Technical Activities 1983

Center for Basic Standards

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Basic Standards

Washington, DC 20234

November 1983

Final

Issued January 1984

Prepared for: U S. DEPARTMENT OF COMMERCE

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National Bureau of Standards

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TECHNICAL ACTIVITIES 1983

CENTER FOR BASIC STANDARDS

Karl G. Kessler, Director

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Basic Standards

Washington, DC 20234

November 1 983

Final

Issued January 1984

Prepared for: U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Malcolm Baidrige. Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director



TABLE OF CONTENTS

Part II Page

Technical Activities:

Introduction 1

Quantum Metrology Group 2

Electricity Division 21

Temperature and Pressure Division 81

Length and Mass Division 123

Time and Frequency Division 135

Quantum Physics Division 187

i i
I1I

II

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li11
INTRODUCTION

This book is Part II of the 1983 Annual Report of the Center for

Basic Standards and contains a summary of the technical activities of

the Center for the period October 1, 1982 to September 30, 1983. The

Center is one of the five resources 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, Washington, D.C. 20234.


IMII

fe1I
QUANTUM METROLOGY GROUP

SUMMARY OF ACTIVITIES

FISCAL YEAR 1983

I. OVERVIEW

In the period of 1979 to 1982 there had been a general contraction

of the activities and staff of the Quantum Metrology Group. It is a pleasure to report that this trend was significantly reversed during

the past year. Two full-time staff people have been added to the

group and three guest workers were in residence. Since no entirely

new programs were begun, expansion and acceleration of existing

programs in precision x-ray and y-ray wavelength measurements and

inner shell physics occurred. In addition the important measurement

of a Si crystal lattice spacing was revived.

Efforts in the area of precision x-ray and y-ray wavelengths have

been concentrated on bringing into operation a four-meter Dumond

curved crystal spectrometer. Basil Duval, a guest worker from Culham

Laboratory and Oxford University, and Ernie Kessler were the primary

contributors to this effort. Firm plans to move a precision double

flat crystal spectrometer to the Institut Laue-Langevin (ILL), Grenoble,

France, have been made and the instrument should be in place and

operational by late November 1983. This activity has been discussed a number of times over the past 4 years but only during the past year

have funds and staff made this venture possible. Geoff Greene, a new

staff member, will be the resident NBS scientist for the first year of

operation. During installation and initial operation, Ernie Kessler

and Richard Deslattes will also be at ILL. Precision measurement of

high energy gamma-rays (>2 MeV) is the purpose of moving this facility

to ILL.

A manuscript with Kansas State University and Brookhaven National

Laboratory on the Is Lamb shift measurement from C£+^7 is nearing

completion. Data concerning the Is Lamb shift of Ar * recoil ions

have been recorded at Gesellschaft fur Schwerionenforschung (GSI) and are being analyzed. Richard Deslattes, Paul Cowan and Robert LaVilla

contribute to this effort.

The major thrust in the area of inner shell physics has been the

preparation of a beamline to be installed at the National Synchrotron

Light Source (NSLS). The vacuum envelope has been completely tested,

the mirror manipulators are installed, and the monochromator testing

is almost complete. Shipment of the beamline to NSLS should occur

before the end of 1983. The beamline is primarily the work of Paul

Cowan, Terry Jach, A1 Henins, Ernie Kessler and Sean Brennan. The

2
first experiments will use the tunable monochromati zed synchrotron

light as a probe of the inner shell region of atomic and molecular

species. Brennan, the second new staff person, has had extensive

experience at the Stanford Synchrotron Radiation Laboratory (SSRL)

before joining the beamline effort during the spring of 1983. His

interest in solid state studies using synchrotron radiation is a natural extension of the presently planned studies of atomic and

molecular systems.

Position sensitive detectors of the backgammon type have been

studied by Jochen Barth, a guest worker from the University of Hamburg,

and Basil Duval. With the aid of Gabe Luther a number of new detectors

were built with some improvements in linearity and resolution.

Spectra from chlorine and chlorine molecules were studied by

Rupert Perera, a guest worker from Virginia Polytechnic Institute and

State University, and Robert LaVilla using a curved crystal spectrometer

and position sensitive detector. Information related to mul ti -vacancies

and molecular binding is derived from this data.

The NBS measurement of the lattice spacing of a Si crystal was published in 1976 and was unchallenged until 1982 when a measurement

at PTB differed by 1.8 ppm from the NBS value. After interchange of

Si crystal samples, an unexplained difference close to 1.8 ppm still

remains. In order to understand this difference the x-ray interferometer

facility has been brought back into operation in a manner which will

permit a definitive test of the 1976 result and an entirely new measurement if it is necessary. Richard Deslattes is the driving

force behind this effort just as he was in 1976 with Geoff Greene,

A1 Henins, and Mary Cutkosky making significant contributions. An

automated crystal lattice comparison facility is also nearing completion.

This facility (primarily the work of A1 Henins) will permit more accurate comparison of NBS and PTB crystal samples as well as more accurate comparison of various crystals in use at NBS.

Finally in early August, Richard Deslattes, the group leader,

took up residence at the University of Heidelberg as a von Humboldt

fellow. In addition to his studies at Heidelberg, he will collaborate

on high Z one-electron measurements at GSI and in the high energy y-ray

measurements at ILL. Also in August, Jim Snyder moved to NBS Boulder

for a year under the auspices of the NBS Gai thersburg-NBS Boulder

exchange program. He will be closely associated with John Hall of the

Quantum Physics Division.

3
II. TECHNICAL ACTIVITIES

1. Optical Physics

J. Snyder

Objectives

This program is concerned chiefly with experimental laser spectroscopy and the development of related technology.

Current Activities

The principal investigator (Snyder) is currently a Visiting Fellow

at JILA, Boulder, for a period of one year ending September 1984. As

a result, some of the activities of this program will be suspended

until his return.

The collaboration with the West German national standards laboratory

(Physikalisch-Technische Bundesanstal t) (PTB) continued this year with

a second visit of one month by Snyder to Braunschweig, Germany. The

joint experiment is intended to investigate the potential of the

narrow calcium intercombination line at 657 nm as a possible future

optical frequency standard, as well as to develop the combined spectroscopic techniques of merged laser-atomic beams and time-domain Ramsey

excitation. The dye laser linewidth has been reduced to about 1 kHz

during the past year and is expected to be further reduced to the

region of a few hundred hertz. The major effort at the present time

is to develop efficient high-frequency laser modulators capable of

generating the required frequency shift of ^2 GHz. In addition a new collaboration has been initiated with Borde at the University of Paris

to model the proposed use of multiple pulse (^40 pulses) Ramsey

excitation to reduce fringe complexity and width.

The Fizeau wavemeter project is essentially dormant at NBS at the

present time. The original instrument continues in full-time routine

use in the Temperature and Pressure Measurements and Standards Division

(Rosasco). The University of Maryland Fizeau Wavemeter is currently

being modified by the introduction of single-mode fiber input coupler.

It is hoped that the fiber (which will replace the pinhole used as a spatial filter) will alleviate some problems due to pulsed laser

damage of the pinhole substrate.

The wire-wrap prototype of the Frequency Meter, although functional,

had insufficient noise margin and insufficient speed due to stray

capacitance of the wire-wrap pins. A second, printed-circuit prototype

was designed using the new NBS computer-aided-design (CAD) facility.

This board is currently being built at a commercial firm. Further

work on the Mossbauer-drive lambda meter awaits completion of the

Frequency Meter electronics.

4
A new collaboration with a group at the University of Rochester was begun to develop interferometers for characterizing the mode structure

of pulsed amplified spontaneous emission (ASE) sources.

Accomplishments

The second round of experiments on calcium at the PTB had limited

success due to the limitations of the high-frequency phase modulator.

However, the new optical cavity was built and tested successfully, and

the modulation and detection electronics were completed.

An invited paper on the calcium experiment was presented at the

Sixth International Conference on Laser Spectroscopy.

The NBS Fizeau Wavemeter has been temperature stabilized. This

appears to have significantly reduced short-term drift of the instrument's

cal ibration.

A printed-circuit board prototype of the Frequency Meter was designed.

A high-finesse Fizeau interferometer for spectral analysis of

pulsed lasers and other light sources was developed and is in use at the

University of Rochester.

A second firm, under license from NTIS, is now advertising the

Fizeau Wavemeter.

Future Plans

The PTB collaboration will continue. The next experiments, possibly

in summer 1984, require an efficient high-frequency modulator to produce

the necessary 2 GHz shift of the laser frequency. In addition, it will

eventually be very useful to operate with a supersonic or perhaps even a decelerated calcium beam.

The use of a single-mode fiber input coupler for the Fizeau Wavemeter

will be investigated in detail.

The new Frequency Meter prototype will be tested and de-bugged.

When fully functional, it will be tested in operation with the JILA

lambda-meter, and later with the Mossbauer-drive lambda-meter.
2. Gravity

G. Luther (3/4)

Objectives

Our present objectives are two-fold and only indirectly related.

They are, first to exploit the unique capabilities of the apparatus

used to measure the Newtonian Gravitational Constant and second, to

study the general limits of physical measurements.

Accomplishments

A paper was prepared and delivered to the Third Meeting of the

Marcel Grossman Conference on the Recent Developments of General

Relativity (to be published) on "The Redetermination of the Newtonian

Gravitational Constant at NBS".

A study was made to determine if the present apparatus could be

made to yield data regarding the test of the equivalence of active

gravitational mass and inertial mass. All precision measurements of

the Etvos type equate the passive gravitational mass to the inertial

mass. Only one experiment performed by L.B. Kreuzer in the late 1960's

has been performed to specifically test this equivalence. It was determined that a significant contribution could be made with relatively

little effort and expense, and a preliminary measurement was performed

using some bronze masses already on hand. The results were encouraging

enough (a paper describing this measurement is being prepared) so that

a set of alumina masses were ordered and obtained. The sphericity and

homogeneity of these were measured and determined to be sufficient unto

the task.

Several quartz and tungsten fibers were tested and discarded for

various reasons. At present, the small -mass system is suspended on a tungsten fiber of about 10 microns diameter which shows considerable

promise.

In line with the objective "to study the general limits of physical

measurements", an autocoll imator has been designed and built which is

capable of resolving rotations as small as a nanoradian. The advantages

of this instrument are, in part, its small size (it is approximately

the size of a "Big Mac"), its light weight (it may be made to weigh

less than a pound), and its low power dissipation (less than 1/8 watt).

A paper describing this autocoll imator has been submitted to the

Review of Scientific Instruments .

Current Activities and Future Plans

The system is now being prepared for what is hoped will be the

final series of big G measurements. A gain of a factor of 2 in precision

6
is anticipated. The configuration will also be suitable for the

determination of the equivalence principle as mentioned above with only

a slight change in the measurement regimen. It is also hoped it will be

possible to perform a measurement of the radial dependence of big G.

The anticipated precision of the measurement of the radial dependence of

big G should be sufficient to discriminate among several theories now

current.
3. Synchrotron Radiation

P. Cowan (3/4), S. Brennan, T. Jach (1/2), A. Henins (1/4),

M. Cutkosky (1/3), E. Kessler (1/4), g. Greene (GW)

Objectives

Quantum Metrology Group activities in synchrotron radiation

research can be classified in two ways. First experimental facilities

are being constructed to allow synchrotron radiation to be used in

experiments which are extensions of those performed by the Group inhouse. Secondly, new experiments are being designed which virtually

require the special characteristics of synchrotron radiation. The

best example of the latter activity is the recently published study of

threshold excitation of Ar Kb and its satellites. This experiment

would be virtually impossible without the intense beam of a monochromatic x-ray photons available at synchrotron. Work will be directed

toward studies similar to this initial experiment and to developing

other novel experiments using synchrotron radiation.

Current Activities

Presently the principal activity in this area is to construct,

test, and install an UHV soft x-ray beamline at the National Synchrotron

Light Source. In addition members of the Group are collaborating on experiments in-house and performed at other synchrotron radiation

facilities.

The x-ray ring at the National Synchrotron Light Source (NSLS)

has not been completed due to a series of problems at that facility.

This necessarily has delayed the installation of the UHV soft x-ray

beamline. Instead the beamline has been assembled at NBS for testing

and computer interfacing. This work is largely completed although

some testing and refining of the instrument will continue at NBS until

the NSLS staff are ready to allow final beamline installation at

Brookhaven.

Despite the unavoidable delay of initial beamline operation,

careful study has been directed towards "second generation" instrumentation to replace or enhance the original equipment. This work has

produced a novel scheme for photon energy analysis by reflectivity

modulation using x-ray mirrors. This work has been submitted for

publication and is expected to be useful in certain future synchrotron

radiation experiments. In addition studies of solid state (PIN)

detectors as x-ray detectors has continued. The Group's development

of "backgammon" position sensitive proportional detectors will have

application at synchrotrons as well. Initial designs of curved

crystal secondary spectrometers have also been completed.

Preliminary experiments have been performed, both in the lab and

at other synchrotron radiation facilities, which may lead to new areas

of research. This disparate work generally involves studies of solid

3
surfaces using x-rays at glancing incidence angles. For example

laboratory studies have been initiated at NBS by Cowan and Jach toward

using the x-ray evenescent wave effect to study surface chemical shifts.

X-ray surface scattering experiments have been conducted by Brennan at

SSRL in association with Eisenberger et al_. from Exxon Research

Laboratories. Also, the theoretical ground work has been laid for

several other novel experiments using x-rays at glancing incidence.

This area is largely unexplored and is rich in potential applications

ranging from the fundamentals of x-ray optics to surface and interface

character!' zation.

Accompl i shments

Construction and assembly of beamline hardware is complete.

Beamline UHV control system is installed and programmed.

A description of photon energy analysis by reflectivity modulation

has been presented at the Third National Conference on Synchrotron

Research Instrumentation and a manuscript has been submitted to

Nuclear Instruments and Methods for publication.

Results of experiments on the Ar K 3 spectrum have appeared in

print and a subsequent paper with theorist Ken Dyall has been submitted

for publication.

Surface x-ray scattering experiments have been completed and results

are analyzed for publication.

Future Plans

The major task of the coming year should be the installation,

commissioning, and characterization of the UHV soft x-ray beamline at

NSLS. However, it presently appears that installation cannot begin

before January 1984. Assuming installation in early 1984, experiments

on x-ray fluorescence and scattering from gases should resume by summer 1984. Preliminary laboratory experiments and equipment development will continue with the aim toward eventually expanding the range of

synchrotron experiments. In the event that initial beamline operations

at NSLS are delayed further, consideration must be given to expanding

our experimental programs at other synchrotron radiation facilities.

9
4. X-ray Spectroscopy/Position-Sensitive Detector

R. LaVilla (3/4), R. Perera (GW), J. Barth (GW), B. Duval (GW-1/2)

Objective

The objective is to study the limits of a single particle interpretation of x-ray emission and absorption processes to help support the

application of x-ray spectra in elucidating the electronic structure

of matter. In the recent past we have studied the manifestations of

many-body effects in the x-ray spectra of atoms, molecules and solids,

with particular attention to the excitation and decay of multi-vacancy

configurations and the dynamics of a core hole. Since count rates are often low, state of the art instrumentation for acceptable signal-tonoise ratio are necessary for experimental measurements of these

effects

.

Current Activities

(1) Vacuum Double Crystal Spectrometer

Following the wavelength measurements of argon Ka ls2 and potassium

Ka ls2 from KCi, the encoder on the precision axis was discovered to

have slipped. After repairing the encoder to spindle axis coupling, a highly efficient scheme was implemented to automate the axis calibration

and the axis was recalibrated with a precision of -vl ppm. Then the

argon Kc^ , 2 and potassium Ka ls2 emission lines were remeasured. These

lines serve as calibration wavelengths for the one-electron chlorine

and argon spectra. Data was also collected on the argon KBi 9 3 emission line before disassembling the instrument to modify the axis

drives.

(2) Curved Crystal Spectrometer

The assembly and initial operation of a highly efficient flexible

curved crystal spectrometer was completed. The instrument uses a 1/2

meter bent crystal coupled to a position-sensitive detector of the

"backgammon" type and a conventional demountable x-ray tube. By

operating the instrument in an enclosed helium atmosphere, measurements

down to the chlorine K-edge region (2830 eV) can be obtained. The

instrument is currently being used to study the excitation and radiative

decay of multi -vacancy configurations in the chlorine KB region by

monitoring the fluorescence and K absorption spectra from gaseous

methyl chloride (CH 3 Ct) and vinyl chloride (CH 2 CHCt) by taking advantage

of the near coincidence between characteristic emission lines and core absorption edges of different elements. The quasi -monochromatic

character of the exciting radiation permits the specification of the

nature of the initial excited state of the specimen. The high efficiency

of the instrument enables the acquisition of emission and absorption

spectra with high statistical quality.

10
(3) Position-Sensitive Detector

Development work on the position-sensitive detector has proceeded

with a study of its performance characteri sties as a function of different

design parameters and modes of operation. A better understanding of the

detector has evolved, however there is a need for quieter preamps to

take full advantage of these detectors.

Accompl i shments

A highly efficient curved crystal spectrometer has been assembled,

tested, and used for initial measurements. A manuscript of the Ct Kb

spectra of CH 3 C£ and CH 2 CHC£ obtained at resonant excitation near the

Cs, K threshold has been prepared.

The Ru l_ 3 "white line" absorption feature has been measured from

ruthenium metal and ruthenium dioxide. The Ru La and Lb emission spectra

have been obtained at the resonant excitation of the Ru L 3 "white line".

A paper on the position-sensitive detector work was presented at

the Third National Conference on Synchrotron Radiation Instrumentation

at Brookhaven National Laboratory. This paper will be included in the

Conference proceedings published by Nuclear Instruments and Methods.

Future Plans

The axis drives for the vacuum double crystal spectrometer will be

modified to improve the efficiency of operation. Upon satisfactory

operation, when the spectrometer is back in operation, the Krypton

Ka lJ2 and some Xenon L series lines will be measured.

The Ta emission spectrum in the region of the Ta L 3 "white line"

absorption feature will be recorded following resonant excitation.
5. X-ray-Optical Interferometry/Lattice Spacing Comparison

R. Deslattes (3/4), G. Greene (3/4), A. Henins (3/4),

M. Cutkosky (2/3)

Objective

We intend to redetermine the silicon (220) crystal lattice plane

spacing with improved accuracy and so to resolve the discrepancy between

the values as obtained at NBS and more recently at the Physikal ischTechnische Bundesanstal t (PTB). The lattice spacing of perfect single

crystal silicon in absolute units is an experimental quantity of great

importance for a variety of reasons. It is an important input into the

least squares adjustment of the fundamental constants. The most accurate

determination of the Avogadro constant and all absolute wavelengths in

the x-ray and y-ray region are tied directly to this quantity. Much

work in exotic atomic spectroscopy relies on this quantity.

The value of the silicon lattice spacing with a quoted accuracy of

about 0.1 ppm as published by PTB is 1.8 ppm smaller than the earlier

NBS value. The difference is considerably larger than what is expected

from sample to sample variation in silicon. An interchange of samples

and intercomparison at both laboratories explains only about 0.1 ppm of

this discrepancy. In view of the importance of this quantity every

effort should be made to resolve this apparent discrepancy.

Current Activities

Two instruments are being constructed to address the silicon

lattice spacing question. The first consists of significant modifications to the x-ray/optical interferometer (XROI) apparatus earlier used

by this group to directly measure the silicon lattice spacing in terms

of both Lamb dip and iodine stabilized He-Ne lasers. The second is a new two-crystal single axis goniometer for measuring the samll differences

between lattice spacings of different crystals (Ad apparatus).

The XROI instrument uses the linear translation stage and crystal

of the earlier measurements. By using the same single crystal silicon

interferometer the lattice spacing determination can be directly compared

with the previous NBS measurements. The important difference is the

present apparatus consists of the installation of four independent beam

polarization encoded angle interferometers which will be employed to

accurately characterize the translation path (curvature) of the moving

"ear" with respect to the stationary "ears". This will allow unambigous

determination of any Abbe sine errors present. Additional improvements

include a more robust and agile position locking servo-loop, improved

acoustical and vibration isolation, and a fully automated micro-computer

control of all aspects of data collection. In this way we hope to

provide a definitive determination of the lattice spacing of our Si

crystal. Most of our efforts have gone into bringing this instrument

12
on line.

The Ad-apparatus is an entirely new device which should be capable

of comparing the lattice spacings of crystals having nearly the same spacing to parts in 10 8 or better. By providing direct comparison

between samples it will be possible to ascertain with a great deal of

confidence if sample to sample variation is responsible for some of the

NBS and PTB discrepancy. Ultimately one would compare the actual

artifacts used in both XROI measurements. This apparatus will also be

used to transfer lattice spacing information to crystals used in

wavelength measurements. The device is under full microcomputer control

during data collection.

Accompl i shments

The new XROI apparatus has been assembled and is now capable of

taking data. The new four-beam path curvature interferometer has been

installed. A PDP-11/23 controlled CAMAC system has been commissioned

and is currently controlling all facets of the experiment. A new frequency offset locked laser system has been installed. The entire

XROI laboratory has been refurbished to give better acoustical and

vibrational isolation.

Fabrication of most of the Ad-instrument and its assembly has been

completed. A novel electronic fringe counting interferometer for angle

measurement is nearing completion. Connections to the PDP-1 1/23-CAMAC

system for computer control is underway.

Future Plans

We hope in the near future to complete our XROI measurements and

make lattice comparisons between the NBS and PTB silicon samples. Based

on that experience we hope to continue the XROI/Ad program to provide

an order of magnitude improvement in determination of the lattice

spacing (^lCf 8

) and its dissemination to other crystals. Such carefully

characterized crystals will then be employed in our group's efforts to

extend the accuracy of y-ray standards, in the determination of a new collection of fundamental constants, and in the accurate determination

of highly ionized atomic spectra.
6 . Precision X-ray and y-ray Wavelength Measurements

E. Kessler (3/4), B. Duval (GW-1/2), R. Deslattes (1/4),

R. LaVilla (1/4), P. Cowan (1/4), G. Luther (1/4), G. Greene (1/4)

Objectives

The objective of this project is accurate wavelength standards in

the 20 keV to 5 MeV region. The standards are related to visible

wavelengths and the Rydberg, R^, through the x-ray/optical interferometry measurement of the lattice spacing of a silicon crystal. X-rays,

y-rays and absorption edges have been measured with an accuracy of a few ppm, 0.1 to 1 ppm, and 15 ppm respectively. The wavelength

standards are used for testing state-of-the-art relativistic atomic

calculations, calibrating curved crystal spectrometers and Ge detectors

and in critical absorption measurements.

Precision y-ray measurements have the potential of contributing

to the fundamental constants. By combining wavelength measurements of

capture y-ray cascades with mass spectroscopy measurements of the

associated mass differences, a mass-wavelength conversion factor can

be obtained.

Current Activities

The four-meter Dumond curved crystal spectrometer has been extensively tested and modified during the past year. This instrument is

located in the Radiation Physics Building and uses x-rays produced by

bombardment of targets with electrons from a 4 MeV Van de Graaff. The

uniformity of the crystal bend was tested by diffracting x-rays from

small areas of the crystal. Because significant non-uniformity of

bend was detected, an optical testing facility was established. This

facility uses a laser to illuminate the x-ray source slit and the bent

crystal along with a detector to receive the light reflected from the

surface of the bent crystal. Very accurate characterization of the

crystal bend was achieved and improper focussing was detected. Other

modifications to this instrument were improved electronic resolution

on the detector motion, a more stable x-ray slit mounting, improved x- ray intensity monitors, and more efficient software to control the

spectrometer. Because the Van de Graaff has been plagued with electron

source problems for the past eight months, no usable x-ray data has

been recorded. Measurements of satellite lines associated with high Z K series x-rays and Kai , 2 and < 81,3 lines from elements with Z > 92

await an operational Van de Graaff. Preparation of a precision double

flat crystal spectrometer for shipment and installation at Institut

Laue-Langevin (ILL), Grenoble, France, was a major undertaking. Many

electronic components were replaced with more reliable modules, interconnecting cables were remade, and computer software programs were

modified. Packing for shipment was done with great care in order to

insure that the instrument could be made operational shortly after

14
arrival. The spectrometer will be shipped in early October and should be

operational by mid-November. Precision y-ray wavelength measurements in the 2

MeV to 5 MeV region is the goal of moving the spectrometer to ILL. Sources in

this energy region are short-lived neutron capture sources which require the source to reside in the reactor during measurement. The scientific interest in

these measurements are accurate y-ray standards for calibration of Ge detectors,

a measurement of the wavelength-mass conversion factor by combining y-ray

cascade measurements with a mass difference measurement, and improved resolution

of complex nuclear spectra.

Accurate wavelength measurements of highly ionized atoms are theoretically

interesting because a number of terms scale as some power of Z. Although the

spectra are very weak, and subject to large Doppler shifts, successful measurements have been made with fixed curved crystals and position sensitive detectors.

Measurements on the Lyman a spectrum of Ct+16 were made at the tandum accelerator

at Brookhaven National Laboratory in collaboration with Kansas State University.

This work tests the Lamb shift to ^ 10 percent. Measurements on the Lyman a spectrum of recoil Ar+17 ions were made at GSI in collaboration with Dr. Heinrich

Beyer. Analysis of this data is continuing. The precision measurements on Ar Ka]_ ,2 and K Ka ls2 using the vacuum crystal spectrometer discussed under 4

above, served as the calibration lines for these one-electron measurements.

A mul ti-configuratior. Dirac Fock computer code was acquired from Oxford

Uni versi ty' and installed on the NBS computer. After an initial learning

period, extensive calculations were made over a wide range of Z (13 to 98) in

order to compare experimental and theoretical data. A book chapter on precision

experimental x-ray measurements and comparison of experimental and theoretical

data was written and submitted for publication.

Accompl i shments

A manuscript on precision mid-to-high Z x-ray measurements and their

comparison with theoretical calculations was published.

The curved crystal spectrometer has been significantly improved and will

be used to make x-ray measurements as soon as the Van de Graaff becomes

operational

.

A major new measurement facility was established at ILL which provides the

ability to make precision y-ray measurements at energies >2 MeV.

Data on one-electron spectra from highly ionized species has been acquired

and the analysis is nearing completion.

15
State-of-the-art theoretical calculations for many-electron atoms

have been installed on the NBS computer and used to make extensive

theoretical calculations for comparison with experimental data. A book

chapter comparing experimental and theoretical x-ray data has been

submitted for publication.

Future Plans

Precision measurement of hypersatel 1 i te lines (double K vacancies)

from heavy elements will be made using the four-meter curved crystal

spectrometer. This instrument will also be used for measurements of

Kai ,2 and K£ 1>3 for elements with Z > 92 to test theoretical calculations

in this important region.

After initial measurements high energy measurements using Ta, a hydrogen sample will be prepared to measure the n-p capture y-ray at 2.2

MeV. This is an important measurement from which the mass of the

neutron can be derived.

Additional data analysis and measurements on one-electron spectra

for high Z atoms are planned.

16
INVITED TALKS

Quantum Metrology Group - 52Q.06

G.G. Luther, "Gravity and Levity in the Peoples' Republic of China", October 6,

1982, Center for Absolute Physical Quantities' Colloquium, NBS, Gai thersburg,

Maryland.

J.J. Snyder, "Longitudinal Ramsey Fringe Spectroscopy: A Potential Optical

Frequency Standard?", October 15, 1982, Physics Department Colloquium, Stanford

University, Stanford, California.

E.G. Kessler, Jr., "Utilization of MeV Van de Graaff Electrons to Produce

Characteristic X-rays for Precision Measurements", November 8-10, 1982,

Conference on the Application of Accelerators in Research and Industry, North

Texas State University, Denton, Texas.

R.D. Deslattes, "Thoughts Old and New on Connecting Visible and Gamma-ray

Secondary Standards", March 2, 1983, Center for Absolute Physical Quantities'

Colloquium, NBS, Gaithersburg, Maryland.

G.G. Luther, "Measurement of Big ' G

' at the National Bureau of Standards",

April 18, 1983, Physics Department Colloquium, North Carolina State University,

Raleigh, North Carolina.

R.D. Deslattes, "Normal Atoms, Stripped Atoms, and Exotic Atoms", April 28,

1983, Physics Department Colloquium, Polytechnic Institute of New York,

Brooklyn, New York.

J.J. Snyder, "Longitudinal Ramsey Fringe Spectroscopy in a Calcium Beam", June

28 - July 1, 1983, Sixth International Conference on Laser Spectroscopy,

Interlaken, Switzerland.

P.L. Cowan, "Photon Energy Analysis by Reflectivity Modulation", September 12-

14, 1983, Third National Conference on Synchrotron Radiation Instrumentation,

Brookhaven National Laboratory, Upton, New York.

J. Barth, "Position Sensitive X-ray Detector", September 12-14, 1983, Third

National Conference on Synchrotron Radiation Instrumentation, Brookhaven

National Laboratory, Upton, New York.

R.D. Deslattes, "Present Difficulties and Future Possibilities of Absolute

Gamma-ray Measurements", September 20, 1983, Physics Department Colloquium,

Schweizerisches Institut fur Nuklearforschung (SIN), Villi gen , Switzerland.

17
PUBLICATIONS

Quantum Metrology Group - 520.06

E.G. Kessler, Jr., R.D. Deslattes, D. Girard, W. Schwitz, L. Jacobs, and

O. Renner, "Mid-to-High-Z Precision X-ray Measurements", Phys. Rev. A 26,

2696-2706 (1982). ~

R.D. Deslattes, R.E. LaVilla, P.L. Cowan, and A. Henir.s, "Threshold Studies

of A Multivacancy Process in the K3 Region of Argon", Phys. Rev. A 27,

923-933 (1983). ~

P. L. Cowan, J.B. Hastings, T. Jach, and J.P. Kirkland, "A UHV Compatible

Two-Crystal Monochromator for Synchrotron Radiation", Nucl . Instru. and Meth.

208 , 349-353 (1983).

A. Henins, E.G. Kessler, Jr., and P.L. Cowan, "Flexure Pivot Mirror Support",

Nucl. Instru. and Meth. 208, 287-289 (1983).

Richard D. Deslattes, "X-ray Fluorescence Spectroscopy", Nucl. Instru. and

Meth. 208, 655-658 (1983).

Terrence Jach and P.L. Cowan, "Pin Diodes as Detectors in the Energy Region

500 eV - 10 keV", Nucl. Instru. and Meth. 208, 423-425 (1983).

E.G. Kessler, Jr. and R.D. Deslattes, "Utilization of MeV Van de Graaff

Electrons to Produce Characteristic X-rays for Precision Measurements", IEEE

Trans, on Nucl. Sci . NS-30 , 991-995 (1983).

Gabriel G. Luther, "Redetermination of the Newtonian Gravitational Constant '

1 "

Proc. Third Marcel Grossman Meeting on the Recent Developments of General

Relativity held in Shanghai, China, August 30 - September 3, 1982.

J.J. Snyder, J. Helmcke, and D. Zevgolis, "Longitudinal Ramsey Fringe Spectroscopy

in a Calcium Beam", Proc. 6th Internat. Conf. on Laser Spectroscopy held in

Interlaken, Switzerland, June 27 - July 1, 1983.

Richard D. Deslattes and Ernest G. Kessler, Jr., "Experimental Estimation of

Inner Vacancy Level Energies for Comparison with Theory", Atomic Inner-Shell

Physics (to be published).

G.L. Greene, "Trapping of Low Energy Neutrons, Proc. Workshop on Spectroscopic

Applications of Slow Atomic Beams held at NBS, Gaithersburg, Md., April 14-15,

1983.

J.J. Snyder, J. Helmcke, and D. Zevgolid, "Longitudinal Ramsey Fringe Spectroscopy

in a Calcium Beam", Applied Physics B (to be published).

J.J. Snyder, J. Helmcke, M. Glaser, and D. Zevgolis, "Longitudinal Ramsey

Fringe Spectroscopy in an Atomic Beam", Proc. 6th Internat. Conf. on Laser

Spectroscopy held in Interlaken, Switzerland, June 27 - July 1, 1983.

Gabriel G. Luther, Richard D. Deslattes, and William R. Towler, "Single Axis

Photoelectronic Autocoll imator" , Review of Scientific Instruments (to be

published)

18
P.L. Cowan, "Photon Energy Analysis by Reflectivity Modulation", Proc. Third

National Conference on Synchrotron Radiation Instrumentation held at

Brookhaven National Laboratory, Upton, New York, September 12-14, 1983.

(to be published).

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

Sensitive X-ray Detector", Proc. Third National Conference on Synchrotron

Radiation Instrumentation held at Brookhaven National Laboratory, Upton,

New York, September 12-14, 1983 (to be published).

19
SEMINARS FOR STAFF AND GUESTS

Quantum Metrology Group - 520.06

C. Mande, Nagpur University, Department of Physics, Nagpur, India - CAPQ

Colloquium, "Chemical Effects in X-ray Absorption Spectra", October 5, 1982.

S. Brennan, EXXON Research and Engineering, San Francisco, California - CAPQ

Colloquium, "Surface EXAFS and Surface Bragg Scattering - An Overview", October

13, 1982.

J. Arthur, Massachusetts Institute of Technology, Department of Physics,

Cambridge, Massachusetts - CAPQ Colloquium, "Testing Quantum Mechanics with a Neutron Interferometer" , October 15, 1982.

G.L. Greene, Yale University, Department of Physics, New Haven, Connecticut - CAPQ Colloquium, "Neutron Optical Activity", October 20, 1982.

R. Powers, California Institute of Technology, Department of Physics, Pasadena,

California - CAPQ Colloquium, "Two Recent Applications of Hadronic Atoms:

Measurement of the Sigma Minus Magnetic Moment; Study of the Pion-Nucleus

Optical Potential", November 15, 1982.

20
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TECHNICAL ACTIVITIES

ELECTRICITY DIVISION, 521

FISCAL YEAR 1983

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 community as well as industry and commerce; and to ensure that

the U.S. system is consistent with those of other countries and the

internati onal ly accepted system.

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 responsibi 1 i ty for which the Bureau was originally

founded in 1901. The major technical problems which benefit from the

ED's work include fundamental physical theory; electrical power revenue

metering, transmi ssi on, 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 manuf acturers; 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, and a viable national defense 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 calibrations and MAP's; the measurement methods and

instrumentation it develops; and the tests and calibrations of instruments and apparatus it performs. For example, each year on the order of one thousand calibrations are carried out on primary electrical standards

that belong to some of the Nation's most important corporati ons , utilities, and government organizations, including Hewlett-Packard, General

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

Electric Power, the TVA, and FAA, and the DoD.

21
To fulfill its responsibilities, the ED carries out work in

eight principal areas with the objectives as indicated:

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 i nternati onal ly

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 measurement 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 thoughout 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. Carry out international comparisons of the basic electrical

units, thus ensuring that the U.S. system of electrical measurement

is consistent with those of other countries.

7. Participate in voluntary national and international standardizi ng

activities related to the electrical units, and the fundamental physical

constants, in order to eliminate and prevent non-tariff barriers to

trade, and to contribute to internationally acceptable data compilations.

8. Provide training for personnel active in the field of electrical

measurements and standards, including the generation of tutorial

written material, thereby elevating the overall level of competence in

the field.

The objectives, current activities, FY 83 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. Construction of the entire room temperature

version of the new ampere balance to determine the ratio of the NBS

22
as-maintained ampere to the SI ampere to an accuracy of 0.1 ppm by

equating electrical and mechanical work has been essentially completed.

Tests of the apparatus and preliminary measurements are expected to be

underway early in FY 84. The redetermination of the NBS as-maintained

farad and ohm in terms of their respective SI units via the NBS

calculable capacitor has also progressed and a tie between the NBS

bank of 10 pF capacitors and 1 ohm resistors used to maintain the NBS

farad and ohm should be completed to an accuracy of 0.1 ppm early in

FY 84.

2. Develop and Maintain U.S. Reference Standards . Extensive

investigations of the quantized Hall resistance in GaAs-AlGaAs heterostructures were carried out, including measurements as a function of

device temperature and current, as part of the ED's effort to develop

the quantum Hall effect into a reproducible, highly accurate (e.g.,

0.01-0.02 ppm), and easily used resistance standard based on fundamental physical constants. A precision approaching 0.01 ppm was achieved

and an accuracy in terms of the NBS ohm of 0.05 ppm. New, non-linear

phenomena were discovered and described in a paper to appear in Physical

Review Letters.

3. Pi ssemi nation . Electrical calibration services including MAP's

were genera I ly provided in a timely way and without serious problems.

Measureable improvements in turnaround time were achieved in most areas except ac-dc transfer standards for which a scheduling system was instituted. On the order of 1000 calibration reports were issued and over 200 individual clients served; 22 MAP's were conducted and calibration income totled $430 K. The reevaluation of NBS primary, secondary,

and working standards and measuring systems for ac current and voltage

begun in July 1981 was nearly completed. A replacement for the MaxwellWien bridge used to calibrate standard inductors for the last 35 years

has been constructed and is being tested. Automated measurement systems

for calibrating 10 and 100 ohm resistance standards and resistance

standards from 100 to 10 kohm have essentially been completed. A new transport standard of dc voltage using unsaturated standard cells has

been developed and is under test. The operating instructions for the

dc voltage MAP have undergone major revision.

4. New Methods, Instruments, and Standards . A prototype, improved

10 pF fused silica capacitance standard with significantly reduced

voltage dependence has been developed in conjunction with the development of an automated capacitance bridge. If the early promise of the

standard is fulfilled, it could ease the difficulty of realizing the

SI farad and ohm via the NBS calculable capacitor. It may also lead

to improved maintenance of the NBS farad and ohm.

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

be used to determine the f i ne-structure constant a, the work described

above under areas (1) and (2) relating to the realization of the SI

23
ohm and determining the quantized Hall resistance directly impacts the

determination of a via the Hall effect. Construction of the apparatus

for the new determination of the proton gyromagnetic ratio also

progressed wel 1 during FY 83. The precision solenoid and straightedge

are now installed, the detector coils required to measure its dimensions

are wound, and the solenoid cooling system is operational. Preliminary

dimensional measurements of the solenoid should be underway sometime

during the first half of FY 84. Two new Precision Measurement Grants were

awarded, one for the theoretical study of quantum nondemolition experiments, the other for the development of a cryogenic hydrogen maser.

6. International Comparisons . An international comparison of one ohm and 10 kohm resistance standards was carried out with the National

Research Council, Canada. Measurements were begun on the three NBS

one-ohm resistors to be used in the international comparison of

resistance standards to be conducted by and at the International

Bureau of Weights and Measures (BIPM) during the winter of 1983-1984.

Plans have been made to carry out an international comparison of one- ohm resistance standards with the Australian national standards laboratory (CSIRO Division of Applied Physics) in the first half of 1984.

The three NBS travelling capacitors circulating between national

standards laboratories under BIPM auspices were returned to NBS for

remeasurement and subsequent reshipment to East Germany.

7. Standardi zati on . The ED contributed to and actively participated in the 16th Session of the Consultative Committee on Electricity,

held at the International Bureau of Weights and Measures in March 1983.

At this meeting, plans were made to improve the international standardization of electrical measurements by internationally adopting in 1985

a new value of 2e/h for volt maintenance purposes, and a value of the

quantum Hall resistance for maintaing the ohm. The draft standard.

Recommended Practice for Eddy Current Conductivity Measurements, prepared for ASTM Committee E7, Nondestructive Testing, and which spells

out how eddy current NDT measurements using currently available

commercial instruments should be carried out and how the instruments

should be calibrated, was approved.

8. Training. In collaboration with the National Conference of

Standards Laboratories, two well attended and well received seminars on electrical measurement assurance programs were given, one in Fullerton

California, the other in Peabody Massachussetts . A highly successful

workshop on the laser cooling and trapping of neutral atoms was held

at NBS in collaboration with the Office of Naval Research. Three

tutorial NBS Technical Notes were published: Testing to Quantify the

Effects of Handling of Gas Dielectric Capacitors; Transportable 1000 pF

Standard for the NBS capacitance Measurement Assurance Program; and

the Practical Uses of AC-DC Transfer Instruments. Three foreign guest

workers (two from the PRC, one from Egypt) were trained in various

aspects of electrical measurement. Under AID auspices, assistance

24
was provided the National Institute for Standards, Egypt, in selecting

new equipment to upgrade their capabilities in basic electrical measurements and standards.

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 84.
DISSEMINATION SERVICES: SUPPORT AND OPERATION INCLUDING MAP DEVELOPMENT

(N. B. Belecki, C. B. Childers, R. F. Dziuba, W. G.

Eicke, R. C. Fronk, J. R. Hastings, C. R. Levy, R. E. Long, T. P. Moore, D. D. Prather, J. E. Sims, S. B. Till ett , A. R. Wise; F. L. Hermach, E. S. Williams)

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 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 requi rements , 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 voltage, and resistance

at direct current, as well as MAP services for capacitance, dc voltage,

and dc resistance. Some measurements are also done on ac ratio standards

26
of the highest accuracy. In FY83, 22 MAP transfers and approximately 973

calibrations of basic standards were performed, as detailed at the end of

this project description, for a total income of about $430K for the year.

As in past years, efforts have been made to reduce calibration

turnround time. In the ac-dc difference area, scheduling of calibrations

has been made more realistic by making more conservative estimates of

test times. While a large queue exists for those wanting service in this

area, scheduling is running more smoothly than in the past. Overtime and

additional manpower will be used to minimize the queue until automated

measurement systems are implemented. In the other areas, turnaround

times have been measurably improved.

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. 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.

Measurement services support activities fall into two broad

categories: the development of improved measurement methods and

standards (including MAP development work), and the automation of the

measurement systems used to perform both calibrations and MAP activities.

Work in the former category is directed toward improvement of the

processes by which the ohm is maintained and scaled and of both ac and dc

voltage and current measurement and dissemination techniques. In the

automation area, objectives are to complete automation of the systems

used for ac-dc difference measurements on thermal voltage and. current

converters (ac V&I), resistance measurements through 100 teraohms, and

standard cell calibrations.

Accompl ishments

AC Current and Voltage

The re-evaluation of NBS primary, secondary, and working standards

and measuring systems in the ac current and voltage area begun in July

1981 has been nearly completed. This effort was undertaken by F. L.

Hermach, under contract. In this re-evaluation, a set of multi junction

thermal converters has been established as the new NBS primary standard;

they have ac-dc differences of only a few tenths of a ppm with an uncertainty of 0.5 ppm. The reference (secondary) and working standards

have been re-evaluated by comparison to the primary standards, and by

bootstrapping techniques over the voltage, current, and frequency ranges

beyond those directly accessible via the primary standards. A detailed

comparison of the redetermined values of ac-dc differences of the working

27
standards with the previously-determined values shows generally excellent

agreement, except over a limited range of current. Further measurements

have been made covering half of this range and show good agreement with

the data taken earlier in the re-evaluation. The differences, however,

are well within our customary calibration uncertainty. In the very worse

case, a few customer calibrations at really low frequencies (20 Hz) were

done with a quoted uncertainty of 50 ppm using a reference whose value

was in error by 35 ppm or so. (The transfer uncertainty is small - no more than 5 ppm.) Follow-up measurements over the second half of the

range are scheduled shortly.

The re-evaluation measurements cover a broader range than those upon

which past values of NBS standards are based. (The values in the case

above resulted from extrapolation of data taken over a more limited

range.) The range has been extended to 16 A and 50 kHz for the current

standards and to 600 V and 100 kHZ for the voltage standards. A detailed

report describing this work has been written for NBS use; a condensed

version is planned for publication. This work was supported in part by

the DoD Calibration Coordination Group (CCG). [Hermach (under contract),

Hastings, Williams (under contract), Childers, Kri shnamurthy (student)]

E. S. Williams, under a contract supported by the CCG, has begun

an investigation of solid-state thermoelements directed toward the

development of a secondary or transport standard capable of 10 to 50 ppm

accuracies. Measurement circuitry and an automated ac-dc comparison

system have been developed for comparing these newer thermoelements, with

their tenfold-higher output emf's, to conventional vacuum thermoelements.

The new devices form the basis for ac voltage measurement accuracies of

commercial voltmeters that are within an order of magnitude of NBS

calibration uncertainties. [Williams (under contract), Hastings]

Impedance

A replacement for the Maxwell -Wien bridge, used for calibrating

standard inductors for the past thirty-five years, has been constructed

and is being tested. The new bridge is an offshoot of the Division's

eddy-current conductivity work and is based on the use of inductive

voltage dividers to eliminate the need for switched resistors and

capacitors. It uses two fixed resistors to establish ratios and one of

four fixed resistors to establish the amplitude of the resistive

component of the inductors it measures. The new bridge has a frequency

range of 100 Hz to 100 kHz and a low-end inductance limit of 100

microhenries because of current limitations. Testing is expected to be

completed in about six months. Its use will enable the uncertainties of

inductance calibrations to be reduced by about an order of magnitude, or from 200 ppm to 20 ppm over the most frequently used magnitude/frequency

combinations. [Free, Levy]

28
Resi stance

The design of a standard printed circuit relay-control board has

been completed and put into use. This board is used to control

low-thermal relays used in critical applications in the automation of

resistance measurement systems by S-100-based microcomputers. [Dziuba,

Wisniewski (student)]

A commercial direct-current-comparator bridge has been modified to

permit high-accuracy automatic comparisons of nomi nal ly-equal resistors

in the range from 100 ohms to 10 kohms. The modifications include

improved shielding of leads, replacement of open terminals with shielded

terminations, and the replacement of the photocell amplifier with one with an isolated output. A microcomputer controls the current reversal

,

detector balancing, and the determination of the sensitivity of the

bridge. A computer program collects and processes the data. [Dziuba,

Wisniewski (student), Poneleit (student)]

A guarded series/parallel (Hamon) resistance transfer standard for

scaling from 100 ohms to 10 kohms has been designed and constructed. The

guarding feature suppresses errors due to leakage currents through the

insulated supports of the resistors and the mineral oil in which the

standard is immersed (in the event of breakdown or contamination). The

standard has been used to verify the assigned values of the NBS 10 kohm

standards relative to the legal ohm to better than 0.05 ppm. [Dziuba,

Campbell (student)]

A direct-reading ratio set for comparing resistors of nominally

equal values in the range from 100 ohms to 10 kohms has been modified to

improve its resolution by two orders of magnitude (to 0.01 ppm). In

addition, a guard circuit has been installed to reduce errors caused by

leakage currents to negligible levels, and the instrument tested and

calibrated. [Dziuba, Rice (student)]

A special series/parallel resistance transfer standard was constructed to be used in the chain of measurements for the calibration

of quantized Hall -resistance standards in terms of the legal ohm. Using

three measurement systems simultaneously ( the one-ohm system, a dc-current-comparator resistance bridge, and a modified direct-reading

ratio set), the intercompari son can now be performed in four hours

without moving any critical resistance standards. Measurements using

this transfer standard verified the discrepancy of the order of 0.8 ppm

between the as-maintained unit of resistance and that derived from

quantized Hall resistance experiments using the accepted value of the

fine-structure constant. [Dziuba]

Modifications were made to the automated one-ohm measurement system

to enable it to compare resistors in auxiliary baths at any temperature

to the NBS primary reference group of resistors maintained at 25 degrees

C. These included interfacing a thermometer bridge for measuring

platinum thermometer resistances to the microcomputer. The system is

29
currently being used to monitor three one-ohm standards at 20 degrees C for use in a multi-national i ntercompari son at the B I PM in the first part

of 1984. [Dziuba, Fronk, Poneleit (student)]

The measurement system used to calibrate customers' standard

resistors at the 10 kohm level has been improved to reduce errors due to

leakage currents and decrease the measurement time required to perform a calibration. [Dziuba, Wisniewski (student), Prather]

Automation of the dc current-comparator potentiometer for the

calibration of 10 and 100-ohm resistance standards will be completed by

the end of FY83. The system will be tested and put into operation early

in FY84.

A communications link to permit automatic transfer of data between

the microcomputers in the resistance laboratory and the central

minicomputer has been completed. This eliminated the need for

transferring data by hand (speeding the calibration process) and permits

experiments to be controlled and data gathered by microcomputer, while

reserving the central minicomputer for complex data analyses and report

production. [Dziuba, Fronk]

Voltage

A new transport standard of dc voltage has been developed and is

under test. The standard is based on the use of unsaturated standard

cells in a temperature-controlled enclosure. The premise behind its use

is that, although unsaturated cells drift with time, they are considerably more robust than saturated cells with respect to temperature

and mechanical disturbances. Environmental testing is currently

underway. [Eicke]

Two seminars on dc voltage MAP techniques were given. The first was

in Fullerton, CA in January, and the second in Peabody, MA in September.

Despite the recent economic slump, both were well -enrolled and many

requests v/ere received for the course material by those not able to

attend. [Eicke, Belecki, Croarkin (CAM), Vecchia (CAM), Eberhard (CAM),

Belanger (OPMS), McCoubrey (CBS)]

Mew power supplies were designed for the VTP saturated cell

enclosures. These new supplies are more reliable and useable than the

original design proved to be. Prototype models have been built and

tested, printed circuit boards fabricated, and production versions are now under construction. [Eicke, Long]

The operating instructions for the Volt Transfer Program, the dc

voltage MAP service, have undergone major revision. They new include

information on how to use digital meters for standard cell measurements,

more distinct instructions regarding data submission, and complete

30
explanations of all aspects of the reports issued after each transfer.

[Sims]

Calibrations of Zener-diode-based voltage standards are now being

done on a new automated system based on a desktop computer. The system

is self-calibrating and can measure any arbitrary voltage less than 10.6

volts relative to a local group of standard cells with an uncertainty of

the order of 0.2 - 0.4 ppm. The system generates ten voltages, each

approximating that of a saturated standard cell, in series, and uses a precision digital voltmeter to compare each of them to cells in the local

standard using a ten by four block design. The resulting calibrated

cumulative voltages are used to calibrate the DVM, and the closest

voltage is used as a reference to measure each Zener-based standard with

the DVM measuring the difference emf. This system affords a fourfold

improvement in accuracy and a considerable reduction in turnaround time

relative to the old, manual system. [Field]

Future Plans

AC Current and Voltage

After the completion of some check measurements, the new values of

ac-dc difference of the working standards used in NBS calibrations will

be substituted for presently-used values. (For the most part, only

slight changes are necessary.) Reductions of the uncertainty estimates

for the calibrations, however, will require further tests and the

implementation of the various quality control procedures recommended by

F. L. Hermach. The reduced uncertainties will depend in more detail

than the previous estimates on the current and voltage as well as the

frequency.

The automated ac-dc comparison system developed in the investigation

of solid-state thermoelements has been redesigned to be compatible with

IEEE standard 488. The redesigned system, now based on a desktop

computer, is being tested and will be used in the coming year to evaluate

these new thermoelements. The development of a secondary standard, based

on these new devices and suitable for field use, will be undertaken.

Efforts will be made to obtain devices that are more readily useable

under adverse environmental conditions than are conventional vacuum thermoelements.

The revised measurement system will also be used as the basis for a new automated system to handle the calibration workload. The new system

will be computer based and IEEE 488 compatible as well. A prototype

version is expected to be ready for testing by the end of FY84.

Longer-range plans are for the completion of the automated system,

and the development of an ac voltage MAP service to support instrument

31
manufacturers and the major standards laboratories of the DoD and their

high-technology suppliers.

Impedance

The major effort over the coming year will be to complete testing of

the new inductance bridge and implement its use for calibrating standard

inductors on a routine basis. Documentation of its use is also expected

to be finished by the end of the year. An investigation of the

possibilty of using the bridge to calibrate resistance standards in the

audio frequency range will be started. Such a service would require

considerable effort in determining the frequency response of at least one resistor and using it as an ac-dc transfer device to characterize the

bridge. This effort is expected to continue for several years.

An improved system for ensuring the quality of capacitor and

inductive voltage divider calibrations will be developed and tested in

the next year. The present systems are separate and rely largely on check standards and analyses of workload historical data to ensure a high

level of quality. While the system will quickly flag irregularities, it

is vulnerable to errors caused by slight, long-term drifts in transformer

ratios. Current techniques for calibrating these ratios are cumbersome

at best and do not lend themselves to frequent use. It is hoped that a technique can be developed to enable the ready calibration of a few

representative ratios. This would be coupled with a scheme for easy

intercomparison of the ratios of the Type II capacitance bridge with

those of the inductive voltage divider set-up. At present, only a general idea of how to approach this exists. Work will begin in FY 84 to

develop and perfect a technique that can be used on a regular basis.

Resi stance

Work will begin on the development of an automated, unbalanced

bridge system for i ntercomparison of nominally-equal standard resistors

in the range from 100 ohms to 1 megohm. This would include the design

and construction of interfacing circuitry and a switching module for the

system. The system will be controlled by an S-100-based microcomputer

which will pass data to the central minicomputer for reduction and

analysis. Considerable work on the development of software systems to

control switching and measurements and reduce the final data will be

required. The entire project will require three to four years for

completion.

An improved capacitive discharge system for the calibration of

resistors in the range from 100 gigaohms to 100 teraohms will be

completed in the coming year. The system will run under computer control

and enable resistors to be tested at arbitrary voltages up to 1000 volts

with accuracies of 0.1% or better. It is planned to reinstate the

32
calibration services for resistors of nominal value of a teraohm or higher as soon as the system is thoroughly tested.

Vol tage

Effort in the dc voltage area will primarily be devoted to

automating several measurement systems in the Volt Facility and on documentation. The measurements required for calibrations of customers'

standard cells, those required to do environmental testing of standards,

and those required to monitor the laboratory environment are slated for

automation. A prototype system to do regular calibrations, based on the

IEEE 488 Interface Standard and the use of a desktop computer, will be

finished in the next FY and testing of it will be well under way.

Implementation will probably occur early in FY85. The remaining systems,

including a new system to replace the current volt MAP measurement

system, will follow shortly thereafter. The computers controlling these

systems will be networked with the central computer using a desktop

computer as an interface.

The new transport standard developed during the past year will

undergo extensive testing. If it proves successful, several copies will

be made and pressed into service.

Completion of the documentation of qua! ity-control procedures

throughout the voltage lab will be finished by the year's end.

Two more voltage MAP seminars will be given. The first is scheduled

for early spring in Dallas and the second for late summer, probably in

the Midwest.

