AiilOl 5 bs 4s 3LICATIONS

NBSIR 81 -2391

Technical Activities 1981

Center for Absolute Physical

Quantities

aHHHtr «mana

U.S. DEPARTMENT OF COMMERCE

National Bureau of Stanoards

National Measurement Laboratory

Center tor Absolute p hysicai Quantities

Washington, DC 20234

November 1 981

100

U56

181-2391

1981

C , 2

for: APARTMENT OF COMMERCE

if Bureau of Standards

gton, DC 20234

NATIONAL BUREAU

OF STANDARDS

LIBRARY JUN 1 1983

NBSIR 81-2391

TECHNICAL ACTIVITIES 1981

CENTER FOR ABSOLUTE PHYSICAL

QUANTITIES

Karl G. Kessler, Director

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Absolute Physical Quantities

Washington, DC 20234

November 1 981

Prepared for: U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Director

ABSTRACT

This report summarizes research projects, measurement method development, calibration and data evaluation activities carried during Fiscal

Year 1981 in the NBS Center for Absolute Physical Quantities. These

activities fall in the areas of: quantum metrology; measurements and

standards for the electrical units, temperature and pressure, length and

mass, time and frequency; and quantum physics.

Key words: Electrical measurements and standards; length and mass measurements and standards; temperature and pressure measurements and

standards; time and frequency; quantum metrology; quantum physics.
II1III{
TABLE OF CONTENTS

Part II Page

Abstract ii

Technical Activities:

Introduction 1

Center Office 2

Quantum Metrology Group 4

Electrical Measurements and Standards Division 24

Temperature and Pressure Measurements and Standards

Division 67

Length and Mass Measurements and Standards Division .... 97

Time and Frequency Division 107

Quantum Physics Division 127

INTRODUCTION

This book is Part II of the 1981 Annual Report of the Center for

Absolute Physical Quantities and contains a summary of the technical

activities of the Center for the period October 1, 1980 to September 30, 1981.

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 Absolute Physical Quantities, B160 Physics

Building, National Bureau of Standards, Washington, D.C. 20234.

1
I*1IIII
.otoabsorption

v. A.

.y. Committee on Arrangej. 1 Fiber Communication Journal,

executive Committee, Optical

Society of America, Publications

.cative. Consultative Committee for the

, American Institute of Physics Publishing Policy

2

CENTER OFFICE

SUMMARY OF ACTIVITIES

Fiscal Year 1981

The Center Office includes two scientists who, in addition to their

administrative support function also engage in a variety of technical

activities.

Mr. John W. Cooper provides theoretical assistance within the

Center and in other Centers to experimental groups working in the area

of atomic physics. He provides suggestions for key experiments to be

performed using current resources, assists in the planning and carrying

out of such experiments and provides interpretations and supporting

cal cul ations

.

As a part of his duties as assistant to the Center Director,

Dr. W.G. Schweitzer provides collaborative support to the Length and

Mass Measurements and Standards Division in the area of laser technology,

laser spectroscopy and precise laser wavelengths for standards in

metrology and spectroscopy.

PUBLICATIONS

Submitted

G. Mehlman, J.W. Cooper and E.B. Saloman, "The Absolute Photoabsorption

Cross Section of the K Shell of Atomic Li thium," Phys. Rev. A.

COMMITTEE MEMBERSHIPS

K. G. Kessler, Chairman, American Physical Society, Committee on Arrangements, Washington Meeting.

K. G. Kessler, Chairman, Committee on Optical Fiber Communication Journal,

Optical Society of America.

K. G. Kessler, Board of Directors and Executive Committee, Optical

Society of America.

K. G. Kessler, Chairman, Optical Society of America, Publications

Committee.

K. G. Kessler, NBS representati ve. Consultative Committee for the

Definition of the Meter.

K. G. Kessler, member, American Institute of Physics Publishing Policy

Committee.

2
II1IIil*
K. G. Kessler, Representative for the OSA to the AAAS Consortium of

Affiliates for International Programs.

K. G. Kessler, member, Commission 14, International Astronomical Union.

J. W. Cooper, member. Atomic & Nuclear Data, Editorial Board.

3
11iII\
.ethod

.ol ishache

>1 ven work in this

unfortunate from

serious. Related

.-riments and on the

iti nue at a low! evel

j guest worker in the

jll into the areas of X-ray

in the y-ray and X-ray regions,

port, more noticeable output and

nonetheless not free of problems and

4

QUANTUM METROLOGY GROUP

SUMMARY OF ACTIVITIES

FISCAL YEAR 1981

I OVERVIEW

The year just past was one involving both temporary arrangements

and appreciable change. R. Deslattes was largely absent while serving

as Director of NSF's Physics Division. Various patterns of periodic

and continuous contact were attempted through the year. Main management responsi bi 1 i ty fell to E_;_ Kessl er while J_;_ Snyder was assigned

interim responsi bi 1 i ty for work in the gravity and laser areas.

Work in the Quantum Metrology Group remains diverse but is of

diminishing range owing to staff reduction, loss of a hi re-i n-progress

and lowered expectations. Efforts in the area of spectra from laboratory and astrophysi cal plasmas have been terminated (with loss of one staff person) except for a small, short-term guest worker manned

project to complete an externally funded study of laser produced

plasmas. In the area of laser spectroscopy of H and He, a planned new

hire was halted by the inauguration, a staff member was eliminated by

the RIF procedure, and a part-time person is on extended 1 eave-wi thoutpay. The one remaining staff person in this general area ( Snyder) has

been involved in the development of radiofrequency and laser wavelength

measurement technology. Scientific opportunities which led to the

laser effort remain valid while it is still to be seen whether a future

regeneration becomes possible.

As will be described in more detail below, the Gravitational

Constant work of Luther (NBS) and Towl er (University of Virginia) has come to a terminus of sorts. They have succeeded in obtaining a significant new result on "G" but without exploiting the "Beams" method

on which our work has been alleged to be based. Instead, the publishable material from this long effort represents a repetition of the

"perturbed period" work of Heyl and Heyl and Chrzanowski . Given

present austerity, it seems inappropriate to give further work in this

direction high priority. Such a termination is mildly unfortunate from

an aesthetic point of view but probably not otherwise serious. Related

work on ancillaries for gravitational radiation experiments and on the

conceptual limits of measurement will probably continue at a low level

in the former case and with the aid of a retired guest worker in the

1 atter

The remaining efforts of the Group fall into the areas of X-ray

spectroscopy and precision measurement in the y-ray and X-ray regions.

These efforts have enjoyed better support, more noticeable output and

less personnel attrition; they are nonetheless not free of problems and

4
constraints. In the area of qualitative spectroscopy , we had a singularly successful run at the Stanford Synchrotron Radiation Laboratory

early this summer which is still to be put in publishable form. Our

main effort focusses on preparations for experiments at Brookhaven's

National Synchrotron Light Source (NSLS). Our work, to which P, Cowan

has been the principal contributor, goes more slowly than desirable but

is not behind other comparable efforts and work on the NSLS itself.

The main area in which one can see continued technical growth,

good results and outstanding future opportunities is that of precision

X-ray and y-ray studies. The principal person involved is E. Kessler,

who was joined this past year by Dominique Girard who came as a guest

worker under CNRS sponsorship. Among accomplishments to date one finds new results on pion and kaon masses, tests of QED in muonic atoms and

of relativistic SCF calculations in normal atoms. There is an approved

Y-ray experiment at Grenoble and a proposal (jointly with Oxford) for

work on stripped atom X-rays at Darmstadt. There is a successful

double flat crystal Van de Graaff program at completion and a newly

commissioned 4 meter DuMond instrument. There is even controversy

since our colleagues at PTB have this year succeeded in an independent

X-ray/optical i nterferometer measurement of a Si crystal that appears

discrepant with ours from long ago. This needs investigation and

understanding since it underlies our entire measurement chain from the

visible to y-ray region.

5
II. TECHNICAL ACTIVITIES

1. X-ray Diagnostics of Laboratory and Astrophysical Plasmas

A. Burek

Objectives

This project applies crystal diffraction theory and technology to

the study of X-ray spectra from laboratory and astrophysical plasmas.

In particular we have been involved in optimizing efficiency and

resolution in instrument design and crystal utilization. We provide

state-of-the-art calibration to help secure maximum scientific return

and explore new approaches including development of geometries and

diffraction systems having characteri sties not available otherwise.

Current Act i v i t i es

Effort in this area was prompted by a contract from NASA via

Lockheed to develop technology for and proceed with X-ray radiometric

and diffraction optics calibration of a large number of large aperture

flat and curved crystals to be used as dispersing elements in a high

resolution X-ray polychromator to study solar flares. Now that the

Solar Maximum Mission (SMM) is in orbit and returning high quality Xray spectra, we worked with the SMM team on various aspects regarding

the applications of crystal calibration to the analysis of data. These

activities involved development of ray tracing techniques for experimentally determined curved crystal figures, development of methods for

deconvolving instrument functions from observed spectra and evaluation

of effects of off-axis reflections. As part of a Guest Investigator

Program funded by NASA, an observing program was defined and incorporated in the mission sequence that will study the evolution of hot

plasma in magnetically confined coronal loops. This observing program

utilizes certain unique features of the physics of anomalous X-ray

Bragg diffraction near absorption edges in crystals to obtain plasma

diagnostic information not otherwise possible. A comp! ementary laboratory study and theoretical modeling of Bragg diffraction from resonant

bound states in crystals has been completed.

The calibration exercise for SMM generated a large amount of data

concerning the X-ray radiometric and diffraction properties of real

crystals that is of importance to workers in the plasma physics and

synchrotron radiation communities. The compilation and extension of

this data is being prepared for publication.

We pursued the development of novel crystal dispersing elements

and devoted some time to the problem of fabricating large lithium

fluoride panels for a space experiment. We also investigated the

application of epitaxially grown heavy metal crystals and multilayer

structures to monochromator construction. Development of such dispersing elements would dramatically decrease the expense and enhance the

prospects for high resolution X-ray spectroscopy of X-ray stars.

6
Finally, a proposal to DOE for the development of efficient

crystal spectrometers and X-ray i nterferometers for inertially confined

plasma studies was funded. Although planning and crystal calibration

have occurred, the work is being transferred to the University of

Rochester due to a reduction-in-force

.

Accompl i shments

We have continued to work with the SMM team on various aspects of

data analysis and have provided X-ray calibration data to a number of

other groups in the X-ray astronomy and plasma physics communities. A

paper applying X-ray calibration techniques to the analysis of high

resolution solar X-ray data has been published in the Astrophysical

Journal

.

Preparations for X-ray diagnostics of laboratory plasmas have been

made.

Future PI ans

Because of reduction in staff, all work on X-ray diagnostics of

laboratory and astrophysical plasmas has been discontinued.

7
2. Optical Physics

J. Snyder, H. Holt (60%)

Objectives

This program is concerned chiefly with theoretical and experimental

laser spectroscopy and the development of related technology.

Current Activities

The experimental collaboration with the Molecular Spectroscopy

Division in the Center for Chemical Physics continues, albeit slowly

because of the increased administrative responsibilities of the collaborators. This situation has eased recently, and we hope for a more

active program in the coming year. The collaboration involves the

application of recently developed techniques for high-sensitivity

saturated absorption spectroscopy to the systematic study of simple

molecules using a tunable cw dye laser. The new wavelength-measuring

technology will also be of major importance in this work.

The original Fizeau Wavemeter is currently being used to evaluate

the long-term instrumental accuracy, and to further improve the software.

This instrument is also seeing occasional use for measuring wavelengths

in some experimental studies in the Molecular Spectroscopy Division.

A second Fizeau Wavemeter is presently under development for

eventual use in a collaborative effort at the University of Maryland.

This instrument will be used on-line to determine the wavelength of

coherent uv light generated by mixing tunable pulsed dye laser radiation

with quadrupled YAG radiation. It is optimized for pulsed applications,

and has been configured for easy interfacing with any small computer.

A guest worker from the University of Maryland has been working here on the new instrument since spring. At the present time, construction of

this Wavemeter is complete, and we are in the midst of calibrating the

instrument against a uranium hollow cathode spectrum.

Work on a third Wavemeter has been initiated in collaboration with

the Instrument Development Group of the Center for Analytical Chemistry.

This device is being interfaced to an 8-bit microprocessor instead of to

a 16-bit minicomputer as had been previously done.

A hybrid prototype of the Frequency Meter which uses a digital

filter technique to increase the resolution of a frequency measurement

is being tested in use with Michel son-type laser wavelength meters

("Lambda Meters"). These tests involve collaborations with J I LA and the

Time and Frequency Division in Boulder, and with the Molecular Spectroscopy

Division in Gai thersburg . The major effort at the present time is in

improving the optics of these i nterferometers in order to be able to

effectively utilize the resolution enhancement.

8
Our theoretical program is currently inactive due to illness of the

principal investigator.

Accompl i shments

Initial tests of the modified Fizeau Wavemeter were successful and were reported at the Los Alamos Conference on Optics. The instrumental

accuracy is now believed to be close to one part in 10~ 7 (the design

goal), and is presently limited by the accuracy of available references.

The Wavemeter was successfully converted to interface directly with a small lab minicomputer which has been configured to simultaneously scan the laser, measure the wavelength, and record up to 16 channels of input

data. This system has seen some limited use in studies of optogalvanic spectra.

A second Wavemeter for use in a collaborative effort with the

University of Maryland has been constructed and is being calibrated.

A second company has applied for a license from NTIS to market the

Fizeau Wavemeter.

The new Frequency Meter has been analyzed in detail and was described at the 35th Annual Frequency Control Symposium. Further

analysis by Allan and Barnes (Time and Frequency Division), showing that

the Frequency Meter algorithm can improve the characteri zation of

precision oscillators, was also presented at the Symposium. The adoption

of a "modified Allan Variance" incorporating the Frequency Meter

algorithm was suggested.

The hybrid prototype of the Frequency Meter was tested on the

3-meter J I LA Lambda Meter. An improvement in the numerical resolution

of the wavelength measurement by a factor of 100 was achieved and

reported at CLEO.

Future PI ans

An experimental plan to investigate methods for generating so- called "squeezed states" with reduced shot noise has been proposed. If

approved and supported, we expect to begin this program during the

coming year.

The collaboration with the Molecular Spectroscopy Division will

continue at a higher level. Our intention is to study the spectra of

simpl e mol ecul es

.

The hybrid Frequency Meter has proven its effectiveness, but it is

still too slow and too dependent on a computer. An all-digitalhardware instrument with substantially greater speed and reduced

computer dependence will be built and tested.

9
The new Frequency Meter will be used in the continuing collaboration at J I LA to increase the accuracy of interferometric wavelength

comparisons. We expect to achieve numerical resolution near 10" , and

accuracy possibly approaching 10" 11 if the optical problems can be

sufficiently reduced.

Additional effort involving the new Frequency Meter will concentrate

on increasing the accuracy and read-out speed of conventional Lambda

Meters, and on the development of a new compact Lambda Meter with a total motion of 1 cm. This new Lambda Meter is expected to achieve

accuracy near 1 0" 8 in wavelength comparisons.

10
3. One- and Two-Electron Spectra

K. Harvey

Objectives

This program was primarily concerned with fundamental experimental

studies of simple atomic systems. We had hoped to expand this program

through an additional slot made available to us by NML last year. The

expansion slot was lost during the course of the presidential hiring

freeze last winter, and the program has now been effectively closed

down by the recent loss of its primary investigator.

Accompl i shments

The hydrogen metastable atomic beam chamber, which has been the

focus of most of the effort in this program for several years, was tested and achieved modest flux levels during the past year. Details

of its design and operation are in press. Further work in the apparatus

has been halted pending a decision on future research directions in the

Group

.

The investigation of the thermionic diode was completed and the

results published. This device received an IR-100 Award this year.

11
4. Gravity

G. Luther, W. Towler (IPA)

Objectives

Our present objectives are twofold, and at present only indirectly

related: An accurate measurement of the gravitational constant "G", and

studies of the general limits of physical measurements.

Current Acti vi ti es

A new and metrologically amenable test mass for the "G" measurement

is now being constructed. It is hoped that this mass will contribute

negligibly to the uncertainty of the final measurement. The symbiotic

relationship between torsion fibers and the measurement of the Newtonian

Gravitational Constant goes back several hundred years. While the new

bob is being constructed, the apparatus is being used and the data are being taken in order to analyze, in exquisite detail, the characteri sti cs of torsion fibers made of several different materials (quartz, tungsten,

graphi te)

.

Accompl i shments

The data taken in the past year has been reduced, big "G" has been

calculated, and the value determined was reported at the Second International Conference on Precision Measurements and Fundamental Constants.

The uncertainty in this measurement, 64 ppm, compares quite favorably

with the previously accepted CODATA value which had an uncertainty of

615 ppm. A more powerful computer, an Interdata 7/16, was mated to the

experiment in place of the old reliable Model 70. The capability of

storing data directly on floppy discs is now available, and the NBS Bus

associated with the new computer allows the creation of a software

up/down counter to encode the position of the table. Initial measurements of the new pieces of apparatus indicate that we may yet be able to

improve the precision of the measurement by a factor of two or three

(about 30 ppm)

.

Future PI ans

A final assault on the value of "G" is being mounted. The base

camps have been set up and the routes of climb have been surveyed. Data

shall be taken at two positions of the large mass system allowing the

radial variation of "G" or lack thereof to be determined with sufficient

accuracy to decide the value of some of the current theories.

12
5. Fundamental Theory

R. Hayward (Guest Worker)

Objectives

The gravitational interaction is the only one of the four fundamental interactions (strong, electromagnetic, weak, and gravitational)

in which no dynamical effects have been quantitatively measured. It is

the purpose of this theoretical investigation to assess those features

that are in common with the gravitational and the other interactions

that may present possibilities for experiment.

Current Act i v i t i es

The theoretical effort for the past few years has been concerned

with the study of experimental measurements at the quantum level with

the purpose of determining the ultimate limits of precision of the

measurement which may be the deciding factor in the detection of

gravitational radiation. A scientific paper on this study is in press.

As yet, no experiment has reached the quantum level where these results

may be tested.

The geometrical i nterpretation of general relativity has often

obscured certain physical features that might be more recognizable if

the theory were formulated in an equivalent, but more familiar format,

a wave equation form. Such a formulation has been undertaken during

the past year.

Accompl i shments

A matrix formulation of general relativity has been accomplished,

writing a Dirac type wave equation for the fields of general relativity.

We use a representation of multicomponent four vector wave functions,

rather than the "twistor" fields of Penrose. This is a gauge invariant

theory, in which all features of general relativity may be generated by

commutation relations amongst the fields and operators. The one to one homomorphism between the four vector fields and the coordinates, and

also, the non-Abel ian character of the interaction allows the equivalent

geometrical interpretation. A scientific paper reporting these results

is in preparation.

Future PI ans

An effort will be made to second-quanti ze these fields of general

relativity and to develop a strai ghtforward field theory of gravitation

in analogy with that of quantum el ectrodynami cs

13
6. X-ray Spectroscopy - Synchrotron Radiation

P. Cowan, R. LaVilla, A. Henins (1/2), T. Jach (1/2)

Objectives

This longstanding effort aims toward elucidation of some of the

finer details of X-ray spectra from atoms, molecules and simple solids.

The more interesting features of atomic X-ray spectra involve aspects

such as those due double vacancy processes which are unaccounted in a single vacancy, active electron approximation. Such features are ubiquitous contaminating and often rendering uninterpretabl e spectra

from aggregate systems. Preliminary results already obtained from a storage ring source validate our strategy for untangling this complex

phenomenology.

Current Act i v i t i es

Our work is in a transitional phase as annual runs at Stanford

Synchrotron Radiation Laboratory (SSRL) will be replaced by almost

continuous operation at the National Synchrotron Light Source (NSLS) at

Brookhaven. We have maintained and expect to continue to maintain a strong in-house X-ray spectroscopy program both as a support base for

the offsite work and because many questions can still be most effectively studied by conventional means. The next few paragraphs attend

in order to the home laboratory, the SSRL work presently closed and the

NSLS effort which is under construction at present and hopes to begin

operation by mid 1 982. A miscellany of other work at accel erators

,

LURE (Orsay), and SURF-II (NBS) will not be emphasized.

The home laboratory is well instrumented for general X-ray spectroscopy. Its main apparatus centers on a vacuum double crystal spectrometer

which though launched over 18 years ago remains world-class. This

state of affairs was helped by major recent renewal which gave it a new highly stabilized power source, a CAMAC based control system and a pair

of high performance angle encoders. Requests for time on this facility

have been plentiful including major periods of operation for calibration

of space instrumentation. All crystals processed for these purposes

are now in earth orbit and the program terminated (see 1). Main applications otherwise during the past year included: 1) acquisition of a detailed reference spectrum in support of the SSRL Argon experiment;

2) Burek used instrument from part of December to near end of February

studying crystals but mostly doing Fraenkel's measurement on double

diffraction. Unfortunately a substantial effort was required for

installing and debugging the new power source. In the immediate future

it will be applied to determining Bismuth absorption profiles for a TRIUMF measurement of the m-d strong interaction shift. It will also

be applied to the first precision determination of the Xe L emission

spectrum as part of the precision X-ray program (see 7).

14
Accompl i shments

During the year we had another run at SSRL, that was very successful

in contrast to the previous July 1980 run. We obtained: 1) a more

complete set of data in the KB region including variation of the

r^sonant-Raman , Rayleigh, and intensity profile changes of the K8 1j3 , S

v and 3" group with incident photon exciting energy; 2) an experimental

measure of the contribution of the K3 intensity due to higher harmonics;

3) a detailed absorption measurement of the double excitation 1 s 3

p

feature which shows a Fano line shape; 4) the detection and measurement

of the 1 s 2 p double excitation threshold of argon; 5) the extension of

these double differential measurements to a preliminary study of the Ka

region of argon; 6) data was taken to obtain an experimental partial

cross-section for the double vacancy feature a3) 4 a' ; and 7) the Kai, 2 profile and the resonant-Raman scattering feature were studied for

different photon excitation energies close to the Is threshold.

Future PI ans

For the future we anticipate a dedicated beam line at NSLS equipped

with UHV high resolution primary crystal monochromator and secondary

monochromators for photons and electrons. Conceptual design is far

advanced, all major external procurements are complete, a prototype

double crystal monochromator (designed by P. Cowan) has been built and

operated at the Cornell facility, CHESS. (Cowan's design is sufficiently

attractive that we have been asked to consider furnishing a total of

five to equip the facility beam lines and two other user groups.) Our

overall system will be one of both very large scale (o, 25 meters from

tangent point to target area) and extraordi nary complexity. The double

crystal monochromator will be preceeded by a grazing incident collimating

mirror and followed by a refocussing mirror. Target chambers will have

facilities for both gas and solid samples and be equipped with imaging

X-ray and electron spectrometers. Initial assembly of beam line

components should be in progress at the time of the Panel meeting with

production machining of the final system about to begin.

15
7. Precision X-ray and y-ray Measurements

E. Kessler, D. Girard (GW), and A. Henins (1/2)

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 i nterferometry

measurement of the lattice spacing of a silicon crystal . The standards

which have been measured include: a) X-ray transitions which are used

for testing relativistic self-consistent field calculations, b) y-ray

transitions which are used for calibrating bent crystal spectrometers

and Ge detectors used in mesic X-ray work, and c) absorption edge

determinations used in kaonic X-ray measurements . The targeted

accuracy is 0.1 to 1 ppm for y-rays , a few ppm for X-rays, and 15 ppm

for edge measurements.

Precision y-ray wavelengths have the potential of contributing to

the fundamental constants. The recent interest is in the mass-wavelength

conversion factor which can be obtained by combining wavelength measurements of capture y-ray cascades with mass spectroscopy measurements of

the associated mass differences.

Current Activities

Three facilities exist for precision X-ray and y-ray wavelength

measurements. The two older facilities which have had extensive use

are both double axis flat crystal spectrometers equipped with angle

measuring interferometers . One of the instruments is located at the

NBS reactor (primarily y-ray measurements) while the other is located

at the Radiation Physics Building (primarily X-ray measurements). The

efficiency of these flat crystal spectrometers is a few x 10" 11 so that only very intense lines can be measured. The third facility is a DuMond type curved crystal spectrometer and is just now becoming

operational. The spectrometer has an estimated efficiency n, 10"

greater than the flat crystal spectrometers and is thus better suited

for weak lines. Its targeted accuracy is 1 ppm.

X-ray measurements at the flat crystal facility located in the

Radiation Physics Building have been the main activity during the past

year. The principal researchers are E. Kessler and D. Girard, a guest

worker. Here high Z K series X-rays are produced by electron bombardment using the 4 MeV electron Van de Graaff. We have completed measurements on the Kai, Ka2 , K 6 i , KB 3 lines from Ag, Xe, Ba , Nd , Sm , Er, W,

Aa, Pb, Th and U. Our measurements are compared to theoretical selfconsistent field calculations in order to illuminate deficiencies in our theoretical understanding of atomic energy levels. Our measurements

have been one of the main stimuli which have prompted several theoretical groups to reconsider their calculations during the past year.

16
We have contributed to a new measurement of the mass of the kaon

which was published during the past year. Our part of this work was the

measurement of the K absorption edge of metallic Er foils (E ^ 57.5

keV) which had been used in a critical absorption measurement of kaonic

potassium X-rays. Although the resulting mass value is less accurate

(by a factor of 3) than the currently accepted value, it does eliminate

concern about high order radiative terms.

The curved crystal spectrometer was transferred to NBS from the

University of Colorado cyclotron. It has been upgraded during the past

year by A. Henins, with considerable help from E. Kessler and D. Girard

by: 1) installing precision angular contact bearing on the axis,

2) installing a low friction ball screw drive, 3) equipping the axis

with an angle measuring interferometer , and 4) bending a high quality

crystal to a radius of four meters. This spectrometer which is being

brought into operation by Kessler and Girard with some help by Henins,

is located at the 4 MeV electron Van de Graaff. It will be first used

to study satellite lines from high Z K series X-rays. Previous measurements on hyper satellite lines (double K vacancies) from heavy elements

have differed by more than three standard deviations from theoretical

calculations and we hope to shed some light on this controversy.

During this past year, colleagues at PTB in Germany have published

an independent X-ray/optical interferometer measurement of a Si crystal

which is 1.8 ppm smaller than the value Deslattes and Henins published 5 years ago. This difference is considerably larger than what is expected

because of variations in Si. We have interchanged Si samples with PTB

and are currently comparing the PTB and NBS Si samples (Henins).

Preliminary results appear to be troubled by surface effects, but show

less than 1 ppm difference in the two samples. A thorough investigation

of this discrepancy is underway.

Accompl ishments

A long manuscript which documents in detail our measurement procedures and results has been published in Annals of Physics.

The results of the kaon mass experiment (Er K edge measurement)

have been published.

A significant number of high Z X-ray lines have been measured and

the results made available to theorists as a way of stimulating more

accurate calculations. A manuscript on this work is in preparation.

Only one staff member (Kessler) works full time in this project.

The absence of Deslattes has meant that a significant part of Kessler's

time had to be devoted to administration. The accomplishments in this area during the past year have been affected by Deslattes being on

1 eave

.

17
Future Plans

Our future work will be directed toward extending our opticallybased y-ray standards: 1) toward higher energies, and 2) toward less

intense transitions.

Higher energies:

Our goal is to make precision wavelength measurements in the 5 MeV

region where the sources will be direct neutron capture sources in a reactor. The scientific values of the high energy measurements are more

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 made with a mass spectrometer, and better resolution of complex nuclear spectra in the 2 MeV

range. The Institut Laue Langevin (ILL), Grenoble, France, has a high

flux reactor with source manipulation capability. We have submitted a proposal to ILL and have received approval to place a flat crystal

spectrometer at their reactor. Funding from NBS and the assignment of

staff to this measurement are awaited.

Knowledge concerning the behavior of our flat crystals at high

energies is essential so that we can predict linewidths and resolutions

that will be obtained with capture gamma-ray sources. To this end, we plan to make y-ray measurements on transitions from 1

1

° mAg which has

energies up to 1.5 MeV. This source can be irradiated in the NBS

reactor and removed to our measurement facility located in the Reactor

Bui 1 ding

.

Weaker transitions:

Completion of a precision bent crystal spectrometer should permit

us to measure weaker transitions. We hope to be able to provide the

scientific community with X-ray and y-ray standards accurate to a few

ppm in regions in which intense transitions are not available. An

example of such a region is around 18 keV in which the end point of the

6 spectrum of tritium is located. A precision measurement of this end

point is a potential test of the non-zero mass of the neutrino.

18
INVITED TALKS

Quantum Metrology Group - 520.06

E. G. Kessler, Jr., "Absolute X-ray and y-ray Wavelength Measurements at the National Bureau of Standards - Their Application in

Physics", November 18, 1980, at Institut Laue Langevin, Grenoble,

France, and on November 21, 1980, at Studi ecentrum Voor

Kernenergie, Katholieke Uni versi tei t , Leuven, Belgium.

R. D. Deslattes, "Inner Shell Energies: Experimental Problems",

December 4, 1980, at the Workshop on Foundations of Relativistic

Theory of Atomic Structure, Argonne National Laboratory, Argonne,

Illinois.

P. L. Cowan, "The X-ray Standing Wave Method for Structure Determination: Applications in Surface Science", February 6, 1981, at

Sandia Laboratori es , Albuquerque, New Mexico.

J. J. Snyder, "A Novel Ultra-High Resolution Frequency Meter:

Applications and Implications", February 10, 1981, at Center for

Absolute Physical Quantities Colloquium, at NBS , Gai thersburg

,

Maryland, and on February 24, 1981, at Physics Department Colloquium,

University of Virginia, Charlottesville, Virginia.

R. D. Deslattes, "Gamma-ray Secondary Standards: An Exercise in

Precision Metrology with Application to Basic Standards", March 16,

1981, at Physics Division Colloquium, at the National Research Council,

Ottawa, Canada.

J. J. Snyder, "Fizeau Wavemeter", April 7, 1981, at Conference on Optics '81 - Optics in Energy, at Los Alamos Scientific Laboratory,

Los Alamos, New Mexico.

J. J. Snyder, "Frequency Offset Saturation Spectroscopy" , April 9,

1981, at Physics Department Colloquium, Los Alamos Scientific

Laboratory, Los Alamos, New Mexico.

R. D. Deslattes, "X-ray Spectra of Normal and Exotic Atoms", April 27,

1981, at Physics Department Colloquium, University of Notre Dame,

Notre Dame, Indiana.

J. J. Snyder, "An Ultra-High Resolution Frequency Meter", May 27,

1981, at 35th Annual Frequency Control Symposium, Philadelphia,

Pennsyl vania

.

J. J. Snyder (co-authors: T. Baer and L. Hollberg ( J I LA ) ; and

J. L. Hall (525)), "Lambda Resolution Enhancement Using a Novel

Frequency Meter", June 12, 1981, at Conference on Laser ElectroOptics, Washington, D. C.

19
PUBLICATIONS

Quantum Metrology Group - 520.06

D. Bloch, R. K. Raj, and J. J. Snyder, "Heterodyne Detection of PhaseConjugate Emission in an Ar Discharge with a Low-Power cw Laser," J. Physi que-Lettres 42_, L31-L34 (15 January 1981).

A. J. Burek, D. M. 3arrus, R. L. Blake and E. E. Fenimore, "Analysis of

Solar X-ray Emission Line Profiles," Astrophysical J. 243 , 660-676 (1 981 ).

R. D. Deslattes, "Primary Monochromators Using Crystal Diffraction,"

Nucl . Instr. Meth. 177 , 147-151 (1980).

R. D. Deslattes, E. G. Kessler, Jr., W. C. Sauder and A. Henins,

"Remeasurement of Gamma-ray Reference Lines," Annals of Phys. 1 29 , 373-

434 (1 5 Oct 1 980).

R. D. Deslattes, "The Avogadro Constant," Ann. Rev. Phys. Chem. 3]_,

435-461 (1980).

K. C. Harvey, "Shielded Thermionic Diode Detector for Precision Spectroscopy," Rev. Sc i . Instrum 52(2

)

, 204-206 (February 1981).

K. C. Harvey, "Lyman-Beta Lamp with Cooled Li F Window" (accepted for

publication in Appl . Opt. Lett.).

R. E. LaVilla, G. Mehlman and E. B. Saloman, "Double Excitations in

Sodium Above the 2s Threshold," J. Phys. B: At. Mol. Phys. 1_4, L1-L4

(1981).

G. K. Lum, C. E. Wiegand, E. G. Kessler, Jr., R. D. Deslattes, L. Jacobs,

W. Schwitz and R. Seki , "Kaonic Mass by Critical Absorption of KaonicAtom X-Rays," Phys. Rev. D23_, 2522-2532 (1 June 1981).

R. D. Deslattes and E. G. Kessler, Jr., "Precision Gamma- and X-Ray

Energies," Atomic Masses and Fundamental Constants 6 (1980) , edited by

Jerry A. Nolen, Jr. and Walter Benenson, Plenum Publishing Corporation,

NY, pp. 203-218.

R. D. Deslattes, Neutron Interferometry (1981), edited by Bonse and

Rauch, Oxford University Press, Oxford, pp. 399-415.

R. D. Deslattes and E. G. Kessler, Jr., "Inner Shell Energies: Experimental Problems," Proc. of Workshop on Foundations of Relativistic

Theory of Atomic Structures, Argonne National Laboratory, Argonne, IL,

December 4-5, 1 980.

J. J. Snyder, "Fizeau Wavemeter," Proc. of Conference on Optics '81 - Optics in Energy, Los Alamos, Mew Mexico, April 7-10, 1981.

20
J. J. Snyder, "An Ultra-High Resolution Frequency Meter," Proc.

of the 35th Annual Frequency Control Symposium, May 27-29, 1981,

Philadelphia, PA.

Richard D. Deslattes, "Applications of X-Ray Interferometry ," Proc. of

Second International Conference on Precision Measurement and Fundamental

Constants, Gai thersburg , MD, 7-12 June 1981.

Gabriel G. Luther and William R. Towler, "Redetermination of the

Newtonian Gravitational Constant 'G'," Proc. of the Second International

Conference on Precision Measurement and Fundamental Constants, Gaithersburg

,

MD, 7-12 June 1981 .

K. C. Harvey, "An Optically Pumped Metastable Hydrogen Beam," Proc. of

the Second International Conference on Precision Measurement and Fundamental Constants, Gai thersburg , MD, 7-12 June 1981.

J. J. Snyder, T. Baer, L. Hollberg, and J. L. Hall, "Lambda Meter

Resolution Enhancement Using a Novel Frequency Meter," Proc. of Conference on Lasers and Electro-Optics, Washington, D.C., June 10-12,

1 981 .

21
SEMINARS FOR STAFF AND GUESTS

Quantum Metrology Group - 520.06

W. A. M. Blumberg, Lincoln Laboratory, Massachusetts Institute of

Technology, Lexington, Massachusetts - CAPQ Colloquium, "Laser Photodetachment Spectroscopy of Negative Ions in a Magnetic Field",

November 18, 1980.

R. L. Panock, Bell Labs, Holmdel , New Jersey - CAPQ Colloquium,

"Experimental Studies of Rydberg States of Atomic and Molecular H Helium", December 18, 1980.

T. Baer, J I LA , Boulder, Colorado - CAPQ Colloquium, "Coherent Transient Spectroscopy of Hf with an F-Center Laser", January 22, 1981.

C. M. Caves, W. K. Kellogg Radiation Laboratory, California Institute of

Technology, Pasadena, California - CAPQ Colloquium, "Quantum-Mechanical

Noise in an Interferometer", January 23, 1981.

R. D. Knight, Center for Astrophysi cs , Cambridge, Massachusetts - CAPQ

Colloquium, "Laser Spectroscopy of Stored Ions", February 4, 1981.

G. Mater! ik, Deutsches El ektronen-Synchrotron DESY, Hamburg, Germany - CAPQ Colloquium, "Recent Developments in Synchrotron Radiation Research

at DESY Hamburg", July 13, 1981.

J. Helmke, Physi kal i sch-Techni sche Bundesanstal t , Braunschweig, Germany - CAPQ Colloquium, "Iodine Stabilized He-Ne Laser at 613 nm", July 16,

1981.

M. Ducloy, Universite Paris-Nord, Laboratoire de Physique des Lasers,

Vi 1 1 etaneuse , France - CAPQ Colloquium, "Two-Photon Heterodyne Spectroscopy", July 28, 1 981.

P. Siddons, Wheatstone Laboratory, Kings' College, Strand, London - CAPQ Colloquium, "Measurements of Anomalous Dispersion Using X-ray

Interferometers", August 5, 1981.

22
COMMITTEE MEMBERSHIPS

Quantum Metrology Group - 520.06

R. D. Deslattes, Co-Chairman, International Conference on X-ray Physics,

to be held in Eugene, Oregon, August 1982.

R. D. Deslattes, Member, Brookhaven National Synchrotron Light Source

Users Advisory Committee.

23
o 1 1 owi na

TECHNICAL ACTIVITIES

ELECTRICAL MEASUREMENTS AND STANDARDS DIVISION, 521

FISCAL YEAR 1981

Overvi ew

The Electrical Measurements and Standards Division (EMSD) 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.

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

Bureau's Organic Act, as amended, and is in its prime mission areas, that is the areas of responsibility for which the Bureau was originally founded in 1901.

The major technical problems which benefit from the EMSD's work include

fundamental physical theory; electrical power revenue metering, transmission,

and distribution; industrial process control; quality control in the

manufacture of electronic components and products; testing and maintenance of

electronic systems, which includes the civilian side of defense and aerospace;

and national defense requirements directly under the Department of Defense. End user groups include scientists in universities; electric power utilities, both

public and private; electric equipment manufacturers ; process engineers who

design, build, and use industrial process control systems; manuf acturers 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 EMSD

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 several thousand

calibrations are carried out on primary electrical standards that belong to some

of the Nation's most important corporations , utilities and government

organizations, including Hewlett-Packard, General Motors, IBM, General Electric,

Pacific Gas and Electric, American Electric Power, the TVA, and the FAA, and the

DoD.

To fulfill its responsibilities, the EMSD carries out work in the following

eight principal areas with the objectives as indicated:

24
1. Realize the SI definitions of basic electrical measurement units such as the ampere, volt, ohm, and farad, thereby ensuring that the U. S. legal

electrical units are consistent with the internationally accepted system.

2. Develop and maintain U.S.

basic electrical units and related

for the U.S. system of electrical

legal or national reference standards for the

quantities, thus providing a central basis

measurement.

3. Disseminate

U.S, via a variety

means for doing so,

made throughout the

the basic electrical measurement units to users within the

of measurement and calibration services, and develop new thereby ensuring the traceability of electrical measurements

country to national reference standards.

4.

Develop new methodologies and the required instrumentation which will

lead to advances in the state-of-the-art of electrical measurements, 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 measurements is consistent with

those of other countries.

7. Participate in voluntary national and international standardizing

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, accomplishments, and plans of the

various projects underway within the EMSD which contribute to these principal

areas are described in detail in the following project reports. In brief, in

the area of absolute realizations, good progress was made in the new experiment

initiated in FY 80 to determine the ampere by directly equating electrical and

mechanical energy; and in the experiment to redetermine the MBS farad and ohm

via the calculable capacitor.

In the area of electrical unit maintenance and dissemination, the needs

of the EMSD ' s calibration clients were generally met; over 1000 calibration

reports were issued with no significant errors. The professional staff

situation was significantly improved with the addition of J. R. Hastings and

the reprogramming of W. G. Eicke and J. E. Sims. Significant progress was made

in improving the fabrication of Josephson junctions for voltage standard

applications, in completing the al 1 -cryogenic Josephson voltage standard, and

25
in automating resistance calibrations (10

7

- 10^ 3 ohms). A number of guest

workers and coop and summer students contributed to the work in this area.

In the area of new measurement methods, good progress was made on an automated capacitance bridge covering the range up to 1000 pF and which should

eventually find its way into the EMSD's capacitance calibration service.

Significant improvements in the eddy current conductivity bridge which will be

used to calibrate eddy current conductivity standards were also achieved.

In the area of precision measurement and fundamental constants, good

progress was made in constructing the apparatus required to carry out the new Yp/a determination. Significant progress was made in carrying out a new experiment to determine a and (simultaneously) to develop a new absolute

resistance reference standard based on the quantized Hall resistance in two

dimensional electron gases as realized, for example, in Si MOSFETs and

GaAs-AlGaAs heterojunctions. Measurement accuracies of 0.2 ppm have been

reached in less than a year. The Second International Conference on Precision

Measurement and Fundamental Constants was held as planned 8-12 June 1S81 and was deemed highly successful by all who attended (40% of the nearly 260 participants

were from abroad). The Precision Measurement Grant Program also had a successful year -- with the help of additional funds from the NBS Director and

NSF, four new $30K Grants were awarded.

In the area of international comparisons, the first in a series of

comparisons of one-ohm resistance standards was initiated with CSIR0, Australia.

The ultimate purpose is to test each laboratory's realization of the SI ohm via

the calculable capacitor. Resistance comparisons were also carried out with

PTB, West Germany and NRC, Canada, and a comparison of 10 pF capacitance

standards with PTB was completed.

In the area of standardization, EMSD staff members continued to carry out

their many committee responsibilities. The EMSD hosted the CODATA Fundamental

Constants Task Group meeting in June 1981 and good progress was made on the 1981

least-squares adjustment of the constants.

In the area of training and education, higher priority staff commitments prevented

the EMSD from conducting its DC-LF Seminar. Also, the pressure on the staff to

complete projects already underway and maintain existing calibration services was such that no major tutorial material could be generated. (This situation will

be alleviated to some extent in FY 82 with the preparation of a user's manual for

ac-dc thermal converters by a recent EMSD reti ree on a personal services

contract.) On the other hand, a number of guest workers and coop and summer students were successfully trained during the FY.

In summary, the EMSD has once again met its principal calibration responsibilities and made meaningful progress in a number of research areas. It was a successful year, all things considered.

26
REALIZATION OF THE SI AMPERE

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

Objectives

The objective of this research is to measure the NBS 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 every been

previously achieved. Determination of the SI ampere is periodically undertaken

by NBS. This responsi bi 1 i ty was given to MBS in its original charter as prescribed in the Organic Act.

Although the most modern scientific tools available at a given epoch have

been applied to the ampere experiment, there has not been a significant decrease

in uncertainty in this 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 fundamental constants. A recently suggested method of directly

measuring the MBS ampere in terms of the SI unit by equating electrical and

mechanical energy could reduce the uncertainty of the experiment by at least a factor of 50. Such an improvement would help to resolve the present

discrepancies in the fundamental constants, as well as provide a means for

monitoring the kilogram; and 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 experiment is performed in two parts. 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.

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 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

vol tages.

Accompl i shments

During FY 81 we have continued our preliminary ampere measurements using the

Pellat, rotating coil balance. We have improved the mechanical stability, field

strength, optics, current sources, weighing, and electrical metrology to the

27
point where the day to day random scatter (or "noise") in ampere measurements is

about 1 ppm. This is especially encouraging, since the relative contribution of

both the weighing and voltage "noise" will be reduced by a factor of 100 in the

final, superconducting version of the experiment.

We are aware of a relatively large (10-20 ppm) systematic error in our

Pel 1 at ampere determination, which we have not yet fully evaluated. It appears

that we will only be able to evaluate this error, due to distortion of the

balance beam, to 1-2 ppm. Even so, this would still represent the best direct

measurement of the ampere ever made. Furthermore, this error is absent in the

superconducting version of the experiment. From our experience with the Pel 1 at

balance, we have every reson to expect the final version of the experiment to

yield an accuracy a few parts in 10 7 or better.

Future Plans

We will continue to study the systematic effects which now limit the Pell at

determination of the ampere. If we can evaluate these well enough, we will have

an ampere measurement with an uncertainty of a few ppm or less - better than any

previous direct determination. Because of delays in construction by the outside

contractor, we now expect to receive the superconducting coils early in calender

year 1982. In preparation for this, we are building a non-superconducting

prototype of the coils. This prototype will have noise character!' sti cs similar

to the Pel 1 at balance, but without many of the latter's systematic errors. The

protype will allow us to develop and test the weighing apparatus and moveable

coil for the superconducting experiment before it is delivered and will let us test the operation of the experiment without the expense of liquid helium

operation. The prototype should also provide us with an excellent measurement

of the ampere before the installation of the superconducting coils. Most of the

data acquisition and servo control systems developed for use with the Pell at

balance will be directly applicable to the prototype and to the final

superconducting version of the experiment. Thus, a preliminary result accurate

to 1 - 2 ppm is expected by the end of FY 82 using either the Pell at

configuration, the prototype coils, or superconducting coils.

28
REALIZATION OF THE SI FARAD AND OHM

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

Objecti ves

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, 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 that are manufactured within

the U.S.

The absolute farad and ohm measurements make use of a calculable capacitor

ana 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 108 . 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 fine-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.

Current Activities

The equipment was completed a number of years aqo and is among the best in

the world. Work is presently concentrated on the preparation of this equipment

for a new determination of the absolute farad and ohm. Other current activities

include maintenance of the NBS unit of capacitance at the 10 pF level, and

participation in international comparisons of capacitance.

Accompl i shments

Three capacitors of NBS construction have been circulating for many years

between the major national standards laboratories. A few years ago the

capacitors were subjected to an unfortunately large temperature change. The

only lasting effect of this occurence appears to be an increased drift rate

which is, however, sufficiently small and linear so as to permit international

comparisons at the part in 10<3 level. The capacitors continue to exhibit

excellent stability while being shipped via commercial carrier. They are presently in Canada and scheduled for France and Italy before returning to NBS.

Mr. Ho Chaol ai , a guest

been with the Division since

years here. Because of Mr.

arranged for him to actively

computer programs needed for

gained should enable Mr. Ho

worker from the People's Republic of China, has

April 1981 and is expected to spend a total of two

Ho's expressed interest in computers, it was participate in the writing and testing of two

the absolute ohm determination. The experience

to contribute significantly to the rewriting of our

29
Fortran programs in the enhanced basic language of our newly acqui red desktop

computer.

Essentially all of the lower accuracy calibrations (0.1 ppm or higher)

required for the comparison of the NBS units of capacitance and resistance have

been completed. Although a considerable amount of higher accuracy calibration

work was also done, much of this effort has been nullified by equipment failures

and the resulting time lapse. The short term stability of components at the

parts in 10^ level necessitates that calibrations at this level be made both

before and after a capacitance-resistance comparison, and in a relatively short

period of time. All defective equipment has now been repaired or replaced, and new calibrations have begun.

Future Plans

hew absolute farad and ohm measurements are in progress and will probably

occupy from three to six months. Present thinking is that these measurements

should be made on a yearly basis for the next year or two so as to determine the

drift rates of tne reference capacitors and resistors. Effort will be made to

upgrade the existing apparatus so that measurements of this frequency are practical. Also planned for FY 82 is an international comparison with CSIRO,

Australia, of one ohm resistance 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.

30
REALIZATION OF THE SI VOLT

(F. K. Harris, L. H- Lee)

Objective

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

assi gned val ue.

Current Activities

*» Our volt balance consists of a vertically aligned coaxi al -cyl i nder 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 2 S C

o"z 2 mg,

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

i nterferometer.

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.

Accompl i shments

After assembly of the electrode structure of our el ectrometer , having regard

for the constraints on symmetry and vertical alignment, evaluation of SC/ 3z (see

31
force equation) showed unacceptably large variations over the operating span of

the carriage. Lateral motions of the balance base plate amounting to a few

micrometers and correlated with the position of the carriage elevating screw and

its drive train have been found. Thus, although the carriage orientation

(horizontal alignment) has been decoupled from the elevating screw, the support

structure has not been completely decoupled. Lateral displacement of the

balance base plate must produce axial misalignment of the suspended electrode

and thus contribute to variations in 5C/3z.

Future Plans

The carriage support structure is being modified in an attempt to improve

its stiffness; and the elevating screw is to be replaced with a hydraulic

system. If these changes result in a sufficient improvement in the behavior of

9C/3z, we shall proceed with force measurements at the 1-gram level, where we should have about 1 ppm resolution.

32
JOSEPHSON VOLTAGE STANDARDS

(G. Costabile, R. F. Dziuba, B. F. Field, C. J. P. M. Harmans,

L. B. Holdeman, J. Toots)

Object! ves

The overall objective of this activity is 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. The activity encompasses a number of interralated projects, each having specific objectives within the

purview of the overall goal.

The objectives of the Josephson Volt Maintenance Project are (i) to maintain

the U.S. legal volt by the ac Josephson effect using the assigned value 2e/h =

48.J593.420 GHz/VNBS and (ii) to improve the maintenance of the volt to a part in

10° or better by developing an al 1 -cryogenic voltage standard. The objectives

of the CCG Josephson Voltage Standards Research Project are (i) to develop an all-cryogenic voltage standