt, Lovejoy and

Schuder obtain absorption sensitivities near the shot noise limit of

10‘®/Hz^''^ with 10 /iW of laser power. This powerful combination of high

sensitivity and tuning range permits high resolution study of a wide

range of molecular systems completely inaccessible by previous laser

techniques

.

Using these techniques, Nesbitt, Lovejoy and Schuder have obtained

the first infrared observation of Ar-HF in both the fundamental and

combination band + 1/ 3

) . They observe considerable shifts in the

molecular geometry upon vibrational excitation. It is particularly

interesting that although the excitation energy exceeds the Van der

Waals bond strength by forty fold, the exceedingly narrow line widths of

both the 1/21 and spectra indicate vibrational predissociation

lifetimes greater than 2.4 million vibrational periods. Two groups

(Klemperer at Harvard and Saykally at Berkeley) are presently searching

for the low frequency modes of Ar-HF based on the above spectra.

Spectra of the HF dimer have also been observed in the cooled jet

(T < 10 K) ; the absence of spectral congestion at these temperatures

permits measurement of the predissociation lifetimes for the two HF

stretch modes.

Present efforts in this area of research are heading in sev- eral complementary directions. 1) A search for combination bands in

233
Ar-HF based on the symmetric Van der Waals stretch is underway and will

complete the identification of all three vibrational modes. 2) The cor- responding He-HF, Ne-HF, and Xe-HF will be pursued in order to establish

the systematic trends as a function of inert gas polarizability, size,

etc. 3) Similar studies on DF complexes are planned. The isotopic

dependence of vibrational frequency, rotational constants, etc. provides

important additional tests of the potential surface. 4) Predissociation

dynamics of HF dimer will be investigated by linewidth studies as a function of initial rotational state and tunnelling component.

Nesbitt is also pursuing three other projects using state-of-theart infrared generation and detection capabilities. With Schuder, he

is investigating the quantum state dynamics of sublimation phenomena.

Their approach relies on ultra sensitive detection of molecules that

have freshly sublimated into a vacuum, before collisions can scramble

the nascent quantum states. Such information provides insight into the

nature of solid-gas interactions at the interface, as well as determining by detailed balancing the sticking coefficients for collisional

deposition as a function of internal quantum state.

Nesbitt is developing new methods for probing molecular properties

such as dipole moments of vibrationally excited species by coherent

transients. The approach uses the capability to saturate an infrared

transition in the presence of a uniform electric field. The heterodyne

quantum beats that are generated on the laser as the external fields are collapsed correspond to the tuning of the molecular m^ levels in the

presence of the field. By appropriate choice of molecular symmetry,

these quantum beats can provide very precise, direct measurement of

vibrationally induced changes in the dipole moment.

' P. Engelking (JILA Visiting Fellow, 1985-86) and Nesbitt are pursuing the study of ultracold radical spectroscopy in a supersonic jet

excited by a weak Corona discharge. Engelking has pioneered the development of these Corona discharge methods to generate copious quantities

of radicals under cooled beam conditions . Combining these methods with

the infrared capability available in Nesbitt's laboratory, he and

Nesbitt plan to study the vibrational spectroscopy of these highly reac- tive species.

Energy Transfer - S. R. Leone

The study of energy transfer processes is important for making high

powered lasers more efficient, for accurately describing the collisional

excitation processes and emission processes in the upper atmosphere and

interstellar media, and for interpreting a wide variety of chemical

reaction dynamics problems such as occur in combustion. In addition,

energy transfer processes are one area for which accurate theoretical

interpretation of the results is possible.

234
D. Neuschafer and Leone are studying electronic energy transfer

processes in atomic calcium vapor as a function of the orbital "alignment" of the calcium excited state in the collision. Using linearly

polarized laser light for the excitation and an atomic beam apparatus to

define the relative velocity direction, they can align the p-orbital of

the excited calcium either parallel or perpendicular to the collision

direction. The rates of electronic energy transfer processes are then

studied as a function of this alignment. Dramatic dependences on the

orbital alignment are observed with a variety of rare gas collision

partners for the transfer from the Ca 5 state to the Ca 5 ^Pj state.

For He and Ne the perpendicular configuration is more efficient than

the parallel alignment by 40% and 70% respectively, whereas for Xe the

parallel alignment is more efficient by 25%. No preferential alignment

effect occurs for Kr. The results are interpreted with reasonable suc- cess in terms of curve crossing models. Work in the future will investigate the effect of alignment on an elementary chemical reaction, such

as Ca* + H2 with specific probing of the CaH product alignment.

R. Schwenz (NSF Summer Faculty Fellow) is exploring new processes in Sr

atoms for implementing similar alignment techniques.

D. J. Donaldson and Leone have developed a successful method to

study the rates of vibrational deactivation of vibrationally excited

methyl radicals. A molecule such as acetone is photolyzed with the

193 nm output of a rare gas halide excimer laser to produce methyl radicals in selected vibrational states. The deactivation processes are followed by time-resolved infrared emission. With this method some of

the first rates for state-selected vibrational deactivation of the free

radical have been obtained with a variety of collision partners. The

amount of data on free radical deactivation is extremely limited, and

thus the value in this new method of measurement. The observed rates

are uniformly more rapid than measured rates for similar "closed-shell"

molecules, indicative of the strong attractive interaction of the free

radical species with other molecules. These rates are important in

basic combustion processes.

In separate experiments L. Cousins and Leone are studying the

vibrational excitation and reaction processes of energetic H and D

atoms, also produced by photolysis techniques. Preliminary results have

been obtained on the vibrational excitation of HF and DF by collisions

of 2 eV H atoms with these molecules. A new apparatus is being developed to carry out these fast atom experiments under crossed beam conditions, so that single collision results are achieved. In addition new

sources of fast atoms will be developed, such as from laser ablation

or desorption from surface films.

C. Hamilton, V. Bierbaum, and Leone have obtained some of the first

rates for vibrational deactivation of an ion, CO'*’, with several collision partners under well-characterized conditions. They obtained these

rates by direct optical monitoring of the ion vibrational states by

laser- induced fluorescence. The only previous method of obtaining ion

235
deactivation rates relies on a chemical monitoring method whereby the

vibrationally excited ion reacts with another reagent, but the vibrationally cold ion does not. The optical probe method promises to obtain

significant new details about ion vibrational deactivation with greater

state specificity, such as in the capability to study a whole series of

vibrational states. As a first demonstration of the concept, the vibrational deactivations of CO"^ in a low vibrational state, v=l, and in a much higher vibrational state, v=4, were studied with CO. The rates

were found to be identical (5 x 10"^° cm^ molecule*^ s"^) . From quantitative measurements of the disappearance and appearance of various

vibrational states, it was determined that the vibrational deactivation

occurs primarily through charge transfer of the CO'*' with CO (i.e. transfer of the charge to the other molecule that is not vibrationally excited) . This work will continue to explore other vibrational states and

collision partners in order to elucidate the mechanisms and underlying

dynamics of ion vibrational deactivation.

Ion-Molecule Collision Dynamics - S . R . Leone

Ions are important in all kinds of media such as plasmas, lasers,

and the upper atmosphere. This program is designed to push the stateof-the-art in measurement capability in ion reaction dynamics and other

ion collision processes. The results included here are in many cases

the only determinations of product state distributions for elementary

ion-molecule reactions at thermal energies.

Hamilton, Bierbaum, G.-H. Lin, J. Maier, C. Chee and Leone in two

separate experimental apparatuses have completed an extensive series of

investigations on the thermal energy charge transfer reactions between

N"'' + CO, Ar'*’ + CO, and Ar'*' + N2

. They have carried out experiments to

obtain both the vibrational and rotational distributions under single

collision (crossed beam) conditions. They find that some channels in

the ion-molecule reactions behave strictly according to a Franck- Condon

mechanism, thus forming vibrational and rotational product states

according to vertical transitions. Other channels are formed by more intimate collision complexes in which high vibrational and rotational

excitation is imparted to the products. A marked difference is observed

in the rotational distributions of the v=0 and v=l vibrational levels of

CO"^ produced in the + CO reaction. The v=0 state rotational levels can be characterized as cold, only 400 K, whereas the v=l state rotations are non-Boltzmann and over 2000 K. This is dramatic evidence that

two very different mechanisms participate in the formation of the two

vibrational levels in the charge transfer. In addition, a major change

in the branching ratio between the two channels is observed with varying

kinetic energy. These effects are being explored in more detail with

simple models and by further experiments to vary the kinetic energy over

a wider range.

236
A. Langford, Bierbaum, and Leone have completed a new set-up to

probe ion velocity distributions under well characterized electric field

drift conditions using a single mode ring dye laser to measure the Doppler profile in laser- induced fluorescence. These experiments, if suc- cessful, will be the first optical measurements of ion velocity distributions under well-defined conditions, and thus available theoretical

analyses will be applicable. The first experiments will be carried out on either Ba"^ or a metastable transition in Ar'*’. Thus far, Doppler profiles under conditions of zero field have been observed for N2

'^, and

clean sources of Ba'*’ ions are being prepared so that experiments can

proceed in the upcoming months

.

Photofragmentation and Neutral Reaction Dynamics - S. R. Leone

Photofragmentation processes are of special interest to chemists

because they represent the latter "half" of chemical reactions. The

initial state preparation is more well-defined in a photoexcitation,

however, and thus these processes are more amenable to theoretical

treatment. In addition, photofragmentation can be used to prepare a wide variety of reactive radicals and atoms for basic studies of reac- tion dynamics

.

Photofragmentation of IBr has been used by H. Haugen, E. Weitz

(JILA Visiting Fellow) and Leone to probe the difference in reactivity

of the two spin-orbit states of the atomic Br atoms. Spin-orbit reac- tivity is a subject of accelerating interest. It is the symmetry of

the reactive potential energy surfaces, and often not the energy, which

determines how reactive these different atomic states will be. The

researchers find that Br ground state atoms are forty times more reac- tive with IBr to form Br2 + I than the low-lying excited spin- orbit

state (Br*, 0.5 eV) . The results explain a number of important features

of the IBr solar photodissociation laser and have immediate consequences

for the interpretation of the reactive potential surfaces. In this

case, there is a strict adherence to the original potential symmetries

in the reactive encounter, and the Br* reactive surface has a high barrier to both reaction and quenching processes.

In last year's report, Leone presented a new method to obtain

highly accurate quantum yields and branching fractions of electronically

excited atoms. The method involves a time -resolved, laser gain- versus

absorption measurement, which samples the initial yield and compares it

to a total atom yield at a slightly later time. The crucial point is

the probing of the "coupled" pair of states with the same laser beam.

The method achieved yields of Br and Br* that were accurate to a few

percent with relatively little effort. During this year, the same method has been applied with a sensitive diode laser probe system at

1315 nm in the near infrared to study the yields of spin-orbit states in

I atoms. This work was carried out by Haugen, W. Hess, S. Kohler (NSF

Visiting Faculty Fellowship for Women), and Leone. A commercially

237
available InGaAsP communications diode laser was tuned to the I atom

transitions, stabilized to the transition of interest, and transient

gain and absorption signals were observed upon photolysis of C3F7I and

CH3I. Accurate yields were obtained, clearing up a many year-old con- troversy concerning the absolute yields of I* from these compounds.

This general class of molecules is of interest for solar-pumped laser

systems, and future work will investigate novel compounds synthesized by

C. Shiner of the CU Chemistry Department for use in these lasers. In

addition, the tuning of these diode lasers for use in spectroscopy will

be explored by insertion of antireflection coated diodes into an external resonator. The impact of the ready availability of these diode

laser probes for important laser species such as I* for laser diagnostics should also be apparent.

J. Smedley and Leone are investigating a long-standing problem

dubbed "collisional release". In this process, a molecule of Br2 is

excited very near to its dissociation limit, and then collisions are allowed to dissociate the molecule upwards in energy. The researchers

have obtained the first quantitative measurements of the rates of such

processes. They use a high resolution pulsed dye laser along with

single isotopes of bromine to excite a single state selectively up near

the dissociation limit. A lengthy series of measurements is necessary

to quantify the yield of the excited atoms, which is the indicator of

the collisional release process. The researchers find that as a collision partner bromine is seven times more efficient than Xe in dissociating a Br2 molecule that is excited to 3 kT below the dissociation

limit. This difference is attributed to the possible formation of a Br3

species, which enhances the collisional release probability due to

favorable thermochemistry. Further work will elucidate the collisional

release probability as a function of energy below the dissociation

limit, with other collision partners where a chemical affinity exists to

form weak Van der Waals molecules that may enhance the rate (e.g., CI2,

HBr, I2) and as a function of rotational angular momentum.

Donaldson and Leone are setting up a time -resolved Fourier Transform Infrared (FTIR) emission experiment to study photofragmentation of

large polyatomic molecules. A high repetition rate excimer laser will

be used to pulse dissociate molecules that produce vibrationally and

rotationally excited free radical species. The firing of the excimer

laser is timed to the mirror sweep of the FTIR in such a way as to

obtain a laser pulse ten microseconds before the sampling of the

infrared detector. This time will be short enough so that at low pres- sures in a jet, there will be no collisions. Sophisticated background

limited detectors will be used to sample the weak emission. As a preliminary experiment to test out the method without yet using the FTIR,

Donaldson and Leone have taken low resolution spectra of the emitting CO

and CH3 fragments upon photodissociation of acetone. From these spectra

they can tell that the CO fragments are highly excited rotationally.

Crude vibrational distributions are observed for both the CO and the

methyl radicals. With the FTIR technique, it will be possible to

238
quantify the extent of both vibrational and rotational excitation under

high resolution in the fragmentation of many complex molecules. The

FTIR has just been installed and is fully operational; Donaldson and

Leone await the arrival of the high repetition rate excimer laser to

begin these experiments.

Surface Scattering Dynamics - S. R. Leone

K. Carleton and Leone have started a new program to study the scattering and sticking properties of Ga atoms on metal surfaces from a basic point of view, but with an emphasis on semiconductor growth technology. A pulsed tunable dye laser is used to detect the Ga atom spinorbit states as they scatter or desorb from a metal surface. Thus far,

the beam of Ga atoms has been detected with high signal- to-noise , and

the ultrahigh vacuum system with complete surface diagnostics has been

tested and is working properly. The first experiments will involve

measuring the different sticking probabilities of the two spin- orbit

states on a clean platinum surface and on a surface already covered with

many Ga adlayers. Future experiments will involve measurements of angular desorption and co-deposition of Ga with other semiconductor -relevant

materials

.

239
PUBLICATIONS

Quantum Physics Division (525)

(P. M. Williams, A. J. Longmore, K. A. van der Hucht , A. Talavera, W. M.

Wamsteker), D. C. Abbott and (C. M. Telesco), "Condensation of dust

around the WC7 star HD 192641 (WR 137)," Monthly Notices Roy. Astron.

Soc. 215, 23P-29P (1985).

D. C. Abbott, "Current problems of line formation in early-type stars,"

in Progress in Stellar Spectral Line Formation Theory (J. E. Beckman and

L, Crivelli, Eds., Reidel, Dordrecht, 1985), pp. 279-304.

D. C. Abbott and (L. B. Lucy), "Multiline transfer and the dynamics of

stellar winds," Astrophys. J. 288, 679-693 (1985).

*G. S. Agarwal, "Finite boundary effects in quantum electrodynamics," in

Quantum Electrodynamics and Quantum Optics (A. 0. Barut, Ed., Plenum,

New York, 1984), pp. 1-13.

*N. Andersen, (T. Andersen, L. Jepsen and J. Macek), "Electron detachment processes in keV H~, Li“, Na“, K“ - rare-gas collisions," J. Phys.

B: Atom. Molec. Phys. 17 , 2281-2294 (1984).

*N. Andersen, I. V. Hertel and (H. Kleinpoppen) , "Shape and dynamics of

states excited in electron-atom collisions: Comment on orientation and

aligment parameters by consideration of attractiye and repulsive

forces," J. Phys. B: Atom. Molec. Phys. 1

7

, L901-908 (1984).

*N. Andersen, (T. Andersen, H.-P. Neitzke and E. H. Pedersen), "A

coherence study of 2pa - 2piT rotational coupling: Li(2^P) and He(2^P)

orientation and alignment in 1-25 keV Li'*'-He collisions," J. Phys. B: Atom. Molec. Phys. 18, 2247-2269 (1985).

*W. J. Alford, N. Andersen, K. Burnett and J. Cooper, "Collisional

redistribution of light: Far-wing line shapes and polarizations for the

Ba-(Ar,Xe) systems," Phys. Rey. A 30 , 2366-2380 (1984).

*W. J. Alford, N. Andersen, M. Belsley, J. Cooper, D. M. Warrineton and

K. Burnett, "Collisional redistribution of circularly polarized li^ht in

barium perturbed by argon," Phys. Rey. A 3 1

,

3012-3016 (1985).

NOTE: Names in parentheses are authors who are not connected with JILANBS or CU. List does not include JILA publications by JILA CU Fellows

and their associates.

*Entries with stars are those resulting from the work of JILA Visiting

Fellows

.

240
PUBLICATIONS

Quantum Physics Division (525)

*D. M. Neumark, K. R. Lykke , T. Andersen and W. C. Lineher^er, "Laser

photodetachraent measurement of the electron affinity of atomic oxygen,"

Phys. Rev. A ^2., 1890-1892 (1985).

*(A. C. Raga) and K.-H. Bohm, "Predicted long-slit, high-resolution

emission-line profiles from interstellar how shocks," Astronhys. J.

Suppl. 5^, 201-224 (1985).

*(E. W. Brugel), K. H. Bohm, J. M. Shull and E. Bdhm-Vitense , "The

unexpected ultraviolet variability of Herhig-Haro obiect 1," Astrophvs.

J. (Letters) 292 , L75-78 (1985).

P. L. Bornmann, "A new method for determining temperature and emission

measure during solar flares from light curves of soft X-ray line

fluxes," Astrophys. J. 293 , 595-608 (1985).

A. Brown, "Outer atmospheres of giant and supergiant stars," in Cool

Stars, Stellar Systems, and the Sun , Proceedings, Cambridge (USA) 1983

(S. L. Baliunas and L. Hartmann, Eds., Springer-Verlag, Berlin, 1984),

pp. 282-295.

K. G. Carpenter, (R. F. Wing) and R. E. Stencel, "Line identifications,

line strengths, and continuum flux measurements in the ultraviolet

spectrum of Arcturus," Astrophys. J. Suppl. 57 , 405-422 (1985).

K. G. Carpenter, A. Brown and R. E. Stencel, "The geometric extent of C

II (UV 0.01) emitting regions around luminous, late-type stars,"

Astrophys. J. 289, 676-680 (1985).

K. G. Carpenter, "Characteristics of the Fe II and C II emission in

high-resolution lUE spectra (2300-3000 A) of Alpha Orionis," Astrophvs.

J. 285 , 181-189 (1984).

A. Brown and K. Carpenter, "The temperature of C II emission line formation regions in cool stars," Astrophys. J. (Letters) 287 , L43-46 (1984),

K. G. Carpenter, "Chromospheric emission lines in high-resolution LWR

spectra (2200-3000 A) of Gamma Cru (M3 III) and Alpha Orl (M2 lab),) in

Future in Ultraviolet Astronomy Based on Six Years of lUE Research , NASA

Conference Publ. 2349 (1984), pp. 450-453.

K. G. Carpenter, "The structures and spectra of magnetic, line-blanketed

model atmospheres," Astrophys. J. 289, 660-668 (1985).

241
PUBLICATIONS

Quantum Physics Division (525)

*S. Chapman, "Nonadiabatic molecular collisions. II. A further

trajectory-surface-hopping study of the ArH system," J. Chem. Phys.

82, 4033-4043 (1985).

*(T.-S. Ho, C. Laughlin) and S.-I Chu, "Laser-assisted charge-transfer

reactions - Li"^-^ + H: Coupled dressed-quasimolecular-states approach,"

Phys. Rev. A 122-133 (1985).

*(S. K. Bhattacharya) and S.-I Chu, "The resonant photoionization of

hydrogen atom in intense magnetic fields," J. Phys. B: Atom. Molec.

Phys. 2i, L275-280 (1985).

*R. M. Crutcher, "Optical and radio study of the Taurus molecular cloud

toward HD 29647," Astrophys. J. 288, 604-617 (1985).

S. A. Drake, "Modeling lines formed in the expanding chromospheres of

red giants," in Progress in Stellar Spectral Line Formation (J. R.

Beckman and L. Crivelli, Eds., Reidel, Dordrecht, 1985), pp. 351-359.

(M. S. Pindzola, D. C. Griffin, C. Bottcher, D. C. Gregory, A. M.

Howald, R. A. Phaneuf , D. H. Crandall), G. H. Dunn, D. W. Mueller and

T. J. Morgan, "Survey of experimental and theoretical electron-impact

ionization cross sections for transition metal ions in low stages of

ionization," Oak Ridge National Laboratory Tech. Memo 9436 (March 1985).

(T. D. Mark) and G. H. Dunn, Eds., Electron Impact Ionization

(Springer-Verlag, Wien, New York, 1985).

(D. C. Gregory, D. H. Crandall, R. A. Phaneuf, A. M. Howald), G. H.

Dunn, R. A. Falk, D. W. Mueller and T. J. Morgan, "Electron Impact

ionization of multicharged ions of ORNL: 1980-1984," Oak Ridge National

Laboratory Tech. Memo 9501 (May 1985).

D. W. Mueller, T. J. Morgan, G. H. Dunn, (D. C. Gregory and D. H.

Crandall), "Absolute cross-section measurements for electron-impact

ionization of doubly charged ions Ti^"^, Fe^"^, Ar^"*", Cl^‘*‘ and F^"*", " Phvs

.

Rev. A 3J^, 2905-2913 (1985).

G. H. Dunn, D. S. Belie, N. Djuric and D. W. Mueller, "Dielectronic

recombination," in Atomic Physics 9 (r. S. Van Dvck, Jr. and E. N.

Fortner, Eds., World Scientific, Singapore, 1984), pp. 505-522.

G. H. Dunn, "Electron-ion ionization," in Electron Impact Ionization

(T. D. Mark and G. H. Dunn, Eds., Springer-Verlag, Wien, New York,

1985), pp. 277-319.

242
PUBLICATIONS

Quantum Physics Division (525)

D. S. Elliott and (J. F. Ward), "Vibrational mode contributions to

molecular third-order polarizabilities," Mol. Phys . 51 , 45-63 (1984).

*G. Alber, J. Cooper and P. Ewart, "Theory of resonant degenerate four- wave mixing with broad-bandwidth lasers," Phys. Rev. A 31 , 2344-2352 (1985).

*P. Ewart and (S. V. O'Leary), "Absorption and saturation effects on degenerate four-wave mixing in excited states formed during collisions,"

J. Phys. B: Atom. Molec. Phys. 17 , 4595-4608 (1984).

*(A. Charlton) and P. Ewart, "A simple, high power, nanosecond pulse

NdrYAG laser," Opt. Commun. 50 , 241-244 (1984).

*P. Ewart and (S. V. O'Leary), "Measurement of relative, extreme-wing

absorption coefficients by excited-state degenerate four-wave mixing,"

J. Phys. B: Atom. Molec. Phys. 17 , 4609-4616 (1984).

(T. Marson) and J. E. Faller, "High precision gravity measurements," in

Proceedings of the Conference on High Precision Geodetic Measurements

(Universita di Bologna, Italy, 1985), pp. 314-328.

M. A. Zumberge, J. E. Faller and R. L. Rinker, "A new, portable, absolute

gravimeter," in Precision Measurement and Fundamental Constants II (B. N.

Taylor and W. D. Phillips, Eds., NBS Spec. Publ. 617, 1984), pp. 405-409.

(a. j. F. Metherell, C. C. Speake, Y. T. Chen) and J. E. Faller, "Optimizing the shape of the attracting mass in precision measurements of G,

in Precision Measurement and Fundamental Constants II (B. N. Tavlor and

W. D. Phillips, Eds., NBS Spec. Publ. 617, 1984), pp. 581-585.

R. L. Rinker and J. E. Faller, "'Super Spring' — A long period vibration isolator," in Precision Measurement and Fundamental Constants 11

(B. N. Taylor and W. D. Phillips, Eds., NBS Spec. Publ. 617, 1984), dp.

411-417.

P. T. Keyser, J. E. Faller and K. H. McLagen, "New laboratorv test ol

the equivalence principle," in Precision Measurement and fundamental

Constants II (B. N. Taylor and W. D. Phillips, Eds., NBS Spec. Publ.

617, 1984), pp. 639-641.

J. E. Faller and P. L. Bender, "A possible laser gravitational wave

experiment in space," in Precision Measurement and Fundamental Constants

II , (B. N. Taylor and W. D. Phillips, Eds., NBS Spec. Publ. 617, 1984),

pp. 689-690.

243
PUBLICATIONS

Quantum Physics Division (525)

J. E. Faller, J. K. Hoskins, P. T. Keyset and T. M. Niebauer, "Fluidfiber gradiometers: Their promise for tunnel detection — A status

report," in Tunnel Detection , Proceedings, 2nd Technical Symposium

(Colorado School of Mines, Golden, CO, 1984).

H. Chatham, D. Hils, R. Robertson and A. Gallagher, "Total and partial

electron collisional lonizatin cross sections for CH , , C«H, , SiH,

and Si^H^," J. Chem. Phys. 8J_, 1770-1777 (1984).

^ ^ ^

R. K. Janev and J. W. Gallagher, "Evaluated theoretical cross section

data for charge exchange of multiply charged ions with atoms III: Nonhydrogenic target atoms," J. Phys. Chem. Ref. Data 13, 1199-1247 (1984).

(F. Hill), J. Toomre, (L. J. November) and K. B. Gebbie, "On tbe

determination of the lifetime of vertical velocity patterns in mesogranulation," in Small-Scale Dynamical Processes in Quiet Stellar

Atmospheres (S. Keil, Ed., National Solar Observatory, Sac. Peak, NM,

1984), pp. 160-172.

J. G. Porter, J. Toomre and K. B. Gebbie, "Frequent ultraviolet

brightenings observed in a solar active region with solar maximum

mission," Astrophys. J. 283 , 879-886 (1984).

S. Geltman and (R. K. Nesbet), "High-energy forward elastic scattering

of electrons: Born amplitudes for a pseudostate model of atomic

hydrogen," Phys. Rev. A 30, 1636-1642.

S. Geltman, "Multiple ionization of a Hartree atom by intense laser

pulses," Phys. Rev. Lett. 54, 1909-1912 (1985).

S. Geltman and G. Leuchs , "Intensity-dependent electron angular

distributions in resonant multiphoton ionization," Phys. Rev. A 31 , 1463-1469 (1985).

S. Geltman, "Dielectronic recombination as a direct free-bound

radiative process," J. Phys. B: Atom. Molec. Phys 18, 1425-1442 (1985)

*D. M. Gibson, "Radio observations of active stars: Direct evidence for

polarity reversals?" in Cool Stars, Stellar Systems, and the Sun , Proceedings, Cambridge (USA) 1983 (S. L. Baliunas and L. Hartmann, Eds.,

Springer-Verlag, Berlin, 1984), pp. 197-201.

244
PUBLICATIONS

Quantum Physics Division (525)

*E. B. Gliner, "Combined effect of potential and nonpotential magnetic

fields on equilibrium in stellar atmospheres,” Astrophys. J. 283, 363-

372 (1984).

L. Hollberg and J. L. Hall, "Measurement of the shift of Rydberg energy

levels induced by blackbody radiation," Phys. Rev. Lett. 53, 230-233

(1984).

W. Ertmer, R. Blatt, J. L. Hall and M. Zhu, "Laser manipulation of

atomic beam velocities: Demonstration of stopped atoms and velocity

reversal," Phys. Rev. Lett. 54 , 996-999 (1985).

P. Nachman, M. D. Rayman and J. L. Hall, "Relativistic time dilation: A

latter-day Ives-Stillwell experiment," in Precision Measurement and

Fundamental Constants II (B. N. Taylor and W. D. Phillips, Eds., MBS

Spec. Publ. 617, 1984), pp. 671-673.

J. L. Hall and (T. W. Hansch), "External dye-laser frequency

stabilizer," Opt. Letters _9^, 502-504 (1984).

M. W. Hamilton and (W. J. Sandle), "Polarization switching with sodium

vapor in a Fabry Perot," in Optical Bistability 2 , (C. M. Bowden, H. m. Gibbs and S. L. McCall, Eds., Plenum, New York, 1984), pp. 39-44.

*(A. Bahring), I. V. Hertel, (E. Meyer, W. Meyer^ N. Spiess^and H.

Schmidt), "Excitation of laser state-prepared Na (3p) to Na (3d) in lowenergy collisions with Na"^: Experiment and calculations of the potential Na^"* curves of *"," d. Phys. B: Atom. Molec. Phys. 17 , 2859-2873 (1984).

*1. V. Hertel and (H. Schmidt), "Comment on 'A theoretical study of

coherence effects in charge transfer collisions: Application to Na

+ Li'*''," J. Chem. Phys. 81 , 3361-3362 (1984).

*1. V. Hertel, "Collisions in the presence of a laser field and the

laser as a tool for state selective preparation of molecular states in

collisions," in Proceedings of the Colloquium on Atomic and Molecular

Collisions in a Laser Field," J. Phys. (Paris) 46, Cl-37 - Cl-41 (1985).

(A. Pauldrach, J. Puls), D. G. Hummer and (R. P. Kudritzkl), "A

radiation driven stellar wind model atmosphere for the Wolf-Ravet hlnarv

V444 Cygni," Astron. Astrophys. (Letters) 148 , Ll-4 (1985).

D. G. Hummer and (G. B. Rybicki), "The Sobolev approximation for line

formation with continuous opacity," Astrophys. J. 293 , 258-267 (1985).

245
PUBLICATIONS

Quantum Physics Division (525)

D. C. Abbott and D. G. Hummer, "Photospheres of hot stars. I. Windblanketed model atmospheres," Astrophys. J. 294, 286-302 (1985).

A. Jain and (D. G. Thompson), "Rotational excitation of CH, molecules by

low-energy positrons," Phys. Rev. A 30, 1098-1100 (1984).

A. Jain and (D. G. Thompson), "EROTVIB , a general program to calculate

rotationally and/or vibrationally elastic and inelastic cross sections

for electron (positron) scattering by spherical, symmetric and

asymmetric top molecules," Computer Phys. Comraun. 32, 367-383 (1984).

A. 0. Langford and (C. B. Moore), "Reaction and relaxation of vibrationally excited formyl radicals," J. Chem. Phys. 80, 4204-4210 (1984).

A. 0. Langford and (C. B. Moore), "Collision complex formation in the

reactions of formyl radicals with nitric oxide and oxygen," J. Chem.

Phys. 4211-4221 (1984).

H. K. Haugen, E. Weitz and S. R. Leone, "Effect of spin-orbit excitation

on chemical reactivity: Laser treatment absorption spectroscopy of

Br(^P./^, 2p-/^) + IBr reactive dynamics," Chem. Phys. Lett. 119, 75

(19S5).

C. A. Wight, D. J. Donaldson and S. R. Leone, "A two-laser pulse-andprobe study of T-R,V energy transfer collisions of H + NO at 0.95 and

2.2 eV," J. Chem. Phys. 83 , 660-667 (1985).

G.-^H. Lin, J. Maier and S. R. Leone, "Nascent vibrational and

ro_^ational di^^tributions from the charge transfer reaction

Ar + CO ^ CO + Ar at near thermal energy," J. Chem. Phys. 82, 2 527-5535 (1985).

C. A. Wight, D. J. Donaldson and S. R. Leone, "A two-laser pulse-andprobe study of T-R,V energy transfer collisions of H + NO at 0.95 and

2.2 eV," J. Chem. Phys. 83_, 660-667 (1985).

C. E. Hamilton, V. M. Bierbaum and S. R. Leone, "Product vibrational

state distributions of thermal energy charge transfer reactions

determined by laser-induced fluorescence: N"^ + CO - CO'*’ (v=0-2) + N," J.

Chem. Phys. 83, 601-610 (1985).

C. E. Hamilton, V. M. Bierbaum and S. R. Leone, "Product vibrational

state distribution of thermal energy charge transfer reactions

determined by laser-induced fluorescence in a flowing afterglow:

Ar"*" + CO -»• CO"*" (v=0-6) + Ar," J. Chem. Phys. 83 , 2284-2292 (1985).

246
PUBLICATIONS

Quantum Physics Division (525)

C. E. Hamilton and S. R. Leone, "Nascent product vibrational state

distributions of thermal ion-molecule reactions determined by infrared

chemiluminescence," in Gas Phase Chemiluminescence and Chemi-ionization

(A. Fontijn, Ed., Elsevier Science Publishers, 1985), pp. 139-156.

K. L. Carleton, K. H. Welge and S. R. Leone, "Detection of nitrogen

rotational distributions by resonant 2+2 multiphoton ionization throus:h

the state," Chem. Phys. Lett. 115, 492-495 (1985).

S. R. Leone, "State-resolved molecular reaction dynamics," Ann. Rev.

Phys. Chem. 35, 109-135 (1984).

L. Hiiwell, D. R. Guyer, G.-H. Lin and S. R. Leone, "Laser-induced

fluorescence measurement of nascent vibrational and rotational product

state distributions in the charge transfer of Ar"^ + N2 - Ar + N 2

'*’ (v=0,l) at 0.2 eV," J. Chem. Phys. 81 , 3520-3535 (1984).

C. A. Wight, F. Magnotta and S. R. Leone, "Vibrational energy disposal

in reactive and inelastic collisions of H(D) + HC£(DC?,) at 1-3 eV," J.

Chem. Phys. 3951-3957 (1984).

S. R. Leone, "Laser probing of chemical reaction dynamics," Science 227,

889-895 (1985).

M. 0. Hale and S. R. Leone, "Laser studies of near-resonant statechanging collisions of calcium (4s6s ^Sq) with the rare gases," Phvs.

Rev. A

3J_,

103-112 (1985).

M. 0. Hale, I. V. Hertel and S. R. Leone, "Effects of orbital alisnment

1 on inelastic collsions of Ca(4s5p ^P^) with helium," Phys. Rev. Lett.

2296-2299 (1984).

*W. Lichten and (A. Robatino), "A new mechanism for positron production

in heavy ion collisions," Phys. Rev. Lett. 54 , 781-784 (1985).

J. L. Linsky, A. Brown, M. C. Marstad, (M. Rodono, A. D. Andrews, C. J. Butler and P. B. Byrne), "Models for the active and quiescent regions on the RS CVn-type system II Pegasi (HD 224085),” in Proceedings, Fourth

European lUE Conference, 15-18 May 1984, Rome, Italy, ESA SP-218 (Julv,

1984), pp. 351-354.

247
PUBLICATIONS

Quantum Physics Division (525)

(P. B. Byrne, J. G. Doyle, A. D. Andrews, C. J. Butler), N. Marstad, J. L. Linsky, T. Simon, (M. Rodono, S. Catalano, C. Blanco, E. Marilli and

V. Pazzani), "Rotational modulation of spots and plages on RS CVn

stars," in Proceedings, Fourth European lUE Conference , 15-18 May IDEA,

Rome, Italy, ESA SP-218 (July, 1984), pp. 343-349.

(C. J. Butler, J. G. Doyle, A. D. Andrews, P. B. Bvrne), J. L. Llnskv,

T. Simon, N. Marstad, (M. Rodono, V. Pazzani and G. Cutispoto), "IIIE observations of BY Draconis," in Proceedings, Fourth European lUE

Conference, 15-18 May 1984, Rome, Italy, ESA SP-218 (July, 1984), np.

243-246.

(R. Hammer) and J. L. Linsky, "Corona models tested with lUE and

Einstein observations," in Proceedings, Fourth European IIIE Conference , 15-18 May 1984, Rome, Italy, ESA SP-218 (July, 1984), pp. 25-32.

(M. Rodono, G. Cutispoto, S. Catalano), J. L. Linsky, D. M. Gibson, A. Brown, (B. M. Haisch, C. J. Butler, P. B. Byrne, A. D. Andrews, J. G.

Doyle, D. E. Gary, G. W. Henry, G. Russo, A. Vittone, B. Scaltriti and

B. Foing), "Coordinated lUE and ground-based observations of active

stars: Flare events on YZ CMi, V 1005 Ori, AD Leo and AR Lac," in

Proceedings, Fourth European lUE Conference , 15-18 May 1984, Rome,

Italy, ESA SP-218 (July, 1984), pp 247-252.

S. A. Drake, A. Brown and J. L. Linsky, "The origin of low-velocity

absorption components in the Mg II resonance lines of hybridchromosphere stars," Astrophys. J. 284 , 774-783 (1984).

J. L. Linsky, "RS CVn binary systems," in Cool Stars, Stellar Systems,

and the Sun , Proceedings, Cambridge (USA) 1 983 Ts"! L^ Baliunas and L.

Hartmann, Eds., Springer-Verlag, Berlin, 1984), pp. 244-258.

S. A. Drake and J. L. Linsky, "Better determinations of mass loss rates

for red giants and supergiants," in Cool Stars, Stellar Systems, and the

Sun , Procedings, Cambridge (USA) 1983 (S. L. Baliunas and L. Hartmann,

Eds., Springer-Verlag, Berlin, 1984), pp. 350-352.

F. M. Walter, J. L. Linsky, (T. Simon, L. Golub and G. S. Vaiana),

"Stellar chromospheres and coronae in the Ursa Maior cluster stars,"

Astrophys. J. 281 , 815-825 (1984).

(W. B. Landsman, R. C. Henry, H. W. Moos) and J. L. Linskv,

"Observations of hydrogen and deuterium toward Alpha Centaur! A,

Astrophys. J. 285 , 801-807 (1984).

248
PUBLICATIONS

Quantum Physics Division (525)

A. Brown, (C. Jordan), R. E. Stencel, J. L. Linsky and (T. R. Ayres),

"High-resolution, far-ultraviolet study of Beta Draconis (C2 Ib-II):

Transition region structure and energy balance," Astrophys. J. 283 , 731-

744 (1984).

A. Brown, (M. V. Penston, R. Johnstone, C. Jordan, N. P. M, Kuin , T.

V. T. Lago, B. Gross) and J. L. Linsky, "Atmospheric prooerties of RU

Lupi derived from high- and low-resolution lUE spectra," in Future of

Ultraviolet Astronomy Based on Six Years of lUE Research, NASA

Conference Publ. 2349 (1984), pp. 472-475

,

S. A. Drake, A. Brown and J. L. Linsky, "Ultraviolet, radio and X-rav

observations of hybrid stars," in Future of Ultraviolet Astronomy Based

on Six Years of lUE Research, NASA Conference Publ. 2349 (1984), np.

472-475.

J. L. Linsky, (T. R. Ayres), A. Brown, K. Carpenter, (C. Jordan, P. Judge, B. Gustafsson, K. Eriksson, M. Saxner, 0. Engvold, E. Jensen, 0.

K. Moe and T. Simon), "A progress report on the analysis of long

exposure SWP high resolution spectra of cool stars," in Future of

Ultraviolet Astronomy Based on Six Years of LITE Research , NASA

Conference Publ. 2349 (1984), pp. 445-449.

(T. R. Ayres, 0. Engvold, 0. K. Moe, T. Simon, C. Jordan, P. Judse) , A.

Brown and J. L. Linsky, "Precise measurements of radial velocities o^^ emission lines in the far-ultraviolet spectra of late-type stars," in

Future of Ultraviolet Astronomy Based on Six Years of lUE Research , NASA

Conference Publ. 2349 (1984), pp. 468-471.

*1. R. Little-Marenin and S. J. Little, "The ^^C/^^C ratio of the carbon

star V460 Cygni revisited," Astrophys. J. 283, 188-191 (1984).

*1. Little-Marenin, (T. R. Ayres and T. Simon), "Three short-period

binaries as seen at high dispersion: UX Ari, Iota Tri and HR 5110," in

Future of Ultraviolet Astronomy Based on Six Years of lUE Research , NASA

Conference Publ. 2349 (1984), pp. 404-407.

R. B. Christensen and D. W. Norcross, "Electron-impact excitation of Li

II: A model study of wave-function and collisional approximations, and

of resonance effects," Phys . Rev. A 31 , 142-151 (1985).

A. Jain and D. W. Norcross, "Ab initio calculations of low-ener?v

electron scattering by HCN molecules," Phys. Rev. A 32, 134-143 (1985).

249
PUBLICATIONS

Quantum Physics Division (525)

R. B. Christensen, D. W. Norcross and A. K. Pradhan, "Electron impact

excitation of ions in the magnesium sequence: Fe XV," Phys. Rev. A 32,

93-104 (1985).

(G. D. Meneses), F. J. da Paixao and (N. T. Padial), "Electron impact

excitation of krypton," Phys. Rev. A 32, 156-165 (1985).

F. J. da Paixao, N. T. Padial and (G. Czanak), "Electron-photon

coincidence parameters for the 4s ' [ 1/2 ]9 (^P, ) and 4s [ 3/2 (^P. ) states

of argon," Phys. Rev. A 30, 1697-1713 (1984).

H. Tischer and A. V. Phelps, "Rapid collisional quenching of the n = 1, v = 2 level of the H„(c^ITy) raetastable state by H ," Chem. Phys. Lett.

117, 550-554 (1985).^ ^

A. V. Phelps, "Ionization in gas discharges: Experiment and modeling,"

in Electron Impact Ionization (T. D. Mark and G. H. Dunn, Eds.,

Springer-Verlag , Wien, New York, 1985), pp. 335-343.

A. V. Phelps and L. C. Pitchford, "Anisotropic scattering of electrons

by N

2 and its effects on electron transport: Tabulations of cross section

and results," JILA Infoirmation Center Report No. 26 (March 1985).

S. J. Buckraan and A. V. Phelps, "Tabulations of collision cross sections and calculated transport and reaction coefficients for

electrons in H_ and D. ," JILA Information Center Report No. 27 (May

1985). ^ ^

A. V. Phelps and (L. C. Pitchford), "Anisotropic scattering of electrons by N„ and its effect on electron transport," Phys. Rev. A 3

1

, 2932-2949 U985).

S. J. Buckman and A. V. Phelps, "Vibrational excitation of D^ by low

energy electrons," J. Chem. Phys. 82, 4999-5011 (1985).

A. K. Pradhan, "Theoretical calculations for dielectronic recombination

cross .sections , " Phys. Rev. A 30 , 2141-2144 (1984).

A. K. Pradhan, "Resonance and intermediate-coupling effects in electron

scattering with highly charged ions. III. Ca^^'*’," Phvs. Rev. A 30, 100-

105 (1984).

A. K. Pradhan, "Recombination-cascade X-ray spectra of highlv charged

helium-like ions," Astrophys. J. 288 , 824-830 (1985).

250
PUBLICATIONS

Quantum Physics Division (525)

A. K. Pradhan and (M. J. Seaton), "Dielectronic recombination. II.

Effects on cross sections for inelastic collisions between electrons and

atomic ions," J. Phys. B: Atom. Molec. Phys . 18 , 1631-1635 (1985).

*A. R. P. Rau, "High excitation of two electrons," in Atomic Physics 9

(R. S. Van Dyck, Jr. and E. N. Fortson, Eds., World Scientific,

Singapore, 1984), pp. 491-504.

*A. R. P. Rau, "The electron-electron Interaction in doubly-excited

states of atoms," Pramana (India) 23, 297-303 (1984).

*G. Alber, J. Cooper and A. R. P. Rau, "Unified treatment of radiative

and dielectronic recombination," Phys. Rev. A 30, 2845-2848 (1984).

H. G. Robinson and (C. E. Johnson), "Measured gj-factor ratio of

'^He'**’( 1 ^S^ /„ ) and ^He(2^Sj)," in Precision Measurement and Fundamental

Constants II (B. N. Taylor and W. D. Phillips, Eds., NBS Spec. Publ.

617, 1984), pp. 229-231.

*(P. Botschwina) and P. Rosmus, "An ab initio calculation of spectroscopic

properties of SiO and HOSi'*’," J. Chem. Phys. 82, 1420-1426 (1985).

*K. Rzazewski and R. Grobe, "Saturation of continuum-continuum transitions in raultiphoton absorption," Phys. Rev. Lett. 54, 1729 (1985).

*(M. Trippenbach) and K. Rzazewski, "Linear versus nonlinear regime in

macroscopic quantum fluctuations of Stokes pulses," Phys. Rev. A 31,

1932-1935 (1985).

*(M. Florj anczyk) , K. Rzazewski and (J. Zakrzewski), "Resonance

scattering of a short laser pulse on a two-level system: Time-denendent

approach," Phys. Rev. A 31 , 1558-1562 (1985).

*J. Smak, "Eruptive binaries. XI. Disk-radius variations in U Gem," Acta

Astron. 34 , 93-96 (1984).

*J. Smak, "Accretion in cataclysmic binaries. IV. Accretion disks in

dwarf novae," Acta Astron. 34, 161-189 (1984).

*(J. R. Thorstensen) , J. Smak and (F. V. Hessman), "The two periods of

TT Arietis," Publ. Astron. Soc. Pacific 97, 437-445 (1985).

D. S. Elliott, M. W. Hamilton, K. Arnett and S. J. Smith, "Correlation

effects of a phase-diffusing field on two-photon absorption," Phvs. Rev.

A 32, 887-895 (1985).

251
PUBLICATIONS

Quantum Physics Division (525)

D. S. Elliott, M. W. Hamilton, K, Arnett and S. J. Smith, "Two-photon

absorption from a phase-diffusing laser field," Phys. Rev. Lett. 53,

439-441 (1984).

P. Zoller, E. Matthias and S. J. Smith, "Configuration interaction in

raultiphoton ionization," in Quantum Electrodynamics and Quantum Optics

(A. 0. Barut, Ed., Plenum, New York, 1984), pp. 313-321.

(P. Lambropoulos) and S. J. Smith, Eds., Multiphoton Processes , Proceedings of the 3rd International Conference, Iraklion, Crete,

Greece, September 5-12 (Springer-Verlag, 1984).

G. Leuchs and S. J. Smith, "Excited electron correlations in resonant

multiphoton ionization via barium Rydberg states," Phys. Rev. A 31 , 2283-2290 (1985).

(W. Hagen) and R. E. Stencel, "On the rarity of RX Com stars," Astron.

J. 9£, 120-122 (1985).

T. Tsubokawa, "A fringe singnal processing method for absolute

gravimeter," Metrologla 20 , 107-113 (1984).

(C. J. Schrijver, R. Mewe) and F. M. Walter, "Coronal activity in F-, Gand K-type stars II. Coronal structure and rotation," Astron. Astrophys.

138, 258-266 (1984).

F. M. Walter, "Post-T Tauri stars in T associations," in Cool Stars,

Stellar Systems, and the Sun , Proceedings, Cambridge (USA) 1983 (S. L.

Baliunas and L. Hartmann, Eds., Springer-Verlag, Berlin, 1984), pp. 75-77.

F. M. Walter, J. E. Neff, (B. W. Bopp and R. E. Stencel), "Rotational

modulation and high speed streams in FK Comae Berenices: Evidence for a massive, highly-evolved binary system," in Cool Stars, Stellar Systems,

and the Sun , Proceedings, Cambridge (USA) 1983 (S. L. Baliunas and L.

Hartmann, Eds., Springer-Verlag, Berlin, 1984), pp. 279-281.

F. M. Walter and (L. V. Kuhi), "X-ray photometry and spectroscopy of T

Tauri stars," Astrophys. J. 284, 194-201 (1984).

(C. J. Schrijver, R. Mewe) and F. M. Walter, "Coronal structure and

rotation in late-type stars," in Cool Stars, Stellar Systems, and the

Sun, Proceedings, Cambridge (USA) 1983 (S. L. Baliunas and L. Hartman,

Eds., Springer-Verlag, Berlin, 1984), pp. 166-168.

252
PUBLICATIONS

Quantum Physics Division (525)

*(M. M. Shara, A. F. J. Moffat) and R. F. Webbink, "Unravelling the

oldest and faintest recovered nova: CK Vulpeculae (1670)," Astrophvs. J.

294, 271-285 (1985).

*R. F. Webbink, "Structure parameters of galactic globular clusters,"

in Dynamics of Star Clusters , lAU Symposium 113 (J. Goodman and P. Hut,

Eds., Reidel, Dordrecht, 1985), pp. 541-577.

*R. F. Webbink, "Eighth North American Workshop on Cataclysmic Variables and Related Systems (Louisiana State University, Baton Rouge,

Louisiana, February 27-March 1, 1984)," Comm. Astrophys. 10, 189-198

(1985).

*(J. T. Knudtson) and E. Weitz, "Infrared spectra and bandstrengths of

the fundamental and first overtone of HCl and DCl in liquid xenon

solutions," J. Chem. Phys . 83 , 927-933 (1985).

*(D. R. Burgess, Jr., I. Russia, P. C. Stair, R. Vlswanathan) and E.

Weitz, "Pulsed laser induced thermal desorption from surfaces:

Instrumentation and procedures," Rev. Sci. Instr. 55 , 1771-1776 (1984).

(V. A. Apkarian, J. M. Lindquist) and E. Weitz, "Vibrational energv

transfer pathways of CH^F under weak and strong excitation conditions:

A comparison," Chem. Phys. Lett. 112 , 328-334 (1984).

*K. H. Welge and (H. Rottke), "Resonant two-photon ionization and

dissociation of the hydrogen atom and molecule," in Multiphoton

Processes , Proceedings of the 3rd International Conference, Iraklion,

Crete, Greece, September 5-12 (P. Lambropoulos and S. J. Smith, Eds.,

Springer-Verlag, 1984), pp. 151-163.

*(H. Rottke) and K. Welge, "State-selective photoionization and

photodissociation spectroscopy of the H

2 molecule from excited states,"

in Proceedings of the Colloquium on Atomic and Molecular Collisions in a Laser Field, J. Phys. (Paris) 46 , Cl-127 - Cl-134 (1985).

C. A. Wight and (J. L. Beauchamp), "Infrared laser photodetachment of

electrons from vibrationally excited allyl anions," J. Phys. Chem. 88 , 4426-4430 (1984).

(J. Mlynek, C. Tamm, E. Buhr) and N. C. Wong, "Amplitude- and frequencvmodulation Raman heterodyne detection of optical double resonance," J. Opt. Soc. Am. 1, 492-493 (1984).

253
PUBLICATIONS

Quantum Physics Division (525)

(J. Mlynek, C. Tamm, E. Buhr) and N. C. Wong, "Raman heterodyne

detection of radio-frequency resonances in SM vapor: Effects of

velocity-changing collisions," Phys . Rev. Lett. 53, 1814-1817 (1984).

(Publications in press)

D. C. Abbott, (J. H. Bieging and E. Churchwell), "Observations of nonthermal emission from early-type stars," in Proceedings, Radio Stars

Workshop , Boulder, Colorado, June, 1984 (R. Hjellming and D. Gibson,

Eds., Reidel, Dordrecht, in press).

D. C. Abbott, "Wolf-Rayet star atmospheres," (Report for lAU Commission

36) in Reports on Astronomy (in press).

D. C. Abbott, "Thermal radio emission from the winds of single stars,"

in Proceedings, Radio Stars Workshop , Boulder, Colorado, June, 1984 (R.

Hjellming and D. Gibson, Eds., Reidel, Dordrecht, in press).

D. C. Abbott, "The theory of radiation-driven winds from earlv-type

stars," in Proceedings, III Trieste Workshop at Sacramento Peak

Observatory (in press).

*N. Andersen, J. W. Gallagher and I. V. Hertel, "Alignment and

orientation of atomic outer shells induced by electron and ion ipact:

Some recent developments and reamining problems," in Proceedings

,

Seventh International Conference on Laser Spectroscopy (in press).

*T. Andersen and (S. Mannervik), "Multiply-excited three-electron

systems studied by optical emission spectroscopy," Comments At. Mol.

Phys. (in press).

*K. R. Lykke , D. M. Neuraark, T. Andersen, V. J. Trapa and W. C.

Lineberger, "Photodetachment spectroscopy of ~CH2 CN," in Proc., Seventh

International Conference on Laser Spectroscopy (Springer-Verlag, in press).

*T. Andersen, K. R. Lykke, D. M. Neumark and W. C. Lineberger, "Photodetachment spectroscopy of FeO~," in Invited Papers of the XIVth

International Conference on the Physics of Electronic and Atomic

Collisions (D. C. Lorents, W. E. Meyerhof and J. R. Petersen, Eds.,

North-Holland , in press).

254
PUBLICATIONS

Quantum Physics Division (525)

(in press)

P. L. Bender and (D. R. harden), "GPS carrier phase ambiguity

resolution over long baselines," in Proceedings, First International

Symposium on Precise Positioning with the Global Positioning Svstem (in

press )

.

*R. Bilham and (P. Williams), "Sawtooth segmentation and deformation

processes on the southern San Andreas fault, California," Geophys. Res.

Lett, (in press).

*R. Bilham, "Southern San Andreas fault geometry and fault-zone

deformation: Implications for earthquake prediction in the Coachella

Valley, California," presented at the National Earthquake Prediction and

Evaluation Council, to appear in U. S. Geological Survey Report.

*E. Bohm-Vitense and (C. Proffitt), "Blue companions of Cepheids,"

Astrophys. J. (in press).

*E. Bohm-Vitense, "Cepheid distances from blue main-sequence

companions," Astrophys. J. (in press).

P. L. Bornmann, "Further analysis of temperature and emission measure

during the decay phase of solar flares derived from soft X-ray light

curves," Solar Phys. (in press).

A. Brown, "Radio continuum emission from T Tauri stars and associated

structures," in Proceedings, Cosmical Gas Dynamics Conference (VNTT

Science Press, in press).

A. Brown, (R. Mundt) and S. A. Drake, "Radio continuum emission from

pre-main sequence stars and associated structures," in Proceedings

,

Radio Stars Workshop , Boulder, Colorado, June, 1984 (R. Hjellming and D.

Gibson, Eds., Reidel, Dordrecht, in press).

*S.-I Chu, "Multiphoton processes in intense laser fields," in

Proceedings, Workshop on Atomic Spectroscopy and Its Related Dynamical

Properties (Instit. of Atomic and Molecular Science and National TsingHua University in Taiwan, R. 0. C. , June 23-25, 1984, in press).

*S.-I Chu and J. Cooper, "Threshold shift and above threshold multiphoton ionization of atomic hydrogen in intense laser fields," Phvs.

Rev. A. (in press).

255
PUBLICATIONS

Quantum Physics Division (525)

(in press)

*S.-I Chu, "Dynamics and symmetries in intense field multiphoton

processes: Floquet theoretical approaches," in Advances in Multi-Photon

Processes and Spectroscopy (World Scientific, Singapore, in press).

G. H. Dunn, D. S. Belle, B. DePaola, N. Djuric, D. Mueller, A. Muller

and C. Timmer, "Field effects on Rydberg product state distribution from

dielectronic recombination," in Atomic Excitation and Recombination in

External Fields (M. H. Nayfeh and C. W. Clark, Eds., Harwood, in press).

T. M. Niebauer, J. K. Hoskins and J. E. Faller, "Absolute gravity: A

reconnaissance tool for studying vertical crustal motions," in Proceedings, Chapman Conference on Vertical Crustal Motions: Measurement and

Modeling, J. Geophys. Res, (in press).

J. E. Faller, P. L. Bender, J. L. Hall, D. Hils and M. A. Vincent,

"Space antenna for gravitational wave astronomy," in Proceedings, Radio

Stars Workshop , Boulder, Colorado, June, 1984 (R. Hielming and D.

Gibson, Eds., Reidel, Dordrecht, in press).

H. Chatham and A. Gallagher, "Ion chemistry in silane dc discharges,"

J. Appl. Phys. (in press).

A. Gallagher, "Silane discharge gas and surface reactions," in

Proceedings, Materials Research Society (in press).

M. O’Callaghan, A. Gallagher and (T. Holstein), "Absorption and emission

of radiation in the region of an avoided level crossing," Phvs . Rev. A

(in press).

B Stumpf and A. Gallagher, "Electron excitation of Na(3S) and Na(3P)

atoms to the Na(3D) state," Phys. Rev. A (in press).

A. K. Pradhan and J. W. Gallagher, "Atomic data for electron-impact

excitation of ions," in Proceedings, Conference on Low Energy Electron

Excitation Data (in press).

(T. J. Morgan, R. E. Olson, A. S. Schlachter) and J. W. Gallagher,

"Charge transfer of hydrogen ions and atoms in metal vapors," J. Phvs.

Chera. Ref. Data (in press).

256
PUBLICATIONS

Quantum Physics Division (525)

(in press)

*(V. A. Osherovich) , E. B. Gliner, (I. Tzur and M. L. Kuhn), "The

magnetic and thermodynamic structure of a polar coronal hole," Solar

Phys. (in press).

W. C. Wong and J. L. Hall, "Servo control of amplitude modulation in

^

spectroscopy: Shot-noise limited measurement of water vanor pressure

broadening," in Proceedings, Seventh International Conference on Laser

Spectroscopy (in press).

D. A. Harmin, "Hydrogenic treatment of stark effects in Rydbers atoms,"

in Atomic Excitation and Recombination in External Fields ('^. H. Navfeh

and C. W. Clark, Eds., Harwood, in press).

*1. V. Hertel, (H. Schmidt, A. Bahring and E. Mever) , "Ansular momentum

transfer and charge cloud alignment in atomic collisions: Intuitive

concepts, experimental observations and semiclassical models," Ren.

Progr. Phys. (in press).

(A. A. Kutepov) , D. G. Hummer and (C. B. Moore), "Rotational relaxation

of the 00(0)1 level of CO^ including radiative transfer in the -^.3 micron band of planetary atmospheres,” J. Ouant. Spectrosc. Radiat.

Transfer (in press).

(R. P. Kudritzki) and D. G. Hummer, "Intrinsic parameters of hot blue

stars," in Luminous Stars and Associations in Galaxies , lAU Svm.posium

116 (Reidel, Dordrecht, in press).

(T. Gehren, D. Husfeld, R. P. Kudritski), P. S. Conti and D. G. Hummer,

"Non-LTE analysis of massive stars in the Maeellanic Clouds," in

Luminous Stars and Associations in Galaxies , lAC S3nnposium 116 (Reidel,

Dordrecht, in press).

A. Jain, "Some theoretical aspects of positron and electron scatterine

by molecules," in Third International Workshop on Positron (Electron)

Gas Scattering (in press).

A Jain, "Positron scattering by NH^ and H^O molecules below positronlum

formation threshold," in Third International Workshop on Positron

(Electron) Gas Scattering (in press).

257
PUBLICATIONS

Quantum Physics Division (525)

(in press)

H. K. Haugen, E. Weitz and S. R. Leone, "Accurate quantum yields by

laser gain-versus-absorption spectroscopy: Investigation of Br/Br*

channels in photofragmentation of Br 2 and IBr," J. Chem. Phys . (in

press).

A. 0. Langford, V. M. Bierbaum and S. R. Leone-, "Auroral implications of

recent measurements on 0(^S) and 0(^D) formation in the reaction of N"*" with O2

," Planetary Space Sci. (in press).

A. 0. Langford, V, M. Bierbaum and S. R. Leone, "Flowing afterglow infrared chemiluminescence studies of vibrational energy disposal in the

ion-molecule reactions F“ + HBr,DBr - HF,DF, + Br~," J. Chem. Phys. (in

press)

.

D. Neuschafer, M. 0. Hale, I. V. Hertel and S. R. Leone, "Energy

transfer processes of aligned excited states of Ca atoms," in Invited

Papers of the XIVth International Conference on the Physics of

Electronic and Atomic Collisions (D. C. Lorents, W. E. Meyerhof and J.

R. Petersen, Eds., North-Holland, in press).

*W. Lichten, "What causes the sharp positron spectrum in heavv atom

collisions? The atomic hypothesis," in Proceedings, Atomic Theory

Workshop (Am. Inst. Phys., in press).

S. H. Saar and J. L. Linsky, "The magnetic field of the BY Draconis

flare star EQ Virginis," Astrophys. J. (in press).

S. A. Drake, (T. Simon) and J. L. Linskv, "A VLA radio continuum survey

of active late-type giants in binary systems: Preliminary results," in

Proceedings, Radio Stars Workshop , Boulder, Colorado, June, 1^84 (R.

Hjellmlng and D. Gibson, Eds., Reidel, Dordrecht, in press).

S. A. Drake, D. C. Abbott, (J. H. Bieging, E. Churchwell) and J. L.

Linsky, "VLA observations of A and B stars with kilogauss magnetic

fields," in Proceedings, Radio Stars Workshop , Boulder, Colorado, June,

1984 (R. Hjellmlng and D. Gibson, Eds., Reidel, Dordrecht, in press).

J. L. Linsky, "Definition and empirical structure of the range of

stellar chromospheres-coronae across the H-R diagram: Cool stars," in

Proceedings, III Trieste Workshop , National Solar Observatory (in

press )

.

258
PUBLICATIONS

Quantum Physics Division (525)

(in press)

J. L. Linsky, "Observed and computed stellar line profiles: The roles

played by partial redistribution, geometrical extent and expansion," in

Proceedings, Workshop on Stellar Spectral Line Formation (in press).

J. L. Linsky, "Beyond Lyman Alpha: The new frontier in ultraviolet

spectroscopy," Comments Astrophys. (in press).

*T. M. Miller, "Electron affinities," in CRC Handbook of Chemistry and

Physics (in press).

*T. M. Miller, "Atomic and molecular polarizabilities," in CRC Handbook

of Chemistry and Physics (in press).

A. K. Pradhan, "Review of electron impact excitation data for the

helium sequence," in Proceedings, Conference on Low Energy Electron

Excitation Data (in press).

A. K. Pradhan, "Improved excitation rate coefficients for the n=2 and

n=3 levels of Ca XIX and Fe XXV including fine structure," Astrophvs. J.

Suppl. (in press).

A. K. Pradhan and J. W. Gallagher, "Atomic data for electron- impact

excitation of ions," in Proceedings, Conference on Low Energy Electron

Excitation Data (in press).

*(H. J. Werner) and P. Rosmus, "Ab initio calculations of radiative

transition probabilities in diatomic molecules," in Comparison of t^e ab

initio Calculations with Experiments — State of the Art (R. Bartlett,

Ed., Reidel, in press).

*(J. Senekowitsch, H.-J. Werner), P. Rosmus and S. V. ONeil, "Ab initio SH'* calculations of radiative transition probabilities in SH, *’ and SH“,"

J. Chem. Phys. (in press).

D. S. Elliott, M. W. Hamilton, K. Arnett and S. J. Smith, "The structure

of the thermal modes in pulsating stars," Astrophvs. J. (in press).

G. Leuchs , G. Alber and S. J. Smith, "Competition between photoionization and two-photon Raman coupling," in Proceedings, Seventh International Conference on Laser Spectroscopy (in press).

259
PUBLICATIONS

Quantum Physics Division (525)

(in press)

*R. F. Webbink, "Epsilon Aurigae in an evolutionary context," in

Proceedings, North American Workshop on the Recent Eclipse of Epsilon

Aurigae (in press).

(Publications submitted)

D. C. Abbott, (J. H. Bieging, E. Churchwell) and A. V. Torres, "Radio

emission from galactic Wolf-Rayet stars and the structure of Wolf-Rayet

winds," Astrophys. J. (submitted).

D. C. Abbott, (J. H. Bieging, E. Churchwell) and A. V. Torres, "Radio

emission from galactic Wolf-Rayet stars and the structure of Wolf-Ravet

winds," Astrophys. J. (submitted).

*D. M. Neumark, K. R. Lykke, T. Andersen and W. C. Lineberger,

"Infrared spectrum and autodetachment dynamics of NH“," J. Chem. Phvs

.

(submitted)

.

*T. Andersen, K. R. Lykke, D. M. Neumark and W. C. Lineberger, "Photodetachment spectroscopy of FeO~ autodetaching resonances," J. Chem.

Phys . (submitted).

*(E. Gottwald, A. Mattheus), K. Bergmann and (R. Schinke), "Angularly

resolved vibrational excitation in Na

2 ~He collisions," J. Chem. Phys.

(submitted)

.

*E. Bohra-Vitense , "Theory of transition layers and coronae emission

measures," Astrophys. J. (submitted).

*E. Bohm-Vitense , "Analysis of the transition layer and corona of

Procyon," Astrophys. J. (submitted).

*E. Bohm-Vitense, "Analysis of the solar transition layer and corona,"

Astrophys. J. (submitted).

*E. Bohm-Vitense, "The Cepheid mass problem and Cepheld binaries,"

Astrophys. J. (submitted).

260
PUBLICATIONS

Quantum Physics Division (525)

(submitted)

*E. Bohm-Vi tense , "A simple explanation for the Linsky-Haisch boundary

line for transition layers," Astrophys. J. (submitted).

P. L. Bornmann, "Turbulence as a proposed intermediate energy storage

mechanism during solar flares," Astrophys. J. (submitted).

*M. Kimura, S. Chapmanand N. F. Lane, "Electron capture in Ar"^ + H

2 collisions in keV energy regime," Phys. Rev. A (submitted).

*(T.-S. Ho) and S.-I Chu, "Floquet-Liouville super-matrix approach for

multiphoton processes in polychromatic fields," Phys. Rev. Lett,

(submitted).

*T.-S. Ho, K. Wang) and S.-I Chu, "Floquet-Liouville super-matrix

approach; Time-development of density matrix operator and multiphoton

resonance fluorescence spectra in intense laser fields," Phys. Rev. A

(submitted).

*(K. Wang, T.-S. Ho) and S.-I Chu, "Multiphoton dynamics and resonance

lineshapes in three-level systems: Many-mode Floquet treatment," J.

Phys. B: Atom. Molec. Phys. (submitted).

(D. H. Crandall, R. A. Phaneuf, D. C. Gregory, A. M. Howald), D. W.

Mueller, T. J. Morgan, G. H. Dunn and (R. J. W. Henry), "electron

impact ionization of B^"*" and 0^'*’: Excitation-autoionization in Li-like

atoms," Phys. Rev. A (submitted).

J. A. Luine and G. H. Dunn, "Ion-molecule reaction probabilities near

10 K," Astrophys. J. (Letters) (submitted).

A. Muller, D. S. Belie, B. D. DePaola, N. Djuric, G. H. Dunn, D. W.

Mueller and C. Timmer, "field effects on the Rydberg product state

distribution from dielectronic recombination," Phys. Rev. Lett,

(submitted.

)

S. E. Barlow, J. B. Jeffries, J. Cooper and G, H. Dunn, "Observation

and modeling of cylindrically symmetric, cooperative density waves in an ion cloud stored in a hypterbolic penning trap," Phys. Fluids

(submitted)

.

(J. J. Snyder, T. B. Lucatorto, P. H. Debenham) and S. Geltman,

"Ultra-sensitive laser isotope analysis in an ion storage ring," J. Ont

.

Soc. Am. B, (submitted).

261
PUBLICATIONS

Quantum Physics Division (525)

(submitted)

A. 0. Langford, V. M. Bierbaum and S. R. Leone, "Branching ratios for

electronically excited oxygen atoms formed in the reaction of N"*" with

at 300 K," J. Chem. Phys. (submitted).

D. J. Donaldson and S. R. Leone, "Absolute rate coefficients for methyl

radical reactions by laser photolysis, time-resolved infrared chemiluminescence: CD^ + HX -> DC^H + X (X-Br,I)," J. Chem. Phys. (submitted).

*W. Lichten, "Precise wavelength measurements and optical phase shifts.

II. Applications," J. Opt. Soc. Am. (submitted).

J. L. Linsky, "Nonradiative activity across the H-R diagram: Which types

of stars are solar-like?" Solar Phys. (submitted).

(W. B. Landsman, J. Murthy, R. C. Henry, H. W. Moos), J. L. Linsky and (J.

L. Russell), "lUE observations of interstellar hydrogen and deuterium

toward Alpha Cen B," Astrophys. J. (submitted).

S. H. Saar and J. L. Linsky, "The photospheric magnetic field of the

DM3.5e flare star AD Leo," Astrophys. J. (Letters) (submitted).

(C. Jordan), A. Brown, F. M. Walter and J. L. Linsky, "The outer

atmosphere of Procyon (Alpha CMI F5 IV-V): Evidence of supergranulation

or active regions," Monthly Notices Roy. Astron. Soc. (submitted).

S. A. Drake and J. L. Linsky, "Radio continuum emission from winds,

chromospheres and coronae of cool giants and supergiants," Astrophvs. J.

( submitted )

.

*1. R. Little-Marenln , (T. Simon, T. R. Ayres, N. L. Cohen, P. A. Feldman), J. L. Linsky, (S. J. Little and R. Lyons), "Ultraviolet,

optical, infrared, and microwave observations of HR 5110," Astrophys. J. (submitted).

D. W. Muellerand (D. H. Jaecks), "Polarized photon-scattered particle

correlation measurements in H"*" + He collisions," Phys. Rev. A

(submitted)

.

A. Muller, "Multiple ionization and the charge state evolution of ions

exposed to electron impact," Phys. Letters A. (submitted).

*G. A. Natanson, "Relationship between least-squares and natural

collision coordiantes , " J. Chem. Phys. (submitted).

262
PUBLICATIONS

Quantum Physics Division (525)

(submitted)

*T. Uzer, G. Natanson, and (J. T. Hynes), "Coriolis-induced

intramolecular vibrational energy flow between anharmonlc normal modes,"

Chem. Phys. Lett, (submitted).

*G. A. Natanson, "Selection rules for rotational excitation of

polyatomic molecules by slow electron Impact," J. Phvs. B: Atom. Molec.

Phys. (submitted).

*G. A. Natanson, "Analytical formula for direction cosines of the Eckart

frame of a planar molecule," Chem. Phys. Lett, (submitted).

*G. A. Natanson, "Comment on 'Rotational energy surfaces and high-J

eigenvalue structure of polyatomic molecules,'" J. Chem. Phys.

(submitted)

.

(P. Lee, A. J. Lieber, R. P. Chase) and A. K. Pradhan, "Helium-like

titanium spectra produced by electron-cyclotron-heated tokomak plasmas,"

Phys. Rev. Lett, (submitted).

*R. Grobe, G. Leuchs and K. Rzazewski, "Migration of population to highe

angular momentum Rydberg states through the degenerate Raman coupline,"

Phys. Rev. A (submitted).

*K. Rzazewski and J. Cooper, "Autoionization in a fluctuating electric

field," J. Opt. Soc. Am. B (submitted).

*K. Rzazewski, "Laser induced fluctuations in single photon ionization,"

Phys. Rev. A (submitted).

*K. Rzazewski and R. Grobe, "Angular momentum distribution of electrons

in above threshold ionization," Phys. Rev. Lett, (submitted).

263
1984-1985 VISITING FELLOWS

Quantiiin Physics Division (525)

Visiting Fellow Home Institution Area of Work

Torkild Andersen Institute of Physics

University of Aarhus

Aarhus , Denmark

Dynamics & structure

of negative ions;

photodissociation or detachment processes

of molecular ions by

coaxial ion beam

techniques

.

Klaas Bergmann Fachbereich Physik der

Universitat Kaiserslautern

Kaiserslautern,

West Germany

State- to-state

collision dynamics

& quantum optics

.

Roger Bilham Lamont Doherty Geological

Observatory

Columbia University

Palisades, NY

The development of

improved geodetic

measurement

capability, including

the use of GPS

satellites

.

Karl -Heinz Bohm Astronomy Department

University of Washington

Seattle, WA

Herbig-Haro objects

6c relatively cool

degenerate stars.

Erika Bohm-Vitense Astronomy Department

University of Washington

Seattle , WA

Mixing length theory

of convection,

stellar chromospheres

coronae 6c transition

layers

.

Shih-I Chu Department of Chemistry

University of Kansas

Lawrence , KS

Atomic 6c molecular

collisions, laser

physics 6c molecular

astrophysics

.

William Lichten J. W. Gibbs Laboratory

Yale University

New Haven, CT

Precision laser

research.

Thomas M. Miller Dept, of Physics &

Astronomy

University of Oklahoma

Norman, OK

Laser spectroscopy;

atomic 6c molecular

physics

.

264
1984-1985 VISITING FELLOWS

Quantum Physics Division (525)

Visiting Fellow Home Institution Area of Work

Alfred Muller Institut fur Kernphysik

Universitat Giessen

Giessen, West Germany

Inelastic electronion collisions;

formation of intermediate states decaying by electron &/or

photon emission.

Grigory A. Natanson Department of Chemistry

The University of Chicago

Chicago, IL

Calculations of

ro -vibrational energy

levels

.

Pavel Rosmus Fachbereich Chemie der

J. W. Goethe -Universitat

Frankfurt am Main

West Germany

Quantum chemistry;

esp. radiative transition probabilities

& potential energy

surfaces

.

Kazimierz Rzazewski Institut Fizyki

Teoretycznij PAN

Warszawa, Poland

Theoretical research

in quantum optics;

spectra of electrons

& photons induced by

smooth pulses.

Ronald F. Webbink Department of Astronomy

University of Illinois

Urbana, IL

Evolutionary status

of symbiotic stars.

1984-1985 RESEARCH FELLOWSHIP FOR TEACHERS

Sally Chapman Barnard College Dynamics of molecular

Columbia University Collisions.

New York, NY

265
1985-1986 VISITING FELLOWS

Quantum Physics Division (525)

Visitine Fellow Home Institution Area of Work

James N. Bardsley University of Pittsburgh

Pittsburgh, PA

Atoms in strong

oscillatory fields

and non- equilibrium

phenomena in

ionized gases.

Michael J. Barlow Department of Physics &

Astronomy

University College

London

London, United Kingdom

Properties of hot

stars, physical

properties of

circumstellar and

interstellar dust.

Pierre Connes Service d'Aeronomie du

CNRS

Verrieres-le- Buis son France

High precision

spectroscopic

techniques and

their applications

to astronomy and

to fundamental

physics experiments.

Paul C. Engelking Department of Chemistry

University of Oregon

Eugene , OR

Dipole interactions

of molecules with

electrons

.

Ivan Hubeny Astronomical Institute

Czechoslovak Academy of

Sciences

Ondrejov, Czechoslovakia

Stellar atmospheres,

atomic processes,

line scattering,

numerical simulations

Francis Perkins, Jr. Plasma Physics Laboratory

Princeton University

Princeton, NJ

Magneto -hydrodynamic

theory and its

applications to

solar physics,

magnetic fusion and

astrophysics

.

Weston J. Sandle University of Otago

Dunedin

New Zealand

Optical bistability.

Craig L. Sarazin Leander McCormick Ohs

.

University of Virginia

Charlottesville, VA

Cooling flows in

clusters of

galaxies

.

266
1985-1986 VISITING FELLOWS

Quantum Physics Division (525)

Visiting Fellow Home Institution Area of Work

John P. Simons Department of Chemistry

University of Utah

Salt Lake City, UT

Electronic structure

of negative

molecular ions

;

dynamical behavior

of anions

.

Sumner G. Starrfield Department of Physics

Arizona State University

Tempe , AZ

Study of the nova

outburst; evolution

of both nova

explosions and the

hottest known

pulsating variable

stars

.

Peter E. Toschek I. Ins ti tut fur

Experimentalphysik

Universitat Hamburg

Hamburg, West Germany

Laser spectroscopy;

cooling and study

of trapped ions

.

John Weiner Department of Chemistry

University of Maryland

College Park, MD

Inelastic

collision dynamics

in simple systems.

1985-1986 RESEARCH FELLOWSHIP FOR TEACHERS

Jo Allan Beran Texas A & I University Environmental

Kingsville, TX chemistry.

1985-1986 NBS/JILA EXCHANGE FELLOW

Daniel E. Kelleher Atomic &. Plasma Radiation Division

Center for Radiation Res

.

National Bureau of

Standards

Gaithersburg, MD

Theoretical plasma

spectroscopy

problems

.

267
SCIENTISTS WORKING AT JILA ON SABBATICAL OR OTHER LEAVE

(Other than Visiting Fellows)

Quantum Physics Division (525)

M. C. Begelman

P. L. Bender

P. S. Conti

John Hanley

California Institute of Technology

Pasadena, CA

Feridoun Rabet

University of Tabriz, Iran

Huib Henrichs

Astronomical Institute

University of Amsterdam

The Netherlands

J . Cooper

G . H , Dunn

J. E. Faller

J. W. Gallagher

Data Center

H.J.G.L.M. Lamer

s

Space Research Laboratory

Utrecht, The Netherlands

D. M. Warrington

University of Otago

Dunedin, New Zealand

D, S. Belie

Belgrade University

Belgrade, Yugoslavia

Ratko Janev

Belgrade Univesity

Belgrade, Yugoslavia

Igenio Marsson

University of Trieste

Trieste, Italy

T. J. Morgan

Department of Physics

Weslyan University

Middletown, CT

Nils Andersen

H. C. Orsted Institute

Copenhagen, Denmark

268
SCIENTISTS WORKING AT JILA ON SABBATICAL OR OTHER LEAVE

(Other than Visiting Fellows)

Quantum Physics Division (525)

Gallagher (cont.) Ingolf V. Hertel

Institut fur Molekulphysik

Freie Universitat Berlin

Berlin, West Germany

Douglas 0. Heddle

Department of Physics

Royal Holloway College

University of London, U.K.

Jeffrey I. Steinfeld

Department of Chemistry

Massachusetts Institute of Technology

Cambridge, MA

S. Geltman Leonard Rosenberg

Department of Physics

New York University

New York, NY

J. L. Hall Christian Borde

Laboratoire de Spectroscopie

Paris, France

Jean-Marie Chartier

Bureau International des Poids et Mesures

Sevres , France

H. Jeff Kimble

University of Texas at Austin

Christophe Salomon

University of Paris - Nord

France

Wang Yiqui

Peking University

People's Republic of China

S. R. Leone Susan Kohler (NSF Visiting

Professorship for Women)

Mount Holyoke College

South Hadley, MA

269
SCIENTISTS WORKING AT JILA ON SABBATICAL OR OTHER LEAVE

(Other than Visiting Fellows)

Quantum Physics Division (525)

Leone (cont.)

J . Levine

Richard Schwenz (NSF Summer

Faculty Fellowship)

University of Northern Colorado

Greeley, CO

V . Levshenko

U.S.S.R.

A. Sadovsky

U.S.S.R.

W. C. Lineberger H. Ho top

University Kaiserslautern

Kaiserslautern, West Germany

Wolfgang Kamke

Free University of Berlin

West Germany

J. L. Linsky Erik Eason

University of Washington

Seattle, WA

Ake Nordlund

Copenhagen University

Copenhagen, Denmark

Osmi Vilhu

University of Helsinki

Helsinki, Finland

Israel Oznovich

New Mexico Institute for

Mining & Technology

Hugh Deasy

Trinity College

Dublin, Northern Ireland

Varda Bar

The Amos De-Shalit Science Teaching

Center in Israel

The Hebrew University of Jerusalem

Jerusalem, Israel

270
SCIENTISTS WORKING AT JILA ON SABBATICAL OR OTHER LEAVE

(Other than Visiting Fellows)

Quantum Physics Division (525)

R. A. McCray Timothy Kallman

NASA - Goddard Space Flight Center

Greenbelt, MD

A. V, Phelps Sanichiro Yoshida

Keio University

Yokohama, Japan

S . J . Smith George Basbas , Editor

Physical Review & Physical

Review Letters

Ridge , NY

Arnold Russek

University of Connecticut

Storrs, CT

Gerd Leuchs

Max -Planck Institute

West Germany

Dan Elliott

Purdue University

Lafayette, IN

Harold Metcalf

SUNY, Stony Brook

New York

Murray Hamilton

Universitat Munchen

West Germany

J . Toomre Douglas Gough

Institute of Astronomy

Cambridge , England

Joseph Massaguer

University of Barcelona

Barcelona, Spain

271
SCIENTISTS WORKING AT JILA ON SABBATICAL OR OTHER LEAVE

(Other than Visiting Fellows)

Quantum Physics Division (525)

Toomre (cont.) Michael Proctor

Department Applied Mathematics &

Theoretical Physics

University of Cambridge

Cambridge , England

Edgar Knobloch

Department of Physics

University of California, Berkeley

Berkeley, California

272
CONFERENCES SPONSORED

Quantum Physics Division (525)

Physical Chemistry Workshop - Involved several of the Adjoints and took

place largely in JILA, June 24-26, 1985. Drs . D. J. Nesbitt and B. Koel

organizers

.

273
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Informal Seminars

Ronald F. Webbink (JILA) - Close Binaries as Sources of Gravitational

Waves, March 4, 1985.

Mark Levenson (IBM, San Jose) - Brillioun Scattering in Optical Fibers,

March 21, 1985.

Des Muller (Griffith University) - Low Energy Gollisional Relaxation of

Vibrational States in Polyatomic Molecules, July 1, 1985.

Horst Heydtmann (Johann Wolfgang Goethe -Universitat) - Energy Disposal

in F Atom Reaction, July 3, 1985.

C. J. Borde (Universite of Paris Nord) - Gravitational Wave Detection

Using Non-Linear Optical Spectroscopy of Atoms, August 7, 1985.

George Basbas (Editor of Physical Review Letters) - How PRL Works,

October 1, 1985.

Special JILA Seminars

T. Baer (Spectra Physics) - Femto-Second Pulse Generation Using

Nonlinear Effects in Single-Mode Optical Fibers, October 15, 1984.

Howard Taylor (University of Southern California) - New Methods of

Spectral Assignment in Atoms and Molecular Systems, November 15,

1984.

A. Adam (University of Waterloo) - Coherent Infrared Laser Stark

Spectroscopy of CH3 F in a Molecular Beam, May 10, 1985.

C. H. Kuo (University of Oregon) - Laser Induced Charge Exchange

Spectroscopy of N2

''’ and CO'*', May 21, 1985.

A. W. Castelman, Jr. (Pennsylvania State University) - Studies of Ionic

Clusters, June 6 , 1985.

Barbel Maessen (University of California, Irvine) - Variational

Calculations of Vibrational -Rotational States in Water and

Formaldehyde, June 6 , 1985.

Arnold Russek (University of Connecticut) - Post Collision Interaction

and the Auger Lineshape, June 10, 1985.

274
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Special JILA Seminars (cont.)

Lynn Westling (Institute of Optics, University of Rochester) - Intensity

Fluctuations in Multi-Mode Dye Lasers, June 14, 1985.

Philip Arcuni (University of Chicago) - Decay of He** After Fast,

Changed- Ion Excitation, June 25, 1985.

Alain Aspec (Institute of Optics, Paris) - Quantxim Mechanical

Interferometry With Atoms, July 2, 1985.

Ken'ichi Nomoto (University of Tokyo) - White Dwarf Models for Type I Supemovae, July 2, 1985.

Y. Z. Wang (Shanghai Institute of Optics and Fine Mechanics) - Photon

Statistics By Atomic Beam Deflection, July 8, 1985.

Fucheng Lin (Shanghai Institute of Optics and Fine Mechanics) - Interactions of Intense Laser Fields With Atoms, July 9, 1985.

H. Taktima (Institute For Laser Science, Tokyo) - Preparation of Pure

Excited States By Laser Raman Scattering, July 22, 1985.

JILA Colloquia

Burton Rowe (Laboratoire d'Aerothermique) - Ion-Molecule Reaction

Measurements At Very Low Temperatures, October 16, 1984.

Duane H. Jaecks (University of Nebraska) - Excitation and Molecular

Dissociation Mechanisms in Diabatlc H3VH2"*^-He Collisions,

October 23, 1984.

Karl Welge (JILA Visiting Fellow) - VUV Laser Spectroscopy - Photoionization and Photodissociation Processes, October 30, 1984.

275
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

JILA Colloquia (cont.)

Hartmut Hotop (University of Kaiserslautern) - Photoionization of

Laser-Excited Rare Gas Atoms, November 6 , 1984.

Alfred Mueller (JILA Visiting Fellow) - Electron Impact Ionization of

Ions, January 29, 1985.

Torkild Anderson (JILA Visiting Fellow) - Fast Beam Spectroscopy of

Doubly Excited States in Few Electron Systems, Febiruary 12, 1985.

Shih-I Chu (JILA Visiting Fellow, University of Kansas) - Multiphoton

Processes In Intense Fields, February 19, 1985.

Grigory Natanson (JILA Visiting Fellow, University of Chicago) - Nontrivial Aspects in the Symmetry Theory of Polyatomic Molecules,

February 26, 1985.

Takeshi Oka (University of Chicago) - Infrared Spectroscopic Studies of

Molecular Ions, March 12, 1985.

Kazimierz Rzazewski (JILA Visiting Fellow, Instytut Fizyki Teoretycznij

PAN) - Spectra of Strong Field Resonance Fluorescence, March 19,

1985.

Theodore Hansch (Stanford University) - High Resolution Laser

Spectroscopy of the Hydrogen Atom, April 9, 1985.

Dieter Meschede (Yale University) - Rydberg Atoms and Radiation

Interaction, April 16, 1985.

Aram Mooradian (Lincoln Laboratories, MIT) - Semiconductor Lasers:

Spectral Properties and Applications, May 7, 1985.

David E. Pritchard (Lincoln Laboratories, MIT) - State Resolved Studies

of Vibration-Rotation Energy Transfer, May 14, 1985

Klaas Bergmann (JILA Visiting Fellow, Universitat Kaiserslautern) - Optically Primped Supersonic Beam Lasers: Concept and Possible

Applications, September 10, 1985.

Paul Engelking (JILA Visiting Fellow, University of Oregon) - CH3 O

Radical Emission Spectroscopy, September 24, 1985.

Joint JILA/Phvsics Colloquium

276
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

William Lichten (Yale University) - The Rydberg Constant, November 7,

1984.

Joint JILA/Astrophvsics . Planetary and Astronomical Sciences Colloquia

Bernard F. Burke (MIT) - Interferometry of All Scales, October 1, 1984.

Douglas 0. Gough (University of Cambridge) - Helioseismology: The

Rotation and Internal Stratification of the Sun, October 2, 1984.

Marc Aaronson (Steward Observatory, University of Arizona) - A New

Distance to the Large Magellanic Cloud by Main Sequence Fitting,

October 15, 1984.

Juri Toomre (APAS/JILA) - Solar Five-Minute Oscillations Used to Probe

Giant Cells Below the Surface, October 29, 1984.

Richard McCray (APAS/JILA) - Supernovae and Propagating Star Formation,

November 5, 1984.

Ron Webbink (JILA Visiting Fellow, University of Illinois) - Old Novae,

November 13, 1984

John F. Hawley (Caltech) - Hydrodynamics Around Black

Holes: Supercomputer Experiments and a Movie | , November 19, 1984.

Anil Pradhan (JILA) - Atomic Processes in Fusion and Astrophysical

Plasmas, November 20, 1984.

George Fuller (University of California, Santa Cruz) - Evolution of

Supermassive Stars, November 26, 1984.

George Fuller (University of California, Santa Cruz) - Nuclear Physics

of Stellar Collapse, November 27, 1984.

Craig Hogan (Caltech) - Astrophysics of Cosmic Strings, December 3,

1984.

277
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Joint JILA/Astrophvsics Planetary and Astronomical Sciences ColloQuia

(cont

)

Jack Brandt (Goddard Space Flight Center) - The ICE (International

Cometary Explorer) Mission To Comet Giacobini-Zinner : The First

Comet Mission, December 10, 1984.

Karl-Heinz Bohm (JILA Visiting Fellow; University of Washington) - Circumstellar Gas Dynamics of Young Stars: High Resolution Studies

of Herbig-Haro Objects, February 5, 1985.

Erika Bohm-Vitense (JILA Visiting Fellow, University of Washington)

March 1985.

Julian H. Krolik (Johns Hopkins University) - Radiation Pressure-Driven

Shocks in Winds from Hot Stars, March 18, 1985.

David Hollenbach (NASA/Ames) April 1, 1985.

Ramesh Narayan (Caltech) - The Stability of Differentially Rotating

Disks in Astrophysical Systems, April 22, 1985.

Arieh Konigl (University of Chicago) - MHD Equilibria of Astrophysical

Jets, April 30, 1985.

Myron Smith (National Optical Astronomy Observatory) - The Be Stars.

Tim Heckman (University of Maryland, Johns Hopkins) - Optical Line

Emission From Cosmic Jets, September 16, 1985.

Len Cowie (Space Telescope Science Institute) - Gas in Clusters of

Galaxies, September 30, 1985.

JILA Atomic Physics Seminars

Norbert Bowering (University of Texas at Austin) - Collisional

Deactiviation of Two- Photon Excited Xenon Atoms, October 1, 1984.

Farid Parpia (JILA) - Relativistic Time -Dependent Local-Density

Approximation, October 2, 1984.

278
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

JILA Atomic Physics Seminars (cont.)

Gerd Leuchs (JILA) - The Effect of High Bound State Density on

Photoionization, October 9, 1984.

Jeff Kimble (University of Texas at Austin) - Some Thoughts on Squeezed

States, October 18, 1984.

Joachim Kessler (NBS, Gaithersburg) - Symmetry, Electron Polarization

and Atomic Interactions, November 6, 1984.

Joe Eberly (University of Rochester) - Multiphoton Above -Threshold

Ionization -- A Simple Dynamical Theory, December 11, 1984.

R. A. Phaneuf (Oak Ridge National Laboratory) - Merged Beam Studies of

Low Energy Collisions of Highly Charged Ions with H Atoms, March 1,

1985.

Herbert Orth (Yale University) - Recent Experiments With Muonic Atoms,

March 18, 1985.

Scott Berry (Oak Ridge National Laboratory and University of Tennessee)

- Electron Capture and Loss to the Continuum, March 26, 1985.

Chemical Physics Colloquia

Joseph M. Jasinski (IBM, Yorktown Heights) - Laser Diagonistics of SiH2 radicals, October 5, 1984.

John Hutchinson (Rice University) - Quantum Effects in Molecular

Vibrational Dynamics, October 12, 1984.

Peter Rossky (University of Texas) - Molecular Interactions and Solution

Structure in Aqueous Systems, October 19, 1984.

Thompson M. Sloane (General Motors Research Laboratory) - Experimental

and Computational Studies of Ignition Chemistry in Hydrocarbon-Air

Mixtures, October 26, 1984.

279
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Colloquia (cont.)

Paul Rosmus (JILA and Fachbereich Chemie der Universitat Frankfurt) - Properties of Molecular Ions Calculated from Correlated

Wavefunctions , November 2, 1984.

Hartmut Hotop (Universitat Kaiserslautern) - Energy Transfer of

Optically Aligned Neon Metastables, November 2, 1984.

Danny L. Yeager (Texas A and M) - Many Electron Wavefunctions, November

9, 1984.

Howard Taylor (University of Southern California) - A New View of

Quantum Non-Linear Processes with Applications to Chemistry,

November 26, 1984.

Larry Dubois (Bell Labs) - Novel Chemistry and Physics at the

Metal- Semiconductor Interface, November 30, 1984.

John P. Maier (Universitat Basel) - Spectroscopic Studies of Polyatomic

Cations, December 7, 1984.

William Hinsberg III (IBM, San Jose) - Chemistry of Microlithographic

Materials, December 14, 1984.

Charles B. Harris (University of California at Berkeley) - Picosecond

Studies of the Chemical Reactivity and Molecular Dynamics of Simple

Chemical Reactions in Liquids, January 25, 1985.

Peter B. Armentrout (University of California at Berkeley) - Ion Beam

Chemistry: From Triatomics To Transition Metals, February 1, 1985.

Sally Chapman (JILA) - Nonadiabatic Molecular Collisions in the ArH2

'^ System, February 8, 1985.

Mike L. Knotek (Sandia National Laboratory) - Mechanisms of Stimulated

Desorption, February 15, 1985.

Michael Trenary (University of Illinois at Chicago) - Reflection- Infrared Studies of Chemisorbed CO, February 22, 1985.

Kenneth C. Janda (California Institute of Technology) - Intramolecular

Vibrational Energy Transfer: van der Waals Molecules as Prototypes, March 1, 1985.

280
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Colloquia (cont.)

Rudolph A. Marcus (California Institute of Technology) - Electron

Transfers and the Franck-Condon Principle (The 1985 E. U. Condon

Lecture), March 14, 1985,

Mark Passler (Colorado School of Mines) - Low Energy Electron

Diffraction (LEED) Studies of NO Adsorbed on Nickel Surfaces,

March 15, 1985.

James C. Weisshaar (University of Wisconsin) - Gas Phase Organometallic

Ion Chemistry and Spectroscopy, March 22, 1985.

Timothy S. Zwier (Calvin College) - Multiphoton Studies of Clusters,

April 5, 1985.

David Smith (University of Birmingham) - Ion-Ion Recombination Studies,

April 12, 1985.

Wilson Ho (Cornell University) - Kinetics of Molecular Dissociation at

Surfaces, April 19, 1985.

Lional Goodman (Rutgers University) - Potential Surfaces of Molecules

and Ions as Revealed by Multiphoton Jet Spectroscopy, April 26,

1985.

Kit H. Bowen (Johns Hopkins University) - Negative Ion Photoelectron

Spectroscopy of Negative Cluster Ions, May 10, 1985.

281
INVITED TALKS

Quantum Physics Division (525)

P. L. Bender, "Laser Doppler Experiment Options for a 200 - 250 Km

Altitude Geopotential Research Mission," American Geophysical Union,

Baltimore, Maryland, May 28, 1985.

P. L. Bender, "Space Transponders and Gravitational Radiation," The

Fourth Marcel Grossmann Meeting on the Development of General Relativity, Rome, Italy, June 21, 1985.

G. H. Dunn, "Ion-Molecule Reactions At Very Low Temperatures and Densities," 37th Annual Gaseous Electronics Conference, University of

Colorado, Boulder, Colorado, October 9, 1984.

G. H. Dunn, "Experimental Measurements of the Effect of Extrinsic Fields

on Dielectronic Recombination," Workshop on Atomic Spectra and Collisions in External Fields," National Bureau of Standards, Gaithersburg,

Maryland, October 23, 1984.

G. H. Dunn, "Experimental Analysis of Field Effects," Workshop on Dielectronic Recombination: Coordination of Experiment and Theory,"

Rollins College, Winter Park, Florida, January 17, 1985.

G. H. Dunn, "Rydberg States From Dielectronic Recombination," Gordon

Research Conference On Atomic Physics, Brewster Academy, Wolfeboro, New

Hampshire, July 1, 1985.

G. H. Dunn, "Radiatively Stabilized Collisions: Dielectronic Recombination and Radiative Association," XIV ICEAC Meeting, Stanford University,

Stanford, California, July 26, 1985.

J. E. Faller, "Status and Plans For New Gravity Apparatus," Bavarian

Academy of Sciences, Munchen, West Germany, October 9, 1984.

J. E. Faller, "The Absolute Measurement of Gravity: A New Geophysical

Research Tool," Physics Department, Calvin College, Grand Rapids,

Michigan, April 12, 1985.

A. C. Gallagher, "Plasma Processes in Silane Discharge Deposition,"

Materials Research Society, Boston, Massachusetts, November 20, 1984.

A. C. Gallagher, "Molecular Continuum Radiation," Meeting of the Solar

Energy Research Institute on Amorphous Silicon, Washington, D. C., March

22, 1985.

282
INVITED TALKS

Quantum Physics Division (525)

S. Geltman, "Angular Distribution in Multiphoton Ionization," Center for

Basic Standards Colloquium, National Bureau of Standards, Gaithersburg,

Maryland, March 20, 1985.

J. L. Hall, "Laser Manipulation of Atoms' Velocity: Chirping the Light

Fantastic?!" MIT Quantum Electronics Seminar, Boston, Massachusetts,

October 23, 1984.

J. L. Hall, "Advances In Optical Heterodyne Spectroscopy," Optical

Society of America, San Diego, California, November 1, 1984.

J. L. Hall, "Laser Manipulation of Atom Velocities: Chirping the Light

Fantastic?!" University of Arkansas, Department of Physics,

Fayetteville, Arkansas, November 16, 1984.

D. G. Hummer, "The Internal Partition Function," Opacity Project Workshop, London, England, December 17, 1984.

D. G. H\immer, "Models For Atomic Partitions," Seminar, Institute for

Astronomy and Astrophysics, University of Munich, January 25, 1985.

D. G. Hummer, "The Effect of Wind Blanketing on Spectra of Hot Stars and

on the Determination of Stellar Parameters," Colloquium, Institute for

Astronomy, Zurich, Switzerland, April 16, 1985.

D. G. Hummer, "The Effect of Wind Blanketing on Spectra of Hot Stars and

on the Determination of Stellar Parameters," Colloquium, NORDITA, Copenhagen, Denmark, May 6, 1985.

D. G. Htimmer, "The Internal Partition Function," University of Copenhagen Observatory, Copenhagen, Denmark, May 8, 1985.

D. G. Hvunmer , "The Effect of Wind Blanketing on Spectra of Hot Stars and

on the Determination of Stellar Parameters," Colloquium, Institute for

Theoretical Astro Physics, Heidelberg, West Germany, May 14, 1985.

D. G. Hummer, "Intrinsic Parameters of Hot Blue Stars," Invited review

with R. P. Kudrutzki, lAU Symposium #116 on "Luminous Stars and Associations in Galaxies," Porto Heli, Greece, May 27, 1985.

D. G. Hummer, "The Effect of Wind Blanketing on Spectra of Hot Stars and on the Determination of Stellar Parameters," Colloquium, Department of

Astronomy, University of Leningrad, Leningrad, U.S.S.R., August 29, 1985

283
INVITED TALKS

Quantiim Physics Division (525)

D. G. Hummer, "The Sobolev Method for Line Formation with Continuous

Opacity," Theoretical Astrophysics Seminar, Department of Astronomy,

University of Leningrad, Leningrad, U.S.S.R., August 30, 1985.

S. R. Leone, "Electronic Energy Transfer in Metal Atoms," Short Wavelength Chemical Laser Workshop, Charleston, South Carolina, November 15,

1984.

S. R. Leone, "Reaction Dynamics of State-Selected Atoms and Radicals,"

1984 International Chemical Congress of Pacific Basin Societies,

Honolulu, Hawaii, December 19, 1984.

S. R. Leone, "Laser-Excited Chemical Dynamics, Chemistry Department,

University of Chicago, Chicago, Illinois, January 7, 1985.

S. R. Leone, "Laser Studies of Chemical Dynamics," Chemistry Department

Colloquium, Calvin College, Grand Rapids, Michigan, February 1985.

S. R. Leone, "Laser Studies of Chemical Dynamics," Chemistry Department

Colloquium, Michigan State University, East Lansing, Michigan, February

1985.

S. R. Leone, "Laser State-Resolved Collision Dynamics," Chemistry

Department Colloquium, The Johns Hopkins University, Baltimore,

Maryland, March 1985.

S. R. Leone, "Laser-Excited Chemical Dynamics," ACS Princeton Section

Colloquium, Princeton, New Jersey, March 1985.

S. R. Leone, "Lasers and Chemical Dynamics," University of Georgia,

Athens, Georgia, April 16, 1985.

S. R. Leone, "Lasers and Chemical Dynamics," Natural Science Division,

Tougaloo College, Tougaloo , Mississippi, April 17, 1985.

S. R. Leone, "Energy Transfer Processes of Aligned Excited States of Ca

Atoms," XIV ICPEAC, Stanford, California, July 1985.

S. R. Leone, "Laser State-Selection and Detection of Inelastic and

Reactive Chemical Dynamics , " International Union of Pure and Applied

Chemistry Meeting, Manchester, England, September 13, 1985.

J. L. Linsky, "Are Stars Like the Sun?" National Bureau of Standards,

Gaithersburg, Maryland, November 9, 1984.

284
INVITED TALKS

Quantum Physics Division (525)

J. L. Linsky, "The Outer Atmospheres and Winds of Cool Stars,"

Department of Physics and Astronomy, Michigan State University,

East Lansing, Michigan, November 14, 1984.

J. L. Linsky, "The Goals of Stellar Chromosphere/Corona Research in the

Next Decade," Department of Astronomy, University of Wisconsin, Madison,

Wisconsin, November 30, 1984.

J. L. Linsky, "Outer Atmospheres and Winds of Cool Stars," Max Planck

Institute For Astronomy, European Southern Observatory, Munich Observatory, Munchen, West Germany, April 24, 1985.

J. L. Linsky, "Modelling of Extended Chromospheres," Dunsink Bicentenary

Colloquium, Dunsink Observatory, Dublin, Ireland, September 9, 1985.

D. W. Norcross, "Low Energy Electron Scattering From HCN: Rotational

Excitation and Resonance Effects," Los Alamos National Laboratories,

Los Alamos, New Mexico, October 30, 1984.

D. W. Norcross, "Rotational and Vibrational Excitation of Molecules By

Low-Energy Electrons," Joint Symposium on Swarm Studies and Inelastic

Electron-Molecule Collisions, Granlibakken Resort, Tahoe City, California, July 21, 1985.

A. V. Phelps, "Relations Between Electron-Molecule Scattering and Swarm

Experiment and Analysis," Joint Symposium on Swarm Studies and Inelastic

Electron-Molecule Collisions, Granlibakken Resort, Tahoe City, California, July 20, 1985.

A. V. Phelps, "Electron Energy Transfer and Gas Heating During

Electrical Discharges in Molecular Gases, General Motors Research Laboratories, Detroit, Michigan, September 12, 1985.

A. V. Phelps, "Electron Energy Transfer and Gas Heating During Electrical Discharges," Engineering Physics Colloquium, Polytechnic Institute of New York, Farmingdale, NY, September 16, 1985.

A. V. Phelps, "Electrical Discharges in D2 and N2 at High Electric

Fields and Low Pressure," AT&T Bell Laboratories, Murray Hill, New

Jersey, September 17, 1985.

S. J. Smith, "Experimental Investigations of the Role of Laser Field

Fluctuations in Non-Linear Optical Absorption Processes," Colloquium at

Max Planck Institute Fur Quantem Optik, Garching, West Germany,

September 11, 1985.

285
INVITED TALKS

Quantum Physics Division (525)

S. J. Smith, "Experimental Investigations of the Role of Laser Field

Fluctuations in Non-Linear Optical Absorption Processes," presented at

the International School on Coherent Optics, Ustron, Poland,

September 19-26, 1985.

286
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

P. L. Bender, Member, Fundamental Physics and Chemistry Panel, Space

Science Board Study: Major Thrusts in Space Science: 1995-2015,

P. L. Bender, Member, Gravitation and Cosmic Physics Panel, Physics

Survey Committee of the National Research Council.

P. L. Bender,

P. L. Bender,

P. L. Bender,

NASA.

P. L. Bender,

Deformation,

Associate Editor, Journal of Geophysical Research.

Member, American Geophysical Union Committee on Fellows.

Member, Earth Observing System Science Steering Committee,

Member, Working Group 1 on Recent Plate Movements and

Inter-Union Commission on the Lithosphere.

P. L. Bender, Member, Crustal Dynamics Working Group, NASA.

G. H. Dunn, Member, National Research Council Committee on Atomic and

Molecular Science.

G. H. Dtinn, Member, Executive Committee, Division of Electron and Atomic

Physics, American Physical Society.

G. H. Dunn, Member, Panel on New Instrximents and Facilities in Atomic

and Molecular Science, CAMS. »

G. H. Dtmn, Chairman, Nominating Committee, Division of Electron and

Atomic Physics, American Physical Society.

G. H. Diinn, Chairman, Ad-hoc Committee on Atomic Data, for CAMS.

G. H. Dunn, Member, Program Committee for Conference on Atomic Processes

in High Temperature Plasmas, held at Asilomar, CA. Feb. 1985.

G. H. Dunn, Co-organizer, NATO Advanced Study Institute on Physics of

Electron-ion and Ion-Ion Collisions.

G. H. Dxinn, Organizer/Chairman, Symposium on Electron-Ion Collisions at

Conference on Atomic Processes in Fusion Plasmas, University of

California, Santa Cruz, CA, August 1985.

J. E. Faller, Member, Working Group II of the International Gravity

Commission.

287
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantiim Physics Division (525)

J. E. Faller, Member, Special Study Group 3.86, "Estimation of Absolute

Gravimetric Determinations," of the International Gravity Commission.

J. E. Faller, Member, Special Study Group 3.87, "Development of WorldWide Absolute Gravity Net," of the International Gravity Commis sion.

J. E. Faller, Member, U. S. Interagency Gravity Standards Committee.

J. E. Faller, Member, Management Operations Working Group on Lunar

Ranging.

J. E. Faller, Member, Physics Departments' "Geophysics Committee".

J. E. Faller, Member, External Awards Subcommittee of the American

Geophysical Society.

A. C. Gallagher, Member, Army Basic Research Steering Committee.

J. L. Hall, Delegate, Consultative Committee for the Definition of the

Meter (BIPM) , Sevres, France, 1970 - present.

J. L. Hall, Member, International Steering Committee for Conferences on Laser Spectroscopy.

J. L. Hall, Member, NBS Committee for NBS Precision Measurement Grants.

J. L. Hall, Member, Ad hoc Oversight Committee for Air Force Ring Laser

Gyro Program.

J. L. Hall, Member, Advisory Committee to the Global Oscillation Group,

National Solar Observatory.

D. G. Hummer, Member, Editorial Board, Computer Physics Communications.

D. G. Htimmer, Member, Steering Committee of the United Kingdom Collaborative Computational Project on Stellar Atmospheres.

S. R. Leone, Co-Chairman, Gordon Conference on Molecular Energy Transfer

for 1985.

S. R. Leone, Editorial Advisory Board, Chemical Reviews, 1982-1985.

S. R. Leone, Associate Editor, Journal of Chemical Physics, 1984-1987.

288
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

S. R. Leone, Editorial Advisory Board, Journal of Physical Chemistry,

1984-1987.

S. R. Leone, Member, NRC Committee, Army Research Office Review Board,

1984-1988.

J. L. Linsky, Member, Users' Committee, National Solar Observatory.

J. L. Linsky, Member, Users' Committee, International Ultraviolet

Explorer Satellite.

J. L. Linsky, Member, Management and Operations Working Group, Solar and

Heliospheric Physics Section, NASA.

J. L. Linsky, Chairman, Management and Operations Working Group,

Ultraviolet and Infrared Astronomy Section, NASA.

J. L. Linsky, Chairman, Ultraviolet Astronomy Working Group, American

Astronomical Society.

J. L. Linsky, Co- Investigator , High Resolution Spectrograph, Space

Telescope

.

J. L. Linsky, Member, Far Ultraviolet Spectrograph Explorer Science

Working Group

.

J. L. Linsky, Member, Scientific Organizing Committee, lAU Symposium No.

122, Circumstellar Matter, Heidelberg, Germany, June 23-27, 1986.

J. L. Linsky, Member, Proposal Review Panel, International Ultraviolet

Explorer Satellite.

J. L. Linsky, Member, Editorial Board, Solar Physics.

J. L. Linsky, Member, Committee to Study the Long-Range Scientific

Directions of Large -Aperture Ground-Based Solar Astronomy, Association

of Universities for Research in Astronomy (AURA)

.

J. L. Linsky, Member AURA/NSF Study of the Scientific Goals and Priorities of the National Solar Observatory, AURA and NSF.

J. L. Linsky, Interdisciplinary Scientist on the Advanced X-ray Astrophysical Facility (AXAF) and Member of the AXAF Science Working Group,

NASA.

289
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

J. L. Linsky, Member, Astrophysics Council, NASA.

J. L. Linsky, Member, lUE Long Range Planning Committee.

J. L. Linsky, Member, National Optical Astronomy Observatory (NOAO)

Director's Advisory Committee.

J. L. Linsky, Member, Committee on Coordinated Ground-Based and Space

Observing, NOAO.

D. W. Norcross, Member, Panel on Theoretical Atomic and Molecular

Sciences of the Committee on Atomic and Molecular Sciences of the

National Research Council.

D. W. Norcross, Member, Working Group Supervising Collaborative Computational Project 2 (Continuum States of Atoms and Molecules) of the U. K.

Science and Engineering Research Council, 1983 - present.

D. W. Norcross, Member, Publications Committee, Division of Electron

and Atomic Physics of the American Physical Society, 1985-1986.

A. V. Phelps, Member, Review Panel for Tokamak Modeling Program, Plasma

Physics Laboratory, Princeton University, 1985.

S. J. Smith, Member, Organizing Committee, Tenth International Conference on Atomic Physics, Tokyo, Japan, 1986.

S. J. Smith, Co-Chairman, Third International Conference on Multiphoton

Processes, Crete, September 5-11, 1984.

S. J. Smith, Editorial Board, Metrologia.

S. J. Smith, Chairman, Organizing Committee, Fourth International

Conference on Multiphoton Processes, Boulder, 1987.

290
CONSULTING

Quantum Physics Division (525)

P. L. Bender

Dr. Bender is consulting with the University GPS Consortium con- cerning the accuracy of determining tectonic motions with signals

from the Global Positioning System satellites.

S. Geltman

Dr. Geltman is consulting and advising with the Lawrence Livermore

National Laboratory on problems related to atomic processes in

plasmas

.

J. L. Hall

Dr. Hall is consulting with the Theoretical Astrophysics Group at

Caltech in the area of laser techniques for gravity wave detection,

and informally with colleagues in industry involved with stable

laser design and application, and also consults with:

U. S. Air Force Academy - supervision of Graduate Students Working

on Laser Stabilization and Laser Ring Gyros,

Ad hoc Oversight Committee for Air Force Ring Laser Gyro Program,

Advisory Committee to the Global Oscillation Network Group,

National Solar Laboratory.

D . G . Hummer

Dr. Hummer consults for the X-ray laser project at Livermore and

Los Alamos Laboratories.

291
CONSULTING

Quantum Physics Division (525)

J . L . Linsky

Dr. Linsky consults with NASA concerning (1) future programs in the

area of ultraviolet and infrared astronomy, (2) future programs in

solar and heliospheric physics, (3) operations and long range planning for the International Ultraviolet Explorer satellite, (4)

definition of the proposed Far Ultraviolet Explorer Spectrograph,

(5) definition of the proposed Advanced X-ray Astronomical

Facility, (6) calibration and initial operations of the Space

Telescope High Resolution Spectrograph, and (7) data operations for

future missions.

Dr. Linsky consults with the National Optical Astronomy Observatory and the Association of Universities for Research in Astronomy concerning (1) operation of the National Solar Observatory and

Sacramento Peak Observatory, (2) planning for coordinated groundbased and space observations, and (3) potential need for a large

aperature ground-based solar telescope.

D. W. Norcross

Dr. Norcross is consulting with the Theoretical Atomic and Molecular Physics Group at the Lawrence Livermore Laboratory on problems related to laser modeling, and is a Visiting Scientist (consultant) to Division T-4 of the Los Alamos Laboratory on problems

related to electron collisions with atoms, ions, and molecules.

A. V. Phelps

Dr. Phelps does informal consulting and advising with DoD and DoE

laboratories and their industrial and university contractors in the

area of atomic and molecular processes in high power switches,

laser induced breakdown and charged particle beam propagation. For

the Lawrence Livermore National Laboratory this has been formalized

by the granting of support for a postdoc.

292
OTHER AGENCY RESEARCH

Quantum Physics Division (525)

P. L. Bender NASA Integrated water vapor calibrator.

P. L. Bender JPL Perform integrated water vapor calibration

development

.

P. L. Bender NASA Determination of worldwide tectonic plate

motions and large scale intra-plate

distortions

.

G . H . Dunn DOE Determine atomic, molecular, and nuclear

data pertinent to the magnetic fusion

energy program.

G . H . D\mn KADE Support for Max Kade post doctoral fellowship exchange program, with A. Muller.

J. E. Faller AFGL Absolute gravity system development.

J. E. Faller MERADCOM Fabrication of two gravity gradiometers

for subsequent field testing and evaluation.

J. E. Faller CHINA Storeroom item purchases for China project

J. E. Faller DMA-N Absolute "G" co-op program.

J. E. Faller CANADA Construction of an absolute gravity

apparatus

.

J. E. Faller HANNOVER Construction of an absolute gravity

apparatus

.

J. E. Faller FINLAND Construction of an absolute gravity

apparatus

.

J. E. Faller AUSTRIA Construction of an absolute gravity

apparatus

.

A. C. Gallagher DOE Study spectroscopic diagnostics of

electron-atom collisions.

A. C. Gallagher CU/SERI Diagnostics of a glow discharge used

to produce hydrogenated amorphous

silicon films, with J. Scott.

293
OTHER AGENCY RESEARCH

Quantum Physics Division (525)

A. G. Gallagher AFOSR Electronic energy transfer processes in

the alkali/alkaline earth metal vapors.

J. W.

G. H.

Gallagher &

Dunn

DOE Cross sections and rates describing electron collisions with atoms and ions.

K. B. Gebbie NASA Energy Transport in the Solar Envelope and

Atmosphere

.

K. B. Gebbie NASA X-ray bright points on the quiet sun and

rapid UV brightenings in active regions.

K. B. Gebbie AFGL Solar Oscillations and Convective Flows as Probes of Structure in the Subphotosphere .

S . Geltman LLL Dielectronic theory adaptation.

J. L. Hall AF ACAD Stabilization of diode and gas lasers.

J. L. Hall ONR Study precision atomic beam spectroscopy

using stabilized lasers, with T. Baer

D. G. Hximmer NSF Theory and observation of expanding

atmospheres of early type stars, with

D. Abbott and B. Bohannon

S. R. Leone AF Diode laser probing of energy transfer in

XeF.

S. R. Leone AFOSR Electronic energy transfer processes

in the alkali/alkaline earth metal

vapors

.

S. R. Leone ARO Eximer laser photolysis studies of translation- to-vibration energy transfer.

S. R. Leone NASA Studies of M-1 protypical bonds for potential application to solar-pumped lasers.

S. R. Leone DOE Time-resolved free radicals and laserinitiated chain reactions.

S. R. Leone NSF State-resolved molecular dynamics.

294
OTHER AGENCY RESEARCH

Quantxam Physics Division (525)

S. R. Leone

S. R. Leone

S. R. Leone

S. R. Leone

J. L. Linsky

J. L. Linsky

J. L. Linsky

J. L. Linsky

J. L. Linsky

J. L. Linsky

J. L. Linsky

J. L, Linsky

J. L. Linsky

ACS

NSF

AFOSR

AF

NASA

NASA

NASA

t NASA

NASA

NASA

NASA

NASA

NASA

Infrared laser excitation amd fluorescence

of intramolecular vibrational relaxation

in hydrocarbons

.

Energy transfer and reactive exchange

in simple molecular systems, with

S. Kohler.

Argon ion laser/ring dye laser system.

State -resolved dynamics of ion-molecule

reactions in a flowing afterglow.

Advanced X-ray astrophysics facility

(AXAF)

.

X-ray study of Sigma Orionis E and other

helium- strong Bp stars, with D. Abbott

and A. Brown.

International ultraviolet experiment

studies of astronomical sources, with

C. Ambruster, T. Ayers, J. Bookbinder,

A. Brown, Caillault, K. Carpenter,

S. Drake and F. Walter

Perform basic research in solar physics,

with J. Cooper.

Search for coronal X-ray emission from the

young stars in the Ursa Major cluster

and stream, with C. Ambruster.

High resolution spectroscopy of late K and

M supergiants

.

Measurement of the properties of hot

astrophysical plasmas, with J. Cooper.

Measurement of the properties of hot

astrophysical plasmas.

Corona of Procyon, with F. Walter and

A. Brown.

295
OTHER AGENCY RESEARCH

Quantum Physics Division (525)

D. W. Norcross NSF Research equipment for computational

physics and applied mathematics.

D. W. Norcross DOE Basic research involving computational

physics and applied physics.

D. W. Norcross DOE Atomic and molecular collision processes

D. W. Norcross DOE Atomic data pertinent to the magnetic

fusion energy program.

A. V. Phelps AFOSR Transient discharges in high pressure

gases

.

A. V, Phelps AFWAL Detection of excited states by laser

induced fluorescene

.

A. V. Phelps LLL Non- equilibrium electrons in gases.

A. V. Phelps SANDIA Non-equilibrium electrons and gases.

S . J . Smith DOE Near resonant absorption in intense,

fluctuating laser fields.

296
TRIPS SPONSORED BY OTHERS

P. L. Bender

Quantum Physics Division (525)

October 16-19, 1984 - Greenbelt, Maryland.

Attended a meeting of NASA Lunar Ranging Working

Group, a meeting concerning Tectonic Measurements

with the Global Positioning System, and a meeting

of NASA Crustal Dynamics Working Group.

Sponsor: NASA Goddard.

October 30-November 2, 1984 - Chevy Chase, Maryland.

Attended meeting of NASA Earth Observation System

Science Committee.

Sponsor: NASA Goddard.

November 3-4, 1984 - Reno, Nevada.

Attended meeting of the U.S. Geodynamics Committee.

Sponsor: National Research Council.

January 10-11, 1985 - Pasadena, California.

Attended meeting of Task Group on Fundamental

Physics and Chemistry of the National Research

Council Space Science Board study on "Major

Directions For Space Sciences: 1995-2015."

Sponsor: National Academy of Sciences.

February 8-12, 1985 - Maui, Hawaii.

Attended a meeting of NASA Lunar Laser Ranging

Management/Operations Working Group.

Sponsors: NASA Goddard, University of Hawaii.

May 27-31, 1985 - Baltimore, Maryland.

Attended Spring meeting of the American Geophysical

Union and presented an invited talk.

Sponsor: NASA Goddard.

June 17-21, 1985 - Rome, Italy.

Attended the Fourth Marcel Grossmann Meeting on the

Recent Development of General Relativity and

presented invited talk.

Sponsor: Stanford University.

297
TRIPS SPONSORED BY OTHERS

Bender (cent.)

G . H . Dunn

Quantum Physics Division (525)

July 28 -August 2 , 1985 - Columbus, Ohio; Woods Hole,

Massachusetts

.

Attended a meeting of the MERIT Working Group

(Columbus)

;

Attended a meeting of the Space Science Board Study,

"Major Directions For Space Sciences 1995-2015"

(Hyannis)

.

Sponsors: NASA Goddard, National Academy of

Sciences

.

October 14-November 9, 1984 - Oak Ridge, Tennessee;

Washington , D . C

.

Collaborated on experiements of ionization of

mutually shared ions (Oak Ridge)

;

Attended NAS workshop on VUV and X-Ray Sources

(Washington, D.C.)-

Sponsors: Department of Energy, National Academy of

Science

.

January 8-15, 1985 - Brussels, Belgivim.

Planned and organized summer school on the "Physics

of Highly Ionized Ions," to be held in Belgium in

the autiimn of 1985.

Visited with Professor F. Broulliard of Louvain

University and consulted about electron- ion

collision experiments and their ECR ion source. Sponsor: NATO through Louvain University.

January 16-19, 1985 - Winter Park, Florida.

Attended workship entitled "Dielectronic

Recombination: Coordination of Experiment and

Theory," held at Rollins College.

Sponsor: Department of Energy.

February 23-28, 1985 - Monterey, California.

Attended American Physics Society Topical Conference

on Atomic Processes in High Temperature Plasmas

and presented a contributed paper.

Sponsor: Department of Energy.

298
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Dunn (cont.) April 24-25, 1985 - Washington, D. C.

Attended meeting of the Committee on Atomic and

Molecular Science, National Research Council.

Sponsor: National Academy of Sciences,

Jxine 30- July 7, 1985 - Wolfeboro, New Hampshire.

Attended Gordon Conference and presented invited

talk.

Sponsor: Gordon Research Conferences.

September 28-October 12, 1985 - Brussels, Belgitim.

Co-organizer of North Atlantic Treaty Organization's

Institute on Electron- Ion Collisions, present

invited lectures on dielectronic recombination.

Sponsor: NATO.

J. E. Faller October 7-28, 1984 - Munich, Hannover, Braunsweig,

Hamburg, West Germany; Paris, Corgese, Corsica,

France; Frankfurt, West Germany.

Visited Dr. Boedecker, President of SS-3-87, gave

talk at Bavarian Academy of Sciences;

Visited Munich Gravity Wave group at Institute of

Astrophysics (Munich)

;

Visited Drs . Roeder and Schnuell at the Institute

for Earth Measurement (Hannover)

;

Visited Drs. Germen and De Boer at the PhysikalischTechnisched Bundesantalt (Braunsweig)

;

Visited Dr, Makris at the Institute for Geophysics

(Hamburg)

;

Visited Drs. Sakuma, Speake, and Quinn at the Bureau

International des Poids et Measures (Paris)

;

Attended colloquium on "Kilometric Optical Arrays in

Space," and present a paper (Corgese, Corsica,

France)

;

Visited Institute for Applied Geodesy (Frankfurt)

.

Sponsor: Institute for Earth Measurement.

299
TRIPS SPONSORED BY OTHERS

Faller (cont.)

A. C. Gallagher

Quantum Physics Division (525)

December 2-7, 1984 - San Francisco, California;

Los Angeles, California.

Attended the Fall meeting of the American

Geophysical Union (San Francisco)

;

Attended a Management Operation Workshop Group for

Laser Ranging Advancing (Los Angeles)

.

Sponsor: NASA Goddard.

December 16-23, 1984 - Maul, Hawaii.

Site visit at Lunar Laser Ranging Station;

Consulted and did problem solving and observing on several ranging runs. Sponsor: NASA Goddard.

February 8-12, 1985 - Maui, Hawaii.

Attended a Management Operation Group for Lunar

Laser Ranging sponsored by the University of

Hawaii

.

Sponsor: NASA Goddard.

April 11-14, 1985 - Grand Rapids, Michigan.

Presented an invited seminar at Calvin College.

Sponsor: NASA Goddard.

May 26-30, 1985 - Baltimore, Maryland.

Attended AGU Meeting, participated in MOWG Lunar

Laser Working Group, and attended Federal Gravity

Commission Meeting.

Sponsor: NASA Goddard.

September 15-20, 1985 - Kahalui , Maui, Hawaii.

Attended a Management Operation Group for Lunar

Laser Ranging.

Sponsor: NASA Goddard.

November 27-28, 1984 - Boston, Massachusetts.

Attended the Materials Research Society Conference

and presented a talk.

Sponsor: Solar Energy Research Institute.

300
TRIPS SPONSORED BY OTHERS

Gallagher (cont.)

S . Geltman

Quantum Physics Division (525)

March 18-23, 1985 - Cleveland, Ohio; Washington,

D. C.

Visited Dr. John Ingold, General Electric Lamp Division, and gave talk (Cleveland)

;

Attended Contractor's Meeting of the Solar Energy

Research Institute on Amorphous Silicon

(Washington, D.C).

Sponsor: Solar Energy Research Institute.

August 29-September 30, 1985 - Madison, Wisconsin.

Collaborated at the University of Wisconsin with

C. C. Lin, W. Anderson, and J. Lawler.

Sponsor: University of Wisconsin.

December 3-7, 1984 - Livermore, California.

Consulted with Dr. Richard More on dielectronic

recombination computer package at Lawrence

Livermore Labs

.

Sponsor: Lawrence Livermore Laboratory.

February 4-8, 1985 - Livermore, California.

Consulted with Dr. Richard More on dielectronic

recombination computer package at Lawrence

Livermore Labs

.

Sponsor: Lawrence Livermore Laboratory.

jTine 5-7, 1985 - Livermore, California.

Consulted with Dr. Richard More on dielectronic

recombination computer package at Lawrence

Livermore Labs

.

Sponsor: Lawrence Livermore Laboratory.

September 9-11, 1985 - Livermore, California.

Consulted with Dr. Richard More on dielectronic

recombination computer package at Lawrence

Livermore Labs

.

Sponsor: Lawrence Livermore Laboratory.

301
TRIPS SPONSORED BY OTHERS

J. L. Hall

Quantum Physics Division (525)

October 21-24, 1984 - Boston, Massachusetts.

Presented an invited lecture at MIT Quantum

Electronics Seminar entitled "Atom Velocity

Manipulation with Lasers: Chirping the Light

Fantastic"

;

Interacted with Professors M. S. Feld, S. Ezekiel,

R. Field, and R. Weiss on technical topics of

mutual interest.

Sponsor: Massachesetts Institute of Technology.

November 15-17, 1984 - Fayetteville, Arkansas.

Gave an invited lecture "Atomic Velocity

Manipulation with Lasers: Chirping the Light

Fantastic"

;

Conducted technical discussions with Professor

S. Singh on Photon Counting Problems.

Sponsor: University of Arizona.

January 4-19, 1985 - Sevres, Villetaneuse , Paris,

Orsay, and Ecole Normals, France; Hamburg, West

Germany.

Visited BIPM (Sevres)

;

Visited Lab de Physique des lasers (Villetaneuse)

;

Attended CNRS (Centre Nationale de Recherches

Scientifiques) Memorial Symposium in honor of

A. Kastler;

Visited University of Paris (Paris)

;

Visited with the Gravity Wave Antenna group (Orsay

and at Ecole Normale)

;

Discussions with Professor P. E. Toschek and

Dr. R. Blatt (Hamburg).

Sponsor: Centre Nationale de Recherches

Scientifiques

June 11-14, 1985 - Tucson, Arizona.

Served on an advisory panel concerned with global

solar oscillation network.

Sponsor: National Solar Observatory.

302
TRIPS SPONSORED BY OTHERS

J. K. Hoskins

D . G . Hvimmer

Quantum Physics Division (525)

October 21-27, 1984 - Harpers Ferry, West Virginia;

Bedford, Massachusetts.

Attended Chapman Conference sponsored by the

American Geophysical Union (Harpers Ferry)

;

Consulted with Sgt. Roger Sands at the AF

Geophysical Lab on absolute gravity measurements

and instruments (Bedford)

.

Sponsor: Defense Mapping Agency,

October 1, 1984 - September 30, 1985 - University of

Munich, West Germany.

Accepted an award from the Alexander von Hiamboldt

Foundation, an independent foundation supported by

the Federal Republic of Germany, and used for

support of a 1-year foreign training assignment at

the Institute of Astronomy and Astrophysics at the

University of Munich, West Germany.

Sponsor: Alexander von Humboldt Foundation.

December 10-18, 1984 - London, England.

Opacity Project Workshop: Presented invited review;

Worked with collaborators at Univiversity College

London

.

Sponsor: Science and Engineering Research Council

(SERC)

.

January 6-15, 1985 - Manchester, England.

Collaborative Computational Project on Stellar Atmospheres: 2 -day conference and meeting of Steering

Committee and Work with collaborators at

University College London.

Sponsor: Science and Engineering Research Council

(SERC)

.

March 25-29, 1985 - Frankfurt, Germany.

Attended Bi-annaul Conference of German Astronomical

Society: Presented three papers.

Sponsor: von Humboldt Foundation.

303
TRIPS SPONSORED BY OTHERS

H\immer (cont.)

S . R . Leone

Quantiam Physics Division (525)

April 15-16, 1985 - Zurich, Switzerland.

Presented colloquium at the Institute for Astronomy,

University of Zurich.

Sponsor; University of Zurich.

May 4-8, 1985 - Copenhagen, Denmark.

Presented two Colloquia: NORDITA and University of

Copenhagen Observatory.

Sponsor: NORDITA.

May 14, 1985 - Heidelberg, Germany.

Presented colloquium at the Institute for

Theoretical Astrophysics, University of Heidelberg

Sponsor: University of Heidelberg.

May 26-Jxine 2, 1985 - Porto Heli, Greece.

Presented invited review and three contributed

papers at the lAU Symposium #116, Stars and

Associations in Galaxies.

Sponsor; von Humboldt Foundation.

August 25, 1985-September 5, 1985 - Leningrad,

U.S.S.R.

Presented two colloquia;

Consulted with Professors Yuri Demkov, V. V. Ivanov,

A. A. Kutepov, and V. V. Sobolev at the University

of Leningrad concerning radiative transfer and

spectral line formation.

Sponsor: University of Leningrad.

January 3-8, 1985 - Chicago, Illinois.

Presented departmental colloquium at The University

of Chicago.

Sponsor: The University of Chicago.

304
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Leone (cont.) February 12-15, 1985 - Grand Rapids and Lansing,

Michigan.

Presented a seminar at Calvin College

(Grand Rapids)

;

Presented a seminar at Michigan State University

(Lansing)

,

Sponsors: Calvin College & Seminary and Michigan

State University.

March 18-21, 1985 - Baltimore, Maryland; Princeton,

New Jersey.

Presented a seminar at Johns Hopkins University

(Baltimore)

;

Presented a seminar at Princeton University

(Princeton)

.

Sponsors: Johns Hopkins University and Princeton

University.

April 15-18, 1985 - Athens, Georgia; Tougaloo,

Mississippi

.

Visited University of Georgia and presented a seminar (Athens , Georgia)

;

Visited Tougaloo College and presented a colloquium

(Tougaloo)

.

Sponsors: The University of Georgia and Tougaloo

College

.

July 6-12, 1985 - Wolfeboro, New Hampshire.

Attended a Gordon Conference on Molecular Energy

Transfer

;

Chaired and organized Conference along with

Professor Paul Houston.

Sponsor: Gordon Research Conferences.

August 27, 1985 - Colorado Springs, Colorado.

Visited Frank J. Seiler's laboratory at the U. S.

Air Force Academy to discuss research.

Sponsor: Kirtland Air Force Base.

305
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Leone (cont.) September 7-14, 1985 - Manchester, England.

Attended and presented invited talk at International

Union of Pure and Applied Chemistry meeting.

Sponsor: lUPAC Meeting.

J. L. Linsky September 30-0ctober 2, 1984 - Greenbelt, Maryland.

Attended meeting of FUSE working group.

Sponsor: ORI, Inc.

November 12-16, 1984 -East Lansing, Michigan;

Greenbelt, Maryland.

Gave a colloquium and consulted at the Department of

Physics and Astronomy, Michigan State University

(East Lansing)

;

Attended meeting of the lUE Long Range Planning

Committee at Goddard Space Flight Center

(Greenbelt)

.

Sponsors: Michigan State University and NASA

Goddard.

November 18-20, 1984 - Tucson, Arizona.

Attended meeting of the Director's Advisory

Committee of the National Optical Astronomy

Observatory (NOAO)

.

Sponsor: Association of Universities for Research

In Astronomy, Inc.

November 26-30, 1984 - Madison, Wisconsin.

Attended meeting of the HRS Investigation Definition

Team.

Sponsor: NASA Goddard.

December 10-14, 1984 - Huntsville, Alabama.

Attended meeting of the NASA Solar and Heliospheric

Management and Operations Working Group;

Attended Marshall Space Flight Center Neighborhood

Symposium and presented a contributed paper.

Sponsor: The University of Alabama.

306
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Linsky (cont.) December 20-28, 1984 - Washington, D.C.

Made presentation to Dr. Charles Pellerin, Chief of

the Astronomy Division at NASA, on the Guest

Observer Program of the lUE satellite.

Sponsor: Creative Management Associates, Inc.

Jamiary 13-17, 1985 - Tucson, Arizona.

Attended and presented papers at the American

Astronomical Society.

Sponsor: NASA Goddard.

January 20-24, 1985 - Tucson, Arizona; Princeton,

New Jersey.

Attended meeting of National Solar Obsem/atory Users

Committee (Tucson)

;

Attended meeting of Space Telescope Guaranteed Time

Observers to finalize Space Telescope Observing

plans (Princeton)

.

Sponsors: National Solar Observatory and

Association of Universities for Research in

Astronomy, Inc. and NA.SA Goddard.

February 19-22, 1985 - Greenbelt, Maryland.

Attended meeting of the NASA Astronomy and

Relativity Management and Operations Working Group

Sponsor: NASA Goddard.

March 3-8, 1985 - Greenbelt, Maryland; Austin,

Texas

.

Attended a meeting of the Space Telescope Imaging

Spectrograph Team (Greenbelt)

;

Attended a meeting of the Space Telescope High

Resolution Spectrograph Team (Austin)

.

Sponsor: NASA Goddard.

307
TRIPS SPONSORED BY OTHERS

Quantxim Physics Division (525)

Linsky (cont.) March 13-26, 1985 - Canberra, Australia; Tucson,

Arizona; Washington, D.C.

Attended meeting of the NASA-ESA Australian Far

Ultraviolet Explorer Science Working Group

(Canberra)

;

Attended the National Optical Astronomy Observatory

Directors' Advisory Committee Meeting (Tucson);

Attended meeting of NASA Astrophysics Council

(Washington, D.C.)-

Sponsors: The University of Virginia, Battelle, and

National Optical Astronomy Observatories.

April 2-4, 1985 - Tucson, Arizona.

Attended a meeting of the National Optical Astronomy

Observatories Committee on Coordinated

Ground-Based and Space Observing.

Sponsor: NASA Goddard.

April 19 -May 2, 1985 - Madrid, Spain; Mxinich, West

Germany; Heidelberg, West Germamy; Armagh,

Northern Ireland.

Attended a meeting of the lUE (International Ultraviolet Explorer Satellite) NASA-ESA-UK

Coordinating Committee;

Visited the Institute for Astronomy and Astrophysics

and gave a colloquium;

Attended a meeting of the Scientific Organizing

Committee of lAU (International Astronomical

Union) Symposium No. 122 (Heidelberg);

Wrote a specific paper with colleagues based on lUE

data (Armagh, Northern Ireland).

Sponsors: NASA Goddard, lUE NASA-ESA-UK

Coordinating Committee, Institute Astronomy and

Astrophysics, and lAU Symposium No. 122.

308
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Linsky (cont.) May 12-16, 1985 - Tucson, Arizona; Huntsville,

Alabama

.

Attended a meeting of the National Solar Obser'/ator;.'

User's Committee (Tucson);

Attended the AXAr Science iTorking Group at Marshall

Space Flight Center (Hiir.tsville) . Sponsors: National Optical Astronomy Obser'/atories

(AURA) and i\ASA George C. Marsha^-j. Stace r— tgnt

Center

.

May 20-22, 1985 - Greenbelt, Maryland.

Attended a meeting of the 21ASA. -Astroprrv sics Council

at Goddard Space Flight Center.

Sponsor: Battelle.

Jxine 2-7, 1985 - Charlottesville, Virginia.

Attended the 166th Meeting of the American

Astronomical Society and presented contributed

papers

.

Sponsor: N.ASA

.

Jtme 16-21, 1985 - Tucson, Arizona.

Attended a meeting of the AURA. NSF Study of

Scientific Goals and Priorities of the National

Solar Obser'.’’atory

.

Sponsor: AURA, Inc. Imprest F'und, National Optical

Astronomv Obseir/atories

.

J-une 23-25, 1985 - Washington, D. C.

Consulted with Sam Keller (NASA Deputy/ Assistant

.Administrator for Science and Technology.') and

staff members of the House Committee on Science

and Technology.* covering future NA.S.A missions.

Sponsor: N.AS.A Goddard.

July 23-24, 1985 - Washington, D. C. -Attended a meeting of the AXAF Science Working

Group

.

Sponsor: NASA George C. Marshall Space Flight

Center

.

309
TRIPS SPONSORED BY OTHERS

Linsky (cont.)

D. J. Nesbitt

D. W. Norcross

Quantum Physics Division (525)

September 1-8, 1985 - Dublin, Ireland.

Attended the Dunsink Bicentenary Colloquixim "Circumstellar Material: Late-Type Stars," and presented

an invited talk on "Modeling of Extended

Chromospheres .

Sponsor: National Science Foundation.

July 6-12, 1985 - Wolfeboro, New Hampshire.

Attended Gordon Conference on Molecular Energy

Transfer.

Chaired session on "Intramolecular Vibrational

Energy Transfer"

.

Sponsor: Gordon Research Conferences.

October 28-30, 1984 - Los Alamos, New Mexico.

Consulted with groups T4 and T12 at Los Alamos

National Laboratories on problems in electron-atom

and electron-molecule collisions.

Sponsor: Los Alamos National Laboratory.

December 8-11, 1984 - Washington, D.C.

Attended meeting of the subpanel on Atomic Theory of

CAMS of the NSF.

Sponsor: National Academy of Science.

May 12-14, 1985 - Chapel Hill, North Carolina.

Attended a Department of Energy's contractor

meeting.

Sponsor: Department of Energy.

May 28-31, 1985 - Norman, Oklahoma.

Attended annual DEAP meeting and reported to

membership of DEAP as a member of NRC Panel on AMO

theory.

Sponsor: Department of Energy.

310
TRIPS SPONSORED BY OTHERS

Norcross (cont.)

A. V. Phelps

S . J . Smith

Quantum Physics Division (525)

July 19-23, 1985 - Lake Tahoe, Nevada.

Attended 4th International Swarm Seminar and

Inelastic Electron-Molecule Seminar and presented

invited talk.

Sponsors; Department of Energy and California

Institute of Technology.

November 4-7, 1984 - Waltham, Massachusetts.

Participated in symposium on "Radiation in Plasmas,"

and discussed joint papers and research with

Dr. L. C. Pitchford at GTE Laboratories, Inc.

Sponsor: GTE Laboratories.

July 19-23, 1985 - Lake Tahoe, Nevada.

Attended 4th International Swarm Seminar and

Inelastic Electron-Molecule Seminar and presented

invited talk.

Sponsors: Department of Energy and California

Institute of Technology.

September 11-12, 1985 - Detroit, Michigan.

Visited General Motors Research Laboratories and

presented a colloquixam and discussed their new

research program on the initiation of combustion

with electrical discharges.

Sponsor: General Motors.

September 13-18, Farmingdale, New York; Murray Hill,

New Jersey.

Presented an Engineering Physics Colloquium at Polytechnic Institute of New York (Farmingdale)

;

Visited AT&T Bell Laboratories and presented a seminar on work at JILA with discharges at low

pressures and high electric fields.

Sponsor: Polytechnic Institute and AT&T.

May 12-14, 1985 - Chapel Hill, North Carolina.

Attended DoE Contractor's Meeting.

Sponsor; Department of Energy.

311
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

Smith (cont.) September 12, 1985 - Garching, West Germany.

Presented an invited colloquium at Max Planck

Institute Fur Quantem Optik.

Sponsor; Max Planck Institute.

September 19-26, 1985 - Ustron, Poland.

Presented an invited talk at the International

School on Coherent Optics.

Sponsor: National Science Foundation.

312
UNIVERSITY AND DEPARTMENT COMMITTEE MEMBERSHIPS

Quantum Physics Division (525)

P. L. Bender Thesis Committees for:

Z. D. Bergen

Physics Department, University of Colorado

P. T. Keyser

Physics Department, University of Colorado

M . D . Rayman

Physics Department, University of Colorado

B. Shahid- Saless

Physics Department, University of Colorado

T. M. Van Dam

Geological Sciences Department, University of

Colorado

G . H . Dunn Graduate Committee, Department of Physics

JILA Executive Committee

JILA Shops Committee

Member, several thesis & examinations committees

NML EEC Coordinator

A. C. Gallagher JILA Space Committee

Thesis Committees for:

S . Davidson

Physics Department, University of Colorado

J . Doyle

Physics Department, University of Colorado

X. Han

Physics Department, University of Colorado

M. 0' Callaghan

Physics Department, University of Colorado

313
UNIVERSITY AND DEPARTMENT COMMITTEE MEMBERSHIPS

Gallagher (cont .

)

K. B. Gebbie

S. Geltman

J. L. Hall

Quantum Physics Division (525)

R. Robertson

Physics Department, University of Colorado

G. Schinn

Physics Department, University of Colorado

Thesis Committee for:

D. Haber

Astrophysical , Planetary and Atmospheric Sciences

Department, University of Colorado

JILA Executive Committee

JILA Rules Committee

JILA Editorial Committee

Teaching Evaluation Committee, University of Colorado

Thesis Committee for:

R. Grobe

Physics Department, University of Colorado

Chairman, Thesis Committees for:

M . D . Rayman

Physics Department, University of Colorado

Zhu Miao

Physics Department, University of Colorado

Mike Winters

Physics Department, University of Colorado

314
UNIVERSITY AND DEPARTMENT COMMITTEE MEMBERSHIPS

Quantum Physics Division (525)

D . G . Hummer Thesis Committees for:

D. L. Carroll

Physics Department, University of Colorado

R. Russell

Astrophysical , Planetary, and Atmospheric Sciences

Department, University of Colorado

S. Voels

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

S. McCandless

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

P. Becker

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

S. R. Leone Chairman, Graduate Admissions Committee, Department

of Chemistry

Final Ph.D. Defense Committees for:

Bob Robertson

Physics Department, University of Colorado

Charles Hamilton

Chemical Physics Program, University of Colorado

JILA Executive Committee

J. L. Linsky University Space Science and Policy Task Force

Thesis Committees for:

P. L. Bornmann

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

315
UNIVERSITY AND DEPARTMENT COMMITTEE MEMBERSHIPS

Linsky (cont.)

D. J. Nesbitt

D. W. Norcross

A. V. Phelps

Quantum Physics Division (525)

S . Saar

Astrophysical , Planetary, and Atmospheric Sciences

Department, University of Colorado

T. Bastian

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

J. Neff

Astrophysical, Planetary, and Atmospheric Sciences

Department, University of Colorado

Co-Chairman, JILA Colloquium Committee

JIIA Data Center Advisory Committee

Library Committee, Department of Chemistry

Faculty Secretary, Department of Chemistry

Organizing Committee, Physical Chemistry Workshop

Chairman of JILA, January 1983 - December 1984

JILA Computing Committee

Graduate Committee, Department of Physics

Computing Committee, Department of Physics

Member, President's Search Committee for Director,

University Office of Space Sciences and Technology

Thesis Committee for;

T. Gorczyca

Physics Department, University of Colorado

Thesis Committees for

J. F. Benage

Physics Department, University of Colorado

316
UNIVERSITY AND DEPARTMENT COMMITTEE MEMBERSHIPS

Quantum Physics Division (525)

Phelps (cont,, ) R. H. Chatham

Physics Department, University of Colorado

R. M. Robertson

Physics Department, University of Colorado

M. 0' Callaghan

Physics Department, University of Colorado

S. J. Smith Member, JILA Executive Committee

Member, Chemical Physics Committee, Department o Physics

Member, JILA Building Committee

317
GRADUATE STUDENTS AND POSTDOCTORAL RESEARCH ASSOCIATES SUPERVISED

Quantum Physics Division (525)

Graduate Students Postdoctoral Research

Associates

P. L. Bender J. H . Lyou M. A. Vincent

A. Rizzi

S. D. Swartz

S. J. Walter

G . H . Dunn S. Jefferts B. DePaola

M. Schauer N. Djurid

K. Timmer

E. Wahl in

J. E. Faller P. Keyset J. K, Hoskins (NRC)

T. Niebauer

A. C. Gallagher S. Davidson H. Chatham

J. Doyle J. Kelly

X. Han

M. 0' Callaghan

R. Robertson

G. Schinn

S. Geltman S. Haan

J. L. Hall M. Rayman J. M, Chartier

M. Winters C. Salamon

N. C . Wong

M. Zhu

D . G . Hxamraer D. Carroll D. C. Abbott

R. Russell

S. Voels

S. R. Leone K. Carleton (NSF) V. Bierbaum (25%)

C. Chee W. Bussert

L. Cousins D. J. Donaldson (NSERC)

M. Hale R. Dressier

C. Hamilton H. Haugen

W. Hess A. Langford

G. H. Lin J. Maier (NATO)

J. Smedley H. Meyer

D. Neuschafer

318
GRADUATE STUDENTS AND POSTDOCTORAL RESEARCH ASSOCIATES SUPERVISED

J. L. Linsky

D. J. Nesbitt

D. W. Norcross

A. V. Phelps

S . J . Smith

Quantum Physics Division (525)

Graduate Students Postdoctoral Re: Associates

P . Bornman C. Armbruster

J. Neff A. Brown

S . Saar J. P. Caillault

K. Carpenter

C . Lovej oy

M. Schuder

S . Drake

T . Gorczyca S . Alston

J. Kelly A. Jain

F. da Paixao

D. Harmin

F. Parpia

A. Pradhan

B. Jelenkovid

H. Tischer

B. Wedding

K. Arnett M. Hamilton

319
COURSES TAUGHT AT UNIVERSITY OF COLORADO

Quantum Physics Division (525)

S. Geltman Independent Study in Atomic Collision Theory (Fall

1985)

J. L. Hall Laser Stabilization - Physics 696

S. R. Leone Physical Chemistry Laboratory Course - Development

and construction of new experiments

D. J. Nesbitt Chemistry 558 - Quantum Chemistry (Fall 1985)

D. W. Norcross Recitation - Physics III (Fall 1985)

320
BACKGROUND ON JILA

Quantum Physics is the division through which NBS participates in

the Joint Institute for Laboratory Astrophysics, a cooperative enterprise between NBS and the University of Colorado. In collaboration with

University faculty and visiting scientists, the Division conducts the

kind of long-term, high-risk research on which the Bureau's ability to

provide standards, measurements, and data ultimately depends. The Division's objectives include;

o Developing the laser as a refined measurement tool and applying it

to tests of fundamental laws of physics such as the postulates of

special and general and relativity.

o Improving the theory and instrumentation required to measure astro

physical and geophysical quantities such as the cosmic distance

scale, the acceleration of the Earth's gravity, and the long distances involved in determining crustal movements.

o Researching new techniques for measuring interactions involving

atoms and molecules, to provide data essential in areas such as nuclear fusion, advanced lighting, and laser development.

o Developing and applying measurement techniques to advance fundamental understanding of microscopic molecular processes such as those that occur in combustion and laser- initiated chemical

reactions

.

o Interacting with University faculty and visiting scientists to

maintain expertise at the forefront of research in physics.

o Transferring the results of its research and the technology

developed to the Nation's industries, universities and other

government agencies

.

o Exchanging ideas and skills with other scientists in NBS through

visits, seminars and longer-term interchanges of personnel.

A direct outgrowth of the national space program in the early postwar period, JILA was formed in response to a report of the Space Science

Board of the National Academy of Sciences. That report pointed to serious gaps in our basic understanding of the behavior of atoms and molecules in terrestrial, planetary, solar and stellar atmospheres. The

unifying theme for the Institute therefore became the physics of gaseous

atmospheres. Since then, however, JILA has responded to changing

national needs and to the requirements of its parent organizations.

Thus the Institute has become a world leader not only in atomic and

321
JILA STAFFING 1985-1986

TOTAL - 212

GRAD. STUDENTS f

59

322
molecular science and astrophysics but also in precision measurement,

laser physics, and certain areas of geophysics.

The permanent Ph.D. scientists or "Fellows if JILA" , of which there

are currently 22, form a governing body that sets policy, subject to

review by the Director of NBS and the President of the University. A

Chairman, elected every two years by the Fellows, has much the same role

as the chairman of an academic department. Assisted by an executive

committee, he is responsible for operating the Institute within the

policies set out by the Fellows. Of the 22 Fellows, 8 are fulltime

faculty members from the Departments of Physics, Chemistry, and Astrophysical, Planetary and Atmospheric Sciences; 14 are NBS employees, of

which 13 are in the Quantum Physics Division and 1 is in the Time and

Frequency Division. Although these scientists work side by side, sharing facilities and responsibility for the success of the Institute, each

remains officially responsible to his respective employer, NBS and its

Director in one case, the University and the academic department in the

other

.

Through their adjoint faculty appointments, NBS scientists at JILA

have both the opportunity and responsibility to teach courses and participate in other faculty activities. This gives them access to graduate and undergraduate students, some of whom become interested in pursuing research directed toward NBS goals. Of 59 graduate students in

JILA, 40 are supervised in their research by NBS scientists; of 42 postdoctoral research associates, 33 work with NBS scientists. Some have

subsequently joined NBS and now occupy positions of leadership; others

are carrying the knowledge and skills acquired at NBS to the Nation's

industries, universities and other government agencies. Of over 100

graduate students and research associates supervised by NBS staff at

JILA during the past 8 years, 20% are now in industry, 20% in government

agencies, and the remainder largely in universities.

Besides the graduate students and postdoctoral research associates,

the Visiting Fellows Program is probably the single most important factor in maintaining an atmosphere of change and excitement in JILA. The

Program provides partial funding for some ten internationally distinguished scientists a year to spend up to twelve months at JILA collaborating with resident scientists. Since its inception 24 years ago, the

Program has become internationally renowned. More than 220 senior

scientists from 29 foreign countries as well as the U.S. have participated. The number of applicants exceeds the number of positions typically by a factor of four; in accordance with the Memorandum of Understanding, applicants are chosen according to scholarly achievement, demonstrated interest in the scientific and technical objectives of JILA,

and the recommendations of their peers.

For NBS. and University researchers alike, perhaps the greatest

attraction of JILA is the large concentration of scientific talent in

atomic and molecular physics and closely related areas. Neither

323
institution, with its broad responsibility for measurement in one case and for education in the other, could justify such a large number of

senior scientists in a single area. Together these researchers are able

to collaborate, exchange ideas and attract visiting scientists iri a way

that would be impossible for two much smaller groups operating

separately.

324
NBS-114A WEV. 2-«CI

^.S. OEPT. OP COMM. ' BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR/85-3254

2. Performing Organ. Report No. 3. Publication Date

OCTOBER 1985

4 . TITLE AND SUBTITLE

Technical Activities 1985

Center for Basic Standards

5. AUTHOR(S)

Karl G. Kessler

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

10. supplementary notes

[' 'I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes the research and technical activities of the Center

for Basic Standards during the Fiscal Year 1985. These activities include work

in the areas of electricity, temperature and pressure, mass and length, time and

frequency, quantum metrology, and quantum physics.

12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon

Astrophysics; atomic and molecular physics; electrical standards; fundamental constant

gravity measurements; laser physics; length standards; mass standards; pressure and

vacuum standards; temperature standards; time and frequency standards; X-ray and gamni^;

13. availability ray wavelength standards

1 •/ i Unlimited

J For Official Distribution. Do Not Release to NTIS

i

i Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

IY 1 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGF'

330

1 5. Price

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