I

33
Electricity Division Calibration Workload Summary for FY 83

SP-250 - 3.1 Resistance Measurements

397 Standard Resistors and Shunts

5 MAP Transfers

(12 companies)

3.2 Precision Apparatus

26 Inductive Voltage Dividers

2 Hamon Devices

3.3 Impedance Measurements

171 Standard Inductors

172 Standard Capacitors

1 MAP Transfer

(1 company)

3.4 DC Voltage Measurements

121 Standard Cell Enclosures

(484 cells)

16 MAP Transfers

(28 companies)

32 Unsaturated Cel 1 s 10 Zener-diode Based Standards

3.5 Electrical Instruments (AC-DC)

44 Standard Thermal Converter

Instruments

(813 points)

Estimated FY83 Bill ing $430,000

34
JOSEPHSON VOLTAGE STANDARDS

(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 in 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 (i) to periodically maintain

the U.S. Legal Volt using the assigned value 2e/h = 483593.420 GHz/V^

for the Josephson frequency-vol tage ratio; (ii) to simplify and to

improve the maintenance of the NBS Volt to an accuracy of one part in

100 million or better by developing an all cryogenic voltage standard to

replace the current part room temperature standard; (iii) to investigate

zero-current-bias arrays of Josephson tunnel junctions as a means of

producing significantly larger quantized voltages (100 mV or greater).

This could measurably improve the accuracy and ease with which the U.S.

Legal Volt could be maintained as well as pave the way for the wide-spread

use of Josephson voltage standards in industry; (iv) to develop Josephson

junctions from high transition temperature superconducting materials for

use in voltage standards which can be operated with a mechanical refrigerator rather than with liquid helium. Again, this could lead to the

greater use of Josephson voltage standards in industry; and (v) to

develop reliable Josephson junctions which are impervious to the effects

of room-temperature aging and thermal cycling between liquid helium and room temperatures . These junctions are primarily for use in the commercial 1 ppm Josephson effect voltage standards developed for the Calibration Coordination Group (CCG) of the DoD and KSRI (Korean Standards

Research Institute) but could be offered as an SRM if sufficient

interest existed and the production yield was sufficiently high.

Currently, the goal is to prepare adequate samples for our own in-house

use and for the remaining three instruments and to test, calibrate and

deliver them.

Current Activities

With the departure to private industry early in FY83 of the project's

senior Josephson device researcher, the effort in FY83 was limited to

Objectives (i) and (v). Objective (i), although a continuing activity

since early in 1972, requires a surprisingly large amount of work - - equipment must constantly be tested, repaired, and calibrated. Because

of this Objective's critical importance to electrical measurements

throughout the U.S. and the equipment's high degree of complexity,

maintenance of the U.S. Legal Volt via the Josephson effect must still

be done by highly skilled, knowledgeable, and dedicated professionals.

35
(It should be noted that all customer standard cells are calibrated in

terms of NBS working standards which in turn are calibrated in terms of

reference cells maintained via the Josephson effect. These latter cells

constitute the U.S. Legal Volt.)

Niobium-based tunnel junctions with lead counter electrodes and

having the requisite characteristics are being fabricated for the 1 ppm

voltage standards. These standards are then being tested, repaired,

and calibrated as required to bring them into specification.

Ac comp 1 i shments

A joint proposal with the Electromagnetic Technology Division,

NEL, for collaborative work on Josephson junction arrays [Objective

( i i i ) 1 was submitted to the NBS Director and subsequently funded. However, progress will necessarily be limited until a replacement for the

above mentioned senior researcher is found. Active recruiting is underway.

In FYS3 there were six comparisons of the Josephson voltage

standard against NBS reference groups of saturated standard cells. The

results of these measurements indicate that primary reference groups

NBS-13 and NBS-17 are drifting at the rates of -0.15 ppm/month and

-0.03 ppm/month respectively.

A 1 ppm voltage standard has been under test during the past year.

Problems with fabricating usable Nb-Pb junctions for the standards have

been solved to the point where several junctions are on hand for installation in the remaining instruments. A serious construction fault

was discovered in one of the voltage standard potentiometers that produces an unacceptable error. All the remaining potentiometers were

tested and found not to have this fault. An extra potentiometer will

be substituted for the faulty one.

The glow discharge oxidation process used to produce Nb-Pb junctions has been studied. By varying the process parameters, for example,

direct and indirect exposure time to the discharge, oxygen pressure,

etc., a set of process parameters has been found such that junction

yield has improved significantly, i.e., to the point where almost

every evaporation run of six devices now produces at least one usable

device.

Future Plans

Maintenance of the U.S. Legal Volt via the ac Josephson effect

will continue. Replacement cells with a lower drift rate are being

sought for reference group NBS-13. The enclosure was designed for

smaller NBS type cells, thus replacements must be specially made.

3S
Two commercial voltage standards have been delivered, the remaining three

will be tested, brought into specification, and delivered during FY84.

Production of Nb-Pb junctions will continue for use in the 1 ppm voltage

standards and the al 1 -cryogenic system. Fabrication process parameters

will be investigated to improve the yield of devices, thus reducing the

amount of electrical testing required.

It is expected that the replacement Josephson device research

scientist will be hired and on board no later than mid-FY84. On this

basis, one can expect significant progress towards the completion of the

all -cryogenic voltage standard [Objective (ii)] since it is very nearly

finished - - testing and modest modifications should be all that are required to bring it to the point where it can be used on a routine

basis. One can also expect the collaborative research effort on Josephson junction arrays [Objective (iii)] to be well underway by the

end of FY84. However, this is a difficult technical problem likely to

require several years of creative research to solve (if in fact it can

be solved). Thus, immediate results are not anticipated.

37
REALIZATION OF THE 51 AMPERE

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

Objectives

The objective of this research is to measure 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. Determination

of the SI ampere has been periodically undertaken by NBS since its

founding. This responsibility was given to NBS in its Organic Act.

Although the most modern scientific tools available at a given epoch

have been applied to the ampere realization experiment, there has not

been a significant decrease in uncertainty in its measurement (presently

about 5 to 10 ppm) since the turn of the century. Continuing improvements in the measurements of other fundamental constants have permitted

calculations which indicate that there are possible errors in the present

ampere determinations or in the measurements of these other constants.

A recently suggested method of directly measuring the NBS ampere in

terms of the SI unit by equating electrical and mechanical energy could

reduce its uncertainty by at least a factor of 50. Such an imorovement

would (1) lead to greater consistency between the SI and as-maintained

systems of electrical units; (2) help to resolve the present discrepancies in the fundamental constants; and (3) provide a means for

monitoring the kilogram. There is even the possibility that the new technique could lead to an artifact-independent definition of the kilogram and the mole.

Current Activities

Traditional absolute ampere experiments have measured the force

between current-carrying coils whose dimensions have been carefully

determined. This latter determination, along with uncertainties about

current distributions within the conductors, has 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 exoeriment is performed

in two parts. First, the electrical work is determined from a measurement of the voltage induced in one coil while it moves with respect to

the other, current-carryi ng , coil for a measured time interval. Then

the mechanical work is determined from the force, as measured by

static weighing, between the coils when both carry current and from the

distance traversed. Since only a velocity and displacement need be

measured, the difficulties of determining the dimensions of current

carrying coils are avoided. Because of this, multilayer windings and

superconductors may be used which allows large forces and induced

voltages.

38
Accomplishments

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 crudity of the apparatus,

yielding a statistical measurement uncertainty of about 2 ppm. The

systematic uncertainties were not seriously evaluated, however, because

of the unfavorable Pell at 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 of the complete

system will begin in early FY 84. Figure 1 schematically represents the

essential components. To date, most of the evaluation has been performed

on the balance wheel A. A sensitivity of some tens of micrograms has

been demonstrated. The vertical position of the scale pan hanging from

spider E is read by a laser i nterferometer and the position maintained

Fig. 1. A: Balance wheel

B: main magnetic field

generating coil; C: moveable

coil; D: reference coil;

E: balance support spider;

F: servo magnetic field

generating coil; G: servo

moveable coil; H: marble

slab; J: stone pier.

39
through a computer controlled

applied by a force coil G and

computer controlled hydraulic masses from the scale pans as

servo loop. The correction forces are magnetic field generating coil F. A

weight lifter deposits and removes

appropr i ate.

A temperature controlled oil bath (not shown) houses the main

magnetic field generating coil B. The suspended coils C and D (the

latter serving as a fixed reference) are wound on specially made epoxy

impregnated fiber glass cloth forms. A thermal isolation cabinet (not

shown) encloses these coils. A similar cabinet encloses the servo

coils and balance.

A dedicated tabletop computer has been programmed to perform all servo operations of the balance. A larger mi ni -computer (PDP-11/60) has

been programmed to make all essential measurements to instruct the

tabletop computer which part of the servo operation it must perform.

The apparatus for Phase III is similar to that for Phase II except

that the room temperature magnet B will be replaced by a superconducting

magnet. This will increase the force and voltage to the kilogram and

volt level respectively, and should enable the ultimate 0.1 ppm

accuracy to be achieved. The superconducting magnet is on site and was tested during the FY. It was found that a modification in construction

will be necessary to reduce its liquid helium consumption to an acceptable level.

Future Plans

As noted above, the apparatus for Phase II is completely constructed

and assembled. The principal subassemblies have been evaluated and

appear to behave sati sf actor i ly. The next step is to evaluate the

entire system in operation. Undoubtedly, this will require some parameter changes in the software of the servo programs.

It is expected that preliminary but meaningful measurements will be

made during the winter and spring of 1983 -- 1984. Further, unless

major changes are required, it should be possible to evaluate some systematic effects during this period so that by the end of FY 84 the

NBS ampere experiment can yield a publishable result with a 2-3 ppm

uncertai nty

.

If all goes as planned, we will convert to Phase III in early to mid

FY 85 and begin to evaluate thoroughly all possible sources of systematic

error and accumulate the best possible data.
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,

E 37- 2m9’

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. Thus this year's

activities have been centered on the development of techniques to

accomplish these objectives.

41
Accompl i shments

As previously noted, lateral motion of the balance's base-plate as the

carriage is moved vertically to change electrode position, is a source of

uncertainty in the determination of 3C/3z. Parallel alignment of the

rails on which the carriage moves, and centering of the hydraulic pusher and

its bearings with respect to the guide rails, have reduced this lateral

motion below the 1 ym level over a carriage traverse of 70 mm. Next the

fixed electrodes were assembled on the carriage and adjusted to be

vertical and centered. Also their profiles were studied using a non- contacting capacitance probe with a resolution of approximately 0.1 ym.

The intermediate electrode, suspended from the balance-beam in the annular

space between the fixed electrodes, is now being similarly studied.

Future Plans

The next step will be the determination of 3C./3z, preliminary to force

measurements at the 1 g level. This will complete the first phase of our

volt determination. The center of gravity of the suspended electrode

system will require to be lowered before force measurements can be carried

out at higher levels. This is because the centering force of gravity

acting on the pendulous electrode structure must be greater than the

lateral electrical force resulting from departure of the electrode from

its coaxial position.
REALIZATION OF THE SI FARAD AND OHM

(J. Q. Shields, R. D. Cutkosky, L. H. Lee)

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 absolute farad and ohm measurements make use of a calculable

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

8

. These measurements can also be considered as fundamental constants measurements, with applications to questions

concerning the adequacy of quantum electrodynamic theory and to the

determinations 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 i ne-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 8 was obtained in 1974.

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.

Accompl i shments

Three capacitors of NBS construction have been circulating for many

years between the major national standards laboratories under BIPM

auspices. The capacitors were returned to NBS this past year following

measurements in Canada, France, and Italy. They continue to exhibit

excellent stability while being shipped via commercial carrier. After

remeasurement, they were sent to the ASMW, German Democratic Republic.

43
The laser previously used with the calculable capacitor is being

replaced by a new stabilized, helium-neon laser having much better

stability. The new laser in combination with an acousto-optic

modulator for eliminating the effects of reflected light from the

interferometer should significantly reduce the uncertainty in the

basic length measurement required for the realization of the SI

farad and ohm.

Much of the recent effort to improve the absolute farad and ohm

measuring system has been concentrated on that part of the system

which compares the NBS unit of capacitance with the N8S unit of resistance. The problem of frequent equipment failures in this area appears to have been reduced to a tolerable level as a result of

equipment replacement and modification and the provision for backup

equ i pment

.

Measurements of the stabilities of components used in the measuring system have provided a sound basis for determining acceptable

time-lags between calibration and use of components. The better than

excepted stabilities found for capacitor voltage dependencies is

especially significant in view of the time-consuming nature of voltage

dependence measurements.

Future Plans

New absolute farad and ohm measurements are in progress. Present

thinking is that these measurements should be made on a regular basis

during the next few years so as to determine the drift rates of the

NBS reference capacitors and resistors. Efforts to upgrade the existing

apparatus will continue. An international comparison of resistance

standards at BIPM is scheduled for FY 84. Also planned is a direct

comparison with Australia of one ohm standards calibrated in terms

of each laboratory's calculable capacitor. This comparison should provide a good test of the overall reliability of each laboratory's

measurement chain.
QUANTIZED HALL RESISTANCE

(M. E. Cage, R. F. Dziuba, and B. F. Field)

Objectives

To develop the quantum Hall effect in semiconductors to the point

where it can be used (1) to determine the fine-structure constant a to

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 continually

maintain the U.S. unit of resistance 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, Rh, of metal-oxide-semiconductor field effect transistors (MOSFETs) and of GaAs-AlGaAs heterojunctions at liquid helium

temperatures in large magnetic fields. The Hall resistance (the

ratio between the Hall voltage and sample current I) is given by

= V H = V „ 25,812.8

H HE 2ai i

( 1 )

where Pq is the permeability of vacuum (defined to be 4 tt x 10~ 7 H/m),

c is the speed of light in vacuum, and i is an exact quantum integer.

Currently we are (1) acquiring and building new apparatus to be used

in a second generation measurement system for this project, (2) con- tinuing the collaboration with R. J. Wagner of the Naval Research

Laboratory (NRL) in studies of MOSFET devices using the 15 T superconducting magnet at the NRL high Magnetic Field Facility, and (3) performing quantum Hall effect experiments on GaAs heterojunction samples

using an 8 T magnet installed in a shielded room at NBS.

Accompl i shments

We have demonstrated in a series of experiments that GaAs hetercjunction devices can be used as resistance standards. The shape of

the i=4 (6,453.2 ohm) Hall steps of device GaAs(7) was measured to

high precision and found to be flat to within 0.02 ppm. Furthermore,

45
measurements of Rj-| have a day-to-day reproduci bi 1 i ty on the order of

0.01 ppm and are apparently limited by the stability of the wirewound reference resistors. There would seem to be little doubt that the

quantum Hall effect can eventually be used to maintain the U.S. unit

of resistance.

The temperature dependence of was measured for GaAs(7), and

as Fig. 1 shows, the value of changed by 20 ppm between 1.1 K and

50

40

30

20

10

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

TEMPERATURE (K)

0) o>

o

E

x>

Fig. 1. Although (filled circles in the figure) is temperature

dependent, we can reduce the temperature sufficiently to introduce

less than a 0.01 ppm error, an accuracy which is required if the device is to be used as a resistance standard. V x (the voltage

drop along the channel, plotted with crosses) can be used as a quality factor to determine the inaccuracy of fty. These data were obtained at 25 pA.

and 4.0 K. The temperature-dependent error appears to be less than

0.01 ppm for this device when cooled to 1.1 K. Temperature dependences will have to be determined for every device which is proposed

as a resistance standard. A paper reporting this work will be

prepared in early FY 84 and submitted to Physical Review B.

We also studied the current dependence of GaAs devices and

observed dynamic non-linear behavior resulting from catastrophic

breakdown of the dissipationless current flow (see Fig. 2) at

high currents (correspondi ng to a three-dimensional current density

of 40,000 A/cm"). We demonstrated that this breakdown is spacially

localized and observed transient switching on a microsecond time

scale among a discrete set of distinct dissipation states. A paper

describing this work and which includes a proposed macroscopic

46
T

T

.4

0.3

co "5

>

0.2 ' X

>

0. I

0.0

300 350 400 450

SD CjU-A)

Fig. 2 Current dependence of ARH/R^ s [Rh(I S0 )/Rh(25 uA) - 1] and V x for the i=4 step of GaAs(7) at 1.1 K. The solid lines

are meant to guide the eye. Also shown are the source, drain,

and four potential probes. Each device is 4.6 mm long and 0.38 mn wide. picture which accounts for the novel phenomena observed will appear in

Physical Review Letters (10 October 1983).

We now believe we have an explanation for the 0.8 ppm discrepancy between the values of Rh that we obtained at Bell Labs and

those obtained at the Naval Research Laboratory and at NBS. Part

of the discrepancy can likely be accounted for by the temperature

dependencies of the Hall steps which were only measured at 4.2 K at

Bell Labs. Also, the Bell Labs results were based on i=2 (12,906.4 ohm)

Hall steps while the other measurements at NBS and NRL used i=4 steps.

Part of the discrepancy may thus be due to errors in the calibration stepup from 6453.2 ohms to 12,906.4 ohms.

Future Plans

Providing Bell Labs can locate the samples used in our early

measurements there, we will attempt to verify that the 0.8 ppm

I

47
discrepancy problem has indeed been resolved by carrying out new measurements near 1 K. In the meantime, we will continue to determine the value

of Rh in terms of the NBS as-maintained ohm. To this end, we have

devoted many months work to identifying systematic errors in the quantum

Hall effect measurement system. No errors larger than 0.02 ppm have

been found. We did discover, however, that the room temperature current

comparator bridge may have a systematic error as large as 0.25 ppm when

used to intercompare 6,453.2 ohm and 10 kohm resistors. We plan to

bypass this bridge using four different methods. The first, already com- pleted, uses a Kel vin-Varley divider to measure the 6.4532 kohm/10 kohm

ratio with an estimated uncertainty of 0.13 ppm. The result is a value

of Rq that is 0.27 ppm larger than that obtained using the current

comparator. The second method will use a Hamon device to step-up from

100 ohm to 6,453.2 ohm with an expected uncertainty of 0.01 - 0.02 ppm.

These measurements are ready to commence. The third method will

employ a Hamon step-up from 1 ohm to 6,453.2 ohm, while the fourth will use a cryogenic current comparator bridge for a 0.01 ppm step-up from

1 ohm to 100 ohm, 1 kohm, 6,453.2 ohm and 10 kohm. However, the

determination of Rh in SI units will have to await the results of the

redetermi nati on of the NBS ohm in SI units currently underway using a calculable cross-capaci tor

.

The 15 T magnet system and its associated ^He refrigerator ordered

at the end of FY 82 should be delivered, installed, and tested in

FY 84. This magnet will enable us to investigate the geometry dependence

of Si M0SFET devices at NBS. We also plan to continue temperature

and current dependence measurements and to further verify that the value

of Rh can be device-independent under the proper conditions. A new automated measurement system which should be ready to use during FY 84

will greatly reduce the tedium of data collection.
GAMMA-P and the fine-structure constant

(P. T. Olsen, W. D. Phillips, E. R. Williams, Song Junshou, G. R. Jones)

Objectives

To carry out an improved determination of the gyromagnetic ratio

of protons in H 2 0, 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 Oosephson effect, and the quantum

Hall effect, can be tested. It will also provide an alternate means

to monitor and maintain 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 experiment 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 frequency wp of a proton in a magnetic field

B to the magnitude of the field, ojp/B (the prime indicates the proton

is in a spherical, pure, H 2 0 sample). The precession frequency is

measured by standard nuclear magnetic resonance methods. The magnetic

field is calculated from the measured physical dimensions of a singlelayer 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 interferometer 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 of

the probe; (v) increased S/N ratio for the NMR signal; (vi) improved

temperature control; (vii) improved calibrations of our length and

electrical standards; and (viii) capability for a direct measurement

of all the susceptibility corrections. These advances should produce

an order of magnitude improvement in our previous determination. The

new quantum Hall effect, which provides an independent value of a,

provides additional incentive for completing the yp measurement in the near future.

49
Accompl ishments

We have installed the solenoid and straightedge; the detector

coils are all wound; the cooling system is operational, controls the

solenoid temperature to 0.1 °C, and the temperature can be reliably

read to 0.01°C. Provisions have been made to control the temperature

to 0.01 °C if necessary, but the system as it presently operates should

be adeuqate for a 0.01 ppm experiment. We are changing the automation

system so that the laser for the absolute ampere and yp experiments

are operated by separate computers. This will allow us to run and

debug the two experiments simultaneously. This has delayed automating

the yp experiment, but all the required equipment is now on hand.

The new pick-up coils have 0.01 pm/ / Hz resolution limit (due

to amplifier and resistive noise) for the diameter and pitch measurements. This is a factor of 5 to 10 improvement over the last experiment. However, it does not include the noise, not yet evaluated, due

to mechanical vibrations. A new method to operate two inductive pickup probes simultaneously has been developed and the digital electronics

built. This will allow us to have the entire i nterferometer in vacuum.

Future Plans

Our goal to have a preliminary but publishable value of yp and a by June of 1984 is unchanged. However, we have made several ‘ changes

in the design for automating this experiment and must realize those

changes in the next four months in order to meet this timetable.

Dimensional measurements must be in progress by January 1984. The

perliminary results should yield a value of yp accurate to about

0.1 ppm, (0.05 ppm value of a). It will be very important to have

our measurements coincide with those of the quantum Hall resistance

and the calculable capacitor experiment so that we can eliminate the

question of drift in the electrical units. The present discrepancy

between the old y results and some preliminary quantum Hall results

heightens the need for a 0.1 ppm value of Yp as soon as possible.
ADVANCED IMPEDANCE-MEASUREMENTS RESEARCH

(R. D. Cutkosky, L. H. Lee)

Objective

To design, build, and test components and subassemblies for a family of portable, stand-alone, automatic impedance bridges with

IEEE 488 bus compatibility. A prototype working capacitance bridge

has been the focus of the work for the last several years.

A significant number of important electrical measurement problems

are encountered in the course of providing measurement services,

conducting exploratory research, determining fundamental constants,

and realizing the SI definitions of the electrical units. Yet,

although important, the problems are often too specialized to attract

commercial development of appropriate instrumentation. The purpose

of this project is to help solve these problems by working closely

with the personnel of other projects involved in these activities.

Current Activities and Accomplishments

The prototype automatic capacitance bridge was completed during

FY 83. It has the following specifications: frequency range: 20 Hz

to 20000 Hz; capacitance range: 1200 pF maximum, in three ranges - 0-12 pF, 0-120 pF, and 0-1200 pF; conductance range: 9300 pS maximum,

in the highest range; voltage range: up to 90 volts, dependent upon

range and frequency (1 volt max. at 20 Hz); resolution: up to one

part in 100 million, dependent upon frequency and voltage; stability:

not yet determined, but evidently close to one part in 10 million

per year; accuracy: this will be studied in the coming year, but

should be better than 1 ppm over its entire range.

The bridge is a stand-alone instrument that can be controlled

from the front panel to select and measure one of up to 16 capacitors

connected to its input terminals at any frequency and voltage within

its range. The result is displayed on the front panel in standard

decimal format. Optionally, the bridge can be controlled remotely

via its IEEE 488 bus interface. This would be the expected mode

of operation, since the remote computer or desk calculator could

then be used to store the data and apply the necessary calibration

corrections. Part of the program residing in the read-only memory

of the bridge is devoted to the generation of the internal look-up

table that is accessed by the bridge during its normal operation.

This internal calibration program is in turn controlled over the

488 bus by a program now running on a desk calculator. The lookup table for a bridge can be generated with this system in about

six hours of nearly hands-off operation. The system will allow

a new bridge containing this feature to be placed in operation

very quickly, and will provide a means for re-aligning a bridge

after routine servicing.

51
The interna] capacitance standard gave some cause for concern

last year, but a preliminary model was installed early this year so that the work on the rest of the bridge could proceed. The capacitor

has never been temperature cycled to improve it's stability, but

it is now drifting about one part in ten million per year. It

is expected that future models will be better. A stand-alone

capacitance standard is also being constructed. It will be some

time before anything can be said about it.

Future Plans

Plans are being made to design equipment for performing an automatic external calibration of the bridge under computer control.

This will yield a set of calibration tables indexed with frequency

that could be placed in the desk calculator controlling the bridge

in a calibration environment. The equipment needed for such a process are two or more programmable inductive dividers, sets of

defining transformers and coaxial star junctions, and a few capacitance

and conductance standards of an appropriate value. Some minor

modification to the bridge internal program may be required to

achieve the result required. It should be noted that beyond the

process outlined above, which involves purely ratio measurements,

though complex ratios, it is also necessary to have access to

standards of capacitance and conductance, that are known as a function of frequency, to obtain a complete calibration of the

bridge. Such standards are not presently available, and will have

to be provided by another source.

Other work that will be carried out next year includes con- tinuing the production of drawings, wiring diagrams, and assembly

instructions for the bridge. If more bridges are constructed,

a great deal of time will be spent seeing that these instructions

are complete and correct.

52
NEW DC VOLTAGE METROLOGY

(B. F. Field)

Objectives

The objective of this project is to improve the ten volt voltage

maintenance process so that a laboratory can reliably maintain a unit

of voltage and traceability to NBS at the ten volt level. This includes

(a) developing new voltage standards based on rugged solid-state

devices, and (b) developing measuring instruments and methodologies

to take advantage of the new standards.

Although the latest voltage references on the market provide

stability approaching primary standards (approximately 0.5 ppm/yr),

several problems remain. Shipping of the standards requires careful

coordination between the shipper and receiver because of the

requirement to maintain the unit under power (with limited battery life).

Highest accuracy is obtainable only at the six to ten volt level, a voltage not particularly suitable for calibration with standard cells.

We will develop a measurement system to characterize voltage

reference devices (e.g., Zener diodes) at the six to ten volt level.

Since NBS does not manufacture reference devices, we will establish

liaison with industrial companies and characterize presently

available devices. In addition we will design an easily transportable

10 V standard with good short term predictability (0.5 ppm over several

weeks). This standard will be used in a program to disseminate the

volt directly to the user at the ten volt level at reduced cost as compared

to standard cell calibrations.

Current Activities

We are using the recently developed automated measuring system

to continue evaluation of a number of reference devices (components)

and complete voltage standards (instruments). In particular, we are studying the effects of extraneous ac, long term stability, short

term predictability, and the effects of cycling power and temperature

regulation on and off. This information will be used to help design

the transportable 10 V standard.

The measurement system presently uses a special scanner switch.

We are in the process of developing an improved scanner that may be

easily replicated for use by other laboratories. This scanner is

expected to produce thermal emf errors less than 50 nV and would be

useful for many other electrical measurements. Other laboratories will

thus be able to duplicate our measuring system, permitting them to

make more accurate measurements between one and ten volts (up to 5 times more accurate than present instrumentation).

53
We are working on the design of a 10 V transportable standard.

Our purpose is to develop a convenient standard that can be turned off

and shipped to another standards laboratory by commercial carrier with

a transfer accuracy of 0.5 ppm or better. A group of reference devices

are currently under test to determine their sensitivity to power cycling

on and off and their response to wide temperature fluctuations.

Additionally, we are considering a burn-in procedure to minimize

voltage hystersis on power cycling.

Accompl i shments

An automated measuring system to measure voltage references in the

range of 1 - 10 volts has been completed. An error analysis which

included performing a series of experiments and developing models to

evaluate systematic measurement errors was completed during the past

year. Some of the digital voltmeter (OVM) errors (zero offset and

gain) are determined and corrected during voltage measurements, while

others (linearity, leakage resistance, ac effects from DVM noise) were found to be small enough (< 0.1 ppm) to be neglected. A

sensitive loop closure experiment was designed in which three different

measurements are made on a given reference with the measurements

ideally summing to zero. This study found that the measurement

system has an accuracy of 0.2 ppm (3 standard deviation estimate)

when comparing a properly isolated Zener-diode-based reference to a standard cell.

Extraneous alternating currents, some generated by the reference

under test, continue to be the largest single source of error. We have

concluded that each new type of voltage standard must be checked to

determine what effect normal and common mode noise have on the dc output of the unit.

A special MBS designed low-level switch is used in the measurement

system. We have constructed a first attempt prototype card that can be

used in a commercially available scanner. This card should be reasonably

inexpensive, less than $50 per switch point, and can be readily

duplicated. Figure 1 compares thermal emf errors for two commercial

cards presently available, and our prototype card.

As a result of our on-going study of reference devices and standards,

we have identified several weak areas.

1. Many of the standards exhibit a dc shift when a small amount of

noise is applied at the output (i.e., noise from a DVM input).

2. Some reference devices appear to have much poorer dynamic resistance

than manufacturers specifications. Several stages of preregul ati on are required for good short term stability.

54
0.4

0.2

0.0

- 0.2

I

- I I

* {

V *

-0.4 1

STANDARD

CARD I STANDARD NBS

CARD 2 PROTOTYPE -

-0.6

Figure 1

3. Most transportable standards need to be shipped under power for

best transfer accuracy. Battery life limits the shipping

distance and ease of shipping.

4. Some reference devices are more stable if they are kept "turned

off" with only short term application of power during infrequent

measurements.

5. An extensive testing and selection process appears necessary to

select reference devices with desired noise levels and

stabi 1 i ty.

A commercial voltage standard has been subjected to a long term

test. The data (Fig. 2) shows that if a correction were made for the

long term drift of the standard, an accuracy of 0.4 ppm could be

realized in the laboratory. The test was terminated when the standard

failed, badly overheating the internal reference (105 °C).

TIME (months)

Figure 2

55
Future Plans

We intend to continue testing available reference devices; long

term tests will continue to help estimate their ultimate stability.

Effects of power cycling, temperature, and humidity will be studied to

allow selection of a suitable device for the transportable standard.

The design of the transportable standard should be completed in

FY 84, including a highly regulated and isolated current source, an enclosure with appropriate thermal packaging, and possibly a temperature regulation circuit. Construction of a prototype will begin, to

be followed by an evaluation of its shipping characteristics. Once

the transportable standard has been completed, we will consider

disseminating the volt at the ten volt level. This should increase

the ultimate accuracy available to the end user by eliminating the error associated with scaling the volt at the user's laboratory.
EDDY-CURRENT NONDESTRUCTIVE EVALUATION

(G. M. Free)

Objectives

The eddy-current project has two principal objectives: the development of a calibration service for electrical conductivity standards in

the range 1%- 100% IACS (International Annealed Copper Standard); and

the production of electrical conductivity standards which will become

NBS Standard Reference Materials.

Eddy-current testing of metal components, based on the change in

impedance of a pick-up or test coil placed on the component is

prevalent in industry. The primary uses are in the measurement of

material properties and in the detection of flaws. The tests have

such applications as the sorting of metals, the measurement of cladding

thickness, and the sizing of defects. Despite the large number of

applications, adequate standards for the calibration of eddy-current

instruments do not exist. The development of standard reference

materials and a calibration service for electrical conductivity

standards will meet the need for accurate calibration of conductivity

test systems.

Current Activities

The electrical conductivity calibration service and the calibration of electrical conductivity standard reference materials have as a common factor the instrumentation developed to measure electrical

conductivity. This instrumentation consists of a di rect-current or

dc measuring system by which the dc conductivity of metal samples is

determined. These metal samples then become the primary conductivity

standards at NBS. Using an eddy-current bridge developed at NBS that

is based on a new concept in eddy-current measurement, comparison is

made between the primary conductivity standards and either customer

samples or SRM's to determine their electrical conductivity.

The dc measurement system has been modified so that four-point

measurements can be made on small samples. The feasibility of using

the four-point measurement technique in conjunction with the relationships between conductivity, sample resistance, and sample

thickness developed by Van der Pauw has been tested. Although

accurate measurement of resistance can be made, thermal emf's are

a major source of error. To eliminate this problem, a new temperature

controlled oil bath has been purchased and is now being tested for

temperature stability. The four-point measurement approach . shoul

improve the dc measurement by an order of magnitude since resistivity

is a function of sample thickness instead of sample cross-sectional

area, and the thickness of the sample can be measured extremely

accuratey over a small area. Also, since the samples are small,

optical techniques can be used in machining, thus significantly

improving the dimensional tolerances of the samples.

57
Development work on the eddy-current bridge used to determine the

impedance of the test coil is focussed on simplifying the measurement

and increasing the frequency range of the bridge. In the typical Maxwell

inductance bridge, two sets of balances must be made: the primary

circuit balance (which determines the value of R and L of the inductor),

and the ground circuit balance (which reduces the error due to stray

capacitance). To simplify the measurement either the ground circuit

can be eliminated or the number of balances between the two circuits

can be reduced. Both approaches are being tested but at present

elimination of the ground circuit is not possible. The current method

is to match components in the primary and ground circuits and to use common inductive dividers to drive the components. Using this scheme

the measurement has been greatly simplified. The main circuit is

balanced, a slight adjustment at the highest detector sensitivity is

made to the ground circuit, and then a final balance is made of the

main circuit. In most cases three circuit adjustments are all that

are necessary to obtain final balance.

To increase the frequency range of the bridge it was necessary

to use new broadband operational amplifiers in the ground network;

it now covers the range 100 Hz to 100 kHz. The final configuration of

the ground circuit to obtain minimum noise and drift and high phase

accuracy over this range is being completed.

Accompl i shments

The following was accomplished during FY 83: (1) The dc measurement circuit was modified to make measurements of resistance at the

10 micro-ohm level. (2) A holder for small metal samples was con- structed and the feasibility of making measurements using Van der Pauw's

relationship was tested. The major sources of error in this technique

were determined and steps are being taken to eliminate them, (3) The

frequency range of the eddy current bridge was extended to cover the

range .100 Hz to 100 kHz. (4) Measurements using the eddy-current

bridge have been simplified so that in most cases three adjustments

of circuit parameters are all that are necessary to achieve final

balance at the highest sensitivity. (5) A new sample holder has

been constructed which allows the test coil to metal -separati on distance to be varied by increments of less than 0.1 micrometers.

(6) A new calibration scheme has been devised which incorporates the

capabilities of the new sample holder so that it is now possible to

reduce lift-off error to the ppm level. (7) The effects of coil

heating have been significantly reduced. (Once the lift-off error

is minimized, it is possible to determine the drift rate of the coil

due to heating. By i nterspersi ng measurements of the standard with

those of the unknown, corrections can be made to the measurements to

reduce this error.) (8) A method has been devised to determine the

frequency error in the calibration of the test coil. This has not been

tested as yet, (9) A document on the measurement of electrical

conductivity by the eddy-current method written for ASTM has passed the

58
ASTM main committee ballot and will be published in either the 1984 or 1985 ASTM book of standards. ( 10) • Documentation of the dc and eddy

current measurement systems has been completed in draft form for

possible publication as a NBS Technical Note.

Future Plans

Plans for FY 84 include: (1) Calibration of all primary standards

using the new dc method. (2) Determination of temperature coefficients

of the primary standards over a broader range of temperature, i.e.,

15-30 °C. (3) Calibration of new SRM's at the 100% and 1 % IACS levels.

(4) Completion and publication of the above mentioned documentation

and announcement of the calibration service for eddy current conductivity

standards. (5) Determination of those ferromagnetic materials for

which SRM's would have the greatest impact. (6) Initial design of an eddy-current bridge for the calibration of ferromagnetic materials.

59
LASER COOLING AND TRAPPING OF NEUTRAL ATOMS

(W. D. Phillips, J. V. Proclan, J. J. Metcalf)

Objectives

The fundamental objectives of this project are to decelerate, cool,

and possibly confine (trap) neutral atoms using tuneable lasers.

The motivation for this work is that cooling and trapping provide

solutions to the problems of 2nd order Doppler effect, transit time

effects, and other motional effects which limit the performance of

ultra-high resolution spectroscopy. This work is compl ementary to

the trapped ion cooling work of 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 fi ne-structure constant from Stark

splittings. Spectroscopy of very cold neutral atoms also has possible

applications in microwave and optical frequency standards, and in

atomic theory and fundamental constants

„

Current Activities

Atoms which interact with light that is resonant with an atomic

transition experience forces which can decelerate, deflect, or confine

the atoms. In our initial experiments we have opposed a beam of sodium

atoms with a resonant laser beam. Atoms absorb and re-radiate photons

from the laser beam, with about 30,000 absorptions needed to bring

thermal velocity atoms to rest. A key problem is that atoms which

absorb several hundred photons will decelerate enough to be Doppler

shifted out of resonance with the laser. In addition, after several

absorptions, atoms may be optically pumped to states which are inaccessible to further excitation by the laser. Both of these

problems are solved using a spatially varying magnetic field. This

field causes a spatially varying Zeeman shift which compensates the

Doppler shift, and also allows optical pumping to be avoided when

the laser is circularly polarized. Using these techniques, sodium

atoms have been decelerated to velocities as low as 40 m/s.

During the past year we have improved the performance of the atomic

beam deceleration procedure by providing better vacuum conditions,

increased laser power, and improved laser beam optics to optimize the

cooling process. In addition, we have recently used another technique

for avoiding the Doppler shift problem — rapidly scanning the cooling

laser frequency to stay in tune with the atoms as they decelerate.

This method was suggested a number of years ago but has never before

been successfully used.

Angular divergence of the atomic beam as it decelerates is a process which limits the achievable density of slow atoms. We have

60
constructed a magnetic hexapole lens to re-focus the diverging atomic

beam, and preliminary results indicate that a substantial gain in

density is possible at the lowest velocities.

Using our improved techniques for modest decelerations (about a factor of two) we have obtained cooled atomic beams with velocity

spreads as small as 2% and with densities per unit velocity more than

20 times higher than is achieved in a thermal beam.

We have developed a numerical computer model of the cooling

process which yields results in good quantitative agreement with

experiments, and which we hope will be helpful in further experiment

design.

A well received workshop on laser cooling and trapping of neutral

atoms was held which stimulated a number of new ideas, and the

proceedings published as NBS Spec. Pub! . 653, Laser Cooled and Trapped

Atoms.

Future Plans

We will continue to study the basic cooling process, with a view to

better understanding its limitations and how to optimize it. In

particular, we will be attempting to achieve lower final velocities,

narrower velocity distributions, and higher densities. We will be

continuing with the studies of magnetic refocussing and we will be

investigating the effects of our detection process on the final atomic

velocity distribution.

Recent theoretical developments in the field of laser trapping of

atoms indicate that stable trapping of sodium atoms for periods as long as ten seconds should be possible. While the energy of atoms in

such traps is still lower than the lowest energies we have obtained,

we will be considering techniques to decelerate the atoms as they

enter the trap, with an ultimate goal of trapping and further cooling

the atoms.

We are also considering the deceleration of a beam of atoms having

a narrow visible transition as a possible candidate for an optical

frequency standard. At present, calcium seems to be a likely first

candidate, since the observation of the red interccmbi nation line yields

the narrowest observed feature in the visible spectrum, and the width

is limited by the second order Doppler effect. Cooling calcium as we

have cooled sodium should virtually eliminate the second order Doppler

width.

61
FRACTIONAL CHARGE ELECTROMETER

(G. R. Jones, E. R. Williams)

Objectives

To construct a device capable of measuring the net electric charge

on a small test mass (a sphere with a diameter of approximately 6 mm) to

an accuracy of one tenth of an electron charge. This instrument shall

be used in a search for stable fractional charges.

Previous attempts to detect stable fractional charges have led

to null results except for the Stanford experiment. The majority of

these tests measure the response of a magnetically suspended test mass

to an applied electric field, i.e., a force measurement. The test masses are typically small steel or niobium spheres with diameters of

less than 0.3 mm. Due to the nature of this experimental technique,

spurious effects, such as the patch effect, can mimic fractional

charges. The method discussed here would avoid many of these "artificial"

signals by making a direct measurement of the net electrical charge on the test mass. This will be accomplished by placing the sphere within

a Faraday cage and measuring the image charge induced on the outer

surface of the cage through the use of a modulating capacitor. From

Gauss' Law it is apparent that theoretically only the net charge of

the sphere, and not the charge distribution or orientation of the

sphere, is important. Because this method of detecting fractional

charges is fundamentally different from previous attempts it should

be able to resolve the apparent conflict between the Stanford results

and those of other experimental groups. Furthermore, this method

allows far more massive objects to be examined than in earlier tests.

Current Activities

At present the first apparatus capable of effectively testing the

Faraday cage/modulating capacitor system is being fabricated in the NBS

shops. The means by which the capacitance modulation is achieved

is depicted schematically in the figure. A 10 cm disk, with 300 teeth in

QUARK ELECTROMETER

LEVITATION MAGNET

(OR STRING)

VA = q sin {2nf 1 i)/[Co+ C 1 s!n(2nf2

t)]

I, = 1 to 100 Hz

$2 = Rotation freq. x no. of teeth = 100 kHz

If q = e and C0 = Cq = 10 pF, then VA = 1Q3 V P? C0 = Average capacHanca at A

C1 = Peak modulation capacitance

62
a pattern similar to that of a gear, is spun at rotational frequencies

of up to 20000 rpm. A small probe with a complimentary tooth pattern

is placed approximately 10 micrometers from the rim of the disk. As

the disk rotates the gap between the disk and the probe varies due to

the patterns, the result being a periodically varying capacitance with

an average value of approximately 10 pF.

In the initial tests of the apparatus the test sphere will be

suspended within the Faraday cage by means of a quartz fiber. However,

the height of the sphere within the Faraday cage can be adjusted to

test for false signals due to the supporting fiber. Further, the test mass will be periodically shielded from the Faraday cage by a second,

grounded cage rotating with the capacitor disk. By thus "removing"

the test sphere from the measurement Faraday cage, that part of the

output signal of the device due to the charge of the sphere can be

separated from the part due to noise sources within the electronics.

The deisgn of the equipment is such as to allow the inclusion of a magnetic suspension system to levitate the sphere at a later date.

The entire apparatus is placed within a vacuum chamber to reduce

the transfer rate of charges between the test mass and the surrounding

environment. Magnetic and electrical shields are also being made to

fit around the capacitor and the Faraday cage.

Accomplishments

Preliminary experiments at atmospheric pressure and with minimal

shielding were encouraging in that sensitivities of a few 100 e/ /Hz

were obtainable. However, due to the rapid transfer of charge to and

from the test sphere it was obvious that a shielded and vacuum enclosed

system was necessary to continue the experiments to achieve the optimal

geometry and measuring techniques required for this test.

A variety of different methods of producing the modulated

capacitance were examined with a motor driven flutted wheel being

chosen as the best method by which sufficient modulation (50%) of a small capacitance could be accomplished. (The motor is mounted outside

the vacuum system and drives the wheel through a ferrofluidic rotating

feedthrough capable of spinning at 30000 rpm.) A full scale model of

the 10 cm diameter disk (without the teeth) has been successfully

rotated at 20000 rpm using a 1.9 cm diameter ceramic rod as the spindle.

To mount the ceramic rod between a bearing and the motor, aluminum

caps (which reduce the diameter of the resulting shaft from 1.9 cm

to 0.64 cm) were heat shrunk to the ends of the rod. Due to

misalignment between the motor at one end of the rod and the bearing

at the other end, the 0.64 cm diameter aluminum shaft eventually

snapped. This problem will be eliminated through the use of steel

end caDS ? bearings at each end of the rod, and a flexible couDling

between the motor shaft and the rod.

63
Future Plans

Once the equipment is completed, various geometries involving the

measuring Faraday cage, grounded shielding cage, and capacitance disk

will be examined to determine the system which produces the best

sensitivity. After this preliminary examination, test spheres of

different materials and sizes will be measured. Further, the innermost

shield around the disk and cage is of 6 cm thick copper which will

allow the system to be cooled to liquid nitrogen temperatures . This

cooling may be necessary to freeze any thin electrically charged

films which could be on the surface of the capacitor, and hence be a source of noise.

If the necessary sensitivity can be achieved, this method will

greatly increase the total amount of matter examined for fractional

charges. (At present, the total mass studied in all experiments

i s less than a gram.

)

64
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 re- commended values of these constants for international use.

The close relationships that exist between the fundamental con- stants and precision measurements, basic measurement units such as the

ampere, volt, and ohm, fundamental physics, and state-of-the-art

measurement technol ogy, 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 for a system of

reproducible, artifact-independent measurement units. Such a system

is the ultimate long-range goal of metrology.

Current Activities

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 OSRD (this publication lists preprints

as well as reprints of PMFC papers); (5) attending and organizing

national and international conferences on PMFC, visiting laboratories

carrying cut work in this field, and giving talks on the present

65
status of the fundamental constants; and (6) answering inquiries from

both within and without MBS relating to the PMFC field.

Accompl ishments

Accomplishments in FY 82 include:

(i) Publication of four quarterly issues of PPMFC and continued

maintenance of the Data Center's PMFC reprint file.

(ii) Completion, in collaboration with W. D. Phillips of the Electricity

Division, of all the editorial and proofreading work for the

Proceedings of the Second International Conference on Precision

Measurement and Fundamental Constants (held at MBS 1981 June 8-12),

to be published as a hard-bound volume under the title MBS

Special Publication 617, Precision Measurement and Fundamental

Constants II. Uncontrollable production problems have delayed

publication but the volume should be available by the end of

1983 or in early 1984.

(iii) Participation in the work of the NAS/NRC Advisory Committee on Fundamental Constants, in particular, the writing and editing

of a report documenting the importance of the PMFC field to

physics and the need for continued, strong support of research

in this field. The report has now been published under the title

Research Concerning Metrology and Fundamental Constants.

(iv) Presentation of three talks related to the fundamental constants:

The Boston Chapter of the IEEE Society on Instrumentation and

Measurement (20th anniversary meeting); the APS January 1983

General Meeting; the International Bureau of Weights and Measures;

and the NBS Research Advisory Committee's (RAC) Seminar "New

Directions in Fundamental Constants."

(v) Representing MBS at the 16th Session of the Consultative Committee

on Electricity and participating in discussions of measurements

of 2e/h in SI units and determining the fine-structure constant

from the quantum Hall effect; meeting with the NBS RAC and

providing input to their deliberations on PMFC work at NBS;

visiting several laboratories in France carrying out PMFC related

work (LCIE, BIPM, Thomson-CSF) ; reviewing four papers for Physical

Review Letters in the PMFC area; and answering a number of

telephone and written inquiries relating to PMFC and providing

assistance to W'inel and and colleagues (NBS/Boulder) on mp/me via

ion cyclotron resonance, Hughes (Yale) on Uy/pp from the muonium

hyperfine splitting, Sapirstein (Cornell) on a

-1 from the muonium

hyperfine splitting, Barker (Auckland) and Greene (NBS) on NAh/c,

and Berquist ( MBS/Boul der ) on mp /me via laser spectroscopy.

66
(vi) The main effort during FY 83 was directed towards completing the

1983 Least-Squares Adjustment of the Fundamental Constants

(LSAFC83). While considerable progress was made in this direction,

the task is yet to be completed (it is about one quarter finished).

Unfortunately, administrative burdens during this period were

especially heavy, thus preventing the progress hoped for.

Nevertheless, it is expected that the LSAFC83 will be completed

by mid- 1984.

Future Plans

The following is planned for FY 84: (i) continue overseeing the

publication of PMFC-II (it should be out in early 1984 at the latest);

(ii) publish as usual the quarterly PPMFC; (iii) respond to inquiries

as received; and (iv) attend and participate in the April 1984 meeting

of the NAS/NRC Fundamental Constants Committee. However, the main

objective in FY 84 will be (v) to complete LSAFC83, to oversee its

adoption for international use by CODATA, to submit a detailed report

for publication in the J. Phys. Chem. Ref. Data, to prepare a short

report for publication by CODATA, to prepare a semi -popular version

for publication in Physics Today, and to give talks on the 1983

adjustment at the ninth CODATA Conference and CPEM 84.
PRECISION MEASUREMENTS GRANTS

(NBS Precision Measurements 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 to eight 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 MBS programs

are chosen as grantees. 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 and the Outside

Advisory Committee (consisting of senior university professors) to submit more detailed proposals. The same committees evaluate these, and on the basis of this evaluation, the grantees are finally selected. The

criteria used in evaluating the preproposals and full proposals include

the importance of the proposed research to science, the feasibility of the

research, and the past accomplishments of the applicant.

68
Accomplishments

A renewal proposal was prepared and sent to NSF requesting that

they continue to support the renewal grants of the two new 30 kS PMG's

awarded with NSF funds in FY 81 (i.e., D. F. Bartlett, U. of Colorado

and C. E. Johnson, North Carolina State U). The proposal was subsequently

approved. The procedures outlined above for selecting candidates,

which were first instituted in FY 77, were again used successfully in

FY 83. 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). Proposals were received from 29 candidates,

four of whom were chosen to submit final, full proposals. The two

grantees selected from these four were:

C. M. Caves, California Institute of Technology

Proposal Title: Quantum-Mechanical Analysis of High-Precision

Measurements on Harmonic Oscillators

W. N. Hardy and A. J. Berlinsky, University of British Columbia

Proposal Title: Development of a Cryogenic Hydrogen Maser

For FY 83, the NBS Precision Measurement Grants Committee consisted

of Drs. Deslattes, Hall, Taylor, and Wineland; the Outside Advisory

Committee of Professors Fortson, Rich, Robinson, and Schuessler.

The following Grants were renewed in FY 83: D. F. Bartlett,

U. Colorado, Eotvos Experiment - Cryogenic Version; D. A. Church,

Texas A & M U., Low Energy, Highly Charged Ion Precision Spectroscopy;

C. E. Johnson, N. C. State U., RF Spectroscopy of Atomic and Molecular

Ions; M. G. Littman, Princeton U., Fine-Structure Constant Determination

Using Precision Stark Spectroscopy; R. C. Dunford, Princeton U.,

Lamb Shift in Singly Ionized Helium; and D. C. Tsui, Princeton U.,

The Quantized Hall Resistance as a Primary Resistance Standard.

Plans

FY 84 plans naturally focus on renewing the four current Grants and

awarding two new Grants. Visits to several recipients will also be

made in conjunction with other travel.

69
Electricity Division Sponsored Seminars/Workshops

A Seminar on Electrical Measurement Assurance Programs, held January

24-28, 1983 at Griswold's Motel, Fullerton, CA.

Workshop on Spectroscopic Applications of Slow Atomic Beams, held 14-15

April 1983 at NBS Gaithersburg , MD.

A Seminar on Electrical Measurement Assurance Programs, held September

26-30, 1983 at the Holiday Inn, Peabody, MA.

Invited Talks

M. E. Cage, "A Possible Quantum Hall Effect Resistance Standard,"

National Conference of Standards Laboratories 1982 Workshop and Symposium.

NBS Gaithersburg, MD, October 1982.

M. E. Cage, " The Quantum Hall Effect and the Development of a Resistance

Standard," Special Colloquium of the Sigma Xi Society, NBS Gaithersburg,

MD, March 1983.

R. F. Dziuba, "The Quantum Hall Effect in Two Dimensional Electron Gases:

An Atomic Standard of Resistance," Washington Area Chapter of the

Precision Measurements Association, NBS Gaithersburg , MD, January 1982.

W. G. Eicke, Jr., "Measurement Assurance Programs in a Field Environment,"

National Conference of Standards Laboratories 1982 Workshop and Symposium,

NBS Gai thersburg , MD, October 1 932.

B. F. Field, "Quantized Hall Effect for Resistance Measurements,"

Precision Measurements Association, Orange County Section, Anaheim, CA,

September 1982.

B. F. Field, "A Precision DC Voltage Measuring System," Region Three

National Conference of Standards Laboratories Meeting, Johns Hopkins

Applied Physics Laboratory, Laurel, MD, September 1983.

G. M. Free, "Status of the MBS Electrical Conductivity Project," MBS

Office of Non-Destructive Evaluation Seminar Series, NBS Gaithersburg,

MD, October 1982.

W. D. Phillips, "Laser Cooling of Atomic Beams," Physics Department

Colloquium, University of Virginia, Charlottesville, VA, November 1982.

W. D. Phillips, "Laser Deceleration of an Atomic Beam," Physics Department Colloquium, North Carolina State University, Raleigh, NC,

November 1982.

70
W. D. Phillips, "Laser Cooling of an Atomic Beam," Colloquium, Johns

Hopkins Applied Physics Laboratory, Laurel, MD , January 1983.

W. D. Phillips, "Laser Deceleration of an Atomic Beam," Physics Department Colloquium, Harvard University, Cambridge, MA, February 1983.

W. D. Phillips, "Laser Cooling of an Atomic Beam," Conference on Lasers

and Electro-Optics, Baltimore, MD, April 1983.

W. D. Phillips, "Neutral Atomic Beam Experiments at NBS," Workshop on Spectroscopic Applications of Slow Atomic Beams, NBS Gaithersburg, MD,

April 1983.

W. D. Phillips, "High Resolution Spectroscopy and Laser Cooling of Atoms,"

Society of Physics Students Induction Ceremony, Towson State University,

Tows on, MD, May 1983.

W. D. Phillips, "Laser Cooling of a Free Atomic Beam," Sixth International Conference on Laser Spectroscopy, Interlaken, Switzerland,

June 1983.

W. D. Phillips, "Laser Cooling of a Free Atomic Beam," Division of

Electrical Sciences Colloquium, National Physical Laboratory, Teddington,

England, June 1983.

W. D. Phillips, "Trapping and Laser Cooling of Neutral Atoms," Physics

Department Colloquium, Cornell University, Ithaca, NY, September 1983.

J. V. Prodan, "Cooling a Thermal Atomic Beam Using Laser Light," Joint

Institute for Laboratory Astrophysics Colloquium, Boulder, CO, February

1983.

J. V. Prodan, "Chirping the Light - Fantastic? Recent NBS Atom Cooling

Experiments," Workshop on Spectroscopic Applications of Slow Atomic

Beams, NBS Gaithersburg, MD, April 1983.

J. V. Prodan, "Laser Production of a Very Slow, Cold Atomic Beam, 1 ' Physics

Department Colloquium, Colorado State University, Fort Collins, CO,

May 1 983

J. V. Prodan, "Atomic Beam Velocity Modification Using Laser Light,"

1983 Gordon Research Conference on Atomic Physics, Colby-Sawyer College,

New London, NH, July 1983.

B. N. Taylor, "Quantum Electricity," 20th Anniversary Meeting of the

Boston Chapter of the IEEE Society on Instrumentation and Measurement,

Boston, MA, October 1982.

71
B. N. Taylor, "Status of the 1983 Least-Squares Adjustment of the

Fundamental Constants," Annual Joint Meeting of the American Physical

Society and American Association of Physics Teachers, New York, NY,

January 1983.

B. N. Taylor, "The Fundamental Constants and Electrical Measurements,"

International Bureau of Weights and Measures Colloquium, Sevres, France,

March 1983.

B. N. Taylor, "Introduction to the Fundamental Constants," MBS Research

Advisory Committee Seminar, "New Directions in Fundamental Constants,"

NBS Gaithersburg , MD, September 1983.

E. R. Williams, "Testing Physics via Improved Electrical Measurements,"

Physics Department Colloquium, State University of Mew York, Stony Brook,

NY, January 1983.

E. R. Williams, "Dimensional Metrology and Its Avoidance in Electrical

Measurements," Second International Precision Engineering Seminar, NBS

Gaithersburg , MD, May 1983.

72
Publications FY 83

1. In Print . [NPL indicates publication did not appear in FY 83 but was jiot previously JHsted]

K. R. Baker and R. F. Dziuba, Automated NBS 1-n Measurement System, IEEE

Trans. Instrum. Meas. IM-32 , 154 (1983).

G. Birnbaum and G. M. Free, Eds., Eddy-Current Characteri zation of

Materials and Structures, ASTM Spec. Tech. Publ. 722, PCN 04-722000-22

(American Society for Testing and Materials, Philadelphia, 1981). [NPL].

M. E. Cage and S. M. Girvin, The Quantum Hall Effect I, Comments Solid

State Phys. 1_1, 1 (1983).

M. E. Cage, R. F. Dziuba, and B. F. Field, A Possible Quantum Hall

Effect Resistance Standard, National Conference of Standards Laboratories

Newsletter 23, No. 1, 16 (March 1983).

W. Y. Chen, J. R. Purcell, P. T. Olsen, W. D. Phillips, and E. R. Williams,

Design and Construction of a Superconducting Magnet System for the

Absolute Ampere Experiment, in Advances in Cryogenic Engineering , Vol. 27,

R. W. Fast, Ed. (Plenum, New York, 1982 )~p. 97.

W. G. Eicke, Jr., T. Leedy, B. Moore, and C. Brown, Measurement Assurance

Programs in a Field Engironment, National Conference of Standards

Laboratories Newsletter 23>, No. 1, 51 (March 1983).

G. M. Free, NBS Eddy Current Standards Program, in Eddy Current Nondestructive Testing, G. M. FreeEd., Natl. Bur. Stand. (U.S.), Spec. Publ. 589

(USGPO, 1981), p. 133. [NPLJ.

G. M. Free, Ed., Eddy Current Nondestructive Testing, Natl. Bur. Stand.

(U.S.), Spec. Publ. 589 (USGPO, 1981). [NPL]

G. M. Free, G. Birnbaum, H. Berger, V. Kljuev, and Y. Fedosenko,

Standards for Eddy Current Nondestructive Testing, in Proceedings of

the Tenth World Conference on Nondestructive Testing, Vo). 6 (Moscow,

1982), p. 262. [NPL].

G. M. Free and J. Morrow, Transportable 1000 pF Standard for the NBS

Capacitance Measurement Assurance Program, NBS Technical Note 1162,

October 1982.

S. M. Girvin and M. E. Cage, The Quantum Hall Effect II, Comments

Solid State Physics 1_1, 47 (1983).

C. R. Levy, Testing to Quantify the Effects of Handling of Gas Dielectric

Standard Capacitors, NBS Technical Note 1161, October 1982.

73
W. D. Phillips, J. V. Prodan, and H. J. Metcalf, Neutral Atomic Beam

Cooling Experiments at NBS, in Laser Cooled and Trapped Atoms, W. D. Phillips, Ed., Natl. Bur. Standi (U.S.), Spec. Publ. 653 (USGPO, Wash.

DC, 1983), p. 1.

W. D. Phillips, Ed., Laser Cooled and Trapped Atoms, Natl. Bur. Stand.

(U.S.), Spec. Publ. 653 (USGPO, Wash. DC, 1983).

W. D. Phillips, J. V. Prodan, and H. J. Metcalf, Laser Cooling of an Atomic Beam, Conference on Lasers and Electro-optics Technical Digest,

Optical Society of America (IEEE Cat. No. 83CH1852-3, 1983), p. 34.

J. V. Prodan, W. D. Phillips, and H. J. Metcalf, Laser Production of a Very Slow Monoenergetic Atomic Beam, Phys. Rev. Lett. 49, 1149 (1982).

J. V. Prodan and W. D. Phillips, Chirping the Light -- Fantastic?

Recent NBS Atom Cooling Experiment, in Laser Cooling of an Atomic

Beam, W. D. Phillips, Ed., Natl. Bur. Stand . (U.S.) Spec. Publ.

6F3-

( USGPO, Wash. DC, 1983), p. 137.

B. N. Taylor, Constants, Fundamental, in Concise Encyclopedia of Solid

State Physics , Ed. by R. G. Lerner and G. L. Trigg (Addi son-Wesley

Reading Mass. , 1983), p. 26.

D. Van Vechten, L. B. Holdeman, R. J. Soulen, Jr., and J. Toots, The

Superconductive Energy Gaps of Thin-Film AuAl, and Auln J. Low Temp.

Phys. 5j_, 329 (1983).

E. S. Williams, The Practical Uses of AC-DC Transfer Instruments, NBS

Technical Note 1166, October, 1983.

2. In Press, In Review, or Nearing Completion

M. E. Cage, R. F. Dziuba, B. F. Field, C. F. Lavine, and R. J. Wagner,

Status of the NBS-NRL Determination of the Fi ne-Structure Constant

Using the Quantized Hall Resistance Effect, in Precision Measurement

and Fundamental Constants II, Ed. by B. N. Taylor and W. U. Phi I lips,

Natl. Bur. Stand. (U.S.), Spec. Publ. 517 (USGPO, Wash. DC, 1983).

M. E. Cage, B. F. Field, E. R. Williams, S. M. Girvin, A. C. Gossard,

D. C. Tsui, and R. J. Wagner, Dissipation and Dynamic Non-Linear

Behavior in the Quantum Hall Regime, Phys. Rev. Lett. 51 (October 10,

1983). ~~

B. F. Field and G. M. Free, An Eddy Current Imaging System, NBSIR.

L. B. Holdeman and J. T. Holdeman, Jr., Support Electrode Torque on

a Spherical Superconducting Gyroscope (submitted to IEEE Trans. Magn.).

M. Littman and W. D. Phillips, A New Method for Measuring the FineStructure Constant Using Stark Spectroscopy, MBS Spec. Publ. 617.

74
H. J. Metcalf and W. D. Phillips, Time Resolved Subnatural -Width Spectroscopy, NBS Spec. Publ. 617.

P. T. Olsen, W. D. Phillips, and E. R. Williams, A Measure of the NBS

Ampere in SI Units, NBS Spec. Publ. 617.

W. D. Phillips and J. V. Prodan, Cooling Atoms with a Frequency Chirped

Laser, Proceedings of the Fifth Rochester Conference on Coherence and

Quantum Optics, Rochester New York, June 1983.

W. D. Phillips, J. V. Prodan, and H. J. Metcalf, Laser Cooling of Free

Neutral Atoms in an Atomic Beam, Laser Spectroscopy VI, (Proceedings of

the Sixth International Conference on Laser Spectroscopy) Springer

Series on Optical Science Vol . 40 (Springer, Berlin).

B. N. Taylor and W. D. Phillips, Eds., Precision Measurement and

Fundamental Constants II, Natl. Bur. Stand. (U.S.), Spec. Publ. 617

(U$GP0, Wash. DC, 1983).

E. R. Williams, P. T. Olsen, and W. D. Phillips, The Proton Gyromagnetic

Ratio in H

2 0 - A Problem in Dimensional Metrology, NBS Spec. Publ. 617.
Technical and Professional Committee Participation and Leadership

N. B. Belecki, member, ANSI C39/100, American National Standards Institute Committee on Electrical Standards, Instrumentation, and Devices;

and SC.l, Subcommittee on Reference Voltage 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 Secretariat 13, Measurement

of Electrical and Magnetic Quantities.

N. B. Belecki, Co-chairman, U.S. National Working Group, OIML (International Organization of Legal Metrology) Reporting Secretariat 13.1,

International Compatibility 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).

R. D. Cutkosky, member, TC-2, DC and LF Standards, Instrumentation

and Measurements Committee of the Instrumentation and Measurement Society,

Institute of Electrical and Electronics Engineers (IEEE).

R. D. Cutkosky, Assistant Secretary, IEC TC25, International Electrotechnical Commission Technical Committee on Quantities, Units and Their

Letter Symbols.

W. G. Eicke, Jr., member, ANSI C-18, American National Standards Institute Committee on Specifications for Dry Cells and Batteries.

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; and E7, SC7.02, Glossary (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.

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.

76
B. N. Taylor, Chairman, NBS Precision Measurement Grants Committee.

B. N. Taylor, NBS representati ve. Consultative Committee on Electricity

(CCE), International Committee on Weights and Measures.

B. N. Taylor, member. National Science Foundation (NSF) Interagency

Atomic and Molecular Physics Group.

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 Verfication.

B. N. Taylor, member TC-2, DC and LF Standards, Instrumentation and

Measurements Committee of the Instrumentation and Measurement Society

(S-IM), Institute of Electrical and Electronics Engineers (IEEE);

S-IM representative to the IEEE Research and Development Committee;

member. Editorial Review Board of IEEE Transactions on Instrumentation

and Measurement.

B. N. Taylor, NBS representati ve to Conference on Precision Electromagnetic

Measurements (CPEM) Executive Committee and Comptroller, CPEM.

77
Collaborations, Consulting, Miscellaneous Activities

N. B. Belecki consulted throughout the year with the staff of the Office

of Measurement Services on MAP activities at MBS and in industry.

He also served as a member of NBS 1 Calibration Advisory Group.

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 1 s calibration services and their own transport standards.

Some of the equipment is being furnished by the NCSL Measurement

Assurance Committee.

M. E. Cage collaborated with S. M. Girvin of the Surface Science Division

(541) on two invited review articles on the quantum Hall effect

published in Comments on Solid State Physics.

M. E. Cage, R. F. Dziuba, and B. F. Field are col 1 aborati ng with

S. M. Girvin of the Surface Science Division (541) 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 P. J. Stiles and D. Syphers of Brown University and J. Browning of Boston

University on quantized Hall resistance experiments with Si MOSFET

devices cooled to mK temperatures . These experiments are to be done

using a superconducting magnet at the National Magnet Laboratory.

M. E. Cage, R. F. Dziuba, and B, F. Field are collaborating with

R. J. Wagner of the Electronics Technology Division of the Naval

Research Laboratory, and with M. Pecker of the Research Device Facility

of the Naval Research Laboratory, in the fabrication and testing of

Si MOSFETs using a new, jointly developed mask set. They are also

collaborating on quantized Hall resistance measurements using the 15 T

NRL superconducting magnet and Si MOSFET devices.

78
M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with G.

P. Carver of the Semiconductor Materials and Processes Division (725)

on setting up a testing procedure for selecting Si MOSFET samples for

quantum Hall effect experiments.

R. F. Dziuba provided consulting support to approximately twenty-five

companies on problems in precision resistance measurements and standards

applications.

R. F. Dziuba and J. Q. Shields are collaborating with G. Small and

coworkers, CSIRO, Division of Applied Physics, Australia, on the

comparison of the NBS and CSIRO realizations of the SI ohm via the

calculable capacitor by measuring a new type of one-ohm, transportable

resistance standard.

W. G. Eicke has provided consulting services to personnel in the Office

of Energy-Related Inventions in the area of electrochemical power.

W. G. Eicke is collaborating with OIR and the National Institute

for Standards (NIS), Egypt, on the selection of new equipment for the

NIS Electrical Measurements Laboratory.

B. F. Field is collaborating with C. Waters, Superconducting Technology,

Inc., on the development of a portable, reliable, and easy-to-use

1 ppm commercial Josephson-effect voltage standard.

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.

J. R. Hastings and F. L. Hermach are collaborating with T. Matsumura

of NRC, Canada by determining the ac-dc differences of one multi

junction and two single-junction NRC thermal converters. Matsumura

visited NBS and conferred extensively on ac-dc measurement procedures;

NRC lacks the equipment for these determinations to be performed there.

P. T. Olsen 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 S. Ezekiel of M.I.T. on the

production of a slow atomic beam for applications to high resolution

resonance Raman spectroscopy.

W. D. Phillips is collaborating with C. Cohen-Tannoudji of Ecole

Normal e Superieur, Paris on the laser trapping of neutral atoms.

79
Wo D. Phillips organized the NBS Research Advisory Committee sponsored

seminar "New Directions in Fundamental Constants," held at NBS

Gaithersburg Maryland, 15 September 1983.

B. N. Taylor is collaborating with E. R. Cohen, Rockwell International,

and the CODATA Task Group on Fundamental Constants, on a new leastsquares adjustment of the fundamental Physical constants to be com- pleted in mid 1984 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. Braudaway, Sandia, and K. Jaeger,

Lockheed, on the implementation of a Josephson voltage standard at

their respective laboratories by fabricating Josephson tunnel junctions.

E. R. Williams, P. T. Olsen, and W. D. Phillips are collaborating in

the training of Song Junshou, an electrical engineer from Chongqing

University, Sichuan, PRC,

E. R. Williams is collaborating with G. T. Gillies, Oak Ridqe National

Laboratory, on the development of a new approach to detecting free

fractional charges.

80
1]I

TEMPERATURE AND PRESSURE DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1983

DIVISION CHIEF'S OVERVIEW

One of the major administrative efforts this past year was to hold

a series of meetings with the Project Leaders. In these meetings a total of 12 major activities of the Division were identified, evaluated

by a set of criteria and assorted changes made. As a result of this,

all Division activities were restructured in terms of 8 major activities. This year's accomplishments are discussed within this framework.

An abbreviated summary will be given at the Evaluation Panel Meeting.

The following listing of the 8 projects forms the Table of Contents for

the Annual Report that follows:

I. HIGH TEMPERATURE SCALE RESEARCH 900 K < T < 2000 K

II. INTERNATIONAL PRACTICAL TEMPERATURE SCALE (IPTS-68)

13 K < T < 1500 K

III. LOW TEMPERATURE SCALE 0.001 K < T < 30 K

IV. MEDICAL THERMOMETRY 0 °C < T < 200 °C

V. DYNAMIC P AND T 0.2 atm < P < 10 atm; 300 K < T < 2000 K

VI. PRESSURE: PISTON GAGES 10 5 Pa < P < 1.2 GPa

VII. PRESSURE: VACUUM 10" 6 Pa < P < 10 5 Pa

VIII. LEAK STANDARDS

I. HIGH TEMPERATURE SCALE RESEARCH

The temperature range covered here extends from 904 K to approximately 2000 K. The goal is to develop a temperature scale accurate to

100 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 an optical fiber thermometer. Development of

the optical fiber thermometer using the Planck radiation law is a new task assumed by Division personnel this year with the direct support

(financial and administrative) of the Director of NBS. It is coordinated with the other Division projects - gas thermometry and hightemperature PRT's - as will be explained below.

81
I. A. OPTICAL FIBER THERMOMETER

The principle goal of the Optical Fiber Thermometer (OFT) program

is to establish values for the thermodynamic temperature of the thermometric fixed points, silver and gold, relative to that of aluminum and

to provide a means of interpolating temperature between these fixed

points with an uncertainty not exceeding 100 ppm. At present, serious

discrepancies exist between various national laboratories as to the

proper definition of the temperature scale above the antimony point

(630.74 °C). The OFT appears to have the potential for making useful

measurements at temperatures as low as 600 °C. Through its development

and use as a primary thermometer, we hope to resolve the current uncer- tainty associated with temperatures measured in the interval 630 to

1064 °C and to provide the basis for the formulation of a new scale for

that region.

The high temperature probe of the OFT is a single crystal of sapphire (10-50 cm long, ground and polished to a 1.5 mm diameter perpendicular to its C-axis); the radiometer portion of the OFT consists of a lens system and a narrow-band interference filter plus a silicon photodiode detector and associated electronics. At the peak wavelength of

the filter, the attenuation loss in the fiber is extremely small.

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 2000 °C). In practice three major sources

of error, in addition to the uncertainty in the assigned thermodynamic

temperature of the calibration point, 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 characteri sties of the optical system (particul arly

the interference filter and detector); and (3) uncertainties in the

linearity of the detector and the electronic circuitry. The experimental program is designed to provide state-of-the-art measurements of

the various parameters of the OFT so that the overall inaccuracy of a determination of temperature will be less than 100 ppm.

The program is a cooperative effort of the TPD (CBS) and the

Radiometric Physics Division (RPD) (Center for Radiation Research) under

the leadership of R. Soulen (TPD). TPD has the respons i b i 1 i ty for

providing the test facilities in which many of the optical and all of

the thermometric measurements will be made as well as expertise in the

measurement of temperature and realization of the thermometric fixed

points. Martin Reilly has the major scientific responsibility here. He

has been programmed full-time to this project as of October 1, 1983.

The first phase of the program is: (1) the measurement of the

reflectivity of pure sapphire, followed by (2) the measurement of the

optical attenuation of candidate probes. Both properties will be

82
determined as a function of wavelength (500 to 800 nm) and temperature

(600 to 1100 °C).

The second phase of the program- involves the characterization of

the band pass of the interference filter and the linearity of the photodetector and associated electronics. This work will be done by RPD

personnel under the leadership of J. Geist.

Work on these two phases was begun in the last quarter of FY 83:

the major accomplishments being the setting up of the laboratory, a feasibility study of the OFT, and two publications.

Early in FY 84, the performance of the OFT will be compared with

that of several long-stem high-temperature platinum resistance thermometers in order to determine the noise and long term stability at various

temperatures between 600 to 960 °C. These measurements, as well as those of phase 1, will be made in a horizontal pressure-control led heat

pipe tube furnace which has a stable isothermal region (*0.005 °C) 25 cm

in length.

Once the performance of the OFT is well understood, measurements at

the aluminum, silver and gold fixed points will be made. Subsequently

the OFT will be compared directly with the NBS Gas Thermometer from the

aluminum point to as high a temperature as practical. This latter

experiment will provide the definitive calibration for the OFT from

which new values for the thermodynam ic temperature of the gold and

silver fixed points will be derived. We hope to complete this work

during FY 84.

In a related development, a company has been established to provide

these probes on a commercial basis (and with less accuracy) to a wide

variety of users. It is expected that NBS will use the aforementioned

facilities to provide a calibration service for these devices in FY 85.

Also the NBS effort will provide much valuable information on stability,

reproducibility and overall performance of OFT, which will assist in the

commercialization of this concept. It is also possible that the OFT

will perform sufficiently well to be considered as the international

(i.e., BIPM) transfer temperature standard for the next formulation of

the International Practical Temperature Scale in this temperature scale.

The Evaluation Panel undoubtedly knows as well as this Division

Chief that the understaffed Division does not need added responsibi 1 i ty

such as the OFT, but it seems to be too good a bet to miss.

1.8. GAS THERMOMETRY

Dr. L. A. Guildner retired, leaving the project entirely in the

hands of his long-standing collaborator, R. E, Edsinger. Dr, J. F. Schooley (US, DC Ret.) was prevailed upon to temporarily set aside his

low-temperature gas thermometer and to work on the high-temperature gas

83
thermometer with Edsinger. As indicated below, several changes have

been made with extremely encouraging results.

To review some history, the gas thermometry project has provided,

up to the present time, values of thermodynamic temperature in the range

0-457 °C, These were published in the NBS Journal of Research in 1976

(Vol. 80A, 703-738) in the form of differences between thermodynamic

temperatures and the IPT5-68. Among the results (obtained by immersing

the gas thermometer in a stirred liquid bath) are the following:

Since 1976, a new gas furnace has been built to replace the stirred

liquid bath for hi gher -temperature measurements. The new furnace is

provided with some eight distinct heating zones and the capability for

introduction of Ar gas as a partial heat-transfer medium. Using the new

furnace, the gas bulb with its enclosing casing of Inconel was heated to

960 °C for many days in order to outgas it and to work out the appropriate heating protocols for various temperatures.

During FY 83, test measurement runs with the new furnace up to the

A1 point gave results that were not p

1 aus i bl e--i ndi cated differences

between the KTTS and the IPTS-68 were occasionally more than 0.5 °C.

More careful study, including the practice of filling the gas bulb at

the fiducial point (0 °C) in order to verify the extent to which the

filling pressure was maintained during a measurement sequence and including measurements in the 0-457 °C range, indicated that the gas bulb

had become defective, perhaps because of h i gh-t emper atur e creep. A

destructive examination of this bulb indicated that indeed it had sagged

enough for the bottom to contact the Inconel case at or near the ice

point.

Therefore, the gas bulb was replaced with a new one. Three sets of

measurements have been made with the new bulb. In the course of these

measurements, the zinc-point difference published in 1976 has been

reproduced within about twenty mi 1 1 idegrees, a substantial improvement

in performance over the defective bulb, and preliminary measurements

have been made up to the aluminum point.

The present project plans include the provision of an estimated

thermodynamic temperature of the aluminum point to the Consultative

Committee for Thermometry prior to its May 1984 meeting. Depending on

Temperature, °C T(KTTS) - T ( IPTS-68) , °C

100 (Steam pt)

232 (Tin pt)

419 (Zinc pt)

457 (Limit of liquid bath)

-0.025

-0.044

-0.066

-0.080

84
these results the gas thermometer will be pushed to as high a temperature as possible, perhaps to the Au point.

I. C. HIGH TEMPERATURE PLATINUM RESISTANCE THERMOMETRY

Presently the thermocouple is the specified transfer standard in

this temperature range and it is used to define IPTS-68. The need for a more accurate and stable transfer standard cannot be overstated. One

possibility is the development of the OFT mentioned above. The success

of the preliminary results notwithstanding, the glacial inertia of the

BIPM (which will have the ultimate say on which transfer is to be used

in the redefinition of the new temperature scale) makes the development

of a platinum resistance thermometer which can withstand the rigors of

exposure to this temperature range an important avenue to explore.

Until recently, NBS had two part-time efforts to fabricate and test

homemade PRT's - one by R. E. Edsinger and one by J. P. Evans. Higher

priorities elsewhere in the Division has caused both efforts to be

dropped. Instead, NBS has engaged in a collaboration with Yellow

Springs Instrument Company. YSI will make commercial units based on all

technical information developed by the NBS programs and J. P. Evans of

NBS will conduct most, if not all, evaluation of the resistors. The

first commercial resistors from YSI are expected in November 1983.

J. P. Evans is now the NBS focus for all high-temperature PRT work

and he is now fully integrated into all ramifications of the program.

Evans provides the calibrated PRT's needed for the OFT program; he has

evaluated the available high-temperature PRT's, and he is working on improving the NBS standard Ag, Au and Cu melting point cells. These

activities are elaborated upon below.

Prior to the NBS/YSI agreement, J. Evans studied the stability of a group of four thermometers on loan from the National Institute of

Metrology, Beijing, and a group of three thermometers manufactured

before 1983 at the National Bureau of Standards.

The NIM thermometers have bifilar helix resistors of nominal

0.25-ohm resistance at 0 °C; the 0.4 mm diameter resistor wire is supported on a single notched blade of silica glass. The NBS thermometers

have toroidal type resistors, in which the 0.25 mm diameter resistor

wire is supported on a silica-glass tube notched at the ends; the resistance at 0 °C is about 0.37 ohm. The NBS thermometers have guarded

leads while the NIM thermometers do not, but in other respects the

thermometers are similar.

In the first experiment, the resistance of each thermometer was

determined at each of the laboratory thermometric fixed points in an appropriate sequence. The thermometers were then heated for 100 h at

1100 b

C and remeasured at the fixed points in order to assess

thermometer stability and several other characteristics. In the second

85
experiment, the thermometers were fitted with a special external electrical guard and then measured at the freezing point of silver.

Resistance measurements both with the guard connected and without the

guard connected yielded information about electrical leakage within the

thermometers. In the third experiment, thermometer resistance was determined as a function of immersion depth in a zinc freezing point cell

to determine thermometer immersion characteristics.

Numerical results of the tests, without analysis, were distributed

to members of the CCT and to other interested national standards

laboratories. NBS was the first to report on such data to the CCT even though over 20 resistors were distributed by NIM to all national

standards laboratories at the same time.

These results, especially the importance of guarding, were of

considerable help to YSI.

The results of the tests described above were evaluated to provide

information on the long time stability at high temperatures of the

thermometers, their short time stability upon temperature cycling, the

temperature coefficient of resistance, immersion characteristics,

heating effects of measuring currents, electrical leakage effects, thermometer durability, and agreement among thermometers of derived temperature values. It was found that there was little significant difference

in the performance of the two groups of thermometers , and that as a class, the thermometers performed as well as or better than any thermometers previously reported.

One method of analysis used was to establish a "temperature scale"

designated as t

1 by fitting a quadratic relation between resistance

ratio and temperature at the tin and zinc points, and extrapolating this

scale to the higher temperature fixed points. The average results

obtained with this set of thermometers are compared with similar results

from other sets of thermometers in Figure 1. The noticeable differences

at the gold and silver points may be due either to the effects of

electrical leakage or to real differences in fixed points.

Improvements in transfer standards have caused a closer examination

of the quality of the NBS-maintai ned fixed points for this region. It was established that the Ag point was okay, but that a new Au point was

needed. Evans made a new one using several improved techniques (commercially fabricated glassware, designed to permit final assembly to be

done easily in the laboratory, high purity metal in shot and splatter

form, heat pipe furnace for initial vacuum melting of the sample). Preliminary measurements indicate that the freezing point of the new cell

is ^30 mK higher than the one used previously. In addition, the same

techniques will be applied to the construction of copper freezing point

cells. To this end, samples of high purity copper have been purchased

from a commercial refiner and from the NBS Office of Standard Reference

86
At'

(vnK)

+ 20

- 5 k y

-20

*40

-<*o

0 ftiROCAGC (V^io)

Sb Al

_J L

i

cmjo

As Au

Figure 1. Variation of mean values of t' at fixed points for three

types of PRT. Deviations are shown relative to "Birdcage"

values. The error bars represent +one standard deviation.

Materials. The major importance of this reference point is that it

might replace the much more expensive Au point in the next IPTS.

We cannot discuss resistance thermometry and PRT's without mentioning the impact of R. D. Cutkosky's automatic resistance bridge used

to measure them. R. S. Kaeser has built 12 of these for this Division

and two others. The bridges in this Division are used to measure hightemperature PRT's at temperatures as high as 1330 K and are used to

measure Rh-Fe resistance thermometers at temperatures as low as 0.5 K. Kaeser and Cutkosky received the I R- 100 Award for this effort.

Mr. Cutkosky is turning his efforts to automatic capacitance

measurements. A working prototype bridge capable of 0.01 ppm resolution

has been built and efforts are now being devoted to development of

stable reference capacitors. We look forward to finding applications

for this bridge in Division activities.

87
An additional note on automation. W. S. Hurst and R. S. Kaeser are responsible for automation in general and through their efforts several

new S - 100 based microcomputers were added to the Division, including

those for Kaeser, Schooley, the Division Office, the Pressure Group, and

for the Optical Fiber Thermometry work. Minor modifications to the

hardware configurations were made (most important, switching to Qume

disk drives), improved versions of CDOS were implemented, and CDOS was customized for easing data acquisition tasks (clock functions improved,

auto restart implemented, deficiencies in printer drivers corrected). A

large task was a complete writing of Z80 code drivers to implement the

full capabilities of the IEEE-488 instrumentation bus through the

Pickles ana Trout card. These greatly simplify the programming tasks,

implement features not available in the drivers supplied, and execute 3 to 30 times faster than previous code. The drivers have been implemented in Cromemco SBasic and Microsoft's Fortran (F-80) and Basic

(Basic-80). The drivers have been released to the NBS M i coprocessor

Committee and are in use throughout NBS.

88
II. IPTS-68

I I. A. THERMOCOUPLES

These cover the range 904 K to 2300 K, and the thermocouple laboratory is managed by G. W. Burns with the assistance of M. S. Scrcger.

The activities generally fall into two categories: routine calibrations

(M. Scroger) and non-routine calibrations (G. Burns).

• Routine Calibrations

(1) The laboratory is fully automated, greatly improving turnaround time, and test folder output. (2) About 70k$ in test fees were

performed in FY 83 (270 thermocouples for 90 customers). (3) M. Scroger

is- continuing to work in her spare time to produce a training document

which would be of use to a new trainee in the event of her leaving the

laboratory.

• Non-routine Tests: Some Samples

(1) Two emf stability tests of 0.8 mm diameter Type K thermocouples (one at 1290 °C for 50 h and another at 1315 °C for 34 h) were

carried out for the Aircraft Engine Group of the General Electric Co.,

(Cincinnati, Ohio). The G. E. Co. is using Type K thermocouples for

monitoring the temperature during critical heat treatments of single

crystal turbine blades in vacuum in the 1250 to 1300 °C range. Experience at G. E. with Type K thermocouples has shown that they may be used

under such conditions for short periods of time with no appreciable

changes in calibration. However, since no published data exists to

support the use of Type K thermocouples in vacuum at such temperatures,

G. E. wanted an experimental verification of thermocouple performance

done by an independent laboratory to convince their military contractors

that temperature determinations made during their heat treatments are reliable. Burns found in the 1290 °C test that the Type K thermocouples

changed by not more than the equivalent of 1 °C during the first 15

hours of testing; the emf of the thermocouples had decreased after 50

hours of testing by the equivalent of about 4 to 5 °C. While the change

in the thermocouple emf was relatively small, a substantial reduction in

the diameter of the thermocouple wires occurred during the test, due to

evaporation. In the test at 1315 °C, the thermocouple wires failed

mechanically after about 34 hours of testing, as a result of excessive

evaporation, but the thermocouples experienced a decrease in emf at

1315 °C equivalent to only about 4 °C.

(2) Special calibrations of some 1 mm diameter, Pt 30% Rh

sheathed, Pt-40% Rh versus Ir-40% Rh thermocouples were carried out at

the melting point of platinum (1759 °C) for the Pratt & Whitney Aircraft

Co. Such thermocouples are used at Pratt & Whitney in jet engine development work for combustion temperature measurements. The calibrations were performed by the melting-wire method and were needed since

89
these thermocouples are a non-st andardi zed type for which no emftemperature tables exist. The repeatability of the thermocouples during

successive platinum melts was found to be equivalent to about 1 °C.

(3) To assist ASTM Committee E20.04 with the development of a new standard covering W-3% Re/W-25% Re and W-5% Re/W-26% Re thermocouples, emf-temperature tables in both °C and °F were computed using

existing polynomials and provided to the Committee in the appropriate

format for inclusion in the standard.

(4) Progress on the project devoted to assisting the ASTM task

group on immersion thermocouples for measuring temperature of molten

metals was limited due to lack of funding and personnel. However, some

thermocouple sheaths of boron nitride were fabricated for evaluation in

molten steel. Whereas previously developed thermocouple sheaths con- sisting of molybdenum tubing having an outer coating of Cr^O^, Al^O^,

and Mo applied by arc-plasma spray techniques were found to survive in

molten iron for periods of 30 minutes, they are very expensive and

difficult to fabricate. Recent work reported by the Kawasaki Steel

Corporation in Japan indicates that thermocouple probes using boron

nitride protection sheaths survive repeated use in molten steel (90 to

130 immersions over a period as long as 15 hours in molten steel in a continuous casting operation). As a result of these findings, we procured some 12-inch long rods of hot pressed boron nitride from Union

Carbide Corporation and had six thermocouple protection tubes prepared

from the rods by a local machine shop. Some stabilized zirconia tubing

that will be joined to the boron nitride tubes with a high-temperature

ceramic cement were also procured. Assembly and evaluation of the new thermocouple protection materials are planned for early FY 84.

(5) A number of calibrations of N

i - 18% Mo versus Ni thermocouples were performed to assist the ASTM Committee E20.04 with re- solving a problem concerning differences in industry used emftemperature tables for this non-standardized thermocouple type. Ipsen

Industries, a major manufacturer of heat treating furnaces and systems,

sought help from ASTM in resolving differences between existing emf

tables for this thermocouple. There are three tables now used by

industry: two older tables produced by the General Electric Co. and a recently published table produced by the AMAX Specialty Metals

Corporation, which at the present time is the sole manufacturer of the

N i -18% Mo/Ni thermocouple in this country. The two G, E. tables agree

closely with the newer tables by AMAX Specialty Metals Corporation in

the 500 to 1100 °C range, but about 1100 °C and below 500 °C substantial

differences (as much as 15 to 20 °C) exist between the tables. Ipsen

Industries, as well as a few other furnace manufacturers typically

install the N

i - 1 8% Mo/Ni thermocouple for controlling the temperature of

heat treating furnaces that operate with vacuum or hydrogen atmospheres.

Several calibrations were performed by us on recently produced

thermocouples obtained from the AMAX Specialty Metals Corp. The

90
calibration results were compared with the existing tables and reported

at the E20.04 Committee meeting on May 11, 1983. Due to the nature of

the differences between our calibration data and the existing tables,

the ASTM Committee recommended that N8S prepare a new emf-temperature

tables for the thermocouple and that the NBS table be published in an appropriate ASTM publication to promote its industry-wide acceptance and

usage.

Additional thermocouple materials have been obtained from the

AMAX Specialty Metals Corp. for preparing the new tables. In addition,

preliminary tests have been carried out to estimate the melting temperatures of the thermocouple materials and to assess their sort-term thermoelectric stability in argon at temperatures near the solidus temperature of the N i -18% Mo thermoelement. Some short-term emf stabilitytests were also performed in high vacuum at about 1290 °C.

II. B. PLATINUM RESISTANCE THERMOMETERS

These devices provide a temperature scale extending from 904 K to

13 K. Several projects including a calibration service, MAP, and development of improved fixed points and thermometers are conducted by Dr.

G. T. Furukawa with the assistance of Mr. W. G. Bigge.

• Fixed Points

The recent IPTS-68 specifies that a PRT will be calibrated at

certain reference temperatures (fixed points). Dr. Furukawa has made

many contributions to the evaluation of these fixed points; his attention this year was focused on the triple point of O

2

. He evaluated

some samples of specially purified O

2 using PRT's that participated in a 1974 international round robin. His results indicate that: (1) the NBS

IPTS-68 has been maintained since 1974 on PRT's to within 0.2 mK at the

O

2 triple point, and (2) the new triple point material is very pure.

In addition to evaluating and improving the IPTS-68 fixed points,

additional fixed points are being studied by Division personnel

Cd ( 321 °C), In (157 °C), Hg (-39 °C), Xe (-112 °C), and Kr (-158 °C) for

use as redundant checks on calibration between the fixed points.

Furukawa continues to study Hg cells and has plans to purify Xe and

Kr, while B. W. Mangum is assembling In cells for study.

• PRT's

YSI is now manufacturing PRT's now that L&N has sold them the

rights. A study by Furukawa shows that the baton may have been dropped

as it was passed from one company to the next (there is an unacceptably

high moisture level inside the YSI PRT's) and YSI has been informed of

the NBS results.

91
• MAP

We run a continuing MAP with standard PRT's. This past year, the

MAP work with the White Sands Missile Range was completed - showing that

calibrations at the fixed points were good to 3 mK. WSMR is quite

satisfied with the results.

To test the quality of calibrations performed by industrial standards 1 aborator i es, NBS established a 20-member industrial MAP. To

date, we have tested 10 subscribers and found that a few laboratories

deviated from NBS by as much as 0.5 K, but most laboratories are capable

of 0.01 K to 0.02 K level of performance.

» Thermometry Liaison

G. Furukawa has been active on several subcommittees of the ASTM

E-20 Committee on Temperature Measurement:

E-20.03 - Helped write industrial PRT standard helped revise E-644.

E-20. 04 - Helped review thermocouple standards.

E-20. 07 - Helping to write ASTM Special Technical Publication on the

application of fixed points in thermometer calibrations.

E-20. 10 - Helping to write a monograph on resistance thermometry.

9 Calibration

A total of 75 PRT’s were calibrated for a total fee value of

7 2. 7K$. Furthermore, five other PRT's were calibrated for other NBS

users at no fee.

As a first step in automation of the calibration service, a Cutkosky bridge (the heart of the automation) is being compared with the

Guildline dc comparator bridge (what has been used to date). Systematic

differences have been found at these fixed points: Zn (0.2 mK), Sn

(0.3 mK), and 0-? (0.04 mK). These are a factor of 2 or 3 larger than

the reproducibility that is routinely obtained with the Guildline

bridge. The source of the discrepancy is being sought.

II.C. LABORATORY THERMOMETERS

A total of 700 1 iquid-in-glass thermometers , 15 low-temperature

thermocouples, and 39 assorted types of thermometers were calibrated by

J. Wise.

A computer has been obtained to automate the data acquisition of

the PRT thermometer used as the primary thermometer in this laboratory.

J. Wise and R. Soulen have written the draft of a document which

will be used to establish L-I-G calibration laboratories in every state

92
laboratory in the USA. This effort is in concert with the NBS Office of

Weights and Measures.

II.D. GAS THERMOMETRY

Dr. C. Van Degrift finished an extensive study of the properties of

solid He-3 at very low temperatures. He developed the technology of

tunnel diodes to a fine art to accomplish those goals.

Late this FY he applied the same technology to the development of

miniature gas thermometer sensors. An apparatus was built to test six

prototypes from 0.4 K to room temperature. Six prototype thermometers

were built with somewhat different properties so that several parameters

may be studied in these prototypes. As can be seen from the table below

all devices have an anticipated wide temperature range as well as high

sensitivity. In late September, Dr. F. Pavese, of the IMGC (Italy)

visited the laboratory and one of these devices was studied. It was

found that epoxy in this unit led to unsatisfactory performance and some

design changes are being pursued before any of the units are scaled with

He-3 gas and used as actual gas thermometers.

Approximate Properties of Gas thermometers #1 Through 6

# f ( P=0

(MHz)

Diaphragm

thickness (urn)

P(300 K) of He-3

(kPa)

Range

(K)

dT/df

(uK/Hz)

1 1041 112 100 0.72 - 90 0.26

2 873 140 10 0.48 - 70 4.5

3 897 211 10 0.48 - 120 15.4

4 948 295 10 0.48 - 40 43.

5 944 297 10 0.02 - 150 70.*

*only for T 30 K

93
III. LOW TEMPERATURE SCALE

This project is divided into two parts: the temperature region

covered by the EPT-76 (0.5 - 30 K) and the region below 0.5 K covered by

the temperature scale NBS-CTS-1 (0.010 K - 0.5 K).

III. A. EPT-76

E. R. Pfeiffer was assigned the lead responsibility for the EPT-76

program at NBS.

Some improvements in the cryogenic apparatus were made after ex- periments early in the FY indicated that changes were necessary. Also

an improved Cutkosky bridge was incorporated into the measurement of the

Rh-Fe Resistance Thermometers (RIRT). Furthermore, the protocol to make

dc resistance readings was changed along with some software development.

Armed with these changes, a considerable portion of the 2nd and 3rd

quarters of FY 83 was devoted to carrying out a final

cal ibration/research run with the apparatus and analyzing the resultant

data. The run began with cooldown on March 1 and ended about April 7. During this period the experiment ran 24 hours/day, usually seven days a week, with no major difficulties or interruptions and with the attention

of only a single operator. Some specific results of the run are the

following:

(1) Using the Cutkosky bridge, a new comparison of our EPT-76

reference Rh-Fe Resistance Thermometers (the two RIRT's carrying the

smoothed NPL calibrations) showed that their temperatures generally

agree within 0.15 mK over the range 0.5 K to 27.1 K. The current

results generally confirm the results of a similar comparison reported

last year. Both recent comparison results obtained using the Cutkosky

bridge are far superior to the earlier results obtained with the dc

measurement system which were reported at the 5th Temperature Symposium.

The bridge was used also for a new comparison of EPT-76 temperatures between 13.8 K and 27.1 K obtained from two NBS-cal i brated

capsule Platinum Resistance Thermometers (PRT's) against EPT-76 obtained

from a reference RIRT. The PRT- and RIRT-based scales are in near

agreement at the fixed point temperatures of 13.8044 K, 20,2734 K and

27.102 K, but at other temperatures the PRT's yield higher temperatures

by as much as 0.8 mK.

(2) Compared EPT-76 obtained from two reference Germanium Resistance Thermometers (GRT's), HW-540 and HW-570, against EPT-76 from a reference RIRT. HW-540 served as the reference standard for the NBS 2-

20 Scale calibrations which were sent to Australia for the GRT temperature scale intercompar i son experiment of Besley and Kemp. HW-570 was

recalibrated against HW-540 during that same NBS 2-20 calibration run. Thus, the NBS 2-20 calibrations on HW-540 and HW-570 are the

94
calibrations at NBS most closely tied to the calibrations used by Besley

and Kemp which were the basis for the scale differences between EPT-76

and NBS 2-20. (The whereabouts of the actual GRT's used by Besley and

Kemp is presently unknown.)

The above GRT's also carry (by transfer) the hydrogen fixed

points of Cataland and Plumb, and calibrations (by transfer) on the 1958

Helium-4 Vapor Pressure Scale by Edlow and Plumb. HW-570 also carries

the neon fixed point realizations of Furukawa. All of these calibrations and fixed points were converted to EPT-76 and compared with the

EPT-76 realized from the reference RIRT. Differences as large as 2.5 mK

were observed.

(3) Compared a GRT, CC-80, calibrated on EPT-76 by Rusby against

EPT-76 from a reference RIRT. This GRT has consistently indicated

higher temperatures than the reference RIRT's -- about 1.5 mK around

25 K, which has always seemed greater than the estimated imprecision of

our experiments and has caused us some concern. However, the same

comparison utilizing EPT-76 derived from the only NBS 2-20 calibration

(in 1966) on CC-80 yields differences as large as -7.2 mK. Our conclusion is that this GRT's R-T characteristics have changed since both the

NBS 2-20 and NPL calibrations and that, as a consequence, it should not

be used as a reference GRT.

This experiment now qualifies NBS as having established a legitimate version of EPT-76. E. Pfeiffer will publish a document

describing the program as the first task in FY 84. Establishment of the

EPT-76 laboratory provides the basis for several other activities including a calibration service, MAP, and fixed point research (see

below)

« Calibration Service

Calibrated six GRT's on EPT-76 from 1 K to 30 K for two commercial

manufacturers of cryogenic instruments — Lake Shore Cryotronics, Inc.

and Cryosystems, Inc. The calibrations averaged 62 points each and were

smoothed by our least-squares fit procedure by 13th order logR-logT

polynomials with standard deviations (s.d.) of 0.19 * 0.02 mK.

Calibrated a low-resistance RIRT on EPT-76 from 1 K to 30 K for

Rockwell International Corp. The calibration of 62 points could be

smoothed by a 12th order R-T polynomial with a s.d. of 0.10 mK. This

was the first calibration of a customer's RIRT against our standard RIRT

using the Cutkosky bridge. (The above s.d. compares with a s.d. of

about 0.25 mK for a calibration last year of a high-resistance RIRT from

0.5 K to 10 K for J. F. Schooley. The improvement is due mainly to

better data in the 1 K to 2 K region.)

95
The calibration billings for FY 83 to date total $7,342 for 7 thermometers compared with $3,677 for 4 thermometers in FY 82 (the FY 83

totals do not reflect the recent substantial fee increases).

Calibrated three GRT's for undesignated NBS use (one GRT from 0.3 K

to 30 K, and two from 0.8 K to 30 K).

« MAP

Having set our own house in order we are ready to begin a "AP for

this temperature region.

® Fixed Points

J. F. Schooley, when he is not collaborating with R. E. Edsinger in

high-temperature gas thermometry, has reactivated the SRM 767 superconductive fixed point work. Presently this unit provides 5 of the 11

defining reference temperatures for EPT-76. The goal of this program is

to provide a new SRM 767a which has superconductive transition temperatures which are sharper and to add a sixth superconductor (Nb). The SRM

767a is to be calibrated on the NBS-maintai ned EPT-76. In order to ensure that Pfeiffer's EPT-76 lab and Schooley 1 s SRM 767a lab are providing the same EPT-76, both labs were equipped with recently updated

Cutkosky resistance bridges. Pfeiffer provided Schooley with a RIRT

calibrated in his lab. Pfeiffer also measured SRM 767a (unit Bravo) on

his scale. W. S. Hurst assembled a laboratory microcomputer capable of

driving the bridge; and G. A. Evans improved the techniques for an- nealing the elements Pb, In, Al, Zn, and Cd which make up the SRM 767.

To this group we added samples of the element Nb in order to extend the

range of the device.

Using a modified He-3 cryostat and considerably improved calibration procedures, Schooley has prepared a set of some ten new SRM 767a

devices that are clearly superior to the old SRM 767. A new OSRM

certificate has been prepared in order to issue the new devices under

the catalog number SRM 767a. The properties of the new devices are

given in the table below:

Average T

c of 10 Devices . Range of T

Materi al (EPT-76), K of 10 Devi

Niobium 9.19-9.29 100

Lead 7.200 05 0.15

Indium 3.414 60 0.15

Aluminum 1.180 95 0.15

Zinc 0.850 15 0.10

Cadmium 0.519 98 0.08
In order to achieve the restricted range of transition midpoints

shown in the table, we have imposed a limit of 1 mK on the acceptable

width of all transitions excepting Nb, which is not available in better

purity levels than about 99.995%. Furthermore, the calibration procedure involves the use of two standard SRM devices in each measurement

run in addition to the Rh-Fe thermometer. Also, the earth's field is

nulled during each run; we have found that it is not necessary to null

it for each individual sample. Finally, we use only a single source of

each element to prepare the samples.

We have compared the T

c values obtained by E. R. Pfeiffer in the

Low Temperature Scale cryostat for one device with the Tp values obtained in the SRM 767a cryostat in order to evaluate tne level of

agreement maintained between the two laboratories. The results indicate

an average level of 0.14 mK random deviation for the five samples

examined.

Experiments yet to be performed before relegating this work to a simple maintenance of OSRM supplies include the following:

(1) Comparison of the T

c values of the SRM 767a with samples prepared from other high-purity sources of the elements;

(2) Measurement of the isotopic abundances for the polyisotopic

elements (Pb, In, Zn, Cd);

(3) Re-measurement of the dependences of the T

c values upon magnetic field, to verify literature data.

III.B. NBS-CTS-1

This scale, developed at NBS and distributed worldwide 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 2 mK to 500 mK by the CCT when the next scale is

formulated.

The scale is based on a comparison of two absolute thermometers

based on noise and nuclear orientation. Research in both of these areas this past year has been directed to understanding all systematics so that ultimately a scale accurate to 0.1% will evolve. Specifically:

• Noise Thermometry

J. Colwell, in collaboration with R. Soulen and H. Seppa (V.T.T.,

Helsinki) studied the influence of several parameters on the measured

noise which indicate that systematics in the noise measurement can be

reduced to 0.1%. The results were reported in the 7th International

97
Conference on Noise on Physical Systems, Montpellier, France, and were

found to agree with theoretical models.

Stringent tests of reproducibility of the noise thermometer were

performed by thermally cycling it to room temperature and to low temperature four times. The results are shown in the accompanying table,

and indicate that the reproduci b i 1 i ty is also 0.1% or better above

20 mK. {See last column.) Some minor problems degrade the reproducibility to the level of 0.5% at low temperatures. A systematic related

to the influence of one noise thermometer parameter is suspected to be

the culprit and steps to eliminate it are being taken.

R. D, Cutkosky developed a multiple processor system to speed up

the calculation of the variances needed for the noise thermometer. The

new instrument accepts data 100 times faster than the old system and

greatly reduces the measurement speed for the noise thermometer.

The visit of two guest workers from Finland (T. Haavasoja and

H. Seppa) and one from the KOL (A. Reesink) will ensure that close

collaborations will be maintained between these institutions and NBS.

SUMMARY

o FOUR THERMAL CYCLES

o FOUR ADJ. OF NOISE THERMOMETER

o SRM 768, Serial No. 7

Approximate

Temperature Noise Temperatur o

(mK) 10/82 1/4/83 1/27/83 4/12-18/83 Average

12.5 12.44 12.53 12.47 — 12.48 (.4%)

T

c (W) 15.51 15.60 15.54 15.520 15.543 (0.26%)

19 18.84 18.99 18.91 — 18.91 (.«)

T

c (3a) 22.66 22.67 22.69 22.692 22.678 (.08%)

30 29.79 29.89 29.84 — 29.84 (.17%)

43 — 43.06 43.00 — 43.02 (.13%)

53 53.01 — 53.04 — 53.02 (.04%)

60 — 59.42 59.63 59.52 (.24%)

T

c W — — 99.40 99.43 99.415 (.02%)

T

c (AuAl

2

) 160.09 160.00 160.20 160.17 160.12 (.06%)

T

c (Auln

2 ) 204.4 — 204.51 204.39 204.43 (.03%)

98
• Nuclear Orientation (NO)

In order to conduct NO thermometry to the 0.1% accuracy level,

several systematics ignored by other practitioners in the field were

carefully examined by H. Marshak. The effects of pulse pile-up, cascade

summing, and proper fitting of the 7-ray background and lineshape on the

NO thermometer were characterized. These and still other systematics

were discussed in an exhaustive NBS J. of Research article, written this

year by Marshak.

Marshak also wrote a chapter entitled "Nuclear Orientation

Thermometry" for the book Low Temperature Nuclear Orientation , to be

published in 1984. This work is a critical review of the field and

indicates the state of the art of nuclear orientation thermometry.

• Transfer Standards

J. Colwell studied the behavior of two types of resistance

thermometers (doped germanium and carbon) and that of a paramagnetic

thermometer (cerium magnesium nitrate) from 0.01 K to 0.5 K. At the

lowest temperature it is not clear that any of them will perform with

reproducibility comparable with the temperature scale (0.1%).

Other laboratories claim that the He-3 melting curve offers far

superior capabilities. Van Degrift has studied the melting curve of He3 this year as well as the properties of solid He-3. Based on this

experience, we feel confident that consideration of this option merits

further work. Since Van Degrift is occupied with gas thermometry the

coming year, Colwell will examine the suitability of the melting curve

of He-3 as the alternate transfer thermometer for NBS-CTS-1.

A discrepancy in the reproducibility of the superconductive transition of W in SRM 768 was resolved by Colwell (a poorly performing

germanium resistance thermometer was the culprit). The T is now performing at the 0.1% level.

W. R. Fogle, a Postdoctoral Research Associate from Berkeley, has

been contributing to all phases of the research activity and has demonstrated a real talent for metrology.

IV. MEDICAL THERMOMETRY

The goal of this program is to develop a set of fixed temperatures

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 under the responsibility of Dr. B. W. Mangum who is assisted

part-time by G. A. Evans.

Specific accomplishments this FY include:

99
(1) The investigation of the triple point of succinoni tri le as a temperature fixed point was completed and published (Clinical

Chemistry). Some 23 triple-point cells of different sizes and containing succinoni tri le of different purities were studied with regard to

their melting and freezing behavior and their triple-point temperatures.

The samples were prepared by zone-refining techniques, using two stages

of zone refining and varying the number of passes per stage. The

triple-point temperature was determined to be 58.0805 °C with an estimated uncertainty of +0.0015 °C relative to the IPTS-68. The standard

deviation of the mean of 11 measurements on one of the purest samples

was 0.0001 °C. Based on our results, a design of a cell has been

adopted for the SRM's to be produced and tested next year. The results

which we obtained on samples of different purities will be the basis for

the production of the SRM samples. The 0SRM has placed a contract for

the production of 120 cells of succinonitri le and we will test them for

suitability when they are delivered.

(2) We investigated the melting/freezing behavior of 100 triplepoint cells of rubidium which constitute SRM 1969. The rubidium in

these cells was of a higher purity than that which we had previously

investigated. The reproducibility of the plateau of the melting and

freezing curves for these cells is rather good. For the worst case, the

spread in the values of the temperature of the midpoint of the plateau

of the melting curve is less than 10 mK. The spread is 1 to 3 mK for

most of the cells. The distribution of midpoint temperatures for those

100 cells is shown in figure 2. The melting range of the cells varied

from 8 mK to 24 mK, with a mean value of 14 mK. A paper on the rubidium

fixed point is currently being written for the SP -260 Series, giving the

results on the 100 cells, how they were obtained and how the user of the

SRM (SRM 1969) should proceed in realizing this fixed point.

(3) It is thought that an organic material, sealed in glass

cells, with a fairly large heat of fusion would probably be easier for

clinical 1 aboratory personnel to use than the rubidium triple-point

standard which by its nature must be sealed in stainless steel. With

this in mind, some preliminary experiments on several small cells of

pivalic acid (melting point of 35.98 °C) and 1 large cell of ethylene

carbonate (melting point of 36.323 °C) were conducted to evaluate their

feasibility to serve as a temperature fixed point near body temperature

(37 °C). It appears that it is difficult to adequately purify the

pivalic acid using zone-refining techniques, but some more attempts are to be made. The large cell of ethylene carbonate appears from the

preliminary experiments to be better suited for freezing-point than for

melting-point applications. We plan to investigate the melting and

freezing behavior of some small cells of this material next year.

(4) In the course of investigating the rubidium, succinonitri le,

pivalic acid and ethylene carbonate melting and freezing behavior, our thermistor thermometers have been calibrated several times against a long-stem platinum resistance thermometer in a copper block located in

100
39.280 39.290 39.300 39.310 39.320

^midpoint

Figure 2. Histogram of midpoint temperatures of the 100 SRM 1969 cells

investigated.

an oil bath. After showing the feasibility of using the triple point of

succinonitrile as a temperature fixed point, we investigated the possibility of using this fixed point, along with the gallium melting point

(provided by SRM 1968) and the triple point of water, and the equation

1/T = a + b log R + c(log R) 3

to calibrate thermistors, covering the temperature range from 0 °C to

60 °C. We found that temperatures from 0 °C to 60 °C derived from that

three-point calibration agreed to within 1 mK with those measured with

the platinum resistance thermometer in the fluid bath as well as with

those derived from a many-point calibration using the equation

1/T = A + B log R + C(log R) 2 + D( log R) 3

to fit the calibration data. A paper on this subject has been accepted

for publication by RSI.

(5) The investigation of the melting/freezing behavior of highpurity indium in small Teflon cells has continued in order to test the

101
feasibility of using this point as a temperature fixed point, and, if we

find it suitable, to develop it into an SRM. We tested cells of different size, different immersion depth and constructed with different

kinds of high-temperature epoxy. Considerably more work is required on such small cells before we can decide if they will make a good SRM, but we think they will. 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 PRT'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 mel ting/freezing behavior and of the reproducibi 1 i ty of the

melting/freezing-point temperature. We have acquired enough high-purity

indium to make two cells of sufficient size for use with long-stem

SPRT's and capsule SPRT's. Mangum designed the cells and recently they

have been constructed in our shops. A system for filling the cells with

indium must still be constructed. When that is finished and the cells

thoroughly cleaned, the cells will be filled and the experiments

started.

(6) During the year, we have been investigating the behavior of

bead-in-glass-probe type thermistors over the temperature range from

0 °C to 100 °C after heating them to 300 °C and keeping them at that

temperature for varying lengths of time. This provides an accelerated

aging for the thermistors and should lead to more stable thermometers.

The study will be completed by examining their behavior after cycling to

temperatures lower than 300 °C. When this is completed, the data will

be analyzed and a paper written on the results. This will be of great

interest to a large number of users.

(7) The data obtained in the investigation of the stability of 100

small industrial platinum resistance thermometers from 5 companies, as determined by measurements over the temperature range from 0 °C to

100 °C following the thermal cycling of the sensors from 0 °C to about

250 °C, will be analyzed next year and a paper written on the results.

(8) We plan to begin an investigation of diode thermometers at

temperatures below about 400 K. Some of the equipment has been acquired. The remaining equipment will be acquired next year, as will a selection of "the best" diode thermometers, and the experiments started.

102
V. DYNAMIC TEMPERATURE AND PRESSURE MEASUREMENTS

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).

The technique to be used is a CO laser diagnostic one. This is a joint

effort involving the talents of Dr. G. J. Rosasco and Dr. W. S. Hurst.

Measurement and analysis of line broadening, line interference, and

line shift as functions of pressure (4-200 kPa) at room temperature for

the vibrational Q-branch Raman spectra of N

2

» 30, and NO have been

completed. The phenomena of "collisional narrowing", which arises from

line interference, was shown to be very important for the accurate

determination of temperature from the spectra of all these molecular

species. Neglect of narrowing leads to systematic, pressure dependent

(increasing with P) errors in temperature determinations, for example we

have shown 40 K errors at 298 K and 1.0 atm. Calculations by researchers at United Technologies Research Center (UTRC) indicate errors

of 300 K at 900 K and 10 atm caused by neglect of collisional narrowing.

Important modifications of the theoretical spectral distribution

functions have been tested at UTRC by use of NBS values of line broadening coefficients and detailed comparisons to our experimental spectra.

The results are very encouraging; a reduction of errors in temperature

to the 1% level have been demonstrated over a wide range of pressure.

These more complex spectral distributions require, in addition to the

traditional line broadening parameters, another N(N-l)/2 molecular parameters to describe an N-line spectrum. A first-order in density

expression for the spectrum reduces the problem to the determination of

only N-additional parameters. Further, it has been demonstrated that

simple (sca-1 ing/f itting law) models for the J-dependence of state-tostate rotational relaxation can account quantitatively for both line

broadening and mixing. The use of these models has been checked against

the spectra of No over the range 0.2-100.0 atm, 300-1500 K, by the group

at UTRC and against the spectra of NO (0. 2-1.0 atm, 300 K) at NBS. For

the case of NO these rate laws are required to predict the spectra,

because the perturbation approach fails for this strongly overlapped

Q-branch spectrum. In all these tests the results have been excellent;

thus, we are encouraged to think that "rate models" hold promise for

predicting the molecular parameters needed for accurate deconvolutions

of T and P over large ranges of T, P, and composition. Collaborative

efforts have been established with researchers at Princeton University

and the University of Maryland to develop, test (at NBS), and improve

these predictive models. Fundamental questions, such as the

T-dependence of the line broadening parameters and the effects of

"foreign gas perturbers", will be addressed.

A new technique for measurement of the fundamental susceptibility

elements (response functions) which determine diagnostic spectra has

recently been developed. Termed, 3-beam phase modulated coherent Raman

spectroscopy, this technique allows shot noise limited detection sensitivity (2- to 3-fold improvement over our best previous capability) and

103
observation of signals linear in either the real or imaginary parts of

the susceptibility. Further, use of this technique has reduced (by

approximately a factor of 100) the magnitude of "background interferences" which arise from the interaction of the pump and probe beams on the surfaces of the mirrors of the multipass sample cell. We can apply

this technique to the measurement of "non-resonant background" contributions to the susceptibility at about the 5% accuracy level. This represents at least a 4-fold improvement in measurement accuracy for a molecular parameter which must be known to accurately determine T and P from diagnostic (CARS) spectra. Measurements on specific systems are

being discussed with researchers directly involved in diagnostic

applications.

Significant progress has been made on the design and construction

of the pulse amplifier (3-stage) which is necessary for our high temperature and foreign gas broadening work. The required pulse smoothing

accessory for the Nd-YAG laser was ordered in FY 83. All other components have been designed and constructed and final system integration

should begin early in FY 84. Assembly of the high-temperature, variable

pressure furnace was begun is FY 83. Design and fabrication of auxiliary control and safety equipment is in progress and the system should

be ready for testing in the 2nd quarter of FY 84. Calibration of photometric, frequency, temperature, pressure, and composition variables will

begin in the 2nd quarter. A complete, calibrated spectrometer/sample

system for high T, variable P will be on-line by the close of FY 84.

104
VI. PRESSURE: PISTON GAGES (105 Pa - 1.2 GPa)

• Calibration

W. Markus and G. Driver provide the calibration of piston gages in

this region. In FY 83, a total of 110 piston-cylinder gage assemblies

were calibrated for fees totalling 90k$.

• New Developments: 10^ Pa

Presently the calibration service offered here with piston gages

has an inaccuracy of 30-50 ppm. We are in the process of calibrating

three high quality piston gages with the gas thermometer manometer used

for the NBS high-temperature gas thermometer. The work has involved the

talents of Dr. L. A. Guildner (retained on contract), B. Welch, and

R. E. Edsinger. The goal is to reduce the inaccuracy to the 1-10 ppm

level

The calibration measurements (some 200 determinations) have been

completed. The inaccuracy of the manometer is reported to be less than

2 ppm and the precision of each of the piston gages is better than

1 ppm. Remaining tasks are to complete the data analysis, document the

calibration, and make the transfer to the calibration service transfer

gages. We expect the total inaccuracy of the gas calibration service in

this range to be under 10 ppm. We also expect the new service to be

operational by January 1984.

A valuable spin-off from this gas gage project is a new way to

determine piston gage quality. This consists of the measurement of the

decay of the rate of rotation as a function of time. For a good gage,

the curve approaches the time axis asymptotically; a poor gage stops

rotating rather abruptly.

Part of the process of making the transfer from the manometer to

the calibration service is the redetermination of the mass values of the

applicable weight sets. We must also have the capability of weighing

the customer's pistons and weight hangers. We have ordered a state-ofthe-art mass comparator (1 kg capacity with 3 x 10"^

g standard deviation) which should be delivered in October 1983, G. Driver will become

the operator after he has been properly trained by R. Schoonover. We

will save both turnaround time and money by having our own mass measurement capability.

• New Developments: 25-35 MPa

During this past year J. Houck characterized two commercially

available control led-clearance piston gages for the 25 MPa pressure

range, one for gas and one for oil, with the intent that they would

become new primary standards. Unfortunately, neither gage proved to be

satisfactory. The piston and cylinders are not of good enough quality.

105
We need to have roundness of piston and cylinder oore to within 0.5

straightness to within 0.1 m m and clearance between piston and cylinder

of 0.5 to 0.8 ,um. Manufacture of such pi ston-cyl inder sets is extremely

difficult. We have recently learned of a company who may have mastered

the art, and have ordered three piston-cylinder assemblies for trial.

If we are fortunate, two of these will become the new primary standards

for the 25 MPa range. We expect to have these new gages by the end of

October 1983.

• New Developments: Elastic Distortion of Piston and Cylinder

Elastic distortion causes a serious limit of the accuracy of pressure measurement at higher pressures. There are four ways one can deal

with the problem:

(1) Control 1 ed-cl earance piston gage . This device is provided

with a means of applying an auxiliary pressure to the outside of the

cylinder wall to counteract the pressure inside the bore. Since the

effect due to the distortion of the cylinder is normally several times

that due to the piston, controlling the cylinder distortion can offer

significant advantages. The chief problem generally is obtaining

quality pistons and cylinders with appropriate initial clearances.

(2) Calculation . The distortion can be calculated for gages of

appropriate geometry using approximate equations based on elastic

theory. The work we have done in the last few years on the pressure

profile between the piston and the cylinder has contributed much to

making such calculations meaningful.

(3) Similarity method . NPL developed this method. It requires two

ideal pi ston-cyl inder assemblies of identical geometry but of materials

having different known elastic moduli. One then determines the ratio of

the areas of the gages by cross-floating and calculates the distortion

from the elastic moduli and the area data. Manufacturing the matched

gages is an extremely difficult task. The recent BIPM intercompari son

up to 100 MPa between NBS, NPL, LNE, PTB and IGMC also suggest that the

similarity method does not give reliable results.

(4) Cal ibration . If one has a source of well-known pressures, then

it can be used to cal i br ate a piston gage. The distortion can then be

calculated by fitting various equations to the data. This method is

rarely applicable in characterizing primary standards.

V. E. Bean has overall responsi bi 1 i ty for this project. J. Houck

is designing and building a piston gage that will combine methods (1)

and (2). The geometry and mounting of the piston-cylinder assembly is

such that the distortion can be calculated. As the pressure is increased, there comes a point where the gage will no longer operate

satisfactorily due to too short a float time caused by the widening of

the annulus. The mounting of the gage is such that above this pressure,

106
the gage can be operated as a controlled-clearance gage. Using calculation for the low pressure end and controlled-clearance methods for the

high pressure end will result in valuable cross-checks in the overlap

region. In addition to the insight we expect to gain in the two methods, this program will develop the cylinder mounting methods to be

used with the three new gages mentioned.

The equations currently used to calculate the distortion are based

on three assumptions:

(1) The cylinder is infinite in length.

(2) The pressure is uniform.

(3) There are no shear stresses in the plane surfaces formed by

slicing the cylinder into elemental disks dx thick.

In a piston gage, the cylinder length is finite, the pressure falls

to zero within a rather short length, and the cylinder experiences shear

stresses not allowed by assumption (3).

The proper way to calculate the distortion for a piston gage is to

solve the biharmonic equations with appropriate boundary conditions.

Dr. Bean is collaborating with Dr. Ruben Lazos, a guest worker from the

Physics Department at the Universidad Autonoma Metropol i tanaAzcapotzalco, Mexico City, Mexico. The calculations are being continued

by Dr. Lazos, and when they are completed, they will be compared with

measurements of the changes in the outer cylinder diameter conducted at

NBS.

During 1981-82, a 100-MPa oil piston gage was circulated among LNE,

IGMC, PTB, NPL and NBS with each lab calibrating it using their primary

standards. Representatives of the five labs met in February 1983 at

BIPM to prepare a report which will be eventually submitted to J. Phys.

E. Figure 3 is a plot of the relative change in area of the gage as a function of pressure. There are several points to note:

(1) LNE calibrated the gage at the start and at the end of the

round-robin. The gage area increased by 25 ppm between those calibrations. Neither LNE nor the maker of the gage were surprised at the

change for they have seen it before with new piston-cylinder assemblies.

The piston used in the round-robin was new, the original having been

damaged. LNE and the gage manufacturer claim the increase in the area

is due mainly to changes with use in the strains created during the

manufacturing process and by now the area should be nearly constant with

time and use. If all that is true, then it is unfortunate that an unseasoned gage was used for the round-robin, but it was apparently

unavoidable.

107
xIO

*

* «

I [ ra Q.

O

"2 CH0+-

o +

UJ C3 25< + 0

*0 *

+a

o

0 * •<NI E 0

<a

CL

«*

•fl *=t oLn+

alT3

108

8

PT8 o

NPL .

NOS LfJE

A2
(2) In figure 3, the labs are listed in chronological order. NBS

calibrated the gage just before the second calibration at LNE. The

agreement is excellent.

(3) The error bars at 100 MPa are reported elsewhere in the paper

and have been added to figure 3. Only IMGC has larger error bars then

NBS. The elastic distortion work is aimed specifically at reducing

those error bars.

(4) All-in-all, the agreement between the various labs is quite

good but the slope of the curves means that the disagreement will increase as the pressure increases. The differences in the slopes indicate that several labs should re-examine the distortion problem.

• Related Work

(1) BRL hydraulic load cell . We agreed to characterize a hydraulic

load cel T that is made much 1 i ke a control led-clearance piston gage.

The army would like to use the device as a force transfer standard. We

made a series of tests and the unit failed. It was returned to the

manufacturer for rework. B. Welch will go to the factory in Boston to

see the device demonstrated over the full range before we accept it

again for tests.

(2) Sandi a study on fluid compress ibi 1 i ty. Sandia asked us to

measure the compressibility of 10 fluids up to 1 GPa at room temperature. S. Wood is making the measurements. The project should be

finished in early September 1983.

109
VII. VACUUM: BELOW 105 Pa (1 atm)

VII. A. Manometry 1 - 10 3 Pa (10" 3 -1000 torr)

The core of the program is the Ultrasonic Interference Manometer

(UIM) in which the height of a column of mercury is measured by an ultrasonic technique. The UIM is capable of very high precision (1 ppm)

but its accuracy is presently limited to 100 ppm by the inaccuracy in

the speed of sound in mercury. This project is led by Dr. C. Tilford

who is assisted by R. Hyland.

Specific accomplishments this year include:

« Modifications and improvements in the NBS UIM.

• Construction of a second UIM for the National Physical Laboratory

in New Delhi, India.

« Comparison of the two instruments shows that overall, the low

pressure random errors (three sigma) are consistent with our existing

estimate of 10"’ Pa (10"^ torr). At high pressures (140 kPa or 20 psi)

the two instruments agree to within +

3 ppm over periods of days with

short-term (hours) sub-ppm imprecision. The *3 ppm is entirely consistent with our estimate of temperature uncertainties and we expect these

could be reduced if active temperature control were used. An apparent

reversible mechanical creep causes a shift that we believe is in the NBS

manometer. The shift reaches a maximum value of about 10~1 Pa

(10 3 torr) at around 15 to 20 kPa (150-200 torr). This amounts to an imprecision of 5 to 10 ppm at those pressures, which is very small. The

accompanying figure 4 shows the quality of the results thus achieved.

The UIM has been shipped to the NPL.

• The major factor limiting the high pressure accuracy of the

ultrasonic manometer remains the uncertainty in the speed of sound in

mercury. The long-dormant speed-of-sound apparatus was rehabilitated

and modified to incorporate the recent advances in the ultrasonic and

data acquisition systems. We expect to make measurement of the speed of

sound with an inaccuracy of~5 ppm, thereby rendering the UIM accurate

to that level.

• In addition to work of a research nature, the ultrasonic manometer was also used for a number of for-fee calibrations, 16 being performed during FY 83. Most of these calibrations were performed on capacitance diaphragm gages. We have attempted to organize our growing

body of data on widely used instruments in order to evaluate their

limitations as transfer standards.

110
FRACTIONAL DIFFERENCE BETWEEN TWO ULTRASONIC MANOMETERS

AS A FUNCTION OF TIME. PRESSURE WAS RAMPED IN STEPS FROM ZERO TO

106 kPa (1 ATM) AND BACK TO ZERO. SOLID LINES INDICATE THE

PRESSURE. 100 kPa FULLSCALE. IDEALLY, THE FRACTIONAL DIFFERENCES

SHOULD BE RANDOMLY SCATTERED ABOUT ZERO.

Figure 4.

VII. B. Vacuum 10' 4 - 1 Pa (10‘6 -10" 2 torr)

Through the support of the Department of Energy, the Division was able to build a primary vacuum facility. This has been used to study

two types of transfer gages: spinning rotor gages and ionization gages.

This project is led by C. R. Tilford, who is assisted by K. McCulloh and

R. Hyland.

• Primary Vacuum Facility

The high vacuum standard is currently being modified to include a set of constant pressure flow meters. These will permit a cross-check

on the present volume meter and allow a direct check for nonl inearities.

The apparatus also forms part of the leak standard apparatus discussed

below.

Ill
9 Ionization Gages

Evaluation of high vacuum ion gages as transfer gages continued

at a reduced pace. Data were obtained for several different types of

gages. The tests on one particularly promising gage were terminated

when we learned that the gage is no longer commercially available.

Long-term stabilty tests were started on the two most promising gage

types found to date. Several manufacturers were contacted to see if

they were interested in producing a gage with improved metrological

properties that would also meet several practical requirements. One

manufacturer has used the results of our work to guide his own research

and has developed a new ion gage configuration that shows promise of

significant improvement over the best currently available gages. Four

ion gages were calibrated for fee in FY 83.

9 Spinning Rotor Gages

The new NBS primary high vacuum standard for spinning rotor gages

(SRG) was completed and evaluated. We estimate the uncertainty of this

standard to be 1% for most gases. In January we initiated an interlaboratory comparison of this standard with the National Physical

Laboratory (NPL) in Teddington, England, and the Physikal isch-Technische

Bundesanstalt (PTB) in West Berlin. Results have been delayed by equipment problems at NPL and obscured by an apparent shift in one of the SRG

balls. However, the results from NPL are consistent with a 1 % uncertainty for our standard. These results will be factored into our decision as to whether or not to offer an SRG calibration service. We have

received a number of requests for this service.

During the course of this year we used this new standard as part of

a program to evaluate the stability of the SRG's. We experienced con- siderable difficulty in obtaining reproducible results with hydrogen, a gas not favored and little used by vacuum metrologi sts, but of obvious

importance to the fusion energy program, a major sponsor of the vacuum

standards work. Part of the problem may be due to surface interactions

at the ball's surface. We believe a major contaminant may be water

resulting from interactions between the hydrogen and adsorbed oxygen on the chamber walls. Apparently our previous work in calibrating ion

gages with a SRG did not disclose this problem because the contaminants

caused similar errors in the SRG and the ion gages. We have obtained

reasonable results only by taking exceptional steps to maintain

clean 1 iness.

« Extension of NBS Work to Lower Pressures

Through the leak standards program (see VIII) we expect to develop

the ability to develop primary vacuum standards below our present limitation of 10"° torr.

112
VIII. LEAK STANDARDS

Leaks are an important quality control measure for a variety of

products ranging from beer cans to nuclear weapons. The economic implications are very large and the standards metrology is very primitive.

We have been offered a significant level of financial support for an extended period of time (3-5 years) by Sandia Labs and the NBS Office of

Nondestructive Evaluation to establish leak standards. Sandia's specific interest is verification of quality controls for nuclear fuel

shipment casks. NBS's interest is more general but with emphasis on electronic device packaging. In part because the best existing standards, located at Sandia, are based on gas accumulation techniques, we

have plans to base our standards mainly on flow techniques. This work

will begin using our high vacuum gaging standard, but will eventually

require measurements in the very high and ultra-high vacuum ranges. We

will thus acquire standards of pressure in those ranges as a bonus. An

initial comparison with Sandia leak standards is being organized, some

equipment has been acquired, and we are advertising for a new

professional to lead this work. The ball is presently being carried

C. Tilford.

113
INVITED TALKS

Temperature and Pressure Division (522)

Vern E. Bean, "NBS Response to National Pressure Measurements Needs,"

Precision Pressure Measurement Workshop, Sandia National Laboratories,

Albuquerque, NM, March 1, 1983.

R. D. Cutkosky, "Advantages and Limitations of AC Resi stance-Thermometer

Bridges -- Whether Maual or Automatic," American Society for Testing and

Materials meeting of Committee E-20, Louisville, KY, May 11, 1983.

G. T. Furukawa, "Cryoscopic Determination of the Purity of Benzene by

Calorimetry," Symposium on Purity Deterinations by Thermal Methods,

Baltimore, MD, April 25, 1983.

W. S. Hurst, "Drivers for the IEEE-488 Bus Using the Pickles and Trout

S-100 Board," NBS Microprocessors Group Meeting, February 1983.

W. S. Hurst, "Temperature Measurement in Gases Using Nonlinear Raman

Spectroscopic Techniques," Pennsylvania State University, Department of

Engineering Science, University Park, PA, July 1983.

R. W. Hyland, "Calibration Results for a Group of Capacitance Diaphragm

Gages," 12th Annual Symposium on Applied Vacuum Science and Technology,

Clearwater Beach, FL, February 14, 1983.

H. Marshak, "Gamma-Ray Spectrum Analysis in Nuclear Orientation

Experiments," Freie Universitat, Berlin, West Germany, June 29, 1983.

G. J. Rosasco, "High-resolution Nonlinear Optical Measurements of the

Temperature and Pressure Dependence of Molecular Spectra," NASA Langley

Research Center, Hampton, VA, October 8, 1982.

G. J. Rosasco, "Nonlinear Optical Studies of Col 1 isional Broadening and

Narrowing in the Q-Branch Spectra of No and CO," Princeton University,

Department of Mechanical Engineeing ana Aerospace Science, Princeton,

NJ, October 1982.

G. J. Rosasco, "Nonlinear Optical Studies of Pressure Braodening and

Narrowing in the Q-Branch Spectra of N

2 and CO," The Catholic University

of America, Physics Department, Washington, DC, February 1983.

G. J. Rosasco, "Collisional Line Broadening and Mixing in Vibrational

Q-Branch Spectra," 38th Symposium on Molecular Spectroscopy, Ohio State

University, Columbus, OH, June 1983.

114
R. J. Soulen, Or., "Noise and Impedance of an R-SQUID; Implications for

Noise Thermometry," Physics Department, University of California,

Berkeley, CA, February 22, 1983.

R J. Soulen, Or., "Recent Advances in R-SQUID Noise Thermometry,"

Kammerlingh Onnes Laboratory, Leiden, The Netherlands, May 13, 1983.

C. R. Tilford, "Reliability of High Vacuum Measurement," 29th National

Symposium of American Vacuum Society, Baltimore, MD, November 17, 1982.

C. R. Tilford and R. W. Hyland, "Stability of Capacitance Diaphragm

Gages," Vacuum Measurement Standards and Calibration Conferene,

Teddington, England, Oanuary 19, 1983.

C. R. Tilford and K. E. McCulloh, "Performance Characteristics of

Different Hot Cathode Ion Gage Types," Vacuum Measurement Standards and

Calibration Conference, Teddington, England, Oanuary 19, 1983.

C. R. Tilford, "Air Traffic Safety from the Perspective of a Metrologist," Conference on Safety Issues in Air Traffic System Planning

and Design, Princeton, NO, September 26, 1983. (Talk given by Dr. Oames

Lechner)

C. T. Van Degrift, "Experimental Constraints on the Parameters

Describing Unordered bcc ^He," AIP Symposium on Quantum Fluids and

Solids, Sanibel Island, FL, 1983.

115
PUBLICATIONS

Temperature and Pressure Division, 522

IN PRINT:

B. W. Mangum and G. T. Furukawa, "Report on the Sixth International

Symposium on Temperature," (Abbreviated version), Metrologia 18, No. 3,

161-168 (1982).

B. W. Mangum and G. T. Furukawa, "Report on the Sixth International

Symposium on Temperature," (Long version), J. Research NBS, 87_, No. 5,

387-406 (September-October 1982).

G. J. Rosasco, W. Lempert, W. S. Hurst, and A. Fein, "Pressure Dependent

Linewidth and Line-shift Measurements in the Vibrational Q-branch of No

from 4 to 200 kPa," Spectral Line Sha p es, Vo 1

2, ed. by K. Burnett

(Walter de Gruyter and Co., Berlin, 1983) , p. 635.

Charles R. Tilford, "Reliability of High Vacuum Measurements," J. Vac.

Sci. Technol. A 1, No. 2, 152-162 (April-June 1983).

K. E. McCulloh, "Calibration of Molecular Drag Vacuum Gages," J. Vac.

Sci. Technol. A l. No. 2, 168-171 (April-June 1983).

G. J. Rosasco, W. Lempert, W. S. Hurst, and A. Fein, "Line Interference

Effects in the Vibrational Q-branch Spectra of No and CO," Chem. Phys.

Lett. 97, 435 (1983).

R. D. Cutkosky, "Dedicated Multiprocessor System for Calculating

Josephson-junction Noise Thermometer Frequency Variances at High Speed,"

Rev. Sci. Instrum _54, No. 7, 886-889 (July 1983).

B. W. Mangum, "The Sucinoni tri le Triple-Point Standard: A Fixed Point to

Improve the Accuracy of Temperature Measurements in the Clinical

Laboratory," Clin. Chem. 29_, No. 7, 1380-1384 (1983).

V. E. Bean, "Fixed Points for Pressure Metrology," Chapter 3 of High

Pressure Measurement Techniques , G. N. Peggs, editor, (Applied Science

Publishers Ltd., Essex, England, 1983) pp. 93-124.

H. Marshak, "Nuclear Orientation Thermometry," J. Research NBS, 88,

No. 3, 175-219 (1983).

Paul H. E. Meijer and Daniele Clausse, "Rate of Ice Formation in

Supercooled Water," Physica 119B (1983) 243-248.

116
ACCEPTED FOR PUBLICATION:

J. C. Houck, G. F. Molinar and R. M. Maghenzani- "An Intercomparison of

Pressure Standards Between IMGC and NBS," J. Research NBS, 88.

Charles R. Tilford and Donald F. Martin, "Gas/Oil Interface and High

Sensitivity Differential Pressure Indicator Used for the Comparison of

Gas with Oil Piston Gages," Review of Scientific Instruments.

Paul H. E. Meijer, "General Considerations on Liquids at Normal and

Super-cooled Temperatures with Special Attention to Water," Nuovo

Cimento.

Sharrill D. Wood and Vern E. Bean, "Polynomial Representation of the

Decker Equations of State for NaCl and CsCl," High Temperatures - High

Pressures .

George T. Furukawa, Jeanette H. Piccirelli, and Martin L, Reilly,

"Cryoscopic Determination of the Purity of Benzene by Calorimetry,"

Proc. Symposium on Purity Determinations by Thermal Methods, Baltimore,

MD, April 1983.

Paul H. E. Meijer and Mustafa Keskin, "The Dynamic Behaviour of the

Pople and Karasz Model," J. Physics and Chemistry of Solids.

E. Bodegom and and Paul H. E. Meijer, "Spinodal Decomposition and Phase

Separation of Directionally Bonded Liquids Using the Four Cluster

Approximation," J. of Chemical Physics.

Mustafa Keskin and Paul H. E. Meijer, "A Model for Quenching via Hidden

Variables; Non-Equilibrium Behaviour of a System with Two Long Range

Order Parameters," Physica A.

Paul H. E. Meijer, Mustafa Keskir> and Erik Bodegom, "A Simple Model for

the Freezing-In of Metastable States," Physics Review A.

E. Bodegom and Paul H. E. Meijer, "Long Term Behaviour of Phase

Separation; Computations with the Non-Homogeneous, Time Dependent

Cluster Variation Method," Physica A.

Richard W. Hyland and Arnold Wexler, "Formulations for the Thermodynamic

Properties of Dry Air from 173.15 K to 473.15 K, and of Saturated Moist

Air from 173.15 K to 372.15 K, at Pressures to- 5 MPa," ASHRAE

Transactions.

117
Richard W. Hyland and Arnold Wexler, "Formulations for the Thermodynamic

Properties of the Saturated Phase of H?0, (from 173.15 K to 473.15 K),"

ASHRAE Transactions.

B. E. Welch and Vern E. Bean, "Pressure and Temperature Measurements in

the Crevice Between the Piston and Cylinder of a Simple Dead-Weight

Piston Gage," Metrologia.

B. W. Mangum, "The Triple Point of Succinonitri le and Its Use in the

Calibration of Thermistor Thermometers," Review of Scientific

Instruments.

H. Seppa, J. H. Colwell and R. J. Soulen, Jr., "Intrinsic and Extrinsic

Noise Sources in an RF Biased R-SQUID," Proc. 7th International

Conference on Noise in Physical Sciences, Montpelier, May 17-20, 1983.

Robert L. Berger, Thomas Clem, Victoria A. Harden and B. W. Mangum,

"Newer Means of Temperature Measurement in Biochemi stry," Chapter in

Methods of Biochemical Analysis.

H. Marshak, "Precise Gamma-ray Multipole Mixing Ratios Using Nuclear

Orientation," Proc. 6th International Conference on Hyperfine

Interactions, J. Hyperfine Interactions, North Holland Press.

B. E. Welch and Vern E. Bean, "A Method to Determine the Pressure

Dependent Distortion of a Simple Piston Gage Based on Dimensional

Metrology," High Pressure Science and Technology, Proc. of the IX AIRAPT

Conference, Albany, NY, July 25-29, 1983.

J. K. N. Sharma, Kamlesh K. Jain, Vern E. Bean, B. E. Welch, and Ruben

J. Lazos, "Effects of Viscosity, Temperature, and Rate of Rotation on Pressure Generated by a Control led-Clearance Piston Gauge," Review of

Scientific Instruments.

R. D. Cutkosky, R. E. Edsinger, J. P. Evans and R. J. Soulen, Jr.,

"Progress in Temperature Measurement," Proc, ISA, Houston, 1983.

Sharrill D. Wood and Vern E. Bean, "Compression of Cl^ at High

Pressures," High Pre s sure Science and Technolo gy, Proc. of the IX AIRAPT

Conference, Albany, NY, July 25-?9, 1983.

Vern E. Bean, Sharrill D. Wood and Ruben J. Lazos, "Pressure Dependence

of Viscosity of Pressure Transmitting Fluids," High Pressure Science and

Technology, Proc. IX AIRAPT Conference, Albany, NY, July 25-29, 1983."

Craig T. Van Degrift, "Experimental Constraints on the Parameters

Describing Unordered bcc ^He," AIP Conference Proc., Symposium on Quantum Fluids and Solids, Sanibel Island. FL, 1983.

118
J. K. N. Sharma, Kamlesh K. Jain, Vern E. Bean, B. E. Welch and Ruben J. Lazos, "Effects of Viscosity, Temperature, and Rate of Rotation on the

Operation of a Control led-Clearance Piston Gauge," High Pressure Science

and Technology, Proc. IX AIRAPT Conference, Albany, NY, July 25-29,

1983.

Warren G. Hurley and Richard W. Hyland, "General Guidelines for the

Field Calibration of Humidity and Moisture Indicators" NBS Building

Science Series.

119
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

Interdi scipl inary Survey of Property Data on High Pressure Phases.

G. W. Burns, Member, ANSI MC096, American National Standards Institute

Committee on Temperature Measurement Thermocouples.

G. W. Burns, Member, ASTM E-20, American Society for Testing and

Materials Committee on Temperature Measurement, Subcommittee E-20. 04,

Thermocouples.

R. D. Cutkosky, Assistant Secretary, IEC TC25, International

Electrotechnical Commission Technical Committee on Quantities, Units,

and Their Letter Symbols.

R. D. Cutkosky, Member, IEEE IM TC-2, Institute for Electrical and

Electronics Engineers Instrumentation and Measurement Group, DC and LF

Standards.

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. 10, Publications.

W. S. Hurst, Member, ANSI MC088, American National Standards Institute

Committee on Calibration of Instruments, Subcommittee SC.03,

Temperature.

R. W. Hyland, Member, AVS C004, American Vacuum Society Committee on Standards, Subcommittee SC. 01, Gaging.

120
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.

B. W. Mangum, Member, ASTM E-20, American Society for Testing and

Materials, Temperature Measurement Committee; Member, Subcommittee

E 20.03, 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-Gl ass 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, Member, CIPM CCT, International Committee on Weights and

Measures Consultative Committee on Thermometry; and Delegate,

Subcommittee WG3, Replacement of IPTS-68.

J. F. Schooley, Delegate, OIML PS12, International Organization of Legal

Metrology Committee on Measurement of Temperature and Calorific Energy.

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.

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 C0C4, American Vacuum Society Standards

Committee; Member, Subcommittee SC. 01, Gaging..

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.

121
C. R. Tilford, Chairman, RTCA SC150, 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-Gl ass ihermometers and Hydrometers; and Secretary,

Subcommittee E-20. 90, Executive Subcommittee.

122


LENGTH AND MASS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1983

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

research.

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 concordance. A close working relationship is maintained with those divisions in the National Engineering Laboratory which

have the responsibility for providing calibration services to other

government agencies and the public. This cooperation not only concerns

the first transfer of dimensional quantities but also includes the

transfer of techniques and instruments, such as the portable laser

length standard, the submersible balance, and the load cell mass com- parator, each of which was developed in the LMD. Cooperative projects

with outside institutions, such as state standards laboratories and

universities, ensure that our activities are relevant to the problems of

the measurement community. Solutions to these problems are sought

through a program of research which strives to develop improved mea- surement instruments and techniques by an increased understanding of the

fundamental physical principles upon which the standards are based and

by the application of modern technology. Finally, the LMD is frequently

called upon to offer information and assistance to private and public

organizations which have the responsibility for state-of-the-art length

and mass measurements but cannot get adequate support from the private

sector.

The activities of the Division this year were shifted towards the mass area to expedite the completion of the vacuum compatible servo controlled kilogram comparator which was started in mid 1982. Much of

the design work has been completed and construction is proceeding.

Development of the electronic servo system will soon begin. The program

to recalibrate the kilogram prototypes is well underway. Preliminary

measurements have been completed in the Gaithersburg Laboratories.

Calibrations at the BIPM are scheduled to begin in December and will be

completed in February. The Division worked on two density projects this

year. A liquid densitometer which is based on a novel principle has

been designed and drawings have been prepared. Construction and testing

will proceed in the Fall. The silicon density artifacts which were

123
issued by the Office of Standard Reference Materials as a result of our activities last year have been used to certify the densities of certain

glasses which will serve as reference densities for the ASTM.

A small group of theoreticians in the Division are developing

methods to treat electric field effects on atomic processes and the time

dependence of excitation processes under varying field conditions. In

addition to the theoretical work, J.W. Cooper collaborates with workers

in the Center for Radiation Research (CRR) on experimental programs.

124
II. Technical Activities

1 . Length Measurements and Standards

The length activities were curtailed during FY 83 to permit Howard

Layer to work on the servo-controlled kilogram mass comparator. Therefore, only a small fraction of his time was available for length re- search and development activities.

A. NBS Portable Laser Length Standard

ACCOMPLISHMENTS : 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. This instrument is now commercially available from a small company in Gaithersburg which has

traditionally manufactured instruments developed at NBS. One of their

instruments has gone to the group within Hewlett-Packard which manufactures the laser interferometer system and is used as an on-line

reference standard to verify the laser wavelength specification. Prior

to using the iodine stabilized laser, the accuracy of the HewlettPackard laser was specified as 5 parts in 10 7

. The accuracy of their

present instrument is specified as 1 part in 10 7 with stability of about

one part in 10 8

. Hewlett-Packard estimates the precision of the process

used in this measurement to be about 1 part in 10 9

. The NBS Laser

Length Standard has now been integrated into the operations of the two

of the most important length disseminating metrology institutions in the

United States, NBS in Washington and HP in Santa Clara, and represents

an excellent example of government to industry technology transfers.

PLANS FOR FY 1984 : All of the goals of the iodine stabilized

laser length standard have been achieved. Active efforts will be con- tinued to transfer the technology to additional segments of society but

no new technical initiatives are anticipated. A document which describes the design performance and application to metrology is substantially completed. This monograph will combine many aspects of laser

length metrology in one document and, judged by our inquiries, will be

well received.

B. Stabilized Mercury Lasers

The optically pumped mercury laser has been stabilized to an iodine transition using an internal cell. It is similar to the iodine

stabilized HeNe laser but is expected to perform at a higher level of

accuracy and precision. Its frequency (wavelength is 546 nm) can be

measured relative to the cesium clock with the Boulder frequency chain

doubled 1.15 ym transition in Ne and an additional C0 2 laser frequency.

125
ACCOMPLISHMENTS : The optical pumping cavity and the pump lamp

have been redesigned and are operational. Because of the difficulty of

pumping argon, which is the buffer gas used in the mercury pump lamp, a turbomolecular bakeable pumping system has been constructed and has

recently been put into use.

PLANS FOR FY 1984 : Detailed characterization of the laser

performance has begun to determine the operating conditions for optimum

performance. When the system is complete it will be taken to the NBS

Boulder Laboratories to measure its frequency relative to the cesium

clock. The goal of this project is to construct a practical laser

similar to the iodine stabilized helium neon laser, but with better

resetability and lower noise.

2. Mass Measurements and Standards

A. Recalibration of U.S. Kilograms by BIPM

ACCOMPLISHMENTS : Kilograms K20 and K4 (both platinum-iridium

prototypes of the International Prototype Kilogram) along with two

stainless-steel kilograms will be calibrated by BIPM. In preparation

for this exercise, NBS was able to borrow a Pt.-Ir kilogram from BIPM

(#650) for preliminary measurements in Gai thersburg . This artifact was used in a series of measurements on our best mass comparator. Preliminary results indicate that K20 probably has not changed by more than

10 ug since its last calibration in 1948, although other working standards

have changed somewhat more dramatically. The BIPM calibration measurements are scheduled to begin in December 1383.

The automatic balance reader which was mentioned in FY 1982 has not

been completed although all software necessary to collect and analyze

the data has been written.

PLANS FOR FY 1984 : Calibration of K20, K4, and the stain! ess - steel kilograms by BIPM will be completed. Richard Davis of the Division

will handcarry the kilograms to BIPM and remain as a guest worker for

approximately three months to participate in their calibration.

Upon their return to the NBS, the standards will be rechecked for

internal consistency and then used in a recal ibration of the stainlesssteel working standards of the NBS calibration service. Six new vacuum- melted stainless steel kilogram weights have been acquired by the

National Engineering Laboratory. We will assist them in the calibration

and the maintenance of a heirarchical system which will require use of

at least two of the new artifacts. We expect the automatic balance

reader will be operational in time to facilitate these measurements.

126
B. Servo Controlled Kilogram Mass Comparator

ACCOMPLISHMENTS : All of the major components of the prototype

system have been completed or are in the final stages of manufacture.

The balance beam has been vacuum cast in both A356 high silicon aluminum

and beryllium copper in an effort to determine which material and which

mix of thermal and physical properties will produce the most stable

operation. In addition to the beam, the balance consists of four major

structural components: the plate on which the beam is mounted by means

of a flat on the plate and a knife on the beam; the optics plate

which contains the interferometer which measures the beam position;

the base plate and cover whjch form the vacuum enclosure for the entire

system. These plates are made of high silicon content aluminum and are artificially aged for stability. They are kinematically related to each

other and to the laser and photodetector, which are placed outside and

above the vacuum chamber to minimize the heat input to the balance. The

knife, which is the fulcrum for the beam, has been cast from Tantung-G,

a non-ferric tool steel which has a HRC of 60 and is non-magnetic.

The flat, which supports the knife, is made of boron carbide. This

material is an electrical conductor so that the beam will not become

electrostatically charged. The boron carbide flat was polished to less

than one fringe over its entire surface by a gage block manufacturer.

No such commercial service is available, however, for the knives and

this technology had to be redeveloped. By using cast iron lapping discs

and diamond abrasive, a knife edge has been generated by the intersection

of two planes inclined 115 deg with respect to each other. Each surface

is flat to within 1/10 of a fringe along its entire length. These

appear to be the highest quality knives and flats that have ever been

used at NBS.

The computer interface, which includes not only the controls for

the beam servo and the weight handling mechanism but also several ports

which will monitor pressure, temperature and other parameters, is

complete. In addition some beam position measuring and curve fitting

software has been written.

PLANS FOR FY 1984 : The construction and assembly of the

balance will continue and testing will begin immediately. The first

objective is to get the mechanical part of the balance operational. The

second is to align the angle interferometer which measures the beam

position. Finally, the electronic servo will be incorporated. This

system will then be used to test the balance design and the performance

of the components. If the performance goals are met, the weight pan and

the weight-changing mechanism will be constructed.

127
C. Surface Dependent Thermal Effects in Mass Calibration

ACCOMPLISHMENTS : An experiment was conducted to test effects

which arise when masses undergoing calibration are not in thermal

equilibrium with the surrounding air or with each other and when there

are differences in their surface to mass ratio. The results of these

measurements demonstrated that most ordinary mass calibrations and

scientific mass measurements have undetected systematic errors which can

be eliminated with better thermal control. The results of this experiment will be published in the proceedings of the National Conference of

Weights and Measures.

PLANS FOR FY 1984 : A kilogram balance will be set up in the

isothermal environment of the sub-basement in the density laboratory to

determine the magnitude of systematic thermal effects.

D. Density of Solids

ACCOMPLISHMENTS : The project to certify the density of 70

silicon artifacts has been finished and these have now been issued as Standard Reference Materials (SRMs). This fiscal year we were asked by

the Office of Standard Reference Materials (OSRM) to certify the density

of selected glasses. These glasses will serve as reference densities

for ASTM C729 (Standard Test Method for Density of Glass by the SinkFloat Comparator). The measurements are now complete.

The two 800 g silicon artifacts which were sent to IMGC in Italy

were returned at the end of the fiscal year. Preliminary analysis of

the Italian data shows agreement in density measurements with NBS to

slightly better than 1 ppm. This uncertainty includes traceability to

the S.I. definitions of mass.

PLANS FOR FY 1984 : The density of the silicon objects loaned

to IMGC will be redetermined at NBS. This will complete a symmetric

(A-B-A) intercomparison. The final results will be reported in a paper

jointly authored by NBS and IMGC personnel.

E. Special Publication

ACCOMPLISHMENT : A new Industrial Measurement Series of Special

Publications will be published by NBS. Division personnel and an industrial metrologist will co-author the first paper in this series

entitled "A Primer for Mass Metrology." The goal of the publication is

to integrate the many NBS publications covering mass metrology into a single coherent document for industrial metrologists. The new publication does not replace existing NBS documents but serves instead as a guide to their use.

128
PLANS FOR FY 1984 : A final draft of the publication has been

completed. The editorial review process will begin in October. Since

the publication synthesizes the work of many people, careful review is

especially important. Nevertheless, the publication should be available

in the first half of FY 1984.

F. Liquid Densimeter

ACCOMPLISHMENTS : There is a need in metrology for a family

of liquid density standard in the range from 0.6 g/cm 3 to 2.0 g/cm 3 for

calibrating hydrometers to 100 ppm and the most precise vibrating tube

densimeters to a 10 ppm or better. Since it is not practical to provide

these standards with classical hydrostatic weighing or pycnometry, the

Division is developing a new type of densimeter for the Standard Refer- ence Material Program to be used in the certification of liquid density

SRMs

In principle, a force balance is isolated in one leg of a U-tube

manometer by a diaphragm. The force balance is surrounded by an inert

fluid while the other leg contains a sphere of known density surrounded

by a fluid of unknown density. The unknown fluid height is adjusted

such that each side of the diaphragm is at the same pressure and then

the cell is exposed to the force imposed by the sphere mass via the

diaphragm. The analysis and design of the instrument are complete.

Construction and testing will begin in FY 1984.

G. Weights and Measurement Metrology

ACCOMPLISHMENTS : The examination of five state laboratories

for their ability to perform advanced mass metrology is complete and has

been reported. Significant conclusions are:

o Better instrumentation is required to measure the air

temperature, pressure and relative humidity.

o Better thermal control is required in weighing areas.

o Computerized data reduction and analysis are necessary.

PLANS FOR FY 1984 : The program will be continued in FY 1984

with an improved circulating package that will include an electronic

barometer, thermometer and R.H. meter. In addition an HP-85 microcomputer and Division 523 software will be included. An effort will be

made to recalibrate each participant's kilogram mass standards and

eventually their entire metric weight set in their own laboratory.

129
3. Atomic Theory

A. Far UV Absorption of Atomic Barium

OBJECTIVE : To measure the absolute absorptiog cross section

of barium from threshold (2379 K) to approximately 400 A.

CURRENT ACTIVITIES : The £irst step is making measurements in

the region from threshold to ^1 200 A. The equipment consists of (a) a monochromator mounted on the beam line of the SURF-II facility which is

used as the radiation source, (b) a heat pipe capable of producing a well controlled column density of barium vapor, and (c) a detection

system and control electronics. All of these are currently being

assembled.

ACCOMPLISHMENTS : The apparatus for the experiment was assembled

on SURF and the relative measurements made.

PLANS FOR FY 1984 : The data reduction at relative cross sections will be completed. The column density in the barium absorption

cell will be determined after the apparatus has been moved to the

Physics Building and reassembled.

B. Theory of the Stark Effect

OBJECTIVE : To develop the theory of the Stark effect on atomic systems near ionization thresholds.

CURRENT ACTIVITIES : Theoretical methods are being developed

to describe both the level positions and relative intensities of peaks

observed in field ionization measurements. This work is a result of a col laboration with experimentalists performing field ionization measurements at Stonybrook and will be described in a paper currently being

written. Two other papers are currently being written. One describes

the generalization of the theory developed for the Stark effect on the

photoexcitation of one electron system to the more general case where

structure in the atomic core results in multiple ionization limits and

autoionization can occur. The second paper will be a brief review of

recent developments to appear in "Comments in atomic and molecular

physics" and was solicited by the editor of that Journal.

ACCOMPLISHMENTS : The major accomplishment has been the

successful extension of the theory to multichannel systems. In addition, a set of computer programs have been developed which provide

detailed computations of the absorption cross sections with applied

fields which can provide detailed comparisons with existing experimental

data

PLANS FOR FY 1984 : The major effort during the next several

months will be to complete the three papers now being written and thus

document the work that has already been accomplished. Additional tasks

130
will be making more computations and comparing them with existing

experimental data and extending the theory to excited state photoionization. The latter effort will be attempted in order to provide some

useful information on the effects of fields on the dielectronic recom- bination process.

C. Field Effects on Autoionizing States

OBJECTIVES : To study field effects on autoionizing states

using multistep laser excitation.

CURRENT ACTIVITIES : An experiment has been started on three

step excitation in order to study the effects of electric fields on a particular ionizing state in barium. This experiment is expected to be

completed by the end of the year.

ACCOMPLISHMENTS : A paper on the low field effects on autoionizing states of gadolinium was completed and will be submitted to

JOSA.

PLANS FOR FY 1984 : The experiment on barium will be com- pleted, probably within the next several months. If it is successful,

detailed calculations will probably be carried out to compare with the

results using the methods developed by D. Harmin.

D. Theoretical Laser Spectroscopy

OBJECTIVES : To provide theoretical support to experimental

groups. Currently this involves developing a detailed theory of the

properties of many level systems.

CURRENT ACTIVITIES : Current work is mainly directed towards

examining the rather detailed results already in hand on the sodium n=3

system in order to: a) see if these developments can be extended to

provide useful information to experimental groups doing optical pumping

experiments, and b) write up the results in a definitive fashion.

ACCOMPLISHMENTS : The paper on "The Stark Effect in Hydrogen

and Helium at High Fields" was accepted and has appeared. A paper on "Saturated Fluorescence in a Standing Wave Laser Field" has been com- pleted and is currently being reviewed.

PLANS FOR FY 1984 : The major task is the completion of the

work on sodium, and its possible extension.

131
INVITED TALKS

Length and Mass Division (523)

David A. Harmin, "Stark effect lineshape theory," State University of New

York at Stony Brook, December 5, 1982.

David A. Harmin, "Theory of the Stark effect," Yale University, Physics

Department, New Haven, CT. January 26, 1983

David A. Harmin, "Stark effect in non-hydrogenic atoms," New York American

Physical Society meeting, January 27, 1983.

David A. Harmin, "Theory of the Stark effect", Wesleyan University, Hartford,

CT. April 14, 1983.

David A. Harmin, "Theory of the Stark effect", Kansas State University,

Manhattan, Kansas. May 19, 1983.

Randall M. Schoonover, "Advanced mass calibration in state 1 aboratori es

,"

(workshop given at the 86th National Conference on Weights and Measures)

Sacramento, CA. July 18, 1983.

Randall M. Schoonover, "A surface-dependent thermal effect in mass calibration,"

86th National Conference on Weights and Measures, Sacramento, CA. July 19, 1983.

132
PUBLICATIONS

Length and Mass Division (523)

J. W. Cooper and E. B. Saloman, "The Stark effect on the oscillator strength

distribution of helium near the ionization limit," Phys. Rev. A26 , 1452-1465

(1982).

G. Mehlman, J. W. Cooper and E. B. Saloman, "The absolute photoabsorption

cross section of the K shell of atomic lithium," Phys. Rev. A25 , 2113-2122

(1982).

Richard S. Davis, "Determination of silicon density to high precision using

a submersible, servo-control! ed balance," Metrologia 18., 193-201 (1982).

Randall M. Schoonover and Jerry Keller, "A surface-dependent thermal effect

in mass calibration and what you can do about it," Proceedings of the 68th

National Conference on Weights and Measures, Sacramento, CA, July 18-22,

1983.

R. M. Schoonover, "Advanced Mass Calibration in State Laboratories ," NBS

IR #2752 (August 1983).

Helen K. Holt, "Stark quenching of metastable 2S states in hydrogen and

helium at high fields," Phys. Rev. A28 , 1157-1159 (Aug. 1983).

J. W. Cooper, E. B. Saloman, and B. E. Cole, "Electric field effects on the

absorption spectra of H 2 near the ionization limit," Phys. Rev. A28, 1832-

1834 (Sept. 1983).

V. I. Mishin, G. Lombardi, D. E. Kelleher and J. W. Cooper, "Effects of

very low electric fields on autoionizing states in gadolinium," to be

submitted to JOSA.

Helen K. Holt, "Saturated fluorescence in a standing wave laser field,"

in review.

133
COMMITTEES

Length and Mass Division (523)

R. S. Davis, member, American Society for Testing & Materials, E41.06,

Weighing Devices, subcommittee of E.41, Laboratory Apparatus.

R. M. Schoonover, member, American Society for Testing & Materials,

E41.06, Weighing Devices, subcommittee of E.41, Laboratory Apparatus.

134
ssI1aiii:1.3]

TIME AND FREQUENCY DIVISION

FISCAL YEAR 1983

I. OVERVIEW

This report is divided in two halves. The first naif is an overview of the Division which is intended to provide an introduction

for those who are unfamiliar with the Division's objectives and activities. The second half addresses the Division's short-term plans and

accomplishments. It is arranged to permit an easy review of the

Division's performance.

The National Bureau of Standards (NBS) is responsible for the

development and maintenance of a system of measurements required to

support the Nation's economy. 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 is 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

responsible for the standards of frequency and length, two of the six

base units of the Systems Internationale (SI). The most important

product of the Division is the service provided to science and industry. There is no sense in establishing and maintaining standards of

measurement unless they are disseminated. Standards operation and

research and development of standards and methods of measurement

closely supports 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 services. Basic research related to standards is performed over a broad range of fields to challenge the talents of the staff and to

stimulate the development of new ideas. Advisory service to 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. This section presents the program of the Division

in terms of these four basic functions.

SERVICE

In order to have useful standards of time, frequency, and length

it is essential to provide a means of reference to these standards.

This has been accomplished primarily via the radio broadcasts of

stations WWV, WWVH, and WWVB and a time code disseminated from the

GOES satellite system. NBS has also provided telephone time-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 disseminated primarily by publication in scientific journals. Seminars are regularly scheduled to educate new entrants

to the time and frequency field concerning methods of measurement.

Users of the Division's services fall into several broad categori es:

Navi qati on

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 GPS need time much more accurately. When using these systems, an error of only 3 microseconds could cause the same one kilometer error.

Systems Control and Synchronization

Power companies use frequency to control electric power flow at

60 hertz. If they didn't, clocks could not maintain the correct time.

They need time to monitor the power grid to help alleviate "brownouts"

and massive power failures. They use it to help locate power outages

and to know the exact time when outages occur. Time is also important for keeping track of power flow among the various companies in

the interconnected network for billing purposes.

Radio & TV stations need accurate frequency to broadcast signals at

136
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

to synchronize satellite & other communications terminals 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.

Astronomers use time for observing astronomical events, such as lunar occupations and eclipses.

Science and Metrology

Manufacturers need time and frequency to calibrate counters,

frequency meters and test equipment.

Frequency is required by the broadcast industry for spectrum

conservati on.

Accurate spectra of molecules are needed to measure atmospheric

concentrations.

Laser frequency measurements provide accurate calibration frequencies for spectroscopi sts and frequencies for radio astronomy. **********************************************************************

OBJECTIVE: Generate NBS time scales, UTC(NBS) and TA(NBS)

**********************************************************************

NBS atomic time is generated from an ensemble of approximately

ten commercial and laboratory cesium beam frequency standards and a laboratory hydrogen maser. The times of all the clocks are automatically measured every two hours with a precision of a few picoseconds.

The UTC(NBS) time scale is computed immediately following a measure137
ment 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. Using data from the Bureau Internationale de l'Heure,

UTC(NBS) is maintained within 1 ps 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, an excellent model for the clocks in the NBS

ensemble. The second of TA(NBS) is NBS's best estimate of the SI

second based on yearly calibrations of the ensemble by NBS-6. **********************************************************************

OBJECTIVE: Broadcast time from radio stations WWV, WWVH and WWVB and

the GOES satel 1 ites. **********************************************************************

NBS offers several around-the-clock time and frequency dissemination services to the general public. In 1923, 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 for 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. WWVB's

signal is 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 satellite since 1975 in an experimental service. The coverage area is shown in Figure 2. More

than 8 years of experience has shown that such a system can offer

continuous time and frequency reception that is much more dependable

138
60! 90 30° 60°

Figure 2

139
than ground-based AM and FM radio stations, is free from propagation

anomalies, and has a better-than-100-mi crosecond accuracy. Table I summarizes the principal NBS time and frequency dissemination services.

Table II gives -some details of the HF radio broadcasts.

OBJECTIVE: Provide seminars, calibrations and measurement assurance

on a fully reimbursable basis.

X******.**********.*****.*******.**.*.**.******************.*.*.****.*********.***.

Calibration Services for Frequency and Time . An enhanced level of

calibration activity has been encouraged since 19S2. Those calibrations which require the special facilities of the National Bureau of

Standards and those which require traceability to the national standards are actively welcomed. Some calibrations still fall into the

category of special tests but a fee schedule is now published for two

commonly requested measurements. In a period of less than two years,

the calibration program, as measured by the value of calibrations

performed, has increased by more than a factor of ten.

Measurement Assurance Services . Two new time and frequency dissemination services were started in 1983. They permit the user to obtain

time and frequency traceable to the NBS with greater precision and

less work than previously possible. The new services are suitable for users who require time transfer accuracies in the 3 nanosecond to 1

microsecond range or-^|requency calibration capability in the 1 part in

lCr to 1 part in 10

1

range. However, even applications which do not

require this level of precision may take advantage of these services

because of their high degree of automation, simplicity of use, and

degree of support from NBS.

Timing requirements at the 1 microsecond level and-^£requency

calibration requirements at the part in 10

11

to part in 10

iZ

level can

be satisfied using low frequency radio signals from broadcast 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 would contain a receiver, microcomputer, disc units and printerplotter. The user's responsibility is to provide 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

will also receive a bulletin, either by telephone or by mail, which

reports the performance of many of the accurate signal sources. To

assist the user in getting the most out of this system NBS will provide

specific training on the actual equipment involved in its Seminar on Frequency Measurements and Calibrations. This will assist the user in

resolving system failures.

The second service, based upon the NBS designed GPS receiver,

provides much higher precision time and frequency data and a greater

degree of automation. The receiver which is located at the users

140
CHARACTERISTICS

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141

J
STANDARD

FREQUENCY

AND

TIME

SIGNAL

BROADCASTS

IN

THE

HIGH

FREQUENCY

BAND

142
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 both the raw data and the results

of the NBS analysis. Tests between receivers in Colorado and Germany,

France, Spain, Wyoming, and California have demonstrated an ability to

perform time comparisons with a precision of 3 nanoseconds, and frequency comparisons with a precision of 1 part in lCr .

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 in real time. This has proven to

be very useful

Time and Frequency Bulletin . The Division has continued the distribution of its Time and Frequency Bulletin to over 1500 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 will continue to be improved and will be used to support

our calibrations services.

Semi nars . The Division seminars provide industry, calibration labs

and the military with information and training on the use of frequency

standards and time. Three separate seminars were offered in 1983 and

all three were well attended. These will be continued as long as the

demand is there. A special effort is made to have the seminars support

the introduction of new services and to be of particular interest to

the nation's calibration laboratories. **********************************************************************

OBJECTIVE: Maintain international coordination of time scales using

the Global Positioning System. **********************************************************************

A satellite based time transfer system which was developed in the

Time and Frequency Division between 1979 and 1982 is now operational.

Several prototype receivers are operating in Braunschweig, Germany;

Paris, France; Madrid, Spain; Canberra, Australia; as well as Boulder,

Colorado; and Goldstone, California. A computer based automatic data

collection network acquires the data from the receivers in Paris,

Boulder, and Goldstone. This data is combined with the data from the

143
NBS Atomic Time Scale so that the time of the local clock is known

with respect to NBS Atomic Time to a precision of 10 nanoseconds after

one day of averaging.

Three receivers are being used to provide frequency calibrations

between the sites of the NASA Deep Space Net at better than the 1 part

in 10

1

level. The receivers at Boulder, Paris, and Braunschweig, are being used to transfer clock data from NBS and the Physi kal i sch-Technische Bundesanstal t to the International Time Bureau in Paris. This

new system is in the process of replacing Loran-C as the principal

time transfer link for the SI second and the International Atomic Time

Scale (TAI). *** *********** ***************** ***************************************

OBJECTIVE: To provide reference frequencies from the microwave to the

visible. **********************************************************************

Spectroscopic frequency references (measured with respect to the

cesium standard) . The pioneering work done by the Division to extend

direct frequency measurements from the microwave to the visible portion

of electromagnetic spectrum is now being used to measure the frequencies of atomic and molecular transitions which will be used by spectroscopists, astronomers, and atomospheric scientists. Before the advent

of heterodyne spectroscopy (in which the frequency is measured with

respect to cesium) spectral features were measured by wavelength

techniques which were hundreds of times less accurate than these new direct frequency measuring techniques. The knowledge of the frequencies of various selected species allows the spectroscopi st , astronomer

or atmospheric scientist to carefully calibrate his spectrometer or receiver 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 data. Coordinated activity at NBS (between the Time and Frequency Division in Boulder and the Molecular

Spectroscopy Divison in Gaithersburg) involves selection of suitable

molecular calibration candidates, their frequency measurement and

analysis, and dissemination of the results in the form of reference

frequency tables.

Absorption frequency calibration standards must be readily obtained and easily handled with at least one calibration point every 15

GHz (0.5 cm ). The reference lines must be well resolved and free of

accuracy-limiting fine structure each to an accuracy of ± 3 MHz.

The far infrared (0.1 to 5 THz, 3 mm to 60 pm) . Several hundred

optically pumped lasers have been measured and are used by laboratory

spectroscopi sts to measure absorption features. Laser Magnetic Reson- ance (LMR) spectroscopy has been developed into one of the world's

most sensitive techniques for observing and measuring frequencies of

144
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 (TuFIR) promises a much more general technique for measuring frequencies in this region.

The CCL laser which is stabilized to C0~ 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 pm to 12 pm-) . The frequencies

of hundreds of lines of OCS, DBr, CO, and NO now furnish reference

grids for this region. The methane line used to stabilize the He-Ne

is especially noteworthy. It serves as an extra accurate reference

for both metrology and spectroscopy.

Visible region (400 to 700 THz, 0.75 pm to 0.45 pm) . The two major

measurements (one yellow and one red) in molecular iodine which serve

as the basis for the new meter also serve as excellent frequency and

wavelength markers in the visible.

Status and availability of frequency calibration tables

Several molecules have been studied extensively and others have

been studied on a limited basis. We list these below and indicate

their coverage.

Carbonyl sulfide (multiband) . Tables of OCS absorption lines have

been provided for use as frequency calibration standards ixi the following., regions of thed nfrared: 815-892rm , 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 heterodyne frequency measurements for

all except the 2013-2140 cm region. The uncertainties of most cf

the recommended frequency standards are on the order of 1 to 10 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 quadruple split triplets comprising the R(0) and P(l) transitions in the D /3

Br isotope. New DBr constants have been determined

and a table of frequencies, believed to be accurate to 3 MHz,_^is

availably. Separation between 1 i_n^ pairs ranges from about 6 cm at

1980 cm to 11 cm at 1630 cm hence this molecule has limited

utility. It does however, span the OCS gap between 1738 and 1850 cm

145
and partially covers another OCS gap between 1921 and 2013 cm

Carbon monoxide (2-0), 412Q-4350 cm \ The 2-0 ro-vibronic band of

12 16 CO 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 the 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 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 (multiband) . An interim table of N

? 0 frequencies cover-

-1 -1 ^ ing 522 to 657 cm and 1115 to 1340 cm is currently in print.

Heterodyne frequency measurements were not available when the table was compiled and not many have been published at this time.

STANDARDS OPERATION, RESEARCH AND DEVELOPMENT

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 mos^j. stable cesium clocks in the world, 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 this

ensemble since 1975.

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 8 x 10

1

, 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

146
second forward in real time so that it is continuously available.

Provide frequency measurements of lasers suitable for realizing the

proposed definition of the meter . The Comite Consul tatif pour la

Deinition du Metre (CCDM) has proposed "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." With this definition the meter could 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 A would be 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 requires

the measurement of the absolute frequency of suitable spectral lines

in the visible spectral region. To this end, The Division has com- pleted 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 He-Ne

laser. A 26 THz C0~ laser, a color center laser at 130 THz, and a He-Ne laser at 260 THz, were used as transfer oscillators. The mea- sured I- freque.nry was 520 206 808.547 MHz with a total uncertainty of

1.6 par£s in lCr .

The absolute frequency of the 473 THz He-Ne.

? laser (633 nm),

stabilized on the i hyperfine component of the l

11-5 R(127)

transition, was measured by comparing its frequency with a known

frequency synthesized by summing the radiation from three lasers in a He-Ne plasma. The three lasers were an 88 THz CH^ stabilized He-Ne

laser (3.39 pm), a 125 THz color Q^riter laser (2.39 pm) with its

frequency referenced to the Rjj( 26) laser, and a 260 THz He-Ne

laser (1.15 pm) referenced to an I_ stabilized dye laser at 520 THz

(576 nm). The measured frequency is 473 612 214.789 MHz for^the i hyperfine component with a total uncertainty of 1.6 parts in IQ

1

.

These frequencies, when used to realize the new meter, represent

a 25-fold improvement over the present Krypton length standard. The

General Conference on Weights and Measures will act on the CCDM recom- mendation in October 1983. **********************************************************************

OBJECTIVE: Make fundamental improvements in atomic frequency spectroscopy for future application to primary frequency standards.

*****************************************************x****************

Atomic clock based on stored ions . As a step towards realizing a primary frequency standard based on stored ions, the Divis^on

+ has made

a clock based on a ground state hyperfine transition in 'Be . The

uncertainties in all systematic frequency shifts (such as those due to

147
Doppler effects) are smaller than those of the present U.S. primary

time standard, NBS-6, which has an uncertainty of about one part in

10

1

. However, the observed signal -to-noi se ratio does not yet permit

a complete evaluation below this level.

9 +

In these experiments, a few hundred Be ions were confined in a Penning trap and laser cooled to temperatures less than 1 K. 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 commerical 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 g$| collisions causing a second order Doppler

shift of a few parts in 10

1

. This problem can eventually be reduced

by using cryogenic pumping since the present apparatus is at room temperature. 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 are around 30 GHz are now being studied.

Primary cesium standard development . The known limitations to the

accuracy of NBS-6 lie with the microwave cavity phase shifts, exacer- bated 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 system. 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 is now under study.

I on 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 to 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. Therefore detailed studies of ion cloud

temperature, density and rotation are being made using a two-laser

optical -optical double resonance technique.

New trap designs are now under study. Computer designed traps have

shown the way to a trap which is far easier to construct and should

give improved performance. All experiments up to this time have been

operated in room temperature high vacuum systems. New designs will

incorporate cryogenic pumping.

m

m
**********************************************************************

OBJECTIVE: Develop metrology for precise time, frequency and length

measurements

**********************************************************************

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

February 1966 issue of the Proceedings of the IEEE and the 1971 IEEE

Transaction on Instrumentation and Measurement 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

made it possible to easily measure the difference between state-ofthe-art frequency standards even if they are nominally the same frequency. This concept was introduced in 1975 by NBS and NRC (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, ex- plaining 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.

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, layed 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 CH^ 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 of 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'

149
the visible). This is expected to greatly simplify frequency metrology because of the reduction in the number of frequency markers or reference lines necessary to fully cover this spectral region.

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 can act as a good

flywheel of 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 sufficient clocks reliability, redundancy and variety (to avoid systematics from a particular manufacturer), but then to characterize the

clocks with sufficient 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 now in use has its

philosophical basis in 1968. It is important to know how well this

algorithm was approaching optimal performance given the set of clocks

at hand so a cooperative effort was initiated with the Statistical

Engineering Division. 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 for unequally spaced data. A study of the

statistical significance of frequency drift yielded some important

insights. In addition, a Kalman 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, it

is now used to generate the time scale TA(NBS) while the previous

algorithm mentioned is still used to generate UTC(NBS). This effort

resulted in the conclusion that the past algorithm was very near optimum in its performance.

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.

Although no one technique can hope to satisfy these widely disparage needs, some general principles emerge from a survey of the field.

Even for distances as short as 1000 m, the human surveyor and the

steel tape are being replaced by instruments that measure distances in

terms of the time of flight of electromagnetic energy along the path.

150
If the baseline is longer than about 50 km, 1 i ne-of-sight measurements

become more difficult, and indirect methods, such as satellite ranging

or lunar ranging, are more practical.

- In almost all cases, the measurements are made through the atmosphere; conversions of measured times-of-f 1 ight to physical distances

require a knowledge of the atmospheric index of refraction.

The refractivity (the deviation of the index of refraction from

unity) is about 300 ppm for visible wavelengths. Since it is often

necessary to measure distances with fractional uncertainties of less

than 0.1 ppm, the atmospheric correction is very important. The

refractivity of the atmosphere is often determined by measuring the

atmospheric pressure and temperature along the path. These measurements tend to be cumbersome; the sampling is usually done with airplanes or balloons, neither of which can respond to short period or short wavelength fluctuations.

Instruments which determine the refractivity of the atmosphere by

measuring its dispersion have been proposed for some years. The

dispersion across the visible is only about 17 ppm, so that dispersion

measurements are technically difficult. Equally difficult are measurements which determine the humidity by measuring the power emitted at

known water-vapor emission lines or by measuring the dispersion between

optical and microwave frequencies.

We are currently constructing an instrument to determine the

dry-air contribution to the refractivity by measuring the dispersion

across the visible portion of the spectrum. The humidity will be

determined by measuring the microwave-optical dispersion. Using these

techniques, we expect to be able to measure baselines on the order of

50 km in length with uncertainties of a few mm.

A design for a long-baseline system using GPS satellites is also

under consideration. Although initial measurements using uncorrected

data may be useful in some contexts, these measurements will almost

certainly require ancillary refractivity measurements if the uncertainties due to atmospheric water vapor are to be adequately removed. The

GPS satellites are likely to play an important role in time and frequency dissemination and coordination as well, and techniques developed for correcting GPS-based geodetic measurements may prove to be

very useful in other contexts.

Time transfer techniques . The use of communications satellites for

time transfer at all levels of performance appears more promising in

light of this year's efforts. 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, recent work reported by Japan and more recently the result of unpublished tests involving NBS, USNO, and

COMSAT Laboratories have demonstrated one-half nanosecond time compari-

}51
sons using the two-way time exchanges through a communications satellite. Additional laboratory tests indicated that 20 picoseconds were possible using the same techniques. Satellite tests were not possible

at this time since FCC approval to use higher transmit power levels was not obtained in time. The tests were very encouraging and resulted

in an informal agreement between NBS, USNO and the NRC in Canada to

work together to develop a permanent network to serve these three

laboratories. These organizations have began the acquisition of the

necessary equipment to bring this concept to reality.

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 information) can produce a viable and fully reimburseable delivery system serving many important

industrial and government needs in a very economic and reliable fashion

here-to-fore not considered possible. Preliminary system examination

by calculation and consultation with satellite industry engineers and

scientists have confirmed initial feasibility. Potential industrial consumers of such a service have requested FY84 funds for NBS to

further develop these concepts.

The use of routine tracking signals associated with U.S., Japanese,

and European meteorological satellites for the transfer of time has

been described in a CCIR report. This report has resulted in active

interest in Europe, Japan, and Australia expressed by equipment purchases and experimental plans. NBS has assembled and sucessfully

tested two complete receiving systems excluding baseband processing

equipment. The necessary software has been written and installed into

NOAA computers (NOAA is the satellite operator) to retrieve and store

necessary tracking data as it is passed between the NOAA master ground

station and their computers at Suitland, Maryland. Cooperative programs are being discussed between NBS and the Radio Research Laboratories in Japan.

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 the W-Ni metal -i nsul ator-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 very major

role in the laser frequency synthesis chain which connects the cesium

clock to the visible Iodine stabilized lasers and hence 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

152
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 coverage since the technique was 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 C0

?

difference frequency mixing in a tungsten-nickel,

(MIM) diode. Previously, the MIM diode had been used mainly to make

direct frequency measurements from 0.3 to 20.0 THz.

Two tenths of a microwatt of tunable, cw far infrared radiation

has been generated by mixing 250 mw of radiation from each of two CCL

lasers in a MIM diode. The difference frequency was radiated from tne

MIM diode, and was detected in a calibrated indium antimonide bolometer. The use of a waveguide CC^ 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 5000 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).

BASIC RESEARCH

Laser Fluorescence Mass Spectroscopy . As an outgrowth of studies on ion clouds stored in Penning traps for possible frequency standard

applications, a sensitive way to make mass comparisons between different ions has been realized.

9 + . As an illustration of the technique, a small sample of Be ions

(about 25 ions in a cloud of approximately 100 pm diam.) was stored in

a Penning trap (confined by static magnetic and electric fields).

These ions were irradiated near the first resonance line (A=313 nm) by

a laser beam whose diameter was approximately equal to that of the

cloud. This laser cooled the ions (T < 0.1K) and allowed observation

of the laser fluorescence scattering from the ions. If the cyclotron

motion of the ions was driven by resonant rf electric fields, the ion

orbits increased in size causing a decrease in the fluorescence. In

this way mass comparisons could be madq by, for example, measuring the

cyclotron frequencies of different Be i^otgpes in the same magnetic

field. In this <^xpqriment however, the

y Be‘ cyclotron frequency was compared gto

+the B^ electron spin flip frequency to obtain t^ie quantity g^( Be )

• m(

y Be )/6n +to an ^pciqracy of 0.1!i pgm. g.(

y Be ) is

the electron g factor in and m( Be )/m is the be to electron

153
9 + mass ratio. From measured values gf the Be to proton mass ratio and

theoretical calculations of g^(

y Be ), an indirect determination of the

proton to electron mass ratio (m /mo ) to 0.34 ppm accuracy was obtained. (Previous to this measurement, the best accuracy reported for

(m /m ) was 0.14 ppm by direct comparison of the electron/proton

cyBlotron frequencies in a Penning trap.)

S trongly coupled plasma studies . In the language of plasma physics,

the ion clouds in a Penning trap comprise a one component, non neutral

ion plasma. As a result of measurements of cloud temperature and

density we can show that we are approximately in the "strongly coupled"

regime, that is where the ratio of electrostatic energy between near- est neighbors to the kinetic energy per ion is equal to or larger than

unity. In this case the plasma will exhibit liquid properties and for

large values of this ratio (around 150) will become a solid. A large

body of theoretical work has gone into this problem but so far experiments on strongly coupled three dimensional plasmas have yet to be

realized. (Strongly coupled electron plasmas in two dimension—e.g.

electrons floating on liquid helium--have been experimentally studied.)

Our techniques may in fact provide one of the few experimental relizations of three dimensional strongly coupled plasmas.

ADVISORY SERVICES

***************************************** ******************** ** *******

OBJECTIVE: To advise and work with other governmental agencies and

industry to incorporate advanced time, frequency and length metrology

into their programs. **********************************************************************

During the past five years the Division has worked for other

agencies in the areas of the development, improvement and utilization

of frequency standards; frequency metrology; time generation; time

transfer; length standards; and length metrology. The close relationship between NBS and other Agency objectives precludes the separation

of activities by technical area. Thus, all of the preceeding functions

are supported, in part, by other Federal Agencies. This section

highlights three areas which may have very high short-term impact.

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 commerical 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.

154
Much of this work is performed under contract for other governmental agencies. In addition, the Division has established two Industrial Research Agreements with manufacturers of cesium clocks. These

agreements permit the transfer of NBS research results to the private

sector, and also brings guest scientists from industry to the governmental laboratory.

Hydrogen maser technology . The passive hydrogen maser is a new frequency standard developed at NBS, with partial military funding, which

has demonstrated the capability of exceptional frequency stability

from a few hours to a few weeks. Typical time dispersion per day is a factor of 4 to 5 better than the best available commerical cesium

frequency standards.

Several Industrial Research Associates worked at NBS for two

years. Although the research associates have departed NBS, the cooperation continues and the first passive hydrogen maser to be constructed

in this program is nearing completion.

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. **************************************************************** ******

OBJECTIVE: To design and test an instrument to measure the tilt of

the surface of the earth. **********************************************************************

The tilt of a point on the surface of the earth is defined as the

angle between the local normal and the local acceleration of gravity.

Measurements of tilt usually show both secular and periodic changes.

The former have been proposed as precursory signals for earthquakes

and as estimators of local tectonic activity, while the latter can be

used to infer the elastic properties of the local material and to

estimate the shape and size of sub-surface elastic anomalies.

Typical secular tilts are on the order of a few tenths of a micro-radian per year; these tilts are superimposed on diurnal and

semi-diurnal changes of the same order of magnitude. To provide

useful data, a tiltmeter must therefore have both sensitivity and

stability at the nano- radian level.

We have designed a tiltmeter that satisfies these requirements.

It consists of a horizontal pendulum mounted in a borehole approximately 30 m below the surface of the earth. The position of the

pendulum is measured by making it the common arm of two parallel plate

capacitors and by measuring the ratio of the capacitances using a capacitance bridge.

155
The instruments have been evaluated by verifying that the in-si tu

admittance to various extraneous effects such as fluctuations in

ambient pressure and temperature is small; comparisons between the

amplitudes and phases of the periodic effects and theoretical models

based on the known lunar and solar driving forces have also been

successful

We have deployed an array of these instruments in Wyoming to

study the secular stability of the Yellowstone Park area and to validate models of the elastic anomaly that is believed to underlie much

of the park. We currently have five instruments at three sites in the

park. The data from these sites is transmitted to Boulder for evaluation and analysis. In addition to the analyses discussed above, the

data will be correlated with the work of other investigators in the area including determinations of gravity, uplift and heat-flow prof i 1 es. ********** ************************************************************

OBJECTIVE: Measure frequencies of free radicals for radio astronomers. **********************************************************************

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.

The LMR technique uses a variable magnetic field to tune the

molecular resonance into coincidence with a laser frequency. The free

radicals or other species are located inside the laser cavity, and a flow system is used to measure reaction rates. This technique was used to measure the reaction rate of nitric oxide interacting with the

hyperoxyl radical (HO^), and the results significantly altered the

previous estimates of ihs effects of the SST and fluorocarbon on the ozone content of the upper atmosphere.

Subsequently LMR was used to make the first laboratory observation

of the CH 9 spectra. The CH~ radical is an important building block

for all organic molecules ana is present as a free radical intermediary

in many chemical reactions. Measurements of CH, CD n and CD were completed and the spectra of four molecules, GeH^, Gefl, and SiH, one

atom, Si, were identified.

The new techniques of tunable far infrared 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 also will allow the measurement of all far

infrared active molecules, not just paramagnetic ones.

156
INVITED TALKS

Time and Frequency Division (524)

J. Levine, "Technique of Electromagnetic Measurements," International

Association of Geodesy Meeting, Tokyo Japan, May 1982.

D. W. Allan, "NBS Primary Frequency Standards Research and Metrology

of Comparing Time Internationally at the Nanosecond Level," Radio

Research Laboratory, Tokyo, Japan, September 1982.

D. W. Allan, "Using Global Positioning System Satellites to Measure

Remote Clocks to An Accuracy of 10 ns", Tokyo Astronomical Observatory,

University of Tokyo, Tokyo, Japan, September 1982.

D. W. Allan, "NBS Primary Frequency Standards Research; New NBS Time

Scale System and International Time Comparison Techniques", National

Research Laboratory of Metrology, September 1982.

D. W. Allan, "NBS Time and Frequency Research Work on Standards, the

Time Scale, UTC(NBS) and TA(NBS), Clock Characterization and Measurements, and International Time and Frequency Comparison Methods,"

National Institute of Metrology, Beijing, Peoples Republic of China,

September 1982.

D. W. Allan, "Shuttle Experiment to Demonstrate High-Accuracy Global

Time and Frequency Transfer," Chinese Academy of Sciences, Beijing,

Peoples Republic of China, September 1982.

D. W. Allan, "Primary Frequency Standards Research and Details of New

NBS Time Scale System," National Institute of Metrology, Peoples

Republic of China, September 1982.

D. W. Allan, "Measurement and Characterization of Clocks; Generation

of Time and International T/F Comparison Methods, Northwest Polytechnical University, Zian, Peoples Republic of China, September 1982.

D. W. Allan, "Cesium Beam Frequency Standards and Time and Frequency

Metrology Techniques," Shanghai Bureau of Metrology, Peoples Republic

of China, September 1982.

D. W. Allan, "NBS Hydrogen Maser Work and Sub picosecond Dual Mixer

Time Difference Measurements", Shanghai Observatory, Peoples Republic

of China, September 1982.

H. Hemmati , "Generation of CW 194 nm Radiation by Some Frequency

Mixing in an External Ring Cavity," Annual Meeting Optical Society of

America, Tucson, Arizona, October 19, 1982.

157
K. M. Evenson, "Far Infrared Laser Magnetic Resonance: The Measurement

of Submillimeter Lines of Astronomical Interest," and "The Direct

Frequency Measurements of Visible Radiation (The New Meter and the

Exact Value of the Speed of Light", National University of Mexico,

October, 1982.

D. J. Wineland, "Particle Traps," Optical Soc. of America, Tucson,

Arizona, October 20, 1982.

D. W. Allan, "Stochastic Models for Atomic Clocks," 14th Annual

Precise Time & Time Interval Applications and Planning Meeting (PTTI),

Nov. 1982.

W. Itano, "Time and Frequency Standard Based on Charged Particle

Trapping," Conference on Applications of Accelerators in Research and

Industry, Denton, Texas, November 8, 1982.

J. C. Bergquist, "Ultrahigh Precision Spectroscopy Using Stored Ions,"

NBS Research Seminar Series, NBS/Gai thersburg , January 11, 1983.

K. M. Evenson, "The Point Contact Diode at Laser Frequencies," 7th

International Conference on Infrared and Millimeter Waves, France,

January 1983.

D. W. Allan, "Accuracy of Time and Frequency Coordination and its

Relationship to JPL's Deep Space Network," Jet Propulsion Laboratory,

Pasadena, CA, February 1983.

D. W. Allan, "The Benefits of Ensemble Time As May Be Implemented in

the GPS," Air Force Space Division, Los Angeles, CA, February 1983.

K. M. Evenson, "Optical Frequency Synthesis Spectroscopy," presented

at the Workshop on Spectroscopic Applications of Slow Atomic Beams,

NBS, Gaithersburg, MD, April 1983.

K. M. Evenson, "Tunable Far Infrared Laser Spectroscopy", National

Research Council, Ottawa, Ontario, Canada, May 1983.

D. J. Wineland, "Cooled Ion Clocks," present invited colloquium,

Harvard University, May 1983.

J. Levine, "The Geodimeter," Int. Geophysics University of California

in San Diego, May 5, 1983.

D. W. Allan, "Separating the Variances of the Error Components in GPS"

Vandenburg Air Force Base, Vandenburg, CA June 1983.

9 +

J. Bollinger, "Precision Measurement of Laser Cooled Be Ions," 6th

International Conference on Laser Spectroscopy (SICOLS), June 1983.

158
J. Jespersen, "Time and Frequency Measurement Programs," 37th Annual

Symposium on Frequency Control, Philadelphia, Pennsylvania, June 1,

1983.

D. W. Allan, "National and International Time and Frequency Comparisons," 37th Annual Symposium on Frequency Control, Philadelphia,

Pennsylvania, June 1, 1983.

J. Bollinger, "Accurate Laser Cooled Beryllium Ion Clock," 37th Annual

Symposium on Frequency Control, Philadelphia, Pennsylvania, June 1,

1983.

D. J. Wineland, "Theoretical Calibrations of Fine Structure," presented at Atomic Physics Seminar at Yale University, July 1983.

G. Kamas, "Ask the Experts", National Conference of Standards Laboratories, Boulder, Colorado, July 1983.

S. R. Stein, "The Time and Frequency Program at the National Bureau of

Standards," National Association of Watch and Clock Collectors, Inc.,

Colorado Springs, CO, July 23, 1983.

W. Itano, "Spectroscopy of Laser Cooled and Trapped Ions," Gordon

Conference on Atomic Physics, New London, NH, July 5, 1983.

K. M. Evenson, "Tunable Far Infrared Laser Spectroscopy," UNICAMP,

Campinas, Brazil, August 5, 1983.

D. J. Wineland, "Spectroscopy of Stored Ions Using Fluorescence Technique," SPIES Conference, San Diego, CA, August 1983.

J. S. Wells, "Heterodyne Frequency Measurements and Frequency Calibration Standards for Tunable Diode Lasers," SPIES Conference, San Diego,

CA, August 1983.

K. M. Evenson, "Tunable Far Infrared Laser Spectroscopy," University

Southhampton, England, September, 1983.

K. M. Evenson, "Far Infrared Spectroscopy of Free Radicals," 16th

International Symposium on Free Radicals, Brussels, Belgium, September

1983.

R. Drullinger, "The Time and Frequency Division of NBS," International

Symposium on Time and Frequency, Hangzhou, China, September 1983.

R. Drullinger, "Measuring Visible Frequencies: Redefining the Meter,"

International Conference on Lasers, Guangzhou, China Sept. 1983.

D. J. Wineland, "Laser Cooling and Ion Frequency Standards," Symposium

on Atomic Spectroscopy, Berkeley, CA September 1983.

159
D. W. Allan, "GPS Common View Time Transfer," Workshop on Time and

Frequency, Ottawa, Ontario, Canada October 5-6, 1983.

D. W. Allan, "The Benefits of Ensemble Time for GPS," Defense Mapping

Agency, Washington, DC October 1983.

PUBLICATIONS

Time and Frequency Division (524)

(J. A. Barnes), (R. H. Jones), (P. V. Tryon), D. W. Allan, "Stochastic

Models for Atomic Clocks," Proceedings of the 14th Annual Precise Time

and Time Interval (PTTI) Applications of Planning Meeting at NASA

Goddard Space Flight Center, (November 1982).

R. E. Beehler, "GOES Satellite Time Code Dissemination, Proceedings of

the 14th Annual Precise Time and Time Interval Applications and Planning Meeting at NASA Goddard Space Flight Center, (1982).

D. W. Allan, "Millisecond Pulsar," Letter to Editor, Science, Vol.

220, 776, 1983.

K. M. Evenson, D. A. Jennings, F. R. Petersen, R. E. Drullinger, - "Optical Frequency Synthesis Spectroscopy , " Proceedings of Workshop on Spectroscopic Applications of Slow Atomic Beams, Gai thersburg , MD,

27-37, (April 1983).

D. J. Wineland, Wayne Itano, J. C. Bergquist, "Frequency Standard

Research Using Stored Ions," Proc. of Workshop on Spectroscopic Applications of Slow Atomic Beams, Gaithersburg, MD, 1926, (April 1983).

L. Lewis, "Limitations of Atomic Beam Frequency Standards," Proceedings of Workshop on Spectroscopic Applications of Slow Atomic Beams,

Gaithersburg, MD, 38-46, (April 1983).

S. R. Stein, "The Design of Atomic Frequency Standards and Their

Performance in Specific Applications," Proceedings of Workshop on Spectroscopic Applications of Slow Atomic Beams, Gaithersburg, MD

9-18, (April 1983).

(E. C. C. Vasconcel los) , (J. C. Wyss), F. R. Petersen, K. M. Evenson,

"Frequency Measurements of Far Infrared cw Lasing Lines in Optically

Pumped CHCj^F," International Journal of Infrared and Millimeter

Waves, Vol. 4, No. 3, 401-6, (1983).

D. J. Wineland, J J. Bollinger, Wayne M. Itano, "Laser Fluorescence

Mass Spectroscopy," Physical Review Letters, Vol. 50 No. 9, 628-631,

(1983).

M. Weiss, "Position Location Using Sequential GPS Measurements," Record

of Plans 82 Conference, September 29, 1982.

160
J. S. Wells, F. R. Petersen, A. G. Maki , "Heterodyne Frequency Measurements of Carbonyl Sulfide Transitions at 26 and 51 THz, Improved

OCS , (j S and 0C

i4 Molecular Constants," Journal of Molecular Spectroscopy 98, 104-412 (1983).

R. E. Drullinger, K. M. Evenson, D. A. Jennings, F. R. Petersen, J. C. Bergquist, L. Burkins, and H.-U. Daniel, "2.5 THz Frequency Difference

Measurements in the Visible Using Metal-Insul ator-Metal Diodes," Appl.

Phys. Lett. 42, 137 (1983).

J. Levine, Design of a Deep Borehole Tiltmeter, Proc. 9th International Symposium on Earth Tides, New York, 1981, 273-281. Published by E. Schweizerbart 1 sche Verlagsbuchhandl ung, D-7000 Stuttgart, FRG, 1983.

J. Levine, "Performance of a Deep Borehole Tiltmeter," Proc. 9th

International Conference on Earth Tides, New York, 1981, 47-57.

Published by E. Schweizerbart 1 sche Verlagsbuchhandl ung, D-7000 Stuttgart, FRG, 1983.

J. Levine, "Multiple Wavelength Geodesy, Proc. 9th GEOP Conference,

) 99-102, (1978).

(Hamid Hemmati), J. C. Bergquist, Wayne Itano, "Generation of cw 194

Radiation by Sum Frequency Mixing in an External Ring Cavity," Optics

> Letters, No. 2, 73-75 (1983).

(J. M. Brown), K. M. Evenson, "The Microwave and Far Infared Spectra

of the CH Radical," The Astrophysical Journal, 268: L51-L56, (May

1983).

Wayne Itano, D. J. Wineland, (Hamid Hemmati), J. C. Bergquist, J. J. Bollinger, "Time and Frequency Standards Based on Charged Particle

Trapping," IEEE Transactions of Nuclear Science, Vol. NS-30, No. 2,

| 1521-1523 (1983).

D. A. Jennings, C. R. Pollock, F. R. Petersen, R. E. Drullinger, K. M.

> Evenson, E. C. Beaty, J. S. Wells, J. L. Hall, H. P. Layer, "Direct

I Frequency Measurement of the I ? Stabilized He-Ne THz Laser," Optics

j Letters, 8, 136 (1983).

Z

C. R. Pollock, D. A. Jennings, F. R. Petersen, J. S. Wells, R. E. Drullinger, E. C. Beaty, K. M. Evenson," Direct Frequency Measurements

of Transitions at 520 THz (576 nm) in Iodine and 260 THz (1.15 pm) in

n Neon," Opt. Lett. 8, 133 (1983).

(J. A. Barnes), (R. H. Jones), (P. V. Tryon), D. W. Allan, "Noise

Models for Atomic Clocks," Proceedings of the 14th Annual Precise Time

and Time Interval Applications and Planning Meeting (PTTI).

D. A. Howe and F. L. Walls, "A Compact Hydrogen Maser with Exceptional

' Long-Term Stability," IEEE Trans. On Instrumentation and Measurement,

Vol. IM-32, No. 11, 218 (March 1983).

I

3

161
S. R. Stein, D. Glaze, J. Levine, J. Gray, D. Hilliard, D. Howe and

(L. Erb), "Automated High-Accuracy Phase Measurement System," IEEE

Transactions on Instrumentation and Measurement, Vol. IM-32, No. 1,

227 (March 1983).

J. C. Bergquist, H. Hemmati , and W. M. Itano, "High Power Second

Harmonic Generation of 257 nm Radiation in an External Ring Cavity,"

Optics Communications, Vol. 43, 437-442 (1982).

W. M. Itano, "Chemical Shift Correction to the Knight Shift in Beryllium," Physical Review B, Vol. 27, 1906-1907.

PUBLICATIONS IN PROCESS

To Be Publ i shed

D. J. Wineland, Wayne M. Itano, J. J. Bollinger, J. C. Bergquist, H. Hemmati, "Spectroscopy of Stored Ions Using Fluorescence Techniques",

Proceedings SPIE Conference on Laser Based Ultrasensitive Spectroscopy

and Detection.

(J. J. Gagnepain), (M. Olivier), F. L. Walls, "Excess Noise in Quartz

Crystal Resonators," Proceedings of the 37th Annual Frequency Control

Symposium.

R. E. Drullinger, "The Time and Frequency Division of NBS" , Proceedings of the International Conference on Time and Frequency, Hangzhou,

China, (Sept. 1983).

R. Drullinger, "Measuring Visible Frequencies: Redefining the Meter,"

Proceedings of the International Conference on Lasers, Guangzhou,

China, Sept. 1983.

J. S. Wells, F. R. Petersen, "Calibration Standards for Tunable Diode

Lasers," Proceedings of SPIE's 27th Annual International Technical

Symposi urn.

(Trevor J. Sears), (A. R. W. McKellar), (P. R. Bunker), K. M. Evenson,

(J. M. Brown), "Infrared and Far Infrared Transition Frequencies for

the CH 0 Radical" Astrophysical Journal of Letters.

(H. Hemmati), J. C. Bergquist, "Generation of Continuous Wave 243

Radiation by Sum Frequency Mixing," Optics Communications.

D. W. Allan, "National and International Time and Frequency Comparisons," 37th Annual Frequency Control Symposium.

J. J. Bollinger, Wayne Itano, D. J. Wineland, "Accurate Laser Cooled

Beryllium Ion Clock, Proceedings of the 37th Annual Frequency Control

Symposi urn.

162
(Mazataka Mizushima), K. M. Evenson, (J. A. Mucha), D. A. Jennings,

(J. M. Brown), "Laser Magnetic Resonance of the 0

2

Molecule at 699

urn," Journal of Molecular Spectroscopy.

3 3

(Masimo Inguscio), K. M. Evenson, "Direct Measurement of the P q -3 P,

Fine Structure Splitting and the g-Factor of Atomic Silicon by°Laser

Magnetic Resonance," Astrophysical Journal of Letters.

(P. R. Bunker), (Trevor J. Sears), (A. R. W. McKellar), K. M. Evenson,

(P. J. Lovas), "The Rotational Spectrum of the CD„ Radical Studied by

Far Infrared Laser Magnetic Resonance," Journal ofuhemical Physics.

G. Kamas, J. L. Jespersen, "A New Frequency Calibration Ser.vice Offered by The National Bureau of Standards," 37th Annual Frequency Control

Symposium.

D. A. Jennings, R. E. Drullinger, K. M. Evenson, R. F. Petersen, J. S. Wells, "The Speed of Visible Light," Physical Review Letters.

C. R. Pollock, F. R. Petersen, D. A. Jennings, J. S. Wells, A. G. Maki , "Absolute Frequency Measurements of the 2-0 Band of CO at 2.3

pm; Calibration Standard Frequencies from High Resolution Color Center

Laser Spectroscopy. J. Mol. Spectrosc. 99, 357 (1983).

R. E. Drullinger, K. M. Evenson, D. A. Jennings, F. R. Petersen, J. C. Bergquist, Lee Burkins, and H.-U. Daniel," 2.5 THz Frequency Differ- ence Measurements in the Visible Using Metal-Insulator-Metal Diodes,"

Appl . Phys. Lett. 42, 137 (1983).

J. J. Bollinger, D. J. Wineland, Wa^ne

+

M. Itano, J. S. Wells, "Precision Measurements of Laser Cooled ^Be Ions," Proceedings of the 6th

International Conference on Laser Spectroscopy.

D. J. Wineland, Wayne M. Itano, (R. S. Van Dyke Jr.), "High Resolution

Spectroscopy of Stored Ions," Advances in Atomic and Molecular Physics .

(M. A. Zumberge), (J. E. Faller), (J. Gscwind), "Results from a United

States Absolute Gravity Survey," Journal of Geophysical Research.

(J. M. Brown), K. M. Evenson, "The Far Infrared Laser Magnetic Reson- ance Spectrum of the CH Radical and Determination of Ground State

Parameters," Journal of Molecular Spectroscopy.

D. W. Allan, "Frequency and Time Coordination", Chapter 13, Preci si on Frequency Control .

F. L. Walls, J. J. Gagnepain, "Special Applications", Chapter 15,

Precision Frequency Control .

F. L. Walls, Chapter 14 "Other Means for Precision Frequency Control",

Precision Frequency Control .

163
D. J. Glaze, S. R. Stein, "Pico Second Time Difference Measurements

Utilizing CAMAC Based IEEE-488 Acquisition Hardware" , NBS Tech Note

No. 1056.

(Trevor J. Sears), (P. R. Bunker), (A. R. W. McKellar), K. M. Evenson,

(J. M. Brown), "The Far Infrared Laser Magnetic Resonance Spectrum of

the Methylene Radical CH^," Journal of Chemical Spectroscopy and the

Royal Society of Chemistry.

K. B. Persson, "A Derivation of Schroedi nger

1 s Equations from Classical Physics," American Journal of Physics.

D. J. Wineland, "Spectroscopy of Stored Ions Using Fluorescence Technique," Proceedings of SPIES Conference, San Diego, CA.

S. R. Stein, "Frequency and Time, Their Measurement and Characterization," Chapter 12, Precision Frequency Control .

F. R. Petersen, E. C. Beaty, C. R. Pollock, "Improved Rovib^t^gnal

Constants and Frequency Tables for the Normal Laser Bands of l

xd

CL,

J. Mol. Spectrosc. 102, xxx-xxx (1983).

‘

F. R. Petersen, J. S. Wells, K. J. Siemsen, A. M. Robinson, and A. G. Maki , "Heterodyne Frequency Measurements and Analysis of CO^ Laser Hot

Band Transitions," J. Mol. Spectrosc.

“

F. R. Petersen, J. S. Wells, and A. G. Maki, "Improved Deuterium

Bromide 1-0 Band Molecular Constants from Heterodyne Frequency Measurements," J. Mol. Spectrosc.

C. R. Pollock, F. R. Petersen, D. A. Jennings, J.

fS. WeJls, arid A. n

G.

Maki, "Absolute Frequency Measurements of the 00

U 2-00 U

0, 20 i-00

U 0,

and 12 1-00 U 0 Bands of N„0 by Heterodyne Spectroscopy," J. Mol. Spectrosc.

R. J. Saykally, K. M. Evenson, D. A. Jennings, and F. R. Petersen,

"Frequency Measurements of cw FIR Lasing Transitions in CD

3

0H," Int.

J. of Infrared and mm Waves.

K. M. Evenson, M. Inguscio, D. A. Jennings, and F. R. Petersen, "The

Point Contact Diode at Laser Frequencies," Appl. Phys. Lett.

M. Inguscio, F. R. Petersen, and K. M. Evenson, "Pressure Effects on the Frequency of cw Optically Pumped FIR Lasers."

H. Hemmati , J. C. Bergquist, and W. M. Itano, "Sum Frequency Generation of Narrowband cw 194 nm Radiation in Potassium Pentaborate"

Proceedings of the 6th International Conference on Laser Spectroscopy.

164
D. W. Allan, D. Glaze, J. E. Gray, R. Jones, J. Levine, and S. R. Stein, "Recent Improvement in the Atomic Time Scales of the National

Bureau of Standards," Precise Time and Time Interval .(PTTI) Applications and Planning Meeting, 1983.

D. W. Allan and M. Weiss, "Separating the Variances of Noise Components

in the Global Positioning System," Precise Time and Time Interval

(PTTI) Applications and Planning Meeting, 1983.

D. W. Allan, "Clock Characterization Tutorial," Precise Time and Time

Interval (PTTI) Applications and Planning Meeting, 1983.

G. Kamas, "Ask the Experts," Proceedings of the National Conference of

Standards Laboratories," July 1983.

S. R. Stein, G. Kamas, and D. W. Allan, "New Time and Frequency Dissemination Services at the National Bureau of Standards," Precise Time

and Time Interval (PTTI) Applications and Planning Meeting, 1983.

(E. N. Forston) and L. L Lewis, "Atomic Parity Nonconservation Experiments," Physics Reports.

SEMINARS ORGANIZED

Time and Frequency Division (524)

Seminar on Frequency Standards & Clocks , July 14 and 15, 1983, Boulder,

Colorado.

Seminar on Frequency Measurements & Calibrations , October 25, 26, and

27, 1983, Boulder, Colorado.

SPECIAL REPORTS

"National Bureau of Standards Global Positioning System (GPS) Users

Manual," M. Weiss, D. Davis, and D. Allan, 1983.

"Investigation of the Hydrogen Source for Masers," K. B. Persson and

F. L. Walls. Prepared in fulfillment of Navy contract.

"The Optically Pumped Alkali Beam/Cell and Beam Tube for Utility

Atomic Frequency Standards," Mark Feldman. Prepared for Dept, of the

Air Force, Rome Air Development Center.

165
"A Breadboard Optically Pumped Cesium Beam Frequency Standard," L. Lewis. Prepared for Dept, of the Air Force, Rome Air Development

Center, RADC/ESE (Contract No. RADC 83-11.)

"Separating the Variances of Noise Components in the Global Positioning System," D. W. Allan. Prepared for Air Force Space Division, Los

Angeles Air Force Station, Los Angeles, CA 90009.

"Laser Diode Characterization Program," L. L. Lewis, Special Division

Report.

"Laser Diode Evaluation," L. L. Lewis and M. Feldman. Prepared for

Dept, of the Air Force, Space Division/YEC (Contract No. SD30039).

"Recirculating Cesium Oven Development," R. Drullinger and D. Glaze.

Prepared for Dept, of the Air Force, Space Division/YEC (Contract

No. 30039).

"Commercial Cesium Oven Characterization," D. Glaze. Prepared for

Naval Research Laboratory (Contract No. N00173-83-F-D098)

"Industrial Time Service—Plan for a Feasibility Study," D. W. Hanson.

TECHNICAL AND PROFESSIONAL COMMITTEE

PARTICIPATION AND LEADERSHIP

Time and Frequency Division (524)

D. W. Allan, Study Group VII, International Radio Consultative Committee (CCIR)

D. W. Allan, IEEE IM TC-3 Frequency and Time.

D. W. Allan, 1982 PTTI Program Committee.

D. W. Allan, NASA Team Member for Shuttle Timing experiment.

D. W. Allan, International Astronomical Union member.

R. E. Beehler, CCIR Study Group 7; International Chairman of Interim

Working Party 7/4 on "Improved Time Coordination and Dissemination

Usi ng Satel 1 ites"

R. E. Beehler, 1983 SFC Technical Program Committee.

K. M. Evenson, URSI Commission D.

K. M. Evenson, Chairman for next Free Radical Meeting.

166
D. A. Jennings, Member CCDM

0. W. Hanson, Member Technical Advisory Committee for TDRSS, NASA

Satel 1 ite Program.

J. L. Jespersen, Chairman IRIG Timing Committee.

G. Kamas, Measurement Assurance Subcommittee, National Conference of

Standards Laboratories.

J. Levine, Microprocessor Standards Action Group.

J. Levin, Chairman, Electronic Shops.

J. Levine, Computing Policy Committee, Colorado University.

J. Levine, Computing Allocation Committee, Colorado University.

J. Levine, Taskforce on Library Automotion (CAR2), Colorado University.

J. Levine, National Academy of Sciences, Committee on Geodesy.

S. R. Stein, Consultative Committee for the Definition of the Second

(CCDS), CCIR.

S. R. Stein, Committee fo MIL-C-3098 revision.

j S. R. Stein, Executive Committee, PTTI Applications and. Planning

Meeti ng.

S. R. Stein, Chairman Technical Program Committee, Frequency Control

Symposi urn.

I

i S. R. Stein, MNL Merit Pay Performance Review Panel.

|

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.

I

I

I

!

I

167
mmpmmmmpppppppppipp
iIiII

QUANTUM PHYSICS DIVISION

SUMMARY OF ACTIVITIES

Fiscal Year 1983

I. OVERVIEW

The Quantum Physics Division (QPD) was created as the vehicle for

the NBS participation in the Joint Institute for Laboratory

Astrophysics (JILA), which is a cooperative enterprise of the National

Bureau of Standards and the University of Colorado. The statement of

mission says that the division:

0 Engages in research in atomic and molecular physics at the

forefront of the field and performs basic, highly accurate

measurements and theoretical analyses that help establish

a reliable foundation for scientific and technological

measurements and data.

0 Performs work such as the measurement of natural

constants, the development of new basic standards and the

determination of key data and processes in atomic and

molecular physics.

0 Maintains, through its associaton with the University of

Colorado and through its Visiting Scientist Program,

active contact with and experience in advanced research in

physics.

0 Disseminates information of its scientific activities to

other areas of NBS through visits and longer-term

interchange of personnel.

When JILA was formed twenty-one years ago, "Laboratory

Astrophysics" focused special attention on aspects of astronomy and

atomic physics which were relevant to the well-defined national

interest in space which prevailed at that time. However, since its

inception, JILA has responded to the changing national needs and to

the requirements of its parent organizations. The association of

atomic and molecular science and astrophysics at JILA has been

mutually beneficial. Experimental and theoretical contributions have

been made not only to these areas but also to laser physics, precision

measurements, geophysics, and data and measurements necessary for new energy sources; to the collection and evaluation of scientific data;

and to the education of scientists. The need for JILA to be dynamic

in its focus and programs was stated in the Amendment to the

Memorandum of Understanding signed in 1976 by NBS and CU. The QPD is one of the divisions in NBS with heaviest emphasis on basic research

168
and the advancement of measurement science from a fundamental point of

view, and the ability to carry this out is emphatically enhanced and

leveraged by the location of the QPD on the CU campus and

participation of doctoral and postdoctoral students.

The Quantum Physics Division currently has substantial research

programs in five general areas:

1 . Fundamental and precision measurements.

2 . Geophysical measurement methods.

3. Chemical Physics.

4. Atomic and molecular physics and interactions.

5. Astrophysical measurement.

Activities in these areas will be discussed in Section II, Technical

Activities, later, but a portion of the highlights for the past year

are worth noting here.

0 One of the most exciting developments is the careful

measurements of the small shift ( ^103 Hz out of 10^5 Hz)

of Rydberg energy levels due to their strong radiative

coupling with ambient thermal radiation fields.

0 Another outstanding event was the first direct observation

and measurement of the important process of dielectronic

recombination, showing a substantial and important

disagreement with theory.

0 A notable discovery was that the Si

3 radical and H 2 and

Si

3 based chain-reactions dominate silane discharges and

the deposition of amorphous silicon films. There are strong and far-reaching implications from these studies

relating not only to silane pyrolysis, but the pyrolysis

of hydrocarbons as well.

0 A successful collaboration with Bell Laboratories has led

to a very precise ( < 10“3) measurement of the 1 3$- 23$

spacing in the very fundamental and exotic atom,

positronium.

0 First-ever results were obtained for fully state-resolved

thermal energy charge transfer reactions under single

collision conditions.

0 Dramatic patterns in angular distributions of

169
photoelectrons from two-photon photoionization of alkaline

earth atoms show clearly the effects of state mixing, and

the deduced mixing coefficients are an excellent test of

the important multi-channel quantum defect theory.

Currently, there are 172 total personnel in JI LA distributed

according to Figure 1. This figure fluctuates substantially over a year's time, since there is an annual scientific turnover of 40 to 50

persons.

One notes from the figure that of the 138 research scientists in

JILA, that 97 (or 70%) are postdoctorals and students. Another 16 are visitors, for a total of 113 (or 82%) students, postdoctorals, and

visitors. There is thus a high level of youthful vitality and

turnover in the scientific staff, while providing at the same time for

stability, maturity, and focus of programs through the Fellows of

JILA. As envisioned in the establishment of the Institute, both NBS

and CU continue to benefit from the "partnership." The University

gains a large community of international scholars (Visiting Fellows

Program) and a substantial adjoint faculty which trains graduate

students, teaches courses, serves on committees, etc. These roles are more completely detailed elsewhere in this report. The Bureau of

Standards gains the scientific activity and productivity of 70-80

scientists through the supervisory activities of the core 14 senior

NBS Fellows -- thus the Bureau enjoys a very leveraged operation. NBS

Fellows currently supervise 28 graduate students working on Ph.D.'s,

supervise 28 postdoctorals, and enjoy the direct collaboration of more

than a dozen visiting scientists.

The permanent Ph.D. Staff or "Fellows of JILA" of which there are

24 form a collegial governing body which sets policy subject to review

by the Director of NBS and President of CU. A Chairman of the Fellows

is elected bi-annually as the principal officer of the Institute, and

is responsible for operating the Institute within the limits of policy

set forth by the Fellows. As of January 1983, the Chairman of JILA is

Dr. David Norcross. An Executive Committee assists the Chairman with

policy matters of shorter duration or lesser moment than would command

attention of the Fellows, and the Executive Officer deals with most

administrative matters as delegated by the Chairman. Of the 24

Fellows, 10 are CU full-time faculty from the Departments of Physics,

Chemistry, and Astro-Geophysics, 13 are NBS employees in the QPD, and

1 is an NBS employee in the Time and Frequency Division. NBS Fellows

hold adjoint appointments in one of the three academic departments.

While sharing responsibility for the success of the Institute, the NBS

and the University of Colorado each has full operational

responsibility for its own employees who are physically located in and

hold positions as Fellows or Members of JILA. Thus, these parent

bodies apply exactly the same personnel review and reassignment

procedures to each staff member in JILA as would be applied to the

170
J ILA STAFFING

1983 - 1934

TOTAL - 172

Fig. 1.

171
same staff member were that person rostered in another administrative

unit and location, without consideration of any special privileges or liabilities deriving from participation in JILA or from designation as

a Fellow.

Dr. Katharine Gebbie (NBS) is still inactive as a Fellow of JILA

while on temporary assignment (1981-1983) to NBS Gaithersburg. Dr.

William Reinhardt (CU) returned to JILA this fall after a year at NBS

Gaithersburg as the first NBS-JILA exchange Fellow. Drs. Peter Conti

(CU) and Richard McCray (CU) are on Sabbatical leave this year and are inactive as Fellows of JILA. Dr. Mitch Begelman (CU) was hired into

the Department of Astrophysical , Planetary, and Atmospheric Sciences

(formerly Astrogeophysics) as a Member of JILA, with one of the

recently vacated "slots" in mind. Dr. Keith Burnett (CU), elected a Fellow of JILA last year, will be going on leave during the next year

to Imperial College, where he has taken a faculty position.

Recruitment of a faculty position in Physics with membership in JILA

was conducted during the past year. After screening a large field of

candidates, no offer was made, and recruiting will begin anew this

year.

In accordance with the Advisory Panel advice, JILA has evaluated

its posture relative to computing during the past year, and decided

that a modern mid-sized computer will serve the needs of the Institute

most effectively. A proposal to NSF and several other agencies with a strong matching funds component from the University has been sent out.

The Visiting Fellows Program is one of the most important parts

of the Institute, bringing 10 distinguished scientsits to the

Institute each year on a competitive basis. NBS management recognizes

the value of the program and has provided inflationary increases to

the budget, allowing the program to stay vigorous. Last year was the

first JILA-NBS Gaithersburg Visiting Fellow exchange. Dr. Bill

Reinhardt of JILA was in residence at NBS Gaithersburg for the past

year. This year Dr. James Snyder of NBS Gaithersburg is in residence

at JILA as the exchange fellow.

An essential component of the operation of the Institute as a whole is the NSF group grant. This grant, which is subjected to

direct approval of the National Science Board, was renewed last year

for a four-year period after very favorable peer reviews from the

atomic and molecular physics community.

The productivity of the Institute as measured in terms of

publications remains high. Figure 2 shows a plot of numbers of

publications versus year. There have been over 2700 titles published

from JILA over its 21-year history, and over 15,000 requests are received per year for reprints. Of course, not only numbers, but

quality, creativity, and impact must be, considered in truly measuring

172
productivity. The more detailed discussion of the technical programs,

publications, and activities of the Quantum Physics Division in

Sections II and III will help to demonstrate these dimensions of

productivity.

173
NUMBER

OF

PAPERS

62 64- 66 68 70 72 74 76 78 80 82 84

YEAR

Fig. 2.

174
mpppp

mmmm»*mm*mmnmwp
II. TECHNICAL ACTIVITIES

This section contains brief narrative descriptions of research

programs currently underway or recently completed. An alternative

insight to these activities can be gained by reference to Sec. Ill

where tables are found of publications, invited talks. Visiting

Fellows, and seminars and colloquia, academic activities of NBS

personnel, consulting, and technical and professional committee

participation and leadership.

Fundamental and Precision Measurements

Black-body shift. One of the most exciting developments is the

careful measurement by J.L. Hall and L. Hollberg of the small shift of

Rydberg energy levels due to their strong radiative coupling with

ambient thermal radiation fields. Laser frequency control certainly

has been the principal difficulty in this work in the past, as the

Rydberg atom level shifts amount only to 1 or 2 kHz out of the

transition frequency of 10*5 Hz. A powerful spectroscopic method can

be based on the use of rf phase-modulation of the external laser beam

to produce rf sidebands on the light. The frequency of modulation is

sufficiently high that essentially no laser amplitude noise of a technical nature is able to contaminate the observed signals. The

signal/noise ratios obtained are excellent and allow unprecedented

accuracy and precision in locking the cw dye laser relative to an iodine absorption reference line. A programmable frequency

synthesizer driving an acousto-optic frequency shifter unit allows

tuning the highly stable dye laser relative to the I 2 line. A

stability of a few kHz for months is available along with sub kHz

linewidth and short-term stability. With this dye laser source it has

been possible to carefully study the shift of the Rb Rydberg energy

level 36S using the method of two-photon Ramsey fringes. To emphasize

the role of the ir radiation in causing shifts and decays of the

Rydberg levels, Hollberg and Hall arranged a higher temperature

black-body source inside the atomic beam vacuum system. A chopper

alternately blocks and passes this radiation in synchronism with the

laser frequency steps and signal averager channel advance steps.

Typical two-photon Ramsey- fri nge responses are shown in Fig 1, where

part A shows the central Ramsey-fringe and one of the 10 surrounding

Zeeman-split neighboring fringes. Part B shows a 3x expanded view of

this central fringe. Parts C & D show further 4-fold-expanded traces

of the central fringe, in C with the chopper stopped and open, and in

D with the chopper functioning. Least squares fits give a shift of

1420+140 Hz at the laser frequency due to the black-body radiation

field. Shifts of this type are known to be present even in the

primary standard of frequency, the cesium atomic beam tube.

175
o'OMt

roooe

1

i<

a b

d

Ramsey’ profiles of Rb 5S-36S F=3 two-photon transition at 5954.2952 A

a) Scan over central and first neighboring Zeeman componenets. b) Expanded

sweep (3x) of central |mJ = 3 Ramsey component. Note asymmetry due to

laser ac Stark effect. A few points are missing due to brief unlock of

cavity buildup, c) Central Ramsey fringe taken at 800 Hz/channel at

the laser frequency. Blackbody source on, chopper open, d) Central

Ramsey fringe, 1 kHz/channel . Chopper synchronized with laser steps

and channel advance. Blackbody temperature 375 K. Odd channels

(chopper open) are shifted by the blackbody radiation relative to even channels (chopper blocking). Least-squares fits give 1420+140 Hz

shift at the laser frequency.
During the next year this work will be replaced with a new start on atomic beam slowing, using a frequency-swept laser, in collaboration of Hall

with W.D. Phillips at NBSG.

High Resolution IR Spectra . A second area of "delicious" physical

results from Hall 1 s group is the study of rotational -vibrational state

dependance of hyperfine coupling "constants" in the HF molecule, studied with

a frequency-controlled color center laser. The HF ro-vibronic spectrum is

very strong and occurs in the 2.6 ym region where a powerful stabilized laser

would be of considerable use in science and metrology, for example in forming

one route to the visible — from CO2 or the superb OSO4 transitions known in

the 10 ym spectral region. Thus study of the hyperfine and recoil spectra of

HF was a natural preliminary to the ultimate use of the HF-stab i 1 ized color

center laser. The two spin 1/2 nuclei H and F can combine to give 4 states as may be seen from the spectrum of Fig 2. The additional lines arise as "cross-over" lines in our nonlinear optical heterodyne saturation spectroscopy

technique. The principal hyperfine interaction energies are the spin-rotation

coupling of each nuclei with the rotation. Basically the rotation, taken with

a bit of admixed ionic wavefunction, leads to a magnetic field at the fluorine

site for example, due to the moving proton. The observed interaction is the

result of vibrational averaging over the dynamically-evol ving electronic

distributions as a function of the instantaneous internuclear separation.

Factors which affect this averaging, such as increase of the average

internuclear separation with vibrational excitation, give remarkably large

effects since the vibrational potential for HF is so strongly anharmonic. For

example about a dozen terms are needed in a Dunham expansion to give a reasonable accord with the observed ir ro-vibrational spectrum. Even so it is

surprising to find that the hyperfine coupling constant Cf increases 17% with

vibrational excitation. Even the zero-point vibrations increase the value 6 % over the stationary nuclei value at the minimum of the Hartree-Fock potential

curve. These high resolution laser methods show a clear dependence for Cj-| also, -3% for v=0->-v=l. In this work we have a really remarkable glimpse

inside the operation of the Born-Oppenheimer approximation. This work was started several years ago by Hall in collaboration with T. Baer and D. Nesbitt, and excellent sequential postdocs whose energies were mostly directed

to stabilizing the color center laser, building up the ir optical heterodyne

spectrometer system, and getting the first spectra. The HF work was completed

this year by Ch. Breant, a superb advanced-level student from Villetaneuse,

France.

Laser Stabilization . One interesting advance from J. Hall 1 s group in producing a relatively simple laser system for metrology has

been provided by a suggestion by a theoretical consultant (J. Shirley)

in combination with the superb experimental skills of a visiting

professor from Shanghai. The idea is ultimately closely related to some of the published 4-wave mixing schemes, for example the work of

the Paris group ( J.J. Snyder , et al). Basically, we look for rf

modulation transferred onto a laser beam by molecules which are also

exposed to a strong FM-modulated counter-running saturating beam.

This system operates at the shot noise limit and so is incredibly

sensitive. For example the S/N ratio on the usual 612nm I 2

177
9012

, HP

, RQ

,

L0R9NT Z

XS1.54

"10*

-ie.o

*u.o

»g.o

o.o

e.o

V-

-ODU.O -3'JU.O 0.0 SU.O coo.o

Fig. 2. R(0) spectrum,

showing origins of four

main transitions and

three "crossing"

(three-level) resonances.

Width - 12.24 kHz

HWHM . Data are represented by + symbols, while the full

line is a least-squares

fit with Lorentizian

shapes. Frequency axis

in kHz.

173
metrological line can be 250:1 in a 10 kHz bandwidth for a cell

located outside the laser resonator! Proper stabilization to this

resonance would give a few Hz stability at 1 second. Perhaps equally

important, the resonances obtained are ideally antisymmetric with no underlying Doppler background or offsets due to scattered saturating

beam light. In this regard the new system represents a major step

relative to both our previous work on optical heterodyne spectroscopy

and the French work on 4-wave mixing. The first experimental test

beating with the dye laser reference was not completely satisfactory

due to excessive noise in the dye laser system, reaching a stability

level of "only" 300 Hz. After the vibration-shielded environment is

ready we will try the Ar + stable laser with the excellent I 2 lines at

514. 5nm and 501. 7nm. We have already shown accuracy capability in the

sub kHz domain — a factor of about 100 fold improvement over today's

^-stabilized lasers. A patent disclosure and application on this

technique are in preparation. The Zeeman-stabilized laser patent

finally was issued after almost two years' delay.

Another major activity of J. Hall 's labs has been the attempt to

push the laser stabilization toward or to the fundamental limit, set

in our system by photoelectron shot noise. This work has been guided

in part by Dr. J. Hough a visiting Fellow from Glasgow. Two

independent dye lasers have been stabilized onto their own independent

high finesse Fabry-Perot reference etalons, with the performance being

judged by frequency and time domain analysis of the resulting optical

beat signals between the two lasers. Of course vibrations and

acoustic disturbances are the most troublesome, but a clever pendulum

suspension introduced by Hough vastly reduced the coupling of floor

vibrations into the cavity reference system. The final results are

still totally dominated by remediable problems, but show an interesting level of performance: The lasers are separately locked to

their cavities with Hertz-level stability, but the optical reference

cavities are still being vibrated "strongly." The overall result is a linewidth of ^250Hz with a discrete building vibration at ^29Hz

causing a 700Hz excursion. We are now planning to build a better

vibration-shielded room, and use a more suitable laser system (Ar + laser) for the experiments. Analysis shows the ready prospect for

sub-Hertz stability for a few seconds' averaging. Applications to

gravity wave detector research elsewhere (Cal Tech, MIT, Munich) are immediate. The projected results will also form, an important

underpinning of the JILA proposal now being discussed to build a million kilometer gravity wave antennae in space as discussed below

( P.L. Bender , J.E. Faller , and J.L. Hall ). Finally, this sub Hz level

of laser performance is absolutely required by the present radiative

cooling experiments on Hg + now underway at NBS (Wineland and

Bergquist). Additionally, assuming we are successful in

radiatively-ccol ing atomic beams, this level of performance will be

needed for investigation of several optical frequency standard

candidate transitions including Ca (657nm), Ba (878nm) and the

two-photon line in Ag (661nm).

179
Positronium wavelength . J. Hall has been part of a highly

successful outside collaboration with two Bell Labs scientists, A.

Mills and S. Chu, in which the objective is to provide high accuracy

measurements of the optical energy levels of Positronium. This purely

leptonic atom is free of proton structure effects which cause uncertainty in the evaluation for hydrogen of QED interactions such as the Lamb shift. Therefore high accuracy data on the optical energy

levels of Positronium represents a whole new and very powerful area

for the continuing dialogue between QED theory and experiment. On the

other hand, the central approximation is not valid for Ps since the

positron and electron are equally massive. Thus, the Dirac equation

solutions are unavailable and our basic intellectual poverty is

exposed by the need for massive perturbative or expansion techniques

to address the fundamental two-body Coulomb problem. Experimentally

the measurements rest on the development (by A. Mills) over a dozen

years of an effective source of slow positronium atoms--about 3 or 10

such atoms are in the detection volume illuminated on each laser

pulse. The laser system (due to S. Chu) and metrology concept (due to

S. Chu & JLH 11 ) involve a continuously operating dye laser at 486nm.

This frequency stabilized and precisely tuneable laser feeds a chain

of pulsed dye amplifier modules to bring the pulse power up to the

mul ti -Megawatt level needed for the non-linear two-photon Doppler-free

absorption l^S^Z^S in Ps. A plane parallel Fabry-Perot

interferometer inside the positronium production chamber serves as a spectral and angular filter for the high power laser beam to narrow

the spectral linewidth, and minimize the light's k-vector spread,

thereby increasing the measurement precision and accuracy. The Ps

two-photon resonance frequency is measured relative to sub Doppler

saturated absorption peaks in a Te2 vapor cell. The 32 MHz offset

frequency between Ps and Te 2 is expected to be known to sub MHz

accuracy with the removal of the final systematic effects, due to the

Relativistic Doppler Effect (Ps is really light!). The wavenumber of

the Te 2 line is determined with an expected accuracy of 10 MHz (for

the first publication by a JILA-suppl ied Lambdameter, reference laser,

and metrologist at Bell Labs). Later, an ultra accurate Te 2 measurement will be made using the JILA vacuum Lambdameter. We note

that Te 2 also has good reference lines near the Deuterium 3 and

Hydrogen 8 lines. Thus, the JILA high accuracy measurements of Te 2 will be directly useful to ourselves and others (T.W. Hansch and V.W.

Hughes) interested in the H, D, Ps comparison. It is interesting that

the exotic atom of Ps has required less than 1 1/2 years to go from

first observation of its optical spectrum to < 10~8 precision

measurement — the long-term investment in developing the powerful

tools of precision laser spectroscopy has a clear and dramatic payoff!

Eotvos Experime nt. P. Keyser and J. Faller have under

construction a large”Tl.27 m diam) torsion pendulum apparatus with

180
which to test for the equivalence of gravitational and inertial mass.

This large Eotvos apparatus utilizes the surrogate fluid fiber which

was developed at JILA,- and which was used in the earlier (and smaller

- 0.25 m diam) Eotvos apparatus of M. Keiser and Fa! 1 er . The new apparatus is designed to take advantage of sensitivity increase (which

scales as the diameter of the apparatus to the five-halves power) with

size for this type of apparatus. Construction on the large Eotvos

apparatus is now complete and the large system has been successfully

floated and periods of up to 4 hours with "reasonable" Q's having been

observed. Contamination problems in the fluid limited the initial run

to about six weeks. These problems are now thought to be understood.

The interaction of aluminum and water is apparently very

complex — depending critically on the particular type of aluminum and

also critically on the temperature of the water and whether or not

surfactants are present. A number of experimental "fixes" are presently undergoing testing. During the initial run, the system was floated with the upper electrode strucuture in place but without the

full lid -- rather a plastic covering was used so as to permit visual

(as well as electronic) observation. While we are in the process of

testing the various candidate protective surface coatings, we are also

machining a series of observational windows (and also holes for

periodic flushing of the water and for purging and filling the upper

portion with (inert) argon) into the main lid.

Gravitational Waves . Work has continued ( P.L. Bender , J.E.

Faller ) on the feasibility of a future laser gravitational wave detection experiment in space. One major objective is to search for

gravitational wave pulses with periods of minutes to a few hours and

with fractional strain amplitudes of roughly 10“20 0 r larger. The

detection of such pulses would provide an entirely new and unique

capability for studying events in the universe that involve very large masses. This includes present collisions of massive black holes,

which may exist at the centers of many galaxies and probably provide

the energy source for quasars, as well as collisions of such objects

during the earlier history of the universe when galaxy formation was taking place. The second objective is to detect continuously emitted

gravitational waves from both known and unknown rotating binary stars.

The sensitivity needed to be confident of detecting such signals in

the period range of minutes to a few hours is 1

“ 21 -j n a one-day

measurement interval. The basic concept for the experiment has been

described in earlier annual reports. Three test masses in orbit about

the sun with separation of 10 6 km or more would be used, and

variations in the separations would be determined by laser heterodyne

measurements

D. Hi 1 s and Y.M. Chan joined the effort this year, and work

during the year concentrated on a collaboration with j. Hough

(Visiting Fellow), J.L. Hall , and others on the dye laser

stabilization experiments using optical resonators described above.

181
Continuation of the collaboration to carry out similar experiments

with a stability goal of 1 Hz for a 1 sec averaging time is planned.

Argon ion lasers would be employed because results for this type of

laser can be used directly in the promising ground-based laser

gravitational wave experiments now going on at Cal Tech, Munich,

Glasgow, MIT, and elsewhere. The space experiments probably would use helium-neon lasers with only a few milliwatts of output power in order

to maximize reliability, and such lasers would be easier to stabilize

than the argon ion ones.

The demonstration of the very high stability discussed above

would aid in providing confidence that short term' laser phase jitter

would not interfere with the laser heterodyne detection system for the

gravitational wave experiments in space. Work also is being started

on the design of a short-baseline experiment to demonstrate the

sensitivity of the detection method for measuring very small

displacements with periods of minutes to hours. For a nominal beat

frequency of 1 kHz, the times for approximately 1000 zero crossings

would be averaged and used in the later analysis. The desired

sensitivity for one case being studied corresponds to 10~5 radians in

phase, so great care is needed in order to avoid spurious phase

effects due to signal level changes or other effects.

An active weekly meeting has been held which has included P. Bender and J. Faller ; Visiting Fellows, Erast Gliner, Ken Baird and

James Hough; and fifteen to twenty-five student and postdoc

participants. These meetings or seminars are serving to more accurately define the problems and issues of this extensive proposed

experiment.

Geophysical Measurement Development

Gravity Gradiometer . Recognizing the need in the case of the

Edtvos experiment to keep track of changes in the external

gravitational field as well as the potential of a fluid-supported

pendulum apparatus when properly modified as a gradiometer, Fall er is

proceeding at present with the testing of two 0.25 m diam fluid

gradiometers . This development — in addition to its importance for

the Eb'tvds work— is seen to have 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.

The same aluminum-water interaction problems as discussed above for

the Ebtvos work also apply to these smaller floats. Indeed, because

of the smaller size and therefore shorter turn-around times, they are being used for the various tests to identify the best fix to these

problems. Application of these devices to tests of the equivalence of

active and passive gravitation mass as well as to tests of the inverse

square law of gravitation are under study with a new NRC postdoc:

Kerry Hoskins. In addition the construction of a series of somewhat

182
smaller floats fabricated from solid pieces of A1 (to give greater

mechanical integrity) is under consideration.

Absolute Gravimeter (q) . Over this past year, J. Faller has

continued the development of a new absolute gravimeter. The absolute

determination of g, the acceleration due to the earth's gravity, has

long been a measurement of considerable importance. While 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 now has broad applications to

geophysics. A primary concern over the past several years has been

the detection, understanding, and elimination of systematic errors.

In the Spring of 1982, we used this instrument to carry out a survey

at twelve sites in the United States. Over a period of eight weeks,

the instrument was driven a distance of nearly 20,000 km to sites in

California, New Mexico, Colorado, Wyoming, Maryland, and

Massachusetts. The time required to carry out a measurement at each

location was typically one day. As a result of this field testing a number of fairly minor instrumental problems and inconveniences were identified. We are correcting these in the new instruments which we are building in connection with the cooperative field programs which

we are setting up with institutions in Canada, West Germany, Austria,

Finland, China and the USA. Over the next several years, our intention is to see absolute gravity measurements become both useable

and used in the field. With the new instruments we are making, we expect to improve (perhaps by a factor of two) on the 6-10 ygal (2 cm height sensitivity) accuracy of our present instrument. Given

reasonable success with these new instruments 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.

Geopotential Research Mission Accuracy . The proposed NASA

mission called GRAVSAT was described last year. It involved flying

two spacecraft about 100 to 300 km apart in the same polar orbit with

an altitude of roughly 160 km. The separation between the spacecraft

would be measured every 2 to 4 sec with roughly 10"4 cm precision.

Variation in the satel 1 ite-to-satel 1 ite distance would be used to

determine variations in the earth's gravitational field with a resolution of about 100 km.

The original concept has now been changed to include measurements

of the earth's magnetic field on one satellite, and the more currently

used is the Geopotential Research Mission (GRM). P, L, Bender has

worked with NASA’s GRM Data Analysis Group on studying methods for

analysing the gravity field data and on improving earlier estimates of

the expected accuracy. NBS work suggesting that the power spectrum of

the noise involved in the system for measuring the

satel 1 i te-to-satell i te distance might be considerably different than

previously assumed was described last year. During FY/83 Sender was

183
asked to investigate the overall noise spectrum and error correlation

question, and reported the results to the GRM Data Analysis Group.

The conclusion reached is that the power spectrum of the measurement

system noise over the frequency range of importance does not follow

single models and cannot be determined from available data. Thus

additional laboratory measurements on the brassboard system which was assembled earlier are needed. It also was recommended that these

measurements should be made at the system signal levels expected in

the flight measurements.

The main work during the year by Bender connected with GRM

involved the development of a new method for estimating the expected

accuracy of the final geopotential information based on various models

for the measurement errors. Earlier studies had used the

approximation that the relative velocity of the two spacecraft would

vary as the difference in potential (AT) divided by the average

velocity. "(AT/v)" approximation was accurate for most terms in a spherical harmonic expansion of the potential, but breaks down badly

for low frequency terms. This included particularly terms which are nearly sectorial. However, different frequency terms for a given

degree and order are affected differently, so the low frequency part

of the frequency spectrum of the "signal" is changed. A resulting

"signal equation" which gave the correct general behavior but still

had a small error was produced, and the remaining error was corrected

recently by C. C. Goad and C. A. Wagner of the National Geodetic

Survey.

The other part of the work was based on ideas developed earlier

in discussions with B. Bertotti when he was a JILA Visiting Fellow.

The method starts from doing a spherical harmonic decomposition of

residuals from the calculated values for the spacecraft separation or relative velocity data. Some prefiltering to correct for the finite

spacecraft separation and prewhiten the data is needed. The

approximate geopotential can then be solved for using the "AT/v"

approximation. Finally, a matrix based on the correct "signal

equation" is used to correct the results. The solution obtained is

not strictly optimum, but it seems likely to be a good approximation

and to be considerably simpler to find than a rigorous solution.

Tests of the method have not yet been made, but will be carried out if

NASA funding for this work is obtained.

Worldwide Crustal Movements . Further consideration has been

given by P, L. Bender to estimating the limiting sources of error in

laser range measurements to the LAGEOS satellite. This work was stimulated partly by the upgrading of several NASA laser ranging

stations to 2 to 3 cm accuracy capability recently and the planned

upgrading of other stations. The changes included the installation of

sub-nanosecond pulse length lasers and faster photodetectors. A new mobile station being built in the Netherlands seems likely to be

184
capable of calibration to better than 0.5 cm accuracy, so that "normal

points" formed from the data taken over 1 or 2 minute intervals should

have about this accuracy. The NASA stations hopefully can be improved

further to meet this instrumental accuracy level also. However, the

atmospheric propagation correction will give a comparable uncertainty.

The overall expected future accuracy for determining the orbit of the

LAGEOS satellite is 1 to 2 cm. This would lead to similar accuracy

for intercontinental and transcontinental baselines.

University GPS Consortium for Tectonics Studies . It has become

clear that signals from the Global Positioning System satellites can

be used very effectively to determine accurate geodetic baselines and

to study crustal movements. Commercial GPS receivers are now available from two sources, and a third type of receiver is being

developed by NASA. Major programs for geodetic uses of GPS receivers

have been started by the National Geodetic Survey and by NASA. In

order to make the necessary equipment available for use in academic

research programs also, a University GPS Consortium has been set up.

It consists initially of the University of Colorado, Columbia, Cal

Tech, Princeton, and the University of Texas. Two-frequency water

vapor radiometers of the type developed and tested by NOAA will be

used to determine the correction to the speed of propagation for radio waves due to water vapor in the atmosphere. The expected accuracy for

short baselines is 1 cm for the vertical and 2 cm for the horizontal.

For baselines approaching 10 km in length the main accuracy limitation

initially is likely to be uncertainties in the GPS satellite orbits.

The Consortium would rely on close cooperation with NASA, the National

Geodetic Survey, and other agencies to make use of regionally

determined accurate GPS orbits and avoid duplication of efforts. P.L.

Bender , J.E. Faller , and J. Levine (Div. 524.10) expect to work

closely with the Consortium to help in improving the measurement

techniques and in determining the accuracy achieved in field

measurements. J. Levine would aid particularly in designing the

initial experiments, while P.L. Bender would participate in

understanding the atmospheric propagation uncertainties and the

limitations due to the GPS satellite orbit inaccuracies. The absolute

gravimeters developed by J.E. Faller and co-workers would be used in

parallel with the baseline determination to enhance the understanding

of the tectonic processes being studied.

Chemical Physics

Much of the work in this category could probably be included in

the category "Atomic and Molecular Physics and Interactions, " or conversely, some of the work in that category could be included here.

However, it is important to emphasize that J I LA has a very strong

chemical physics program with three Fellows rostered in the Department

of Chemistry (Lineberger (CU), Reinhardt (CU), and Leone (NBS)). It

is Leone 1 s work that is described here as part of the QPD program.

185
Energy Transfer . The study of energy transfer is important to

make high power lasers more efficient, to describe accurately

collisional excitation processes and emissions in the upper atmosphere

and in interstellar media, and to interpret 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

interpretations of the results are possible.

C. Wight and S. Leone are studying one of the simplest and most

basic energy transfer processes, that of T-V or

transl ation-to-vibration excitation. The method involves production

of translationally fast H and D-atoms by photodissociation of

molecules such as H

2 S, HBr, HC1 , and HI with the short wavelengths of

an excimer. The fast atoms collide with other diatomic molecules,

such as CO, NO, HC1 , and DC1 , and the vibrational excitation produced

upon collision is detected by spectrally resolved infrared emission.

A most important and interesting aspect of this collision process is

that the H-atoms are potentially reactive, and thus the interactions

include both strong attractive as well as repulsive forces. Complete

vibrational distributions for CO and NO excitation have been obtained

for collisions with H-atoms at 2.3 eV center-of-mass {Fig. 3). Direct

excitation up to v=6 is observed, with the characteristic steep fall

off of excitation to higher v's as predicted by theory. Accurate

trajectory calculations performed by G. Schatz at Northwestern

University has shown that the vibrational levels v=4-6 in CO are due

to a transient COH complex in which the CO bond is superextended,

resulting in the higher excitation. This directly shows the influence

of an attractive feature in the potential energy surface for H + CO.

Recently, results have also been obtained on the absolute efficiencies

of these T-V processes and on the extent of chemical exchange in

systems like H + DC1 which can result in both DC! or HC1 product

exci tat ion.

H. Haugen and S. Leone are studying another long-standing problem

in energy transfer, that of V-R or vibration-to-rotation excitation in

HF molecules upon vibrational relaxation. This process is thought to

produce high rotational states which are in near resonance with the

vibrational energy, and may be important in the analysis and

efficiency of high-powered HF lasers. The V-R process is also of

fundamental theoretical interest and has been suggested since the

earliest days as a mechanism for the fast vibrational relaxation. A

tuneable infrared F-center laser is used to probe the high-J

populations following relaxation of HF(v=l) molecules excited in a brief pulse with a chemical laser. The rates of relaxation of the

high rotational states (J=12-14) are obtained as well as the fraction

of the total relaxation that proceeds through these levels. The

results are: J=12, 3-6%; j=13, 0.5-2%; and j =14 , 0.05-0.3%. The

important conclusion is that a non-negl igible fraction of the

186
RELATIVE

POPULATION

0.8

0.6

0.4

0.2

£

f~l H+CO

0 H + NO

ss

Ian s —m t—m —

I 2 3 4 5 6

VIBRATIONAL QUANTUM NUMBER

Fig- 3.

Vibrational population distributions produced by T-V collisions of

2.3 eV H atoms with CO and NO.

1S7
relaxation does take place through these high states, and that

rotation probably does play a significant role in the relaxation.

M. Hale and 5. Leone are studying electronic excitation transfer

processes in atomic calcium vapor. Recently they investigated the

fine structure changing collisions within the second

^

manifold.

The closeness of the levels in this case gives a statistical branching

among the levels. A study of the 4s5p Ip and 4s6s IS relaxation

pathways shows that the predominant energy transfer upon collisions

with buffer gases occurs to those states whose wave functions are most

heavily mixed with the initially excited state. Those states which

are very pure in wave function character are avoided. It appears that

several new insights into the fundamental principles that govern

inelastic processes in two electron atoms will be obtained through

these studies.

Ion-Molecule Collision Dynamics . Ions are important in all kinds

of media, e.g. plasmas, lasers, and the upper atmosphere. This

program is designed to push the state-of-the-art in measurement

capability in ion reaction dynamics and ion excitation and

de-excitation processes.

L. Hu'wel, D. Guyer, Lin G.-H. and S. Leone have obtained several

of the first results on fully state-resolved thermal energy charge

transfer reactions under single collision conditions. Complete

vibrational and rotational distributions for the N + + CO and Ar + + N

2 charge transfer reactions are obtained using a novel supersonic beam

ion source apparatus. Only a small fraction of the incoming ions are reacted in order to preserve the single collision conditions.

Saturated laser-induced fluorescence is used to obtain high signal

count rates on the low densities of product ions. The results show a high degree of sensitivity to the potential surfaces for the two

different reactions. The C0+ product is born with very low

excitation, consistent with a Frank Condon distribution of excited

states on ionizing the CO. The N 2 + is born very hot, consistent with

an energy resonance picture of the charge exchange process.

C. Hamilton and S. Leone are studying the dynamics of polyatomic

negative ion reactions by analysis of the product vibrational states.

These reactions are of interest to test the ideas of whether

statistical population distributions result from long-lived

ion-molecule complexes. The first reaction, SFg - + H, produces HF(v)

and SF5 -. The measurements are carried out by infrared

chemiluminescence in a flowing afterglow. This reaction is found to

yield HF in a narrow distribution of states which is very different

from statistical predictions. It appears that this reaction may

proceed via an avoided crossing, where a crossing to the H~ + SFg

species first occurs. The narrow distribution of vibrational levels

may correspond to the small range of internuclear separations between

188
the H and F at the time of the avoided crossing.

R. Klein, R. McGinnis (JILA Research Fellow for Teachers), and S.

Leone used laser optogalvanic spectroscopy for the first time to

determine the threshold photodetachment of a molecular anion, namely

CN~. Previous studies by other workers have only recently observed

atomic negative ion photodetachment by the optogalvanic effect. In the recent work in JILA, the photodetachment threshold measurement was carried out on densities of negative ions in the range of lO^-lO^O

cm-3 s and the electron affinity of CN was determined to a factor of 10

better accuracy than previously known. The method has tremendous

potential to elucidate other details of ion spectroscopy and electron

affinities of other polyatomic radical species.

Photo fragmentation and Neutral Reaction Dynamics . L. Kovalenko,

M. Smith, and S. Leone are studying molecular photofragmentation

processes that lead to free radicals, such as CH3, and their

subsequent reactivity and deactivation. Recently a study of the

enhancement of reactivity by translational excitation has been

completed. Using time and wavelength resolved infrared emission

techniques, it has been possible to show that the enhancement of CH3

reactivity toward Cl 2 and Br2 in the so-called "hot" radical

literature is due primarily to the translational energy, and not due

to the vibrational excitation in the radical after photolysis. J.

Smedley and S. Leone are studying the formation of molecular

exciplexes of excited I*-atoms produced in photolysis. These results

are important in the correct evaluation of photochemical quantum

yields. Future studies will investigate the possible mode specificity

of several radical reactions that produce simple polyatomic product

molecules and will study the details of the photofragmentation of

metal-iodide bonds to produce excited I* species.

Surface Reaction Dynamics . A new program is being started by K. Carleton and S. Leone to measure product molecules that are excited in

reactions on well -characterized single crystal surfaces. All of the

components for an ultrahigh vacuum system which is designed to probe

product states by laser-induced fluorescence and infrared

chemiluminescence are being obtained, and soon the shop will begin

work on the fabrication. A prototype, low vacuum apparatus has been

constructed to test out the detection methods and to survey reactions

for interesting product excitation. An extensive search of the

catalytic literature has been used to define which general types of

reactions might yield product excitation without merely equilibrating

with the surface before desorption. Preliminary results in the

literature from several groups indicates that this area will be a rich

field of investigation and will provide a tremendous amount of new information concerning the dynamics of molecules reacting on catalytic

surfaces.

189
Atomic and Molecular Physics and Interactions

Electron Collisions with Polar Molecules N. T. Pad i a 1 and D. W.

Norcross have been studying vibrational excitation of HC1 by

electrons. The results of their first set of calculations for total

(curve Tabled ' SE ' in Fig. 4) and differential cross sections disagree

with measurements both in shape and magnitude (more than a factor of

ten too low). This is attributed primarily to the neglect of

polarization effects, but is in sharp contrast to results for the

similar molecule HF, in which other workers obtained both correct

shape and magnitude using the same approximation.

In order to include polarization effects, they have developed a local, parameter-free model potential that can be easily generated as

a function of internuclear distance. It employs the free-electron-gas

correlation expression at short distances and the asymptotic form of

the polarization potential at larger distances. The potential is

added to the usual static and exchange terms to complete the

specification of the total e-molecule interaction potential.

Calculations have been done for e-H 2 and e-N2 collisions as test

cases. Total cross sections in both cases are in good agreement with

the results of experiment and much more elaborate calculations. This

model was then applied to vibrational excitation of HC1 (curve Tabled

•SECOP' in Fig. 4).

In most of these calculations a local, free-electron-gas model of

the exchange potential is employed. The test calculations on N 2 showed that a more exact treatment of exchange led to improved

results, and the residual discrepancy in the HC1 results is therefore

attributed to the weakness of the exchange model used. Work is in

progress to improve the representation of exchange by incorporating in

their scattering codes an essentially exact, but separable, form based

on an L2 expansion of the exchange kernal. The first step in this

project, generalization of their codes for generating the static

interaction potential and single-center wave functions to accept

Cartesian gaussians in addition to STOs, has been completed.

Electron Impact Excitation of Atoms and Ions R. B. Christensen

and D. W. Norcross have completed scattering calculations in LS

coupling with the Distorted Wave approximation for eight Mg-like ions

(Ni and lighter). These involve transitions among ten of the lowest

states. Calculation of energy levels and transition probabilities

(including E2 and Ml transitions) in intermediate coupling for the

heavier ions has also been initiated. This employs the Breit-Pauli

approximation and the original LS-coupling structure models; it is the

first step to ultimately evaluating the collision cross sections in

intermediate coupling. In collaboration with A. U. Hazi, the

calculations are presently being extended to heavier ions (e.g., Kr

and Mo).

190
1-1 ? I 1.0 2.0 3.0 4.0 5.0

ELECTRON ENERGY (e V)

Fig. 4. Vibrational

excitation of HC1

The results of

calculations in the

first Born approximation (FBA) and

in the staticexchange approximation, both without

(SE) and with

(SECOP) the inclusion

of polarization

effects, are compared

with the measurements

of Rohr and Linder

(1976).

191
The recent experiments of A. Gallagher and B. Stumpf on excitation out of the first excited state of Na have stimulated a new

set of calculations by B. Christensen-Dal sgaard and D. W. Norcross . Of particular interest is the apparent (within experimental

resolution) finite threshold for excitation of the 3d state, which may

be due to a near threshold resonance. Standard close-coupling codes

have been modified to treat core effects with a model potential,

thereby permitting more accurate specification of the target structure

and much less expensive calculations for many-el ectron systems.

Scattering Theory and Numerical Methods . The derivation of the

first nonadiabatic correction in a model for one or more electrons

outside a spherically symmetric core has been reconsidered by D. W.

Norcross . Previous derivations of this term employed an additional

appeal to perturbation theory for the outer electrons. He showed that

this is not an essential restriction, confirmed earlier conclusions

that no three-body (two electrons plus core) term of this type exists,

and sketched an alternative derivation leading to the same result.

A new method for solving general scattering equations in the

asymptotic region (large r) is being developed by D. W. Norcross and a new graduate student, J. Kelly, in collaboration with H. Saraph and M. J. Seaton. It is based on variable-phase theory, and involves

integration of the phase-amplitude equations cast in the form of

integral equations. The potential advantages of this method are increased speed and stability - a global propagator that can be

partitioned into open- and closed-channel subsets prevents numerical

blow-up without recourse to repeated numerical stabilization.

Experimental Electron-Ion Collisions . In a major breakthrough

dielectronic recombination was for the first time directly observed

and measured. D.S. Bel i (5, G.H. Dunn , T.J. Morgan, D.W. Mueller and C.

Timmer used crossed beams of electrons and Mg + ions, and made

measurements of delayed coincidences between the stabilizing photon

near 280 nm and the resultant neutral atom, and cross sections were determined. Fig. 5 shows a plot of cross section versus energy, and

in addition to the measurements represented by crosses, there are three theoretical curves. The dashed curve is from a DW calculation

of Y. Hahn and K. LaGatutta, and the solid curve is due to A. Burgess

using methods commonly applied now worldwide for plasma modelling.

It's seen that the measured values are several times larger than

theoretical ones. The dotted curve represents an approximate

calculation by LaGatutta and Hahn to account for extrinsic fields in

the interaction region. Since extrinsic fields are also a major issue

in any real environment -- Tokamak, stellar atmosphere, etc. -- the

experiment is being modified so that these effects can be more completely understood.

192
Fig. 5. Cross section versus electron energy for dielectronic

recombination of Mg+: e + Mg+ -* Mg**+ Mg* + hi. Points are experimental. Dashed curve, theory of LaGatutta and Hahn; solid

curve theory of Burgess; dotted curve, approximate attempt of

LaGatutta and Hahn to acccount for extrinsic fields.

193
At Oak Ridge National Laboratory, D. Mueller, T. Morgan, and 6 . Dunn collaborating with D. Crandall, D. Gregory, and R. Phaneuf

measured electron impact ionization of Fe2 +

, Ti2 +

, b 2 +, Cl2+, f 2 +

, and

Ar2 +

. Most are important species in the controlled fusion program as impurities or diagnostic ions. Results for T i 2+ are shown in Fig 6 . Indirect processes such as excitation-autoionization enhance the cross section by more than a factor of two in the threshold region. The

structure or "hump" near 40 eV is not understood, and is perhaps as sharp a structure as has been found in an ionization curve. We

speculate that it is resonant-excitation-double-autoionization (REDA),

a process invoked by Henry and Mszane to explain our earlier results

on Na-like ions (Mg +

, Al2+, Si3+).

Good progress was made by C. Timmer and G. Dunn on design of new apparatus for studying electron-ion collisions, and construction was begun on parts of the apparatus. In this apparatus, trochoidal

analyzers merge and de-merge beams of electrons and ions, and disperse

electrons which are scattered from the ions. By using a position-sensitive detector at the output of the analyzers,

information on scattered electrons with respect to both angle and

energy loss is obtained. With almost 100% collection efficiency this

will offer great advantages for measuring excitation compared to the

fluorescence method we've used previously (efficiency ^10-4), and

will show up important processes like excitation-autoionization and

resonant-excitation-double-autoionization in a distinctive way.

Ion Molecule Reactions at low Temperatures . With activated

charcoal installed in the bore of the superconducting magnet of the

Cold Penning Trap, it has been possible to make measurements on processes doing various isotopic substitutions. For example, S.

Barlow and G. Dunn have been able to make measurements of rates in the

range 10K£T£25K of the group: NH +

3 + H 2 ^ NH 4 + + H;

ND 3 + + H 2 + ND 3 H+ + H; NH 3 + + D2 + NH 3 D + + D; and ND 3 + + D 2 +ND4 + + D * Data of others at high temperatures indicate an activation barrier

about 0.1 eV high despite about 1 eV exothermicity, yielding a curve k versus T with a positive slope for T >100K. Our low temperature data

show a negative slope indicating that at low temperatures a complex is

formed and during the lifetime of the complex quantum mechanical

tunneling occurs. This hypothesis is given strength by the isotopic

data, since reactions with D

2 as the target occur at a much slower

rate, consistent with the slower tunneling of a massive particle.

Though tedious and difficult, our technique remains, so far as we know, the only one for measuring such reactions at these low

temperatures.

Space charge shifts in traps . J. Jeffries, S. Barlow, and G.

Dunn developed theory for the shift of ion cyclotron resonance lines

in an ion trap due to space charge. The work has been written up and

is in press. The work is important not only in Penning traps of the

194
Fio 6. Cross Section versus energy for electron-impact ionization of

Ti^ . Points are experimental, dash curve is Lotz prediction for

direct process. Note dramatic structure near 40eV.

195
type used in our labs, but in ICR cells used throughout the chemistry

world and sold commercially. Mclver et al have shown how our theory

can be used in ICR cells to increase the accuracy of absolute mass determinations by almost an order of magnitude, and their paper will

be published as a companion to ours.

Atom-atom inelastic collisions . M. O'Callaghan and A. Gallagher

are initiating studies designed to give much more detailed information

regarding inelastic atom-atom collisions than is available using

present techniques. They plan to use the absorption and emission of

radiation by the atom-atom collision complex in order to investigate

details of the interaction potentials responsible for the inelastic

processes. Previous studies of inelastic atom-atom collisions have

measured cross sections, differential or total, and inferred the

interactions indirectly from comparing these to calculated cross sections. The method being studied here will give more direct

information regarding these interactions by absorbing and emitting

radiation during the collision, and particularly in the region of

crossings or avoided level crossings. The initial systems being

studied are transitions between the higher states to sodium (e.g. the

6S to 5P transition) due to inert gas collisions.

Collisions between excited atoms. S. Davidson and A. Gallagher , continuing the studies of high density sodium vapor in strong laser

fields initiated with J. Huennekens, have been measuring the processes

Na* + Na* Na (nil) + Na where the final state, n£, may be any of the

S, P, D, and F states energetically available in the collision.

Previous measurements by J. Huennekens and Gallagher obtained the rate

coefficients for transfer only to the n£=5S and 4D states. These new studies are also aimed at attaining temperature dependences and J dependences of the rate coefficients in order to test detailed models

of the Na*-Na* interactions. J. Huennekens and A. Gallagher have also

completed and now published their studies of associative ionization

(Na*+Na* -> Na 2 + + electron. All these processes under study are competing steps leading to laser induced discharges, superfluorescent

emission, and other high-order processes in these highly excited

vapors

Analysis of silane discharges. H. Chatham, A. Gallagher and A.

V. Phelps are investigating models of dc discharge sheath regions in

order to calculate the types of ions produced and ion processing that occurs in silane discharges. These calculations will yield the

relationship of the mixture of Si x

H

n+ ions at the cathode to the

discharge models and ion neutral chemistry taking place in the

discharge. These calculations utilize cross sections for electron

collisional dissociative ionization and ion molecule reactions

measured in the previous year and described in previous reporting

periods. The purpose is to yield detailed diagnostics of the critical

chemical processes leading to amorphous silicon thin-film deposition

196
in these discharges.

Silane neutral chemistry. R. Robertson and A. Gallagher are investigating the neutral silane radical (Si

n ) reactions in the gas

and on the surface of silane chemical vapor deposition and discharge

deposition systems. This is being done by mass spectrometer detection

of the radicals in the presence of large backgrounds of the parent

gas, utilizing differences in ionization potentials. This work is

leading to the first definitive data on the dominant neutral species

in silane discharge and silane pyrolysis, as well as to the

characterization of surface decomposition and surface reactions on amorphous silicon surfaces. The most important discovery so far is

the dominance of the Si H3 radical and of hydrogen and SiHg-based chain

reactions as dominant processes in these gases. These studies will be

extended during the next year into more complete quantitative

measurements of surface reactions, surface decomposition, and of

electron collisional dissociation of silane into neutral radical

products.

Excitation of metastable H?. H. Tischer and A.V. Phelps began

work on this project with the measurement of the pressure dependence

of the uv continuum emitted by the a^ Eg state of H2, since this state

has been reported to be coll isionally coupled to the metastable state.

After considerable effort devoted to the study of the literature on the properties of the c^ nu metastable state of H2, they have begun a search for laser induced fluorescence from the metastables under

collision dominated conditions. At present there is no reliable data

on the collisional destruction of this state.

Vibrational Excitation of D? and H?. S.J. Buckman and A.V

Phelps completed measurements of the infrared emission from mixtures

of D2 or H2 and CO or CO2. These data have been partially analyzed to

obtain coefficients for electron excitation of the D2 molecules by low

energy electrons. Figure 7 shows a comparison of the measured

excitation coefficients with values calculated using our recommended

cross section sets for D2 and CO2.

Electron induced dissociation of H? and 0 ?. M.A. Islam and A.V

Phel ps have completed the development of a new technique for measuring

coefficients for the dissociation for molecules by low energy

electrons. This technique was developed using H2 and they are currently applying the method to O2.

Excited states in discharges . P.A. Vicharelli and A.V. Phelps

have continued the development of models of the time dependent

electron ionization and deionization processes in high pressure, high

energy electrical discharges. During FY 83 they have developed an improved computer code to calculate the growth of current and the

development of a constricted discharge in He. This code is designed

197
EXCITATION COEFFICIENTS FOR D2 USING'

D2-C02 DATA NORMALIZED TO N2~C02 DATA

Fig. 7. Excitation coefficients for the production of vibrational ly

excited D~ by low energy electrons in Dp-CCL mistures. E/N is the

ratio of the applied electric field to the total gas density. The

points are experimental data normalized to data for fL-CCL mixtures.

The curve is calculated using our Boltzmann code and our recommended

cross sections.

198
to allow incorporation of the multi-step collisional ionization

equations developed and tested during FY 82. A point of particular

interest has been to establish procedures for calculating the rates of

gas heating resulting from collisions of neutral atoms with highly

excited atoms. This heating mechanism has recently been found to be

important in alkali metal-rare gas discharges by W.L. Morgan of

Lawrence Livermore Laboratories and A.V. Phelps .

Electron transport and reactions . In collabortion with L.C.

Pitchford of Sandia National Laboratories, A.V. Phelps has continued

calculations of electron transport and reaction coefficients in gases

at high electric fields. A paper describing their investigation of

the effects of various approximations to the distribution in energy of

secondary electrons was published. Considerable effort was devoted to

the evaluation of literature and in the modification of computer

programs so as to provide more reliable electron transport and

ionization coefficients at very high electric field to gas density

ratios and at high frequencies as required by current DoD/DoE

projects.

Laser-induced collisional processes . S. Geltman has been

continuing his theoretical study of laser-induced collision processes.

This type of process might be used to rapidly cause a population

transfer between particular states of two atomic species, with

potential application in the development of lasers. The specific

process studied is the laser-induced collisional charge transfer

Ca

+ (4s 2 S^/ 2 ) + Sr(5s 2 1 Sq) + hv+Ca(4s 2 1 Sq) + Sr + (5p

2

Pi/2,3/2)

for which experimental data exists on the line shapes and cross section magnitudes. The long-range potential curves for the initial

and final atom-ion pairs and the resulting line shapes have been

calculated on the basis of radiative transitions between two molecular

ion states. An alternative treatment using atomic basis states is

also in progress, and preliminary indications are that it will give

much better agreement with experiment than the one based on molecular

ion potential curves.

Small angle electron-atom scattering . In collaboration with

R. K. Nesbet of the IBM Research Laboratory, S. Geltman has been

theoretically investigating the high energy (15-25 KeV) forward

(0-8 mill iradians) elastic scattering of electrons on atoms. They

have carried through the calculation for a hydrogen atom target, in

which all excited states are represented by a single polarization

pseudostate, up to and including the 2nd Born approximation. In this

approximation no strong forward elastic peak is found, in apparent

disagreement with the experimental findings for rare gas atom targets.

A complex optical potential deduced from the pseudostate model appears

to give the observed forward shadow diffraction pattern, and this

199
would imply that low-order Born approximations are too slowly

convergent to give the correct result for forward elastic scattering,

even at such high energies.

Static and microwave electric field ionization of Rydberg states . This work was started by S. Geltman , while on a Humboldt award at the

Max Planck Institute for Quantum Optics in Garching, in collaboration

with J.A.C. Gallas and J. Bergou. This calculation is being done

using both the spherical and parabolic representation for bound and

continuum states in a Coulomb field. The treatment of continuum

states in the parabolic representation has been developed, since it

has not been covered adequately in the literature to date.

Perturbation theory of arbitrarily high order is being used to solve

the time-dependent Schrodinger equation, and to obtain the resulting

ionization probabilities. All intermediate states within the

degenerate manifold of the initial Rydberg state are included, which

is expected to be a valid approximation for the low frequencies

considered. The results of this dynamic calculation will be compared

with simpler static and tunneling models of the ionization process,

and with existing experimental data — including the finding that the

threshold field strength for microwave ionization varies as n

~ 5 rather

than the n*4 one would expect from a simple barrier-lowering picture.

Photoionization of Aligned Rydberg Atoms -- Photoelectron Angular

Distributions . Highly excited atoms with well defined alignment (in

specific magnetic substates) are conveniently produced using resonant

excitation by carefully polarized laser light. G. Leuchs ( J I LA

visitor) and S. J. Smith have developed techniques for measuring

photoelectron angular distributions from such states, effectively

providing a new spectroscopic tool for analyzing angular momentum

characteristics of such Rydberg states. E. Matthias (Visiting

Fellow), P. Zoller (Visiting Fellow), D. S. Elliott, and N. D. Piltch,

with Leuchs and Smith, have demonstrated the power of this type of

spectroscopy in a study of the perturbed Rydberg ( 6 snd) series in

atomic barium. The source of perturbation is a doubly excited (5d7d)

state which lies between the 6s26a and 6s27d states, introducing 5d7d

admixtures into nearby states in the Rydberg series as well as mixing

the singlet and triplet series. Fig. 8 shows measured photoel ectron

angular distributions for the perturbed singlet and triplet series,

and to two different conti nua. Angular distributions for n=19, to the

6 s continuum, can be taken as unperturbed.

In each case the experimental result can be fitted to an expansion in spherical harmonics (represented by the solid lines) and

the coefficients of the expansion can be interpreted in terms of

mixing coefficients Zj in the wave function form

j6snd,J=2> - 1\ | 5 snd^-D 2 > + Z 2 | 6 snd^D 2 > + Z 3 j 5d7d,J=2 >

200
Fig. 3. Measured photoelectron angular distributions (x) for barium

Rydberg states to the 6s and 5d continue, distinguished by electron

time-of-fl ight. Photoelectron angular distributions fo the 5d7d

doubly excited perturber are also included. The top half of the

figure, corresponding to a residual ion in the ground state, exhibits

mainly singlet-triplet mixing. The bottom half, for the residual ion

excited, shows lower photoelectron anisotropy since the excited ions

retain some alignment.

201
as Zoller has done using mul ti-channel quantum defect theory. The

photoelectron angular distributions are particularly sensitive to

singlet-triplet mixing coefficients, which are just the parameters

needed to remove ambiguities in the multi-channel quantum defect

analysis based on barium term energies only (K. T. Lu, private

communication; M. Aymar, private communication). Leuchs and Smith are preparing a remeasurement with improved resolution and other

refinements in order to provide accurate data for the quantum defect

analysis. Measurements in calcium and other multi-valence-electron

atoms are being considered.

D. S. Elliott, working in Munich with H. Walther and G. Leuchs

(former J I LA Visiting Fellows) as part of an NSF sponsored

U.S. -Germany Cooperative Science Program, participated in a successful

pioneering investigation on the influence of laser power in changing

photoelectron angular distributions through a.c. Stark shifts of

participating levels. Elliott and S. J. Smith also participated

(again in Munich through the Cooperative Science Program) in a study

of the behavior of photoelectron angular distributions as the duration

of the photoionizing pulse is shortened into the pico-second range (so

that coherent superpositions of Rydberg states of different orbital

angular momentum are excited).

The Role of Fluctuations in Non-Linear Absorption K. Arnett, M.

Hamilton, D. S. Elliott, and S. J. Smith have initiated a comprehensive series of measurements of the role of fluctuations in

the sodium 3s-4d two photon absorption process, as the first phase of

a program of measurements of the significance of fluctuations in

non-linear optical processes, a subject of current theoretical

interest. These measurements are based on a considerable program of

technical development in JILA, including implementation of highly

stabilized (^50 kHz) one-watt ring laser, following an original design

by J. L. Hail . K. Arnett, a thesis student, has extended methods

developed by Elliott for superimposing random phase (and frequency)

fluctuations onto the relatively monochromatic cw laser beam. The

purpose is to make the laser broad band in a fully controllable

manner. Accousto-optic and electro-optic modulation methods are used

to generate a laser line shape with widths up to 35 MHz with line

shapes ranging from Lorentzian to nearly Gaussian +1 GHz from line

center. With the completion of the 3s-4d two-photon absorption

measurements, we will take up study of the role of fluctuations in a saturated 3S(F=2,Mp=2) 3

3 / 2 )

( F=3,Mp=3) optically pumped two-level

system, by optical double resonance (3P*4D probe) with detection in

the 330 nm decay radiation. In addition to line shape and line width

of the primary laser, probe response will be studied as a function of

laser power and detuning.

202
JILA Atomic Collision Data Center

1983 Accomplishments . During FY83 the JILA Data Center under

direction of Jean Gallagher 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 of the Data Center staff with visiting scientists who

participated in the review and evaluation of data in their fields of

expertise. The results of completed projects are listed in the

"Publications, 1983" section below. Projects started in 1983 and

currently under way are described in the "Work in Progress" section.

Publications, Data Center publications in 1983 include:

1. "Angular and Energy Distributions of Secondary Electrons

from Helium: I. Slow Electrons Ejected by Electron

Impact," Yong-Ki Kim, Phys. Rev. A (in press).

2. "Evaluted Theoretical Cross Section Data for Charge

Exchange of Multiply Charged Ions with Atoms. II.

Hydrogen Atom-Partial ly Stripped Ion Systems,"

J. W. Gallagher, B. H. Bransden, and R. K. Janev, JPCRD

(in press).

"III. Atom (Z 2)-Ion Systems," R. K. Janev and

J. W. Gallagher, JPCRD (submitted).

3. "Survey and Review of Inelastic Collisions Data for

Diatomic Halogens," Jeffrey I. Steinfeld, JPCRD

(submitted)

Work in Progress

1. "Total Cross Sections for Proton Impact Ionization of Gaseous

Targets." This review is being prepared by M. E. Rudd, Y.-K. Kim and

D. Madison in collaboration with the Data Center staff. The authors

spent two weeks at JILA in May 1983 planning the content and their

contributions to the review. Dr. Rudd spent the successive six weeks

reviewing the experimental methods and data (which had been collected

by the Data Center), determining criteria for judging the accuracy of

the data, and with P. Ruttenberg of the Data Center, developing

formulas to represent the data. Dr. Kim will compare the acquired

data with photoionization cross sections in the high energy limit.

Dr. Madison will calculate cross sections for atomic targets using the

distorted wave approximation, and these will be compared with the

experimental data. The authors expect to combine the results of these

efforts into a first draft during the winter of 1983/84. This review

will be submitted to Review of Modern Physics.

203
2. Cross Sections and Equilibrium Yields for Charge Exchange

between Hydrogen (and Deuterium) Atoms, Molecules, and their Ions with

Metal Vapors. This work is being done with Drs. T. J. Morgan ( J I LA

Visiting Fellow, 1982-83), A. S. Schlachter, R. E. Olson, and

Wilmer Anderson. The appropriate references have been identified, and

the data collected in a series of figures. These data will be

evaluated and recommended data will be presented in an article to be

submitted to the Journal of Physical and Chemical Reference Data. A

second article which would be an in-depth review of the experimental

and theoretical techniques associated with these data is being

considered.

3. "Scaling Laws for Inelastic Collision Processes in Diatomic

Halogens." In connection with the compilation of energy transfer data

for diatomic halogens done with Professor J. I. Steinfeld, a series of

scaling laws were applied by the Data Center staff to the few existing

extensive data sets to determine which law provides the best

representation of the data. Although the findings of this study were judged to be not of sufficient orginality to justify submission as an article to a regular scientific journal, the work and its findings

will be documented in Data Center Report No. 23 which should be

complete early in 1984.

4. "Partial Channel Photoionization Cross Sections in

Molecules -- Theory and Experiment." Work started on this compilation

in December of 1982, when Professor P. W. Langhoff, a theoretical

chemist from Indiana University, visited JILA to plan the project.

Letters requesting information on sources of data were circulated to

prominent workers in the field, and an extensive bibliography of

pertinent literature was compiled. Dr. Langhoff spent August, 1983,

at JILA reviewing the accumulated materials and identifying

appropriate data for five molecules. These data are being acquired on Data Center files. Dr. Langhoff will return to JILA in November of

1983 to continue work on the review with Dr. C. E. Brion who has done

significant experimental work in the field. The final report will be

submitted to the Journal of Physical and Chemical Reference Data.

5. "Multiphoton Bibliography, 1981-82." In response to many

requests from workers in the field, a two-year update to NBS Special

Publication LP-92, is planned. Dr. N. D. Pi 1 tch worked during the summer of 1983 identifying appropriate articles in the scientific

literature and indexing these. After the references and indexing have

been entered into a computer file and sorted, the bibliography will be

printed in the established Data Center format.

6. Data base management system for atomic collisions data. This

system has been designed and prototyping has been completed. Loading

of the data has begun and will continue into FY84. New and/or

204
improved programs have been developed for data storage and retrieval

in the form of bibliographic listings, data tables, and figures.

These will be interfaced with the new data base management system.

FY1984 Plans . A major effort will entail continuation and

completion of the six projects described above (work in progress).

An exciting new project planned for FY84 is a review of the

atomic Stark effect, a topic of fundmental scientific interest to

which recent developments in both theory and experiment have led to

increased understanding. The review will be written by

Drs. W. P. Reinhardt and P. M. Koch, who are experts in the

theoretical and experimental aspects of the field, respectively.

Another new project will be done in connection with a proposed

compilation of collision strengths and rates for the electron impact

excitation for selected transitions in ions of astrophysical interest.

In collaboration with Dr. A. K. Pradhan of JILA, recommended data will

be compiled in a more general sense; i.e., for all ions and

transitions for which data are available.

Vigorous efforts are continuing to complete high quality

evaluated compilations and to plan and coordinate new, timely reviews

in areas of current interest. Jean Gallagher, the Data Center

Manager, has also been actively exploring potential for collaborations

with the Data Centers at Oak Ridge National Laboratory and the Queen's

University at Belfast.

Astrophysical Measurements

Wind-blanketing and the Stellar Temperature Scale . D, G. Hummer

and postdoctoral research associate D. C. Abbott have been

investigating the effect on the temperature scale for hot stars of the

radiation scattered back into the photosphere of the star by the

stellar wind surrounding the star. This so called wind blanketing

causes the surface layers of the star to become hotter than without

the wind. One of the principle parameters of stars is the effective

temperature, defined such that the total energy flux leaving the star

is °Te ff4; this is fixed by the nuclear energy sources deep in the

star. Effective temperatures are determined observationally by

measurement of spectral line intensities, which give the surface

temperature T0 , which is then related to Te ff by theory. As the

effect of wind blanketing is to raise the surface temperature relative

to the effective temperature, the values of the effective temperature

obtained will be too large if wind blanketing is ignored. This effort

has concentrated on the 0-type star Zeta Puppis, for which extensive

and accurate observations are available. About ten years ago an effective temperature of 50000°K was obtained by comparing line

strengths of He I and He II with model results. Recently a German

205
group obtained Te ff = 42000°K by using more elaborate models, and the

present work has lowered this value to 39000°K by including wind

blanketing. Detailed comparison of line profiles is underway to

demonstrate that wind blanketed models provide a better description of

the star than models which do not account for this effect. These

results have reported on these results at a number of conferences and

will be prepared for publication when the calculations are completed

within the next few months.

Escape-Probability Theory for Radiation in Media with

3-Dimensional Flows . D. G. Hummer and G. 8. Rybicki (Center for

Astrophysics) have developed an escape probability theory for spectral

lines formed in a gas undergoing general three-dimensional motion with

supersonic speeds. Under these conditions only regions for which some component of the relative velocity vanishes are coupled radiatively,

and the radiative transfer problem is much simplified. However the

mathematical description of the radiation is still very complex, and

in particular a number of special functions arise which are expressed

by complicated three-dimensional integrals. All but one of the

integrations could be evaluated analytically, and in some important

special cases rational expressions for rapid computer evaluation of

the functions have been obtained, thus facilitating the application of

this theory. Functions giving exactly the probability that photons

escape in a particular direction in axially-symmetric configurations

have been derived, so that the computation of both the total intensity

and the line profile seen by a distant observer of, say, an accretion

disk, involves a one-dimensional, rather than a two-dimensional,

integration. Again rational expressions have been obtained for rapid

computer evaluation. This work is in press. Application of this

theory to the accretion disks associated with dwarf novae are being

made by Dr. Hummer's research assistant Douglas Carroll as part of

his thesis work.

Coll i signal -radiative Recombination . D. G. Hummer and Dr. P. J.

Storey of University College London have been engaged in the

calculation of intensities of recombination lines allowing for the

effects of both 1-changing and n-changing collisions. Recently they

have completed an improved treatment of the n-changing collisions, as well as collisional ionization and three-body recombination, which

become important for higher densities. Preliminary results have been

obtained for one, two and three-electron ions, and the final results

for H I and He II are now being computed and prepared for press. In order to provide results for infrared lines, which are being observed

at increasing wavelengths for a growing number of astronomical

objects, intensities are tabulated for all transitions with principal

quantum numbers up to 50. Dr. Hummer is now generalizing these

calculations to include the effects of optical depth in the

recombination lines, in order to extend the conditions under which

these results can be applied.

206
Infra-red Recombination Lines from Wolf-Rayet Stars . D. G.

Hummer in collaboration with Drs. P. J. Storey and M. J. Barlow of

University College London have been developing methods of using the

infra-red recombination lines and the free-free continuum of

Wolf-Rayet stars to determine ionic abundances and electron

temperatures. This can be done, using the results of the

collisional-radiative recombination calculations of Hummer and Storey,

in a nearly model -independent way, which is a very great advantage in

dealing with objects about whose atmospheric structure we know very

little. Recently this approach has been generalized to treat stars in

which the lines formed in the wind are optically thick, making

possible the determination of column densities in the wind, as well.

In order to improve the accuracy of the latter determination. Dr.

Hummer is developing some very simple models to calculate the

probability that a recombination-line photon escapes rather than being

absorbed by the free-free continuum.

Hyperspherical -coordinate theory of two-electron correlation

phenomena . B. Christensen-Dal sgaard (University of Aarhus) has been

working for three years at J I LA on problems of two-electron

correlation in atomic structure and scattering under the supervision

of D. G. Hummer . She has analyzed these problems using hyperspherical

coordinates, in which the individual radial coordinates ri and rz are replaced by R = (ri 2 + r;? 2

) 1 / 2 and a= arctan( r\/rz) , and has written

a set of extremely efficient computer codes to solve the Schroedinger

equation for both bound and continuum states. The properties of a number of H- and He resonances which she obtained agree very well with

experiment, and required much less computational effort than other

methods. A combined hyperspherical and close-coupling method which

she has recently developed for scattering problems combine the

advantages of both methods. She has submitted her thesis to the

University of Aarhus in July and returns to Denmark in October.

Reliable Estimates for Stellar Mass Loss Rates . Li nsky and his

colleagues have begun a comprehensive program aimed at obtaining for

the first time reliable estimates of the rate at which stars lose

matter to space. He is concentrating on stars somewhat cooler and more luminous than the Sun. One indicator of mass loss is asymmetry

in the ultraviolet emission lines produced by the absorption and

emission of the expanding gas in a volume much larger than the star

itself. Such asymmetries are routinely observed in the MG+ resonance

lines near 280 nm in many stars by the International Ultraviolet

Explorer (IUE) satellite, but they have heretofore not been analyzed.

S. Drake and Li nsky have developed a computer code that properly

includes nearly coherent scattering in the atom's rest frame, an extended spherical geometry for the wind, and expansion. An example

of these calculations is shown in Fig. 9. They are now comparing such

calculations with observations to estimate mass loss rates for

207
Fig. 9. Typical examples of asymmetric emission lines, indicative of mass loss from stars, computed by S. Drake and Linsky . The solid

lines are Mg+ resonance lines computed including nearly coherent

scattering in the atom's rest frame for a wind extending out to 1.2,

2, and 10 times the stellar radius. The dashed lines are for the

same cases except making the unrealistic assumption that scattering

completely redistributes photons in frequency within the absorption

profil e.

208
specific stars. In addition, they are observing the same stars with

the Very Large Array (VLA), a 27 antenna radio i nterferometer in New

Mexico, to detect free-free continuum microwave emission produced in

the wind. The strength of this emission is an important constraint on the mass loss rate.

Microwave Emission Processes in Stellar coronae . Linsky and his

colleagues have been studying the million degree plasma located in

coronae that surround stars similar to the Sun by two techniques.

Thermal Bremsstrahlung (free-free emission) produces X-rays that are detected by the NASA Einstein X-ray Observatory satellite. On the

basis of such data they have shown which types of stars have coronae

(and thus are solar-like) and which types do not. D. Gary and Li nsky

have now extended this study to the microwave region by observing many

stars with the VLA radio interferometer. They detect strong emission

from many stars at levels far in excess of that predicted by free-free

emission alone. They propose that the emission is due to thermal

electrons spiralling in coronal magnetic fields. Depending on the

observed harmonic of the local cyclotron frequency, the emission is

called gyro-resonant or snychrotron. They infer coronal magnetic

fields of roughly 300 Gauss, and find that the emission occurs preferentially above dark starspots, which presumably have strong

magnetic fields like spots on the Sun. They are now conducting

experiments to understand the emission processes in more detail.

Stellar Spectroscopy in the Vacuum Ultraviolet . Spectroscopic

studies of ultraviolet emission lines have provided very sensitive

tools for deriving the plasma properties (density, temperature, flow

velocities, departures from thermodynamics equilibrium) of stellar

atmospheres. Linsky and his colleagues and collaborators at J I LA and

elsewhere have pioneered techniques for deriving plasma properties and

model stellar atmospheres by the analysis for col 1 isional ly excited

ultraviolet resonance lines observed with the IUE satellite in the

spectral range 120-320 nm. During the last year they have analyzed an excellent high resolution spectrum of the star Beta Draconis (see Fig.

10), obtained as the longest exposure with the IUE satellite. Using

density-sensitive line ratios, emission line strengths, and line

opacity arguments, they derived a detailed model for the outer

atmosphere of this star with densities nearly an order of magnitude

lower than the Sun. From the observed Doppler shifts of optically

thin lines, they deduced systematic downflows as they now have

detected in other stars. They showed that the star has a 10? K corona, probably confined by magnetic loops, and that the atmosphere

is likely heated by MHD waves. Linsky is a co-investigator on the

science teams responsible for building the High Resolution

Spectrograph on Space Telescope, which will be a very sensitive

instrument for spectroscopy in the 120-320 nm spectral range, and for

planning the Far Ultraviolet Spectrograph Explorer satellite, which

will be capable of spectroscopy in the 10-120 nm spectral range.

Spectroscopy in this new spectral range will pose new challenges for

the development of plasma diagnostic techniques.

209
Fig. 10. A composite high dispersion spectrum (resolving power

A /Av % 10,000) of the star Beta Draconis obtained with the

International Ultraviolet Explorer (IUE) satellite. Note that

the spectrum contains emission lines of ions formed over a wide range

of temperatures. The density sensitive intersystem lines of 0 III,

Si III, and C III are indicated by the ] symbol.

210
III. PUBLICATIONS AND INTERACTIONS

Included in the following pages of this section are tables of

JILA Visiting Fellows for 1982-83 and 1983-84.

Publications during the past year of NBS Fellows and

Visiting Fellows.

Invited papers (talks) of NBS personnel of QPD.

. Technical and professional committee participation and

leadership of QPD personnel.

. Consulting by QPD personnel.

Trips of QPD personnel sponsored by others.

. Conferences sponsored.

. Seminars and colloquia.

Other items of interest to the Panel.

211
III. PUBLICATIONS AND INTERACTIONS

VISITING FELLOWS

Quantum Physics Division (525)

FY 1983

VISITING FELLOWS HOME INSTITUTION AREA OF WORK

Nils 0. Andersen Physics Laboratory II

H. C. Orsted Institute

DK - 2100 Copenhagen

Denmark

Heavy particle

collisions.

Kenneth M. Baird Division of Physics

Nat'l Research Council

Ottawa, Ontario

Canada K1A 0R6

Application of

lasers to

precise length

measurements.

Richard M. Crutcher Astronomy Department

University of Illinois

Urbana, IL 61801

Radio, optical,

& ultraviolet

spectroscopy of

interstellar gas

Erast Gliner formerly the A. Joffe

Physico-Technical

Institute of the U.S.S.R.

Leningrad, U.S.S.R.

Mathematical

physics and

gravitation.

James Hough Department of Natural

Philosophy

University of Glasgow

Scotland G12 8QQ

U.K.

Detection of

gravitational

radiation.

Eckart Matthias Institut fur Atom und

FestkSrperphysik

Freie Universitat Berlin

West Germany

Atomic

spectroscopy.

David A. Micha University of Florida

Gainesville, FI 32611

Ion scattering &

collisions in

intense laser

fields.

212
VISITING FELLOWS

Quantum Physics Division (525)

FY 1983

VISITING FELLOWS

Thomas J. Morgan

Jozef Smak

Peter Zoller

HOME INSTITUTION AREA OF WORK

Physics Department Heavy particle

Wesleyan University collisions.

Middletown, CT 06457

Copernicus Astronomical

Center

Bartycka 18

00-716 Warsaw

Poland

Mass transfer in

binary star

systems.

Theoretical Physics

Institute

University of Innsbruck

Austria

Mul ti photon

physics & quantum

optics.

1983 RESEARCH FELLOWSHIP FOR TEACHERS

Richard P, McGinnis Tougaloo College Laser

Tougaloo, MS 39174

NBS/JILA EXCHANGE FELLOW

spectroscopy,

computer/

instrument

interfacing, . laser-induced

chemical

reactions.

William P. Reinhardt Joint Institute for Theoretical

Laboratory Astrophysics Chemical

University of Colorado

Boulder, CO 80309

Physics.

213
VISITING FELLOWS

Quantum Physics Division (525)

FY 1984

VISITING FELLOWS HOME INSTITUTION AREA OF WORK

Carl G. J. Aminoff Helsinki University of

Techno! ogy

Department of Technical

Physics

SF-02150 Espoo 15

Finland

Laser

spectroscopy,

velocity

selective

optical

pumping.

Paul Ewart Clarendon Laboratory

University of Oxford

Parks Road

Oxford 0X1 3PU

England

Laser

spectroscopy,

photoionization,

line broadening.

David M. Gibson New Mexico Institute

of Mining & Technology

Department of Physics

Socorro, NM 87801

Stellar coronae.

Ingolf h'ertel Freie Universitat Berlin

Fachbereich Physik (FB20)

Institut fur

Mol ekul physik (WE2)

Bol tzmannstrasse 20

1000 Berlin 33

West Germany

Laser studies of

crossed beam

processes.

Wei-Tou Ni Department of Physics

National Tsing Hua Univ.

855 Kuang Fu Road

Hsinchu, Taiwan

Republic of China

Gravitation

theories,

empirical

foundations

of gravitation

and general

relativity.

214
VISITING FELLOWS

Quantum Physics Division (525)

FY 1984

VISITING FELLOWS HOME INSTITUTION AREA OF WORK

A. Ravi Prakash Rau Department of Physics

Louisiana State

University

Baton Rouge, LA 70803

Theoretical

atomic physics.

Eric Weitz Department of Chemistry

Northwestern Univ.

Evanston, IL 60201

Energy transfer

processes in the

gas phase and in rare gas

matrices, unimolecular

reactions.

Karl H. Welge University of Bielefeld

Bielefel d

West Germany

High Rydberg

states in

magnetic fields.

1984 RESEARCH FELLOWSHIP FOR TEACHERS

Irene R. Little-Marenin Department of Astronomy

Whit! in Observatory

Wellesley College

Wellesley, MA 02181

Stellar

atmospheres,

spectroscopy,

spectral classification, and

chromospheres of

late- type stars.

NBS/JILA EXCHANGE FELLOW

James J. Snyder Quantum Metrology Group

Bldg. 221, Room A141

National Bureau of

Standards

Washington, D. C. 20234

Laser wavelength

determination and

improved

frequency

determining

algorithms.

215
PUBLICATIONS

Quantum Physics Division (525)

*(K.Y. Sobha) and G. S. Agarwal, Effect of Spatial Dispersion on the

Classical Field Enhancement Factors near a Rough Surface, Solid State

Commun. £3, 99-103 (1982).

*(P. Ananthalakshmi ) and G.S. Agarwal, The Spectral Characteristics of

Signals in Optical Hanle Effect, Phys. Rev. A 25, 3379-3381 (1982).

*G. S. Agarwal and (S. S. Jha), Surface-Enhanced Second-Harmonic

Generation at a Metallic Grating, Phys. Rev. B 26, 482-496 (1982).

*G. S. Agarwal and J. Cooper, Effective Two-Level Description of

Pressure Induced Extra Resonances in Four-Wave Mixing, Phys. Rev. A

26, 2761-2767 (1982).

*G. S. Agarwal and (S. B. Jha), Surface-Enhanced Raman Scattering in a Two-Oscillator Electromagnetic Model, Phys. Rev, B Z6, 4013-4021 (1982),

*G. S. Agarwal, S. L. Haan, K. Burnett, and J. Cooper, Photoemission

Spectra in Intense Laser Field Induced Autoionization, Phys. Rev. A

26, 2277-2280 (1982).

*G. S. Agarwal and C. Y. Kunasz, Dipole Radiation in the Presence of a Rough Surface. Conversion of a Surface-Polariton Field Into Radiation,

Phys. Rev. B 26 , 5832-5842 (1982).

*G. S. Agarwal, (A. T. Friberg and E. Wolf), Elimination of

Distortions By Phase Conjugation Without Losses or Gains, Opt. Commun.

43, 446-450 (1982).

*G. S. Agarwal, Phase Conjugate Optics, Current Science 52, 193-198

(1983). ~

*G. S. Agarwal, (A. T. Friberg and E. Wolf), Scattering Theory of

Distortion-Correction By Phase Conjugation, J. Opt. Soc. Am, 73,

529-538 (1983).

“

*G. S. Agarwal and C. V. Kunasz, Four-Wave Mixing in Stochastic

Fields: Fluctuation-Induced Resonances, Phys. Rev. A 27, 996-1012

(1983) ~

*S. L. Haan and G. S. Agarwal, Recombination Effects in

Autoionization, in Spectral Line Shapes Volume 2 , Proceedings, Sixth

International Conference, Boulder, CO, July 12-16, 1982 (K. Burnett,

Ed., de Gruyter, Berlin, NY, 1983), pp. 1013-1032.

^Entries with stars are those resulting from the work of J I LA Visiting

Fel 1 ows

NOTE: Names in parentheses are authors who are not connected with

JILA—NBS or CU.

216
PUBLICATIONS

Quantum Physics Division (525)

*6. S. Agarwal and (S. S. Jha), Surface Enhanced Nonlinear Optical

Processes in Molecules in a Two-Oscillator Electromagnetic Model,

Phys. Rev. B (in press).

*G. S. Agarwal, S. L. Haan, and J. Cooper, Photoemission Spectra From

Autoionizing States Under Recycling Conditions, Phys. Rev. A (in

press)

.

*G. S. Agarwal and S. V. ONeil, Effect of Hydrodynamic Dispersion of

the Metal on Surface Plasmons and Surface Enhanced Phenomena in

Spherical Geometries, Phys. Rev. B (in press).

*G. S. Agarwal, Coherent and Incoherent Effects in Laser-Induced

Autoionization, in Proceedings, Fifth Rochester Conference on Coherence and Quantum Optics (Plenum, New York, in press).

*G. S. Agarwal, Finite Boundary Effects in Quantum Electrodynamics, in

Proceedings, NATO Conference on Quantum El ectrodynamics and Quantum

Optics (A. Barut, Ed., Plenum, in press).

*K. M. Baird, Frequency Measurements of Optical Radiation, Phys. Today

36, 52-57 (1983).

P. L. Bender, Scientific Goals of Laser Range Measurements, in

Proceedings, Fourth International Workshop on Laser Ranging

Instrumentation (P. Wilson, Ed., Geodetic Institute, Univ. of Bonn,

1982), Yol. II, pp. 502-511.

D. R. Larden and P. L. Bender, Preliminary Study of GPS Orbit

Determination Accuracy Achievable from Worldwide Tracking Data, in

Proceedings, Third International Geodetic Symposium on Satellite

Doppler Positioning (Physical Science Laboratory, New Mexico State

Univ., Las Cruces, 1982), Vol. 2, pp. 1247-1252.

P. L. Bender and D. R. Larden, Topex Orbit Determination Using GPS

Signals Plus a Si detone Ranging System, in Proceedings, Third

International Geodetic Symposium on Satellite Doppler Positioning

(Physical Science Laboratory, New Mexico State Univ., Las Cruces,

1982), Yol. 2, pp. 1253-1258.

P. L. Bender, Geophysical Reasons For Monitoring Contemporary Plate

Motions and the Earth's Rotation, in Proceedings, Workshop on Multiple

Uses of the Very Long Baseline Array, National Research Council (in

press)

.

217
PUBLICATIONS

Quantum Physics Division (525)

*R. A. Bernheim, (L. P. Gold and T. Tipton), Pulsed Optical -Optical

Double Resonance Spectroscopy of the Gerade Excited States of 7 Li2 , in

Proceedings of the International Conference on Lasers *81 , December

14-18, 1981 (Society for Optical and Quantum Electronics, McLean, Ya.

1982), pp. 193-198.

*R. A. Bernheim, (L. P. Gold and T. Tipton), Rydberg States of Li 2 and

Molecular Constants of Li 2 , Chem. Phys. Lett. 92, 13-15 (1982).

*R. A. Bernheim, (L. P. Gold and T. Tipton), Rydberg States of 7 Li2 by Pulsed Optical -Optical Double Resonance Spectroscopy: Molecular

Constants of 7 Li J, J. Chem. Phys. 78, 3635-3646 (1983).

*J. W. Gallagher, B. H. Bransden, and R. K. Janev, Evaluated

Theoretical Cross Section Data For Charge Exchange of Multiply Charged

Ions with Atoms, II. Hydrogen Atom-Partially Stripped Ion Systems, J.

Phys. Chem. Ref. Data (in press).

*B. H. Bransden, The Theory of Charge Exchange and Ionization By Heavy

Particles, in Proceedings, NATO Advanced Study Institute in Atomic &

Molecular Processes in Controlled Thermonuclear Fusion (Plenum, NY, in

press)

*(W. Boland) and T. de Jong, Carbon Depletion in Turbulent Molecular

Cloud Cores, Astrophys. J. 261 , 110-114 (1982).

*(F. Willems) and T. de Jong, Infrared Observations of OH/IR Stars,

Astron. Astrophys. 115 , 213-215 (1982).

*(P. F. Bowers) and T. de Jong, VLA Positions of OH/IR Stars, Astron.

J. 88, 655-657 (1983).

*T. de Jong, OH/IR Stars. Late Stages of Evolution of

Intermediate-Mass Stars, Astrophys. J. (in press).

R. A. Falk and G. H. Dunn, Electron-Impact Ionization of Be +

, Phys.

Rev. A 27, 754-761 (1983).

R. A. Falk, G. H. Dunn, (D. C. Gregory and D. H. Crandall),

Measurement of the Contribution of Excitation Autoionization to

Electron-Impact Ionization of Ions: Ti 3+

, Zr 3+, Hf3+

, and Ta 3+, Phys.

Rev. A 27, 762-770 (1983).

218
PUBLICATIONS

Quantum Physics Division (525)

D. S. Belie, G. H. Dunn, T. J. Morgan, D. W. Mueller, and C. Timmer,

Dielectronic Recombination: A Crossed-Beams Observation and

Measurement of Cross Section, Phys. Rev. Letters 50, 339-342 (1983).

R. A. Falk, G. Stefani, R. Camilloni, G. H. Dunn, (R. A. Phaneuf, D.

C. Gregory, and D. H. Crandall). Measured Electron Impact Ionization

of BE-Like Ions. B +

, C ( 2+

), N( s+), 0(

4+

), Phys. Rev. A 28, 91 (1983).

J. B. Jeffries, S. E. Barlow, and G. H. Dunn, Theory of Space Charge

Shift of Ion Cyclotron Resonance Frequencies, Int. J. Mass Spectrom.

and Ion Physics (in press).

J. E. Faller, Tunnel Detection Utilizing Field-Stationary Gravity

Gradiometers, in Symposium on Tunnel Detection, July 21-23, 1981

(Colorado School of Mines, Golden, CO, 1982), pp. 247-257.

M. A. Zumberge, R. L. Rinker, and J. E. Faller, A Portable Apparatus

for Absolute Measurements of the Earth's Gravity, Metro! ogia 18,

145-152 (1982). ~

J. E. Faller, Y. G. Guo, R. L. Rinker, and M. A. Zumberge, Advanced

Absolute Gravity Determination, in Proceedings of the General Meeting

of the International Association of Geodesy , Tokyo, May 7-15, 1982 (J.

Geodet. Soc. Japan Special Issue, 1982), pp. 309-318.

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. Pub!

.

617 (in press).

(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 Proceedings, Second International Conference on Precision

Measurement and Fundamental Constants (in press).

J. E. Faller, R. L. Rinker, and M. A. Zumberge, A New and Portable

Absolute Gravimeter, in Proceedings, Symposium on Measurements of

Recent Crustal Movements, Especially With Gravimetric and Geodetic

Methods, Tectonophysics (in press).

J. E. Faller, M. A. Zumberge, and R. L. Rinker, The JILA Absolute

Gravimeter, in Proceedings, 9th International Symposium on Earth Tides

(in press).

219
PUBLICATIONS

Quantum Physics Division (525)

R. L. Rinker and J. E. Faller, 'Super Spring' — A Long Period

Vibration Isolator, in Proceedings, Second International Conference on Precision Measurement and Fundamental Constants (in press).

P. T. Keyser, J. E. Faller, and K. H. McLagen, New Laboratory Test of

the Equivalence Principle, in Proceedings, 2nd International

Conference on Precision Measurement and Fundamental Constants (in

press)

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. Pub!

617, in press)

J. E. Faller, P. L. Bender, Y. M. Chan, J. L. Hall, D. Hils, and J.

Hough, Laser Gravitational Wave Experiment in Space, in 10th

International Conference on General Relativity and Gravitation - Contributed Papers (B. Bertotti, F. deFelice, and A. Pastorini, Eds.,

Consiglio Nazionale della Ricorche, Roma, 1983) Vol. 2, pp. 960-962.

P. T. Keyser, J. K. Hoskins, and J. E. Faller, New Laboratory Test of

the Equivalence Principle, in Proceedings, 10th International

Conference on General Relativity and Gravitation (in press).

J. E. Faller, The Physics of Basketball: An Introduction to Scientific

Thinking, in International School and Symposium on Precision

Measurement and Gravity Experiment, Taipai, Taiwan (in press).

J. E. Faller, Telescopes and the Forces That Mold Them. An

Introduction To Optics and Mechanical Design, in International School

and Symposium on Precision Measurement and Gravity Experiment, Taipai,

Taiwan (in press).

J. E. Faller, G. M. Keiser, and P. T. Keyser, The Fluid-Fiber Based

Torsion Pendulum, An Alternative to Simply Getting A Bigger Hammer, in

International School and Symposium on Precision Measurement and

Gravity Experiment, Taipai, Taiwan (in press).

J. E. Faller, Little *G'. An Introduction to Dropping Things, in

International School and Symposium on Precision Measurement and

Gravity Experiment, Taipai, Taiwan (in press).

220
PUBLICATIONS

Quantum Physics Division (525)

J. E. Faller, Introductory Remarks, Opening Ceremony, January 31,

1983, in International School and Symposium on Precision Measurement

and Gravity Experiment, Taipai, Taiwan (in press).

J. E. Faller, Y. G. Guo, T. M. Niebauer, and R. L. Rinker, Promise and

Plans for the JILA Gravimeter, in International School and Symposium

on Precision Measurement and Gravity Experiment, Taipai, Taiwan (in

press)

.

J. E. Faller and W. A. Koldewyn, A Prototype Measurement of the

Newtonian Gravitational Constant Using an Active Magnetic Suspension

Torsion Fiber, in International School and Symposium on Precision

Measurement and Gravity Experiment, Taipai, Taiwan (in press).

M. A. Zumberge, J. E. Faller, and (J. Gschwind), Results From an Absolute Gravity Survey in the United States, J. Geophys. Res. (in

press)

.

J. E. Faller, Y. G. Guo, (J. Gschwind), T. M. Niebauer, J. Xue, R. L.

Rinker, The JILA Portable Absolute Gravity Apparatus, to appear in

Proceedings 1983 IUGG General Assembly (Hamburg, August 15-27) (in

press)

.

J. Huennekens and A. Gallagher, Cross Sections for Energy Transfer in

Collisions Between Two Excited Sodium Atoms, Phys. Rev. A 27, 771-784

(1983). ~

J. Huennekens and A. Gallagher, Resonance Broadening of the Sodium D

Lines, in Spectral Line Shapes Volume 2 , Proceedings, Sixth

International Conference, Boulder, Colorado, July 12-16, 1982 (K.

Burnett, Ed., de Gruyter, Berlin, New York, 1983), pp. 665-678.

J. Huennekins and A. Gallagher, Self-Broadening of the Sodium

Resonance Lines and Excitation Transfer Between the 3 Pq / 2 and 3P1/2

levels, Phys Rev. A 27 , 1851-1864 (1983).

A. Gallagher, Far Wing Radiation From Atom-Molecule Collisions, in

Spectral Line Shapes Volume 2 , Proceedings, Sixth International

Conference, Boulder, Colorado, July 12-16, 1982 (K, Burnett, Ed., de

Gruyter, Berlin, New York, 1983), pp. 755-767.

J. Huennekens and A. Gallagher, Radiation Diffusion and Saturation in

Optically Thick Na Vapor, Phys. Rev. A 28, 238 (1983).

221
PUBLICATIONS

Quantum Physics Division (525)

B. Kamke, W. Kamke, K. Niemax, and A. Gallagher, Rb and Cs Broadening

of the Na Resonance Lines, Phys. Rev. A (in press).

J. Huennekens and A. Gallagher, Associative Ionization in Collisions

Between Two Na(3P) Atoms, Phys. Rev. A (in press).

H. Chatham, D. Hils, R. Robertson & A. C. Gallagher, Reactions of He +

, Ne+

, and Ar+ with CH4, C 2 H 6 , S i4 , & Si 2H 6 , J. Chem. Phys. (in press)

R. Robertson, D. Hils, H. Chatham, and A. Gallagher, Radical Species

in Silane Discharges, Appl . Phys. Lett, (in press).

S. Geltman, Separated-Atom Theory of Laser-Induced Colli si onal

Ionization of Cs by Sr, in Photon-Assisted Collisions and Related

Topics (N. K. Rahman and C. Guidotti, Eds., Harwood Academic

Publishers, Chur, London, New York, 1982), pp. 35-53.

S. Geltman, Threshold Behavior For Ionization By Electrons and

Positrons, J. Phys. B (Lett.) (in press).

*E. Gliner and (I. Dymnikova), A Covariant Concept of Gravitational

Energy, Phys. Rev. D (in press).

*E. Gliner, Equivalence Relation Between Energy and Geometry, in

Proceedings, Congress of the International Association of Mathematical

Physics (in press).

*E. Gliner, New Analytical Ax i symmetrical Solutions in

Magnetohydrostatics, in Proceedings, Congress of the International

Association of Mathematical Physics (in press).

(R. W. P. Drever), J. L. Hall, F. V. Kowalski, (J. Hough, G. M. Ford,

A. J. Munley, and H. Ward), Laser Phase and Frequency Stabilization

Using an Optical Resonator, Appl. Phys. B 97-105 (1983).

R. Blatt, W. Ertmer, and J. L. Hall, Cooling of an Atomic Beam With

Frequency -Sweep Techniques, in Laser-Cooled and Trapped Atoms , Proceedings of the Workshop on Spectroscopic Applications of Slow

Atomic Beams, NBS Gai thersburg, MD, 14-15 April 1983 (W. D. Phillips,

Ed.) NBS Spec. Publ . 653 (1983), pp. 142-153.
PUBLICATIONS

Quantum Physics Division (525)

W. Ertmer, R. Blatt, and J. L. Hall, Some Candidate Atoms and Ions For

Frequency Standards Research Using Laser Radiative Cooling Techniques,

in Laser-Cooled and Trapped Atoms , Proceedings of the Workshop on Spectroscopic Applications of Slow Atomic Beams, NBS Gaithersburg, MD,

14-15 April 1983 (W. D. Phillips, Ed.) NBS Spec. Pub! . 653 (1983), pp.

154-657.

J. L. Hall, Some Remarks on the Interaction Between Precision Physical

Measurement and Fundamental Physical Theories, in Proceedings, NATO

Advanced Study Institute on General Relativity and Quantum

Electronics, ed. by P. Meystre, K. S. Thorne, and M. 0. Scully (Plenum

Press, NY, in press).

J. L. Hall, H. G. Robinson, T. Baer, and L. Hollberg, The Lineshapes

of Subdoppler Resonances Observable with FM Side-Band (Optical

Heterodyne) Laser Techniques, in Proceedings, NATO Advanced Study

Institute on General Relativity and Quantum Electronics, ed. by T.

Arrechi and H. Walther (Plenum Press, NY, in press).

J. L. Hall, Tunable Laser Stabilization Techniques For UltraHigh

Resolution Spectroscopy, in Proceedings, International Conference on Lasers, Beijing, China (in press).

P. Nachman, M. D. Rayman, and J. L. Hall, Relativistic Time Dilation.

A Latter-Day Ives-Still well Experiment, in Proceedings, 2nd

International Conference on Precision Measurement and Fundamental

Constants (in press).

Ch. Breant, T. Baer, D. Nesbitt, and J. L. Hall, State-Dependent

Hyperfine Coupling of HF Studied With a Frequency -Con trolled

Color-Center Laser Spectrometer, in Proceedings, Sixth International

Conference on Laser Spectroscopy, ed. by H. P. Weber and W. Lutz

(Springer-Verlag, Heidelberg, in press).

L. Hollberg and J. L. Hall, Measurement of Energy Level Shifts of

Rydberg Atoms Due to Thermal Fields, in Proceedings, Sixth

International Conference on Laser Spectroscopy, ed. by H. P. Weber and

W. Lutz (Springer-Verlag, Heidelberg, in press).

L. Hollberg, Ma Long-sheng, M. Hohenstatt, and J. L. Hall, Precision

Measurements By Optical Heterodyne Techniques, in Proceedings, Society

of Photo-Optical Instrumentation Engineers (in press).

223
PUBLICATIONS

Quantum Physics Division (525)

D. 6. Hummer, (M. J. Barlow, and P. J. Storey), The Infrared

Recombination-Line Spectra of Wolf-Rayet Stars, in Wolf-Rayet Stars:

Observations, Physics, and Evolution , IAU Symposium #99 (C. De Loore,

& A. Willis, Eds., Reidel, Dordrecht, 1982), pp. 79-83.

J. Cooper, R. J. Ballagh, K. Burnett, and D. G. Hummer, On

Redistribution and the Equations For Radiative Transfer, Astrophys. J.

260 , 299-316 (1982).

(M. J. Barlow) and D. G. Hummer, The WO Wolf-Rayet Stars, in

Wolf-Rayet Stars: Observations, Physics, and Evolution , IAU Symp. 99

(C. de Loore and A. J. Willis, Eds., Reidel, Dordrecht, 1982), pp.

387-392.

D. G. Hunmer and (G. B. Rybicki), Second-Order Escape-Probabili ty

Approximations in Radiative Transfer, Astrophys. J. 263 , 925-934

(1982).

D. G. Hummer, Radiative Transfer Problems in Planetary Nebulae, in

Planetary Nebulae , IAU Symposium 103 (D. R. Flower, Ed., Reidel,

Dordrecht, 1983), pp. 211-218.

D. G. Hunmer, Co-editor, (with P. G. Burke, I. G. Percival, and W. B.

Eissner) of Atoms In Astrophysics , in Honor of Professor M. J. Seaton

on his 60th Birthday (Plenum Press, New York)

D. G. Hummer, The Generalized Exponential -Integral

V(x,y) =J°° exp(-xt)£n (t+y)dt/t and computer algorithms for y

= 0,1,

J. Quant. Spectrosc. Radiat. Transfer (in press).

(G. B. Rybicki) and D. G. Hummer, The Specific Luminosity of a Three-Dimensional Medium in Terms of the Escape Probability,

Astrophys. J. (in press).

*R. K. Janev and D. S. Belie, Quasi -Resonant Charge Exchange

Collisions Between Multiply Charged Ions, J. Phys. B. Atom. Molec.

Phys. 15, 3479-3487 (1982).

*R. K. Janev and B. H. Bransden, Charge Exchange Between Highly

Charged Ions and Atomic Hydrogen: A Critical Review of Theoretical

Data, IAEA Report, INDC(NDS)-135/GA. (1982).

224
PUBLICATIONS

Quantum Physics Division (525)

*R. K. Janev, Electron Capture into Excited States in Collisions of

Highly Charged Ions with Atoms: A Theoretical and Experimental

Challenge, Comments Atom. Molec. Phys. L2, 277-300 (1983).

*R. K. Janev, Excited States Created in Charge Transfer Collisions

Between Atoms and Highly Charged Ions, in Symposium on the Production

and Physics of Highly Charged Ions, Stockholm, June 1-5, 1982, Physica

Scripta (in press).

*R. K. Janev, D. S. Belie, and B. H. Bransden, Total and Partial Cross

Sections for Electron Capture in Collisions of Hydrogen Atoms with

Fully Stripped Ions, Phys. Rev. A (in press).

*R. K. Janev and D. S. Belie, Electron Capture into Excited States in

H + Ar 18 + Kr 38+ and Xe54+ Charge Transfer Collisions, Physica

Scripta (in press).

*R. K. Janev, J. W. Gallagher, and B. N. Bransden, Evaluated

Theoretical Cross Section Data for Charge Exchange of Multiply Charged

Ions with Atoms. I. Hydrogen Atom-Fully Stripped Ion Systems, J.

Phys. Chem. Ref. Data (in press).

*(L. P. Presnyakov) and R. K. Janev, Excitation and Ionization

Processes in Electron-Multi ply Charged Ion Collisions, in Proceedings,

VINIS Symposium (in press).

D. J. Nesbitt and S. R. Leone, Laser Initiated C£ /Hydrocarbon Chain

Reactions: Time-Resolved Infrared Emission Spectra of Product

Vibrational Excitation, J. Phys. Chem. 8£, 4962-4973 (1982).

S. R. Leone, Infrared Fluorescence. A Versatile Probe of

State-Selected Chemical Dynamics, Accts., Chem. Res. _16, 88-95 (1983).

M. A. Smith and S. R. Leone, Product Vibrational State Distributions

in Thermal Energy Associative Detachment Reactions: F” + H,D -*HF(v),

DF( v) + e-, J. Chem. Phys. 78, 1325-1334 (1983).

C. E. Hamilton, M. A. Duncan, (T. S. Zwier, J. C. Weisshaar) G. B.

Ellison, V. M. Bierbaum, and S. R. Leone, Product Vibrational Analysis

of Ion-Molecule Reactions by Laser-Induced Fluorescence in a Flowing

Afterglow: 0" + HF ->-0H(v=Q, 1) + F~ , Chem. Phys. Lett. 94, 4-9

(1983)

225
PUBLICATIONS

Quantum Physics Division (525)

M. A. Smith, V. M. Bierbaum, and S. R. Leone, Infrared

Chemiluminescence From Vibrationally Excited N0 +

. Product Branching

in the N

+ + 0 9 Ion Molecule Reaction, Chem. Phys. Lett. 94, 398-403

(1983).

“

C. A. Wight and S. R. Leone, Excimer Laser Photolysis Studies of

Translational-To-Yibrational Energy Transfer in Collisions of H and D

Atoms with CO, J. Chem. Phys. 78, 4875-4886 (1983).

V. M. Bierbaum, G. 8. Ellison, and S. R. Leone, Flowing Afterglow

Studies of Ion Reaction Dynamics Using Infrared Chemiluminescence and

Laser-Induced Fluorescence, in Gas Phase Ion Chemistry , Vol . 3, “Ions

and Light," (M. T. Bowers, Ed., in press).

D. R. Guyer, L. Huwel , and S. R. Leone, Single Collision Ion-Molecule

Reactions at Thermal Energy: Rotational and Vibrational Distributions

from N + + CO -* N + C0+, J. Chem. Phys. (in press)

J. E. Smedley and S. R. Leone, Relative Quantum Yield of I*(

2 P i/ 2 ) in

the Tunable Laser UV Photodissociation of i-C3 F7I and n-C3 F7 I: Effect

of Temperature and Exciplex Emission, J. Chem. Phys. (in press).

M. 0. Hale and S. R. Leone, Laser Excited, State Detected Calcium-Rare

Gas Collisional Energy Transfer: Ca(4s5p 1 p1

) Spin Changing and

Ca(4s5p 3 p

x

) Fine Structure Changing Cross Sections, J. Chem. Phys.

(in press)

226
PUBLICATIONS

Quantum Physics Division (525)

M. Schindler, R. E. Stencel , J. L. Linsky, (G. S. Basri and D. J.

He! fand), Ultraviolet and X-Ray Detection of the 56 Pegasi System (KO

I Ip + WD): Evidence for Accretion of a Cool Stellar Wind Onto a White

Dwarf, Astrophys. J. 263 , 269-276 (1982).

R. E. Stencel, J. L. Linsky, (T. R. Ayres, C. Jordan, A. Brown and 0.

Engvold), High Dispersion Far Ultraviolet Spectra of Cool Stars, in

Advances in Ultraviolet Spectroscopy : Four Years of IUE Research,

flASAHToTfrF^ Mead, ancTRT D. Chapman, Eds,,

NASA Goddard Space Flight Center, 1982), pp. 259-262.

R. Hammer, J. L. Linsky, and (F. Endler), On the Correlation Between

Chromospheric and Coronal Emission, in Advances i n U1 travi ol et

Spectroscopy. Four Years of IUE Research NASA Conf. Publ. 2238 (Y.

Kondo, J. M. Mead and R. D. Chapman, Eds., NASA Goddard Space Flight

Center, 1982), pp. 268-272.

(T. R. Ayres, T. Simon), and J. L. Linsky, Evolution of Chromospheres

and Coronae in Solar Mass Stars: A Far Ultraviolet and Soft X-Ray

Comparison of Arcturus (K2 III) and Alpha Centauri A (G2 Y),

Astrophys. J. 263, 791-802 (1982).

(T. Simon) and J. L. Linsky, Ultraviolet Observations of Yellow Giant

Stars, in Advances in Ultraviolet Spectroscopy: Four Years of IUE

Research , NASA Conf. Publ . 2238 (Y. Kondo, J. M. Mead, and R. D.

Chapman, Eds., NASA Goddard Space Flight Center, 1982), pp. 273-276.

(T. Y. Ayres), J. L. Linsky, (A. Brown, C. Jordan, and T. Simon), High

Dispersion IUE Spectra of Active Chromosphere G and K Dwarfs, in

Advances in Ultraviolet Spectroscopy: Four Years of IUE Research , NASA Conf. Publ. 2238 (Y. Kondo, J. M. Mead, and R. D. Chapman, Eds .

.

NASA Goddard Space Flight Center, 1982), pp. 281-284.

N. Marstad, J. L. Linsky, (T. Simon, M. Rodono, C. Blanco, S.

Catalano, E. Marilli, A. D. Andrews, C. J. Butler, and P. B. Byrne),

Results of ah IUE Program of Monitoring the Ultraviolet Emission Line

Fluxes of Four Binary Systems: HR 1099, II Peg, Ar Lac, and BY Dra,

in Advances in Ultraviolet Spectroscopy: Four Years of IUE Research , NASA Conf. Publ. 2238 (Y. Kondo, J. M. Mead, and R. D. Chapman, Eds.

,

NASA Goddard Space Flight Center, 1982), pp. 554-557.

227
PUBLICATIONS

Quantum Physics Division (525)

J. L. Linsky, The Structure and Energy Balance of Cool Star

Atmospheres, in Advances in Ultraviolet Spectroscopy : Four Years of

IUE Research , NASA Conf. Publ . 2238 (V. Kondo, J. M. Mead, and R. D.

Chapman, Eds., NASA Goddard Space Flight Center, 1982), pp. 17-32.

J. L. Linsky, (A. Boggess, S. Bowyer, J. Caldwell, W. Cash, J. Cohen,

A Dupree, R. Green, E. Jenkins, M. Jura, D. Leckrone, H. W. Moos, B.

Savage, M. Shull, T. Snow, J. G. Timothy, E. Weiler and D. York),

Current NASA Studies for a Far-Ultraviolet Spectrographic Explorer

(FUSE), in Proceedings of Third European IUE Conference , Madrid, May

1982, ESA SP-176 (European Space Agency, Paris, 1982), pp. 473-485.

(D. E. Gary), J. L. Linsky, and (G. A. Dulk), An Unusual Microwave

Flare with 56 Second Oscillations on the M Dwarf L726-8 A, Astrophys.

J. (Letters) 263, L79-83 (1982).

(M. S. Giampapa, L. Golub, R. Rosner, G. S. Yaiana), J. L. Linsky, and

(S. P. Worden), A Heating Mechanism for the Chromospheres of M Dwarf

Stars, in Second Cambridge Workshop on Cool Stars, Stellar Systems,

and the Sun (M. S. Giampapa and L. Golub, Eds., SAD Special Report

392, 1982), Vol . 1, pp. 73-79.

J. L. Linsky, P. L. Bornmann, (M. Rondono, V. Pazzani, A. D. Andrews,

C. J. Butler, and P. B. Byrne), Variability of Cool Stars at Optical

and Ultraviolet Wavelengths. II. The Binary (?) Flare Star AU Mic, in

Proceedings of Third European IUE Conferen ce, Madrid, May 1982, ESA

SP-176 (European Space Agency, Paris, 1982), pp. 165-167.

J. L. Linsky, Cool Luminous Stars, Adv. Space Res. 2_, 249-260 (1983).

(B. M. Haisch), J. L. Linsky, P. L. Bornmann, R. E. Stencel , (S. K.

Antiochos, L. Golub, and G. S. Vaiana), Coordinated Einstein and IUE

Observations of a 'Disparitions Brusques’ Type Flare Event and

Quiescent Emission from Proxima Centauri, Astrophys. J. 267 280-290

(1983).

(T. R. Ayres, K. Eriksson), J. L. Linsky, and R. E. Stencel, The

Narrow Ultraviolet Emission Lines of the Red Dwarf, AU Microscopii

(dM1.6e), Astrophys. J. (Letters) 270 , L17-L21 (1983).

(D. E. Gary), J. L. Linsky, and (G. A. Dulk), VLA Observations of

Quiescent and Flare Microwave Emission from Late-Type Stars: A Unique

Probe of Coronal Magnetic Fields, in Proceedings, IAU Symposium 102

(J. 0. Stenflo, Ed., Reidel, Dordrecht, in press).

228
PUBLICATIONS

Quantum Physics Division (525)

J. L. Linsky, The Role of Magnetic Fields in Stellar Chromospheres and

Transition Regions, in Solar and Stellar Magnetic Fields. Origins and

Coronae Effects, IAU Symposium 102 (J. D. Stenflo, Ed., Reidel,

Dordrecht, in press).

J. L. Linsky, The Quiescent Chromospheres and Transition Regions of

Active Dwarf Stars: What Are We Learning from Recent Observations

and Models? in Proceedings, IAU Colloquium 71 (Reidel, Dordrecht, in

press)

.

(T. R. Ayres), R. E. Stencel , J. L. Linsky, (T. Simon, C. Jordan, A.

Brown, and 0. Engvold), Red-Shifts of High-Excitation Species in the

Far-Ul traviolet Spectra of Late-Type Stars, Astrophys. J. (in press).

(T. R. Ayres), J. L. Linsky, (T. Simon, C. Jordan, and A. Brown),

Outer Atmospheres of Cool Stars. XV. High Dispersion Ultraviolet

Studies of Active Chromosphere G-K Dwarfs, Astrophys. J. (in press).

(T. R. Ayres, F. H. Schiffer, III) and J. L. Linsky, Outer Atmospheres

of Cool Stars. XIII. Capella at Critical Phases, Astrophys. J. (in

press).

J. L. Linsky and (D. E. Gary), Microwave Emission from the Coronae of

Late-Type Dwarf Stars, Astrophys. J. (in press).

K. Eriksson, J. L. Linsky, and T. Simon, Outer Atmospheres of Cool

Stars. XIV. A Model for the Chromosphere and Transition Region of

Beta Ceti (G9.5 III), Astrophys. J. (in press).

S. A. Drake and J. L. Linsky, The Formation of Emission Lines in the

Expanding Chromospheres of Luminous Cool Stars. I. The Importance of

Atmospheric Extension and Partial Redistribution Effects, Astrophys.

J. (in press)

.

S. A. Drake and J. L. Linsky, First Detection of Winds in Red Giants

by Microwave Technqiues, Astrophys. J. (Letters) (in press).

*D. A. Micha, Variational Determination of Self-Consistent

Interactions in Atomic Collisions, Int. J. Quantum Chem. (Proceedings,

Bates Symposium 1983, in press).

*R. E. Mickens, Uniformly Valid Asymptotic Solutions of Chemical Rate

Equations for Irradiation-Produced Point Defects, Acta Phys. Pol. (in

press)

.

229
PUBLICATIONS

Quantum Physics Division (525)

*(H-L Dai, E. Specht, M. R. Berman), and C. B. Moore, Determination of

Arrhenius Parameters for Unimolecular Reactions of Chi oroalkanes by IR

Laser Pyrolysis, J. Chem. Phys. 77, 4494-4506 (1982).

*(J. S. Wong) and B. C. Moore, Inequivalent C-H Oscillators of Gaseous

Alkanes and Alkenes in Laser Photoacoustic Overtone Spectroscopy, J.

Chem. Phys. 77, 603-615 (1982).

*T. J. Morgan, Atomic Physics of Negative Ions: A Report on the

US-Mexico Joint Workshop, Comments At. Mol. Phys. 12, 319-326 (1983).

D. W. Norcross, Magnetohydrodynamic Electrical Power Generation, in

Applied Atomic Collision Physics , Yol . 5, Special Topics (H. S. W.

Massey, E-. W. McDaniel and B. Bederson, Eds., Academic, New York,

1982), Chap. 3, pp 69-85.

D. W. Norcross and (L. A. Collins), Recent Developments in the Theory

of Electron Scattering By Highly Polar Molecules, in Advances in

Atomic and Molecular Physics (Academic, New York, 1982) , Vol . 18, pp.

341 - 357 :

D. W. Norcross, Recent Developments in the Theory of Electron

Collisions with Polar Molecules, in Recent Developments in

Electron-Atom and Electron-Molecule Collisions , Proceedings of the

Dares Study Weekend (Science and Engineering Council, Daresbury

Laboratory, 1982), pp. 64-69.

D. W. Norcross, Numerical Methods for Asymptotic Solutions of

Scattering Equations, in Atoms in Astrophysics (P. G. Burke, W. D. Eissner, D. G. Hummer, and I. Percival, Eds. Plenum, New York, 1983),

pp. 55-73.

N. T. Padial, D. W. Norcross, and (L. A. Collins), Vibrationally

Elastic Scattering of Electrons By HC£, Phys. Rev. A 27 141-148

(1983).

“

D. W. Norcross, On the Non-Existence of the First Nonadiabatic

Correction for Two Electrons in the Field of a Core, Phys. Rev. A (in

press)

D. W. Norcross, Theory and Computations for Electron Collisions with

Polar Molecules, in Proceedings, U. S. /Japan Seminar on Electron-Molecule Collisions and Photoionization Processes, 26-29

October, Caltech (in press).

I

I

I

I

I

I

H

I

I

i

230
PUBLICATIONS

Quantum Physics Division (525)

A. V. Phelps, Transport Data for the Modeling of Electrical Breakdown

and Discharges, in Electrical Breakdown and Discharge in Gases:

Fundamental Processes and Breakdown (E. K. Kunhardt and L. H. Luessen

,

Eds., Plenum, New York, 1983), pp. 109-132.

C. Yamabe, S. J. 3uckman, and A. V. Phelps, Measurement of Free-Free

Emission from Low Energy Electron Collisions with Ar, Phys. Rev. A (in

press)

.

C. Yamabe and A. V. Phelps, Excitation of the 0 2(

a

1 A

a

) State by Low

Energy Electrons in O2 -N 2 Mixtures, J. Chem. Phys. 78, 2984-2989

(1983). ~~

S. Yoshida, A. V. Phelps, and (L. C. Pitchford), Effect of Electrons

Produced by Ionization on Calculated Electron-Energy Distributions,"

Phys. Rev. A 27 , 2858-2867 (1983).

*E. L. Robinson, (S. 0. Kepler, and R. E. Nather), Multicolor

Variations of the 11 Ceti Stars, Astrophys. J. 259 219-231 (1982).

*H. G. Robinson and (C. E. Johnson), Measured gj Factor Ratio of

4 He

+

(

1

z S 1 / 2 ) and 4He (2

3S 1 ), in Second International Conference on Precision Measurement and Fundamental Constants (in press).

*G. Shaviv and (E. E. Salpeter), Gas Dynamics of Flow Past Galaxies,

Astron. Astrophys. 110 , 300-315 (1982).

*J. Smak, On the Nature of Dwarf Novae, Astrophys. J. (in press).

R. Roy, D. S. Elliott, D. Meschede, F. M. Pipkin, and S. J. Smith,

Collisional Dependence of Spectral Line Shapes in C0 2 , Chem. Phys.

Lett. 93, 603-607 (1982).

R. Roy, D. S. Elliott, D. Meschede, F. M. Pipkin, and S. J. Smith,

Collisional Dependence of Spectral Line Shapes in CO at Low

Pressures, in Spectral Line Shapes Volume 2 , Proceedings, Sixth

International Conference, Boulder, Colorado, July 12-16, 1982 (K.

Burnett, Ed., de Gruyter, Berlin, New York, 1983), pp. 651-662.

E. Matthias, P. Zoller, D. S. Elliott, N. D. Piltch, S. J. Smith, and

G. Leuchs, Influenence of Configuration Mixing in Intermediate States

on Resonant Multiphoton Ionization, Phys. Rev. Lett. 50, 1914-1917

(1983). ~

231
PUBLICATIONS

Quantum Physics Division (525)

D. S. Elliott, R. Roy, and S. J. Smith, Role of Field Fluctuations in

Nonlinear Absorption, in Spectral Line Shapes Volume 2 , Proceedings,

Sixth International Conference, Boulder, Colorado, July 12-16, 1982

(K. Burnett, Ed., de Gruyter, Berlin, New York, 1983), pp. 989-998.

(G. Leuchs) and S. J. Smith, Photoelectron Angular Distribution in

Resonant Multi photon Ionization of Atoms, in Proceedings of the

International School on Lasers and Applications, 29 June - 7 July

1981, Vilnius, Lithuania (in press).

(G. Leuchs), E. Matthias, D. S. Elliott, S. J. Smith, and P. Zoller,

Resonant Multi photon Ionization via Rydberg States - Angular

Distribution of Photoelectrons, Proceedings of the Sixth International

Conference on Laser Spectroscopy, Interlaken, Switzerland, June

27-July 1, 1983, ed. by H. P. Weber and W. Lutz (Springer-Verlag,

Heidelberg, in press).

*D. Spence, (R. G. Wang and M. A. Dillon), Pseudo-Optical Absorption

Spectra in HgC£2 and HgBr 2 from 4 to 14 eV, Appl . Phys. Lett. 41,

1021-1023 (1982). ~

*(G. Alber) and P. Zoller, Spin Polarization By Selective Laser

Induced Interference, Phys. Rev. A 27 , 1713-1716 (1983).

*J. Cooper and P. Zoller, Radiative Transfer Equations in Broadband,

Time-Varying Fields, Astrophys. J. (in press).

*P. Zoller and J. Cooper, Nonlinear Noise Fields and Strongly Driven

Atomic Transitions, Phys. Rev. A. (in press).

*P. Zoller, Noise and Fluctuations in Multiphoton Processes, in

Proceedings, Fifth Rochester Conference on Coherence and Quantum

Optics (A. Barut, Ed., Plenum , New York, in press).

232
PUBLICATIONS

Quantum Physics Division (525)

("in preparation" or "submitted")

*B. H. Bransden, (T. Scott, R. Shingal and R. K. Roychoudhury )

,

Elastic and Inelastic Scattering of Electrons By Atomic Hydrogen at

Intermediate Energies in a Coupled Channel Second Order Potential

Model, J. Phys. B. Atom. Molec. Phys. (submitted).

*R. M. Crutcher, Optical and Radio Study of the Taurus Molecular Cloud

Toward HD 29647, Astrophys. J. (submitted).

*(B. L. Lutz) and R. M. Crutcher, Observations of Interstellar C 2

Toward Three Heavily Reddened Stars, Astrophys. J. (Letters).

( submitted)

.

*L. W., Davis and (G. Patsaros), Comment on Representation of Vector

Electromagnetic Beams, Phys. Rev. A. (submitted).

J. A. Luine and G. H. Dunn, Ion Molecule Reactions Near 10K, Phys.

Rev. Lett, (submitted).

D. S. Belie, R. A. Falk, G. H. Dunn, D. Gregory, C. Cisneros, and D.

H. Crandall, Electron-Impact Excitation of Na-Like Ions: Mg + and A1 + Phys. Rev. A (to be submitted).

D. S. Belie, R. A. Falk, C. Timmer, and G. H. Dunn, Electron -Impact

Ionization of Metal Ions: A1 +

, Cd +, Hg +, Phys. Rev. A (to be

submi tted)

.

G. H. Dunn, Electron Impact Ionization, a book to be published by

Springer, edited by Gordon Dunn and Tilman Mark (in preparation)

.

G. H. Dunn, Ionization of Ions, a chapter for the book Electron Impact

Ionization written by Gordon Dunn (in preparation)

.

G. H. Dunn, Absolute Cross Sections for Electron Impact Excitation of

Mg + and Al 2f

, for Physical Review A (in preparation)

.

G. H. Dunn, Absolute Cross Section Measurement for Electron Impact

Ionization of Twice Charged Ions Ti 2 +, Fe 2+

, Ar 2+, Cl 2, and F 2+for

Physical Review A (in preparation.

G. H. Dunn, Absolute Cross Section Measurements for Electron Impact

Ionization of Al +

, Cd +

, and Hg + for Physical Review A (in

preparation)

.

233
PUBLICATIONS

Quantum Physics Division (525)

("in preparation" or "submitted")

G. H. Dunn, Transverse Ion Acoustic Modes in a Non-Neutral Plasma for

JQRST (in preparation).

G. H. Dunn, Collisions in Ion Traps, a chapter for Advances in Atomic

and Molecular Physics , a book edited by D. R. Bates and B. Bederson

(in preparation).

H. Chatham, D. Hils, R. Robertson, and A. Gallagher, Total and Partial

Electron Collisional Ionization Cross Sections for CH 4 , C 2H 5 , SiH 4 and

Si 2H 6 , J. Chem. Phys. (submitted).

R. Robertson, D. Hils, and A. Gallagher, Silane Pyrolysis, Chem. Phys.

Lett, (submitted).

*E. Gliner, The Influence of Quantum Evaporation on the Course of

Gravitational Collapse, Phys. Rev. D. (submitted).

*E. Gliner and (V. A. Osherovich), Model of a Solar Coronal Transient

with Forerunner, Astron. Astrophys. (submitted).

*E. Gliner, Combined Effect of Potential and Nonpotential Magnetic

Field on Equilibrium in Stellar Atmospheres, Astrophys. J.

(submitted)

(T. R. Ayres, T. Simon) and J. L. Linsky, Sigma Geminorum (K1 III +

?): Variability of the Ultraviolet Emission Lines Near Conjunction,

Astrophys. J. (Letters, submitted).

R. Hammer and J. L. Linsky, The Chromospheric-Coronal Relationship in

Cool Stars. I. on the Assumption that the Global Energy Balance

Determines the Location of the Transition Region, Astron. Astrophys.

(submitted)

F. M. Walter, J. L. Linsky, (T. Simon, L. Golub, and G. S. Variana),

Stellar Chromospheres and Coronae in the Ursa Major Cluster,

Astrophys. J. (in preparation)

(W. B. Landsman, R. C. Henry, H. W. Moos), and J. L. Linsky,

Observations of Hydrogen and Deuterium Toward Alpha Centauri A,

Astrophys. J. (submitted).

234
PUBLICATIONS

Quantum Physics Division (525)

("in preparation" or "submitted")

A. Brown, (C. Jordan), R. E. Stencel , J. L. Linsky, and (T. R. Ayres),

High Resolution, Far Ultraviolet Study of Beta Draconis (G2Ib - II):

Transition Region Structure and Energy Balance, Astrophys. J. (in

preparation)

.

*(Z. C. Kuruoglu) and D. A. Micha, Collision Dynamics of Three

Interacting Atoms, The Faddeev Equations in a Diabatic Electronic

Basis, J. Chem. Phys. (submitted).

*(J. A. Olson) and D. A. Micha, A Selfconsi stent Eikonal Treatment of

Diabatic Rearrangement, Model H + + H 2 Calculations, J. Chem. Phys.

( submitted)

.

(N. T. Padial) and D. W. Norcross, A Parameter-Free Free-Electron-Gas

Model of the Correlation Polarization Potential for Electron-Molecule

Collisions, Phys. Rev. A (in preparation)

.

(R. B. Christensen) and D. W. Norcross, Cross Sections for Electron

Impact Excitation of Li II, Phys. Rev. A (in preparation)

.

D. W. Norcross and (K. T. Taylor), Multichannel Photodetachment

Theory, Phys. Rev. A (in preparation)

.

D. W. Norcross and (K. T. Taylor), Photodetachment of K “, Phys. Rev. A

(in preparation)

.

D. W. Norcross, N. T. Padial, (T. N. Rescigno, A. E. Orel, A. U. Hazi,

and B. V. McKoy), Ro-Vib rational Excitation of HF By Electrons:

Differential, Momentum Transfer, and Energy Loss Cross Sections, Phys.

Rev. A (in preparation)

.

*J. Smak, Accretion in Cataclysmic Binaries. III. Helium Binaries,

Acta Astron. (submitted).

*J. Smak, Eruptive Binaries. XI. Disk-Radium Variations in U Gem,

Acta Astron. (submitted).

*J. Smak, Accretion Disks in Dwarf Novae, Astrophys. J. (submitted).

235
INVITED TALKS

Quantum Physics Division (525)

P. L. Bender, "Measuring Plate Tectonic Motions by Space Techniques,"

Physics Department Colloquium, Colorado State University, Fort

Collins, Colorado, September 13, 1982.

P. L. Bender, "Continental Drift Measurements via Laser Ranging," 13th

Winter Colloquium on Quantum Electronics, Snowbird, Utah, January 12,

1983.

P. L. Bender, "Geophysical Reasons for Monitoring Contemporary Plate

Motions," Workshop on Multidisciplinary Uses of the Very Long Baseline

Array, National Research Council, Washington, D. C., April 8, 1983.

G. H. Dunn, "Electron-Ion Collisions: A Menagerie for Atomic

Physics," National Bureau of Standards, Gai thersburg, Maryland,

December 1982.

G. H. Dunn, "Electron-Ion Collisions," Department of Physics,

University of Wisconsin, Madison, Wisconsin, December 1982.

G. H. Dunn, "Ion Traps: A Modern Tool for Atomic Physics," Department

of Physics, Colorado State University, Fort Collins, Colorado,

February 1983.

G. H. Dunn, "Electron-Ion Collisions: A Menagerie for Atomic Physics,

Physics Department, Denver University, Denver, Colorado, February 23,

1983.

G. H. Dunn, "Electron-Ion Collisions: Resonances," Invited paper at

the 1983 Gordon Conference on Atomic Physics, New London, New

Hampshire, July 4, 1983.

G. H. Dunn, "Dielectronic Recombination of Some Singly Charged Ions,"

Invited paper at XIII International Conference on the Physics of

Electronic and Atomic Collisions, West Berlin, August 1983.

G. H. Dunn, "Excitation, Ionization, and Recombination in Electron-Ion

Collisions," Invited paper. Symposium on Atomic Collision Data For

Diagnostics and Modelling of Fusion Plasmas," Nagoya, Japan, August

29, 1983.

J. E. Faller, "Introductory Remarks," 1983 International School and

Symposium on Precision Measurement and Gravity Experiment, Taipei,

Republic of China, January 24 - February 2, 1983.

236
INVITED TALKS

Quantum Physics Division (525)

J. E. Faller, "The Physics of Basketball: An Introduction to

Scientific Thinking," 1983 International School and Symposium on Precision Measurement and Gravity Experiment, Taipei, Republic of

China, January 24 - February 2, 1983.

J. E. Faller, "Telescopes and the Forces That Mold Them: An

Introduction to Optics and Mechanical Design," 1983 International

School and Symposium on Precision Measurement and Gravity Experiment,

Taipei, Republic of China, January 24 - February 2, 1983.

J. E. Faller, "Little "g": An Introduction to Dropping Things," 1983

International School and Symposium on Precision Measurement and

Gravity Experiment, Taipei, Republic of China, January 24 - February

2, 1983.

J. E. Faller, Y. G. Guo, T. M. Niebauer, and R. L. Rinker, "Promise

and Plans for the JILA Gravimeter," 1983 International School and

Symposium on Precision Measurement and Gravity Experiment, Taipei,

Republic of China, January 24 - February 2, 1983.

J. E. Faller and W. A. Koldewyn, "A Prototype Measurement of the

Newtonian Gravitational Constant Using an Active Magnetic Suspension

Torsion Fiber," 1983 International School and Symposium on Precision

Measurement and Gravity Experiment, Taipei, Republic of China, January

24 - February 2, 1983.

J. E. Faller, G. M. Keiser, and P. T. Keyser, "The Fluid-Fiber Based

Torsion Pendulum: An Alternative to Simply Getting a Bigger Hammer,"

1983 International School and Symposium on Precision Measurement and

Gravity Experiment, Taipei, Republic of China, January 24 - February

2, 1983.

I J E. Faller, "Two Experiments: The Measurement of g, and a Proposed

Experiment to Detect Gravity Waves in Space," Department of Physics,

Colorado State University, Fort Collins, Colorado, April 25, 1983.

J. E. Faller, "The JILA Absolute Gravimeter," Institute for Geodesy

and Geology, University of Vienna, Vienna, Austria, June 29, 1983.

J. E. Faller, "Modern Gravimetry," WILD Heerbrugg, Ltd., Heerbrugg,

Switzerland, July 1, 1983.

I

I I

237
INVITED TALKS

Quantum Physics Division (525)

J. E. Faller, "g and Eotv'ds Experiments: An Introduction to Dropping

Things," Research Advisory Committee Sponsored Talks on Precision

Measurements, NBS - Gai thersburg, Maryland, September 15, 1983.

Geltman, "Free-Free Transitions Near Feshbach Resonances," Max Planck

Institute for Quantum Optics, Garching, West Germany, June 8, 1983.

(L. Moll berg) and J. L. Hall, "Optically-Pumped Dimer Lasers as Stable

Optical Oscillators,' "Presented by L. Hollberg, Lasers 82 Conference,

New Orleans, Louisiana, December 1982.

(R. Blatt, W.Ertmer) and J. L. Hall, "Cooling of an Atomic Beam with

Frequency -Sweep Techniques," Workshop on Spectroscopic Application of

Slow Atomic Beams," NBS, Gaithersburg, Maryland, April 1983.

(W. Ertmer, R. Blatt) and J. L.Hall, "Some Candidate Atoms and Ions

for Frequency Standards Research Using Laser Radiative Cooling,"

Workshop on Spectroscopic Application of Slow Atomic Beams," NBS,

Gaithersburg, Maryland, April 1983.

J. L. Hall, (with Ch. Breant, T. Baer, and D. Nesbitt),

"State-Dependent Hyperfine Coupling of HF Studied With a Frequency-Control! ed Color-Center Laser Spectrometer," Sixth

International Conference on Laser Spectroscopy (SICOLS), Interlaken,

Switzerland, June 1983.

J. L. Hall, (with L. Hollberg), "Observation of Energy Level Shifts of

Rydberg Atoms Due to Thermal Fields," Sixth International Conference

on Laser Spectroscopy (SICOLS), Interlaken, Switzerland, June 1983.

J. L. Hall, (with L. Hollberg, Ma Long-Sheng, and M. Hohenstatt),

"Precision Measurements By Optical Heterodyne Techniques," presented

by L. Hollberg, SPIE Symposium on Ultra Sensitive Detection, San

Diego, August 1983.

J. L. Hall, "Frequency Stabilization of Tuneable Dye and Color Center

Lasers," 2nd International Conference on Lasers, Guangzhow, China,

September 6-10, 1983.

238
INVITED TALKS

Quantum Physics Division (525)

J. L. Hall, Five Lectures on laser wavelength metrology; progress

toward phase-stable lasers; reference lasers based on hard-sealed

He-Ne laser tubes; high sensitivity laser spectroscopy using of

sideband techniques; and cooling atomic beams using frequency-swept

laser sources, Beijing Institute of Opto-El ectronic Technology,

Beijing, China, September 19 - October 2, 1983.

S. R. Leone, "Laser and Infrared Chemiluminescence Studies of Ion

Chemistry," Air Force Geophysics Laboratory, Hanscom Air Force Base,

Massachusetts, October 1982.

S. R. Leone, "Laser Studies of Reactive Dynamics," Harvard/MIT

Seminar, Harvard University, Cambridge, Massachusetts, October 1982.

S. R. Leone, "Laser Studies of Chemical Dynamics," Department of

Chemistry Seminar, University of Denver, Denver, Colorado, November

1982.

S. R. Leone, "State-Detected Chemical Reaction Dynamics," National

Bureau of Standards, Chemical Physics Center Colloquium, December

1982.

S. R. Leone, "State-Detected Molecular Reaction Dynamics," Department

of Chemistry Colloquium, University of Wyoming, Laramie, Wyoming,

February 1983.

S. R. Leone, "State-Detected Molecular Reaction Dynamics:

Establishing the Relationship Between Reactivity and Energy Transfer,"

Department of Chemistry Colloquium, Northwestern University, Evanston,

Illinois, February 1983.

S. R. Leone, "Laser Studies of Free Radical Kinetics," Notre Dame

Radiation Laboratory, South Bend, Indiana, February 1983.

S. R. Leone, "State-Detected Molecular Reaction Dynamics:

Establishing the Relationship Between Reactivity and Energy Transfer,

Department of Chemistry Seminar, University of Southern California,

Los Angeles, California, April 1983.

S. R. Leone, "Vibrational Energy Disposal in Products of Ion-Molecule

Reactions," 1983 Conference on the Dynamics of Molecular Collisions,

Gull Lake, Minnesota, June 28, 1983.

239
INVITED TALKS

Quantum Physics Division (525)

S. R. Leone, "State-Specific T -* V,R and V -> R Energy Transfer," 8th

International Conference on Molecular Energy Transfer, Cirencester,

United Kingdom, July 5, 1983.

J. L. Linsky, "The Roles of Magnetic Fields in Stellar Chromospheres

and Transition Regions," Astrogeophysics Department, University of

Colorado, Boulder, Colorado, December 6, 1982.

J. L. Linsky, "Gyroresonant Microwave Emissions From Stellar Coronae,"

Physics Department, Johns Hopkins University, Baltimore, Maryland,

February 1, 1983.

J. L. Linsky, "The Outer Atmospheres of Stars: New Information From

X-Ray and Ultraviolet Observations," Physics Department, Johns Hopkins

University, Baltimore, Maryland, February 3, 1983.

J. L. Linsky, "Microwave Observations of Stars with the VLA:

Measuring Stellar Magnetic Fields with a Radio Telescope

Interferometer," National Membership Laboratory, NBS, Gaithersburg,

Maryland, February 4, 1983.

J. L. Linsky, "The 1980's: A Golden Age for Cool -Star Research,"

Division of Astronomical Sciences, National Science Foundation,

Washington, D. C., March 9, 1983.

J. L. Linsky, "What Ultraviolet, X-Ray, and Microwave Observations Are

Telling Us About Stellar Flares and Flare Stars," Armagh Observatory,

Armagh, N. Ireland, April 8, 1983.

J. L. Linsky, "The Roles of Magnetic Fields in Stellar Chromospheres

and Coronae," Armagh Observatory, Armagh, N. Ireland, April 8, 1983.

J. L. Linsky, "The Physical Nature of Winds and Flows in Cool Giants

and Supergiants," The Role of Ultraviolet Observations in Astronomy,

Cumberland Lodge, England, April 13, 1983.

J. L. Linsky, "What the VLA is Telling Us About Stellar Coronae," High

Altitude Observatory, NCAR. Boulder, Colorado, April 21, 1983.

J. L. Linsky, "Observations of RS CVn Systems: Evidence for

Variability, Atmospheric Inhomogeneities, Spots, Plages, and Flares,"

Third Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun,

Center for Astrophysics, Cambridge, Massachusetts, Gctober 5, 1983.

240
INVITED TALKS

Quantum Physics Division (525)

D. W. Norcross, "Theory and Computations for Electron Collisions with

Polar Molecules—Recent Progress," U. S. - Japan Seminar on Electron-Molecule Collisions and Molecular Photoionization Processes,

California Institute of Technology, October 26, 1982.

D. W. Norcross, "The Theory of Electron-Molecule Collisions,"

International Symposium on Molecular Scattering Theory and Quantum

Chemistry, University of Florida, Palm Coast, Florida, March 3-5,

1983.

D. W. Norcross, "Theoretical Progress on Electron Collisions with

Polar Molecules," Symposium on Wave Functions and Mechanisms from

Electron Scattering Processes, Villa Monte Cucco, Italy, July 24-25,

1983.

D. W. Norcross, "Overview of Asymptotic Methods," Workshop on Asymptotic Methods, London, England, December 19-20, 1983.

S. J. Smith, "Multi photon Ionization and Photoelectron Angular

Distributions from Highly Excited and Aligned Atomic States,"

Department of Physics, University of Wisconsin, October 1982.

241
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

P. L. Bender, Associate Editor, Physical Review Letters.

P. L. Bender, Member, Scientific Committee, 10th International

Conference on General Relativity and Gravitation.

P. L. Bender, Member, Working Group 1 on Recent Plate Movements and

Deformation, Inter-Union Commission on the Lithosphere.

P. L. Bender, Member, Crustal Dynamics Working Group, NASA.

P. L. Bender, Member, Section Committee, Physics Section, American

Association for the Advancement of Science.

G. H. Dunn, Member, IAEA Committee on Atomic Data For Fusion.

G. H. Dunn, Member, National Research Council Committee on Atomic and

Molecular Science.

G. H. Dunn, Member, Panel on New Instruments and Facilities in Atomic

and Molecular Science.

J. E. Faller, Member, Special Study Group 3.37 "Special Techniques of

Gravity Measurements," of the International Gravity Commission.

J. E. Faller, Member, Plans Committee of the Geodesy Section of the

AGU.

J. E. Faller, Member, Fellows Committee of the AGU, Chairman for

External Awards.

J. E. Faller, Member, Working Group II of the International Gravity

Commission.

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.

242
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

J. L. Hall, Member, Committee on Long Range Policy and Objectives,,

Optical Society of America.

J. L. Hall, Member, 1984 Meggers Award Committee, Optical Society of

America.

D. G. Humner, Member, Editorial Board, Computer Physics

Communications.

S. R. Leone, Co-Chairman, Gordon Conference on Molecular Energy

Transfer for 1985.

S. R. Leone, Editorial Advisory Board, Chemical Reviews, 1982 - 1985.

J. L. Linsky, Member, Kitt Peak National Observatory Users Committee,

Association of Universities for Research in Astronomy, Inc.

J. L. Linsky, Co-Investigator, ST (Space Telescope) High Resolution

Spectrograph Experiment.

J. L. Linsky, Member, Far Ultraviolet Spectrograph Explorer Working

Group, NASA.

J. L. Linsky, Member, National Solar Observatory Users Committee,

Association of Universities for Research in Astronomy, Inc.

J. L. Linsky, Member, Proposal Evaluation Committee for the

International Ultraviolet Explorer, NASA.

J. L. Linsky, Member, Editorial Board, Solar Physics.

J. L. Linsky, Member, International Organizing Committee for the

Eighth International Colloquium on EUY and X-Ray Spectroscopy of

Astrophysical and Laboratory Plasmas (August 27-29, 1984).

J. L. Linsky, Member, Organizing Committee for the Conference "IUE - Observing at the Limit," (August 15-17, 1983).

D. W. Norcross. Chairman, Local Committee for Annual Meeting of

Division of Electron and Atomic Physics, Boulder, Colorado, 1983.

D. W. Norcross, Member, Program Committee, Division of Electron and

Atomic Physics of the American Physical Society, 1981 - 1984.

243
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

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.

S. J. Smith, Member, Local Committee for Annual Meeting of Division of

Electron and Atomic Physics, Boulder, Colorado, 1982.

S. J. Smith, Member, Organizing Coranittee, Eighth International

Conference on Atomic Physics, Gotteburg, Sweden, 1983.

S. J. Smith, Member, Organizing Committee, Ninth International

Conference on Atomic Physics, Seattle 1984.

S. J. Smith, Chair, Fellowship Committee, Division of Electron and

Atomic Physics of the APS.

S. J. Smith, Co-Chairman, Third International Conference on Multiphoton Processes, Crete, September 1984.

S. J. Smith, Editorial Board, Metrologic.

244
CONSULTING

Quantum Physics Division (525)

P. L. Bender

Dr. Bender is consulting with the following:

the Geodynamics Branch at the Goddard Space Flight Center

concerning data analysis for the proposed Geopotential

Research Mission;

the University GPS Consortium concerning the accuracy of

determining tectonic motions with signals from the Global

Positioning System satellites; and

the Systems and Applications Section at the Jet Propulsion

Laboratory concerning the JPL part of the NASA Crustal

Dynamics Program.

S. Geltman

Dr. Geltman does consulting and advising with the Service

de Physique Atomique, CEN de Sac! ay, France, on problems

related to laser ionization of gases.

J. L. Hall

Dr. Hall is consulting with the Theoretical Astrophysics

Group at Cal Tech in the area of laser techniques for

gravity wave detection; and informally with colleagues in

industry involved with stable laser design and application.

D. G. Hummer

Dr. Hummer consults for the following:

X-ray laser project at Livermore and Los Alamos Labs, and

is one of three foreign consultants for the UK Collaborative

Computational Project on Stellar Atmospheres, sponsored by

the U. S. Science Research Council.

S. R. Leone

Dr, Leone has done informal consulting with the Air Force

Weapons Laboratory on lasers and laser chemistry.

245
CONSULTING

Quantum Physics Division (525)

J. L. Linsky

Dr. Linsky has consulted with the following:

the Association of Universities for Research in Astronomy,

Inc. (AURA)

concerning long term planning for stellar observations

with the McMath Solar Telescope, and

NASA and the National Academy of Sciences concerning the

proposed Far Ultraviolet Spectroscopic Explorer satellite.

D. W. Norcross

Dr. Norcross is consulting with the Theoretical Atomic and

Molecular Physics Group at Livermore Labs on problems

related to laser modeling and is a Visiting Scientist

(consultant) to Division T-4 of the Los Alamos Laboratories

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 charged

particle beam propagation. In the case of Lawrence

Livermore National Laboratories and Sandia National

Laboratories this has been formalized by the granting of

jointly funded support for a postdoc.

246
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

P. L. Bender

6. H. Dunn

J. E. Faller

January 10-11, 1983 - Washington, D. C.

Served on subcorrani ttee of the Physics Advisory

Committee of the National Science Foundation to

review the NSF Gravitational Physics Program.

Sponsor: National Science Foundation.

February 28 - March 2, 1983 - Greenbelt, Maryland.

Attended NASA Workshop on Spaceborne Gravity

Gradiometry.

Sponsor: Science Appl ications, Inc.

April 8, 1983 - Washington, D. C.

Attended Workshop on Multidisciplinary Uses of the

Very Long Baseline Array.

Sponsor: National Research Council.

May 12-13, 1983 - Washington, D. C.

Attended meeting of the Physics Advisory Committee of

the National Science Foundation where the review of

the NSF Gravitational Physics Program was completed.

Sponsor: National Science Foundation

December 1982 - Madison, Wisconsin.

Presented Physics Department Colloquium.

Sponsor: University of Wisconsin, Madison.

July 3-8, 1983 - New London, New Hampshire.

Attended Gordon Conference on Atomic Physics and gave

an invited paper.

Sponsor: Gordon Conference.

August 27 - September 3, 1983 - Nagoya, Japan.

Symposium on Atomic Collision Data for Diagnostics

and Modelling of Fusion Plasmas. IAEA Committee

Meeting on atomic data for fusion.

Sponsor: International Atomic Energy Agency.

January 24 - February 2, 1983 - Taipei, Taiwan

(China)

.

Participated in the PMGE (Precision Measurement and

Gravity Experiment) School and Symposium.

Sponsors: Ministry of Education, National Bureau of

Standards, National Tsing Hua University, & Academia

Sinica.

247
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

A. C. Gallagher

S. Geltman

J. L. Hall

February 24-25, 1983 - Madison, Wisconsin.

Presented a colloquium , "Watching Atoms Collide,"

Physics Department, University of Wisconsin.

Sponsor: University of Wisconsin.

March 8 - June 15, 1983 - Garching, West Germany.

Received Senior U. S. Scientist Award of the Humboldt

Foundation of the Federal Republic of Germany and

worked with Professor Walther at the Max Planck

Institute for Quantum Optics.

Sponsor: Humboldt Foundation of the Federal Republic

of Germany.

March 13-18, 1983 - Murray Hill, New Jersey.

Collaboration in measurement of optical energy levels

of positronium.

Sponsor: Bell Laboratories.

June 7-8, 1983 - Annapolis, Maryland.

Participated on Committee on Objectives and Policy

of the Optical Society of America and attended

lectures in the American Physical Society meeting in

Baltimore

Sponsor: Optical Society of America.

June 9-10, 1983 - Murray Hill, New Jersey.

Collaboration in measurement of optical energy levels

of positronium.

Sponsor: Bell Laboratories.

June 27 - July 1, 1983 - Interlaken, Switzerland.

To attend the Sixth International Conference on Laser

Spectroscopy (SICOLS) and to present an invited

lecture at the Conference.

Sponsor: (SICOLS) Conference Program Committee.

248
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

J. L. Hall

D. G. Hummer

S. R. Leone

September 19 - October 2, 1983 - Beijing, China.

To present, under UNESCO sponsorship, a series of

lectures on laser metrology and to interact with

the staff of the Laser Parameter Testing Center on a consultant basis.

To visit several other scientific labs in the

Beijing area including the Beijing Institute of

of Opto-Electronic Technology, Peking University,

and the National Institute of Metrology.

Sponsor: UNESCO.

December 28, 1982 - January 5, 1983 - Cambridge,

Massachusetts.

Worked with Dr. George Rybicki at the HarvardSmithsonian Center for Astrophysics on theory of line

formation in accretion disks.

Sponsor: Smithsonian Institution.

July 5-29, 1983 - London, England.

Consulted for U. K. Science Research Council and

worked at University College London with Drs. Storey

and Barlow on coll isional-radiation recombination

and applications to infrared lines of Wolf-Rayet

stars.

Sponsor: U.K. Science Research Council.

October 12-16, 1982 - Boston, Massachusetts.

Visited the Air Force Geophysics Laboratory and

presented a seminar entitled "Laser and Infrared

Chemiluminescence Studies of Ion Chemistry."

Sponsor: Air Force Geophysics Laboratory.

Visited Harvard/MIT and participated in a joint

seminar and presented a talk entitled "Laser Studies

of Reactive Dynamics."

Sponsor: Harvard/MIT.

February 1, 1983 - Laramie, Wyoming.

Visited the Chemistry Department of the University of

Wyoming and presented a seminar entitled "StateDetected Chemical Reaction Dynamics."

Sponsor: The University of Wyoming.

249
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

S. R. Leone

J. L. Linsky

February 3-5, 1983 - Chicago, Illinois.

Presented a talk to the Chemistry Department of

Northwestern University entitled "State-Detected

Molecular Reaction Dynamics: Establishing the

Relationship Between Reactivity and Energy Transfer."

Sponsor: Northwestern University.

February 23-25, 1983 - South Bend, Indiana.

Gave a seminar at the Notre Dame Radiation Laboratory

entitled "Laser Studies of Free Radical Kinetics."

Sponsor: The University of Notre Dame.

March 20-24, 1983 - Seattle, Washington.

Received the American Chemistry Society Nobel

Laureate Signature Award for Graduate Education in

Chemistry.

Sponsor: The J. T. Baker Company

April 14-17, 1983 - Los Angeles, California.

Visited The University of Southern California and

presented a chemistry colloquium entitled "StateDetected Molecular Reaction Dynamics: Establishing

the Relationship Between Reactivity and Energy

Transfer.

Sponsor: University of Southern California.

June 26 - July 10, 1983 - Gull Lake, Minnesota.

Attended and presented an invited talk at the

Conference on Dynamics of Molecular Collisions.

Sponsor: Conference on Dynamics of Molecular

Collisions in MW.

August 21-26, 1983 - Baltimore, Maryland.

Attended and presented an invited talk at the

Eleventh International Conference on Photochemistry.

Sponsor: Eleventh International Conference on Photochemistry.

December 9-10, 1982 - Sunspot, New Mexico.

Attended meeting of the National Solar Observatory

Users Committee.

Sponsor: Association of Universities for Research in

Astronomy, Inc.

250
J. L. Linsky

TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

January 3-5, 1983 - Tucson, Arizona.

Attended meeting of the Kitt Peak National

Observatory Users Committee.

Sponsor: Association of Universities for Research in

Astrononjy, Inc.

January 13-14, 1983 - Greenbelt, Maryland.

Attended meeting of the Far Ultraviolet Spectroscopic

Explorer Science Working Group.

Sponsor: ORI, Inc., a NASA Contractor.

January 17-18, 1983 - Greenbelt, Maryland.

Evaluation of proposals for observing time on the

International Ultraviolet Explorer satellite.

Sponsor: ORI, Inc., a NASA Contractor.

February 1-7, 1983 - Greenbelt, Maryland.

Observations with the International Ultraviolet

Explorer Satell ite.

Sponsor: ORI, Inc., a NASA Contractor.

March 8, 1983 - Washington, D. C.

Made presentation to the Committee on Space Astronomy

and Astrophysics.

Sponsor: National Academy of Sciences.

April 7-10, 1983 - Armagh, N. Ireland.

Presented invited colloquia and consulted with

members of the Observatory staff.

Sponsor: Armagh Observatory.

July 5-8, 1983 - Annapolis, Maryland.

Attended meeting of the Far Ultraviolet Spectroscopic

Explorer Science Working Group.

Sponsor: ORI, Inc., a NASA Contractor.

July 21, 1983 - Greenbelt, Maryland.

Attended meeting of the Far Ultraviolet Spectroscopic

Explorer Science Working Group.

Sponsor: ORI, Inc., a NASA Contractor.

251
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

J. L. Linsky

D. W. Norcross

A. V. Phelps

July 22, 1983 - Sunspot, New Mexico.

Attended meeting of the National Solar Observatory

Users Committee.

Sponsor: Association of Universities for Research in

Astronomy, Inc.

August 17-18, 1983 - Tucson, Arizona.

Attended meeting of the Kitt Peak National

Observatory Users Committee.

Sponsor: Association of Universities for Research in

Astronomy, Inc.

October 26-29, 1982 - Pasadena, California.

Attended the United States-Oapan seminar on ElectronMolecule Collisions and Molecular Photoionization

Processes.

Sponsor: California Institute of Technology.

March 3-5, 1983 - Palm Coast, Florida.

Attended the International Symposium on Molecular

Scattering Theory and Quantum Chemistry and gave an invited talk.

Sponsor: University of Florida.

December 19-20, 1983 - London, England.

To attend a meeting of the Working Group supervising

Collaborative Computational Project 2 (Continuum

States of Atoms and Molecules), the Workshop on Asymptotic Methods, and to give an invited talk at

the latter.

Sponsor: U. K. Science and Engineering Research

Council

November 8-10, 1982 - Washington, D.C.

Participated in workshop on Nuclear Lightning and

presented a paper at the Naval Research Lab.

Sponsor: Naval Research Lab.

March 14-16, 1983 - Washington, D. C.

Participated in a workshop on the Relativistic

Electron Beam Heating of Air and presented a paper.

Sponsor: Lawrence Livermore Labs.

252
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

A. V. Phelps

S. J. Smith

July 7-8, 1983 - Albuquerque, New Mexico.

Consulted with Sandia National Laboratories.

Sponsor: Sandia National Laboratories.

October 7-9, 1982 - Madison, Wisconsin.

Gave a Physics Department Colloquium on the subject

of Multiphoton Ionization and Photoelectron Angular

Distributions from Highly Excited and Aligned Atomic

States.

Sponsor: University of Wisconsin.

April 20 - 22, 1983 - Knoxville, Tennessee.

Attended workshop on atomic and molecular physics.

Sponsor: Department of Energy.

June 1 - September 30, 1983 - Munich, West Germany.

Collaborated with Professor Dr. H. Walther, a Director of the Max Planck Institute for Quantum

Optics, and a Professor at the University of Munich,

and with Dr. G. Leuchs, University of Munich, in an experimental study of multi photon processes, using

lasers, leading to ionization in an atomic potassium

beam.

Sponsor: NSF

253
SPONSORED CONFERENCES

Quantum Physics Division (525)

Fourteenth Annual Meeting of Division of Electron and Atomic Physics

of the American Physical Society, May 23-25, 1983, at JILA. David W.

Norcross was the local Chairman.

254
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Informal Seminars

Name/Aff i 1 iati on/Ti tl e/Date

W. Michaelis (Physikali sch-Technische Bundsanstal t, W. Germany) - PTB's Work on G, October 19, 1982.

Teiichiro Ogawa (Kyushu University, Japan) - Translational Energy

Distributions and Production Mechanisms of the Excited Hydrogen Atom

Produced in Controlled Electron Impact on Water and Methane,

November 1, 1982.

Ove Poulsen (University of Aarhus, Denmark) - Resonant Laser/FastBeam Interactions: Saturated Absorption and Two-Photon Absorption,

November 11, 1982.

Nancy D. Pi 1 tch (University of Arizona) - Molecular Ion Spectroscopy,

November 12, 1982.

Alan R. Johnston (University of Nebraska, Lincoln) - Near Threshold

Excitation of He( ) by Electron Impact, November 23, 1982.

David Abbott (JILA) - Monte Carlo Calculations: Early-Type Stars and

the Wolf-Rayet Phenomenon, December 13, 1982.

Tom Stephenson (University of Chicago) - Vibrational State

Dependence of Intersystem Crossing Rates in Benzene,

January 10, 1983.

John Prodan (NBS, Gaithersburg) - Informal Talk about Atom Cooling

Experiments at NBSG, February 8, 1983.

Mike Simon (SUNY, Stony Brook) - Infrared and Radio Observations

of Regions of Star Formation, February 11, 1983.

Steve Strom (Kitt Peak National Observatory) - Herbig-Haro Objects,

February 14, 1983.

Harvey Tananbaum (Center for Astrophysics, Harvard) - Quasars,

February 14, 1983.

Roberta Humphreys (University of Minnesota) - The Brightest Stars

as Extragalactic Distance Indicators, February 28, 1983.

255
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Informal Seminars (continued)

Name/Affi 1 i ati on/Ti tl e/Date

William 6. Harter (Georgia Tech) - What Good Are Molecular

Constants? Order and Disorder in Rotor Dynamics, March 17, 1983.

Peter Zoller ( JILA Visiting Fellow) - Configuration Interaction

and Multi photon Ionization, April 7, 1983.

Pat Palmer (Chicago) - VLA Line Work, April 19, 1983.

Michael J. Seaton (University College London) - Quantum Theory of

Di-Electronic Recombination, April 21, 1983.

Steye Beckwith (Cornell University) - Speckle Interferometric

Studies of Mass Loss from Red Giants and Carbon Stars,

April 26, 1983.

Robert Field (Massachusetts Institute of Technology) - Does

Ligand Field Theory Work for Diatomic Molecules?, May 2, 1983.

Dan Kerner - (Visitor) Atomic Photoionization Cross Section:

Timedependent Picture, May 5, 1983.

Anthony F. Starace (University of Nebraska, Lincoln) - Hyperspherical Coordinate Description of Two Electron Systems,

May 19, 1983.

David Bates (Queen's University, Belfast) - The Oxygen Green Line

in the Nightglow, May 26, 1983; The Formation of Molecules in

Interstellar Clouds by Radiative Association, May 27, 1983.

256
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Seminars

Name/Affi 1 i ati on/Date

A. R. Ravishankara (Georgia Tech) - October 1, 1982.

L. Yiehland (St. Louis Univ.) - October 8, 1982.

F. Kaufman (Univ. of Pittsburgh) - October 22, 1982.

D. Herrick (Univ. of Oregon) - October 29, 1982.

W. Farneth (Univ. of Minnesota) - November 5, 1982.

M. Durup (Orsay) - November 12, 1982.

T. D. Lee (Columbia Univ.) Franz Mohling Memorial Lecture

November 19, 1982.

F. Crim (Univ. of Wisconsin) - December 3, 1982.

C. Wittig (Univ. of Southern Calif.) - December 10, 1982.

N. Lane (Rice Univ.) - December 17, 1982.

S. E. Harris (Stanford Univ.) - January 28, 1983.

R. Saykally (Berkeley) - February 4, 1983.

D. Brenner (Aerospace Corp.) - February 11, 1983.

R. Curl (Rice Univ.) - February 18, 1983.

D. J. Nesbitt (Berkeley) - February 25, 1983.

B. E. Kohler (Wesleyan Univ.) - March 4, 1983.

P. C. Engel king (Oregon) - March 11, 1983.

R. Hall (Exxon) - March 18, 1983.

D. Spence (Argonne) - April 1, 1983.

A. C. Parr (NBS) - April 8, 1983.

257
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Seminar

Name/Affi 1 i ati on/Date

G. B. Bjorkland (IBM) - April 15, 1983.

L. B. Harding (Argonne) - April 22, 1983.

J. I. Steinfeld (MIT) - April 29, 1983.

W. C. Lineberger (Univ. of Colorado) - May 6, 1983.

J. Bowman (Illinois Institute of Technology) - September 9, 1983.

W. P. Reinhardt (Univ. of Colorado) - September 23, 1983.

B. Kay (Sandia National laboratory) - September 30, 1983.

258
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

JILA Colloquium Speakers

Name/Affi 1

i

ati on/Ti tl e/Date

Peter Zoller (JILA Visiting Fellow) - Light Statistics and Multiphoton

Processes, September 29, 1982.

Judah Levine (JILA Fellow) - An Introduction to Terrestrial

Acupuncture, October 19, 1982.

James Faller (JILA Fellow) - Old Gravity, a New Tool for Geophysics,

October 26, 1982.

Hartmut Schmidt (University of California, Berkeley) - Preparation of

Molecular States in an Ion-Atom Crossed-Beam Scattering Experiment by

Laser Excitation, November 2, 1982.

Peter Bender (JILA Fellow) - Ocean Currents and Worldwide Gravity From

Satellite Data, November 9, 1982.

Peter L. Knight (Imperial College, London) - Turning Off Spontaneous

Decay, November 16, 1982.

Richard N. Zare (Stanford University) - Studies of State to State

Chemistry, November 30, 1982.

Neil Lane (Rice University) - On the Threshold of Excitation:

Theoretical Studies of Inelastic Electronic and Atomic Collision

Processes, December 14, 1982.

S. Prasad (Harvard University) - Superfluorescence: Its Initiation in

a Large Spherical Sample, February 22, 1983.

Laurent Levy (Cornell University) - NMR Studies in Spin Polarized

Hydrogen, March 1, 1983.

Tom Baer (Spectra Physics, Inc.) - Nuclear Motion and the Hyperfine

Coupling Constants in Hydrogen-Fl uoride, March 7, 1983.

James Hough (JILA Visiting Fellow) - Laser Interferometers for

Gravitational Wave Detection — Current Status and Future Prospects,

March 16, 1983.

259
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

JILA Colloquium Speakers

Name/Affil iati on/T i tl e/Date

Nils Andersen (JILA Visiting Fellow) - Studies of Excitation in Simple

Collision Systems, March 29, 1983.

Bret Cannon (Cambridge University, England) - V-V and V-T Relaxation

in HCN(Oll) and HCN(lOl), April 12, 1983.

David A. Micha (JILA Visiting Fellow) - Scattering of Atoms by

Many-Atom Systems, April 12, 1983.

Wilmer Anderson (University of Wisconsin) - Charge Changing and

Excitation Collisions with Alkali Atom Targets, April 19, 1983.

David L. Ederer (National Bureau of Standards) - Photoionization from

Laser Excited States by Synchrotron Radiation, April 26, 1983.

Robert Field (Massachusetts Institute of Technology) - Simulated

Emission Spectroscopy: Intramolecular Vibrational Redistribution in

li>C0 and HCCN?, May 1983.

260
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Duncan, M. A.

Dunn, G. H.

Faller, J. E.

Gallagher, A.

University and Department Committees Served On

NBS Laser Safety Committee

Graduate Committee, Department of Physics

JILA Executive Committee

JILA Shops Committee

JILA Data Center Advisory Committee

Member, several thesis & examinations committees

NML EEO Coordinator

Chairman, JILA Shops Committee

C. JILA Space Committee

Thesis Committees for:

Mike Hale

(Chemistry Department, University of Colorado)

Joe Alford

(Physics Department, University of Colorado)

S. Davidson

(Physics Department, University of Colorado)

M. O'Callaghan

(Physics Department, University of Colorado)

R. Robertson

(Physics Department, University of Colorado)

H. Chatham

(Physics Department, University of Colorado)

261
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Geltman, S.

Hall, J. L.

Hummer, D. G.

University and Department Committees Served On

Secretary for JILA Visiting Scientists Program

JILA Executive Committee

Chairman of Thesis Committee,

Stanley L. Haan

(Physics Department, University of Colorado)

Thesis Committees for:

L. Hollberg

(Physics Department, University of Colorado)

M. D. Rayman

(Physics Department, University of Colorado)

Zhu Miao

(Physics Department, University of Colorado)

Thesis Committees for:

Douglas Perry

(Astro-Geophysics Department, University of

Colorado)

Douglas Carroll

(Physics Department, University of Colorado)

Bob Russell

(Astro-Geophysics Department, University of

Colorado)

Ana Torres

(Astro-Geophysics Department, University of

Colorado)

Steve McCandless

(Astro-Geophysics Department, University of

Col orado)

262
Name

Hummer, D. G

Leone, S. R.

L insky, J. L.

Norcross, D.

OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

University and Department Committees Served On

Thesis Committe for:

Dan Kerner

(Chemistry Department, University of Colorado)

Chairman, JILA Computing Committee

Comprehensive Exam Committee, Department of

Astro-Geophysics, University of Colorado

Selection Committee - Junior Faculty Development

Awards, University of Colorado

Search Committee - Department of Chemistry,

University of Colorado

NBS Research Advisory Conmittee

Thesis Committees for:

P. L. Bornmann

(Astro-Geophysics Department, University of

Colorado)

S. Saar

(Astro-Geophysics Department, University of

Colorado)

N. Marstad

(Astro-Geophysics Department, University of

Col orado)

M. Schindler

(Astro-Geophysics Department, University of

Col orado)

W. JILA Executive Comnittee - through

December 1982.

263
Name

Norcross, D.

Phelps, A. V.

Smith, S. J.

OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

University and Department Committees Served On

W. Chairman of JILA - January 1983 - December 1984

Preliminary Exam Committee, Department of

Physics, University of Colorado

Thesis Committee,

M. A. Smith

(Chemistry Department, University of Colorado)

JILA Data Center Advisory Committee

Thesis Committees for:

V. F. Benage, Jr.

(Physics Department, University of Colorado)

R. H. Chatham, III.

(Physics Department, University of Colorado)

R. M. Robertson

(Physics Department, University of Colorado)

R. E. Rodenburg

(Physics Department, University of Colorado)

R. A. Swanson

(Astro-Geophysics Department, University of

Colorado)

H. E. Evans

(Astro-Geophysics Department, University of

Colorado)

JILA Executive Committee

Chemical Physics Committee, Department of Physics,

University of Colorado

Chairperson, Search Committee for Joint

JILA-Department of Physics Position in

Experimental Physics.

264
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Postdoctoral Research

Name

Graduate Students

Supervised

Associates

Supervi sed

Bender, P. L. J. E. A! wood M. A. Vincent

Dunn, G. H. S. Barlow D. Bel ic

M. Schauer

K. Timmer

D. Muell er

Faller, J. E. P. Keyser

T. Niebauer

B. Rinker

J. Xue

(NRC)-d. K. Hoskins

Gallagher, A. C. H. Chatham D. Hi! s

Geltman, S.

S. Davidson

R. Robertson

M. O'Callaghan

S. Haan

B. Stumpf

Hall, J. L. L. Hoi 1 berg

M. Rayman

R. Blatt (DFG,

West Germany)

M. Zhu W. Ertmer (DFG,

West Germany)

Chr. Breant

M. Long-Sheng

(Visiting Prof,

from PRC)

(NRC)-P. Nachman

T. Ohta (Visiting

Prof, from

Kyoto)

Hummer, D. G. D. Carroll

Birte ChristensenDal sgaard

R. Russell

D. C. Abbott

265
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Graduate Students

Supervi sed

Postdoctoral Research

Associates

Supervised

Leone, S. R. (NSF Fellowship) -K. Carleton V. Bierbaum (25%)

D. Guyer (NRC)-D. Do! son

M. Hale (NRC)-M. Duncan

(NSF Fellowship) -C. Hamilton H. Haugen

L. Kovalenko L. Huwel (Max Planck

G. H. Lin Fellowship)

J. Smedley C. Wight

M. Smith A. Langford

Linsky, J. L. P. Bornmann A. Brown

B. Gross K. Carpenter

N. Marstad S. Drake

S. Saar R. Hammer

M. Schindler F. Walter

Norcross, D. W. B. Christensen- F. da Paixao

Dal sgaard A. Jain

N. Padial

Phelps, A. V. S. J. Buckman

M. A. Islam

H. Tischer

P. A. Vicharelli

Smith, S. J. K. Arnett D. Elliott

M. Hamilton

N. D. Pi Itch

266
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Bender, P. L.

Gallagher, A. C.

Geltman, S.

Hummer, D. G.

Leone, S. R.

Norcross, 0. W.

Smith, S. J.

Courses Taught at the University of Colorado

Physics 451 - Modern Optics (Fall 1983)

Physics 695 - Collisional Line Shapes (Fall 1982)

Physics 695 - Collisional Line Shapes (Fall 1983)

Recitation - Physics 111 (Fall 1982)

Radiative Transfer AG-515 (Spring 1983)

Chemistry 550 - Chemical Dynamics (Spring 1983)

Recitation - Physics 111 (Fall 1982)

Recitation - Physics 111 (Fall 1983)

Physics 332 (Fall 1982)

267
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Bender, P.

Conti, P.

Cooper, J & Burnett, K.

Cooper, J.

Faller, J.

Gallagher, J.

(Data Center)

Scientists Working at JILA on Sabbatical or Other Leave (other than Visiting Fellows)

Bruno Bertotti

Pavia, Italy

Phil Massey

DAO

Canada

A. Tutukov

Moscow

U.S.S.R.

G. Wallerstein

University of Washington

Seattle, WA

Christian S. Diatta

Faculte des Sciences

Universite de Dakar-Fann

Senegal

P. L. Knight

Imperial College

Engl and

B. J. O' Mara

University of Queensland

St. Lucia

Queensland, Australia 4067

Y Guo

Nim

China

Tsuneya Tsubokawa

International Latitude Observatory

Mizusawa-Shi, Iwate-Ken 023

Japan

C. E. Brion

The University of British Columbia

Vancouver, B. C. Canada
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Gallagher, J.

(Data Center)

Garstang, R.

Geltman, S.

Hall, J.

Scientists Working at JILA on Sabbatical or Other Leave (other than Visiting Fellows)

D. W. 0. Heddle

Royal Holloway College

University of London

Engl and

Peter W. Langhoff

Indiana University

Bloomington, IN

J. Rumble

NBS-Gaithersburg

J. I. Steinfeld

MIT

Cambridge, MA 02139

Alf Litzen

Lund Sweden

G. Leuchs

University Munchen

West Germany

Rainer Blatt

Johannes Gutenberg Universitat

West Germany

Christian Breant

Labortoire de Physique des Lasers

Universite Paris-Ncrde

France

Wolfgang Albert Ertmer

Institute fur Argewandte Physik

der Universitat Bonn

West Germany

Ma Long-Sheng

East China Normal University

Shanghai

People's Republic of China

269
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name Scientists Working at JILA on Sabbatical or Other Leave (other than Visiting Fellows)

Hall, J. Tatehisa Ohta

Doshisha University

Kyoto 602

Japan

Hummer, D. Birte Christensen-Dal sgaard

University of Aarhus

Aarhus

Denmark

Leone, S. Robert Klein

Institut f. Anorg. Chemie

der j. W. Goethe-Universitat

West Germany

Levine, J. Hirokazu Matsumoto

National Research Laboratory of Metrology

Ibaraki 305, Japan

Koichi Tsukahara

Crustal Dynamics Department

Geophysical Survey Institute

Ministry of Construction

Tsukuba-Gun, Ibaraki-Ken, 305

Japan

L insky, J. Carole Jordan

Oxford University

Oxford, England

Theodore Simon

Institute for Astronomy

University of Hawaii

Honolulu, HI 96822

Robert Stencel

NASA Headquarters

Washington, D. C.

270
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Linsky, J.

Norcross, D.

Smith, S.

Toomre, J.

Scientists Working At JILA on Sabbatical or Other Leave (other than Visiting Fellows)

Dominic Zarro

Australian National University

Canberra, Australia

M. J. Seaton

University College London

London, England

Gerhard Leuchs

University Munchen

West Germany

Douglas 0. Gough

Institute of Astronomy

Cambridge, England

Frank Hill

Sac Peak Observatory

271

NBS-1MA iwev. »-»c> U.S. DEPT, or COMM.

BIBLIOGRAPHIC DATA

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1 . PUBLICATION OR

REPORT NO.

NBSIR-83/2793

2. Performing Organ. Report No. 1 . Publication Date

4. TITLE AND SUBTITLE

Technical Activities 1983

*

. Center for Basic Standards

. —

5. AUTHOR(S)

Karl G. Kessler

€. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

f 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 1. Type of Report & Period Covered

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1 | Document describes a computer protram; SF-IB5, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less foctuol summary of most significant Information. If document includes a significant

bibliography or literature survey, mention it here)

This report is Part II t>f the 1983 Annual Report of the Center for Basic

Standards and contains a summary -of the technical activities of the Center

for the period October 1, 1982 to September 30, 1983. The Center is one

of the five resources ^and operating units in the National Measurement

Laboratory.

12. KEY WORDS (Si* to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Astrophysi cs ; atomic and molecular 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 gamma13. availability ray wavelength s tandards

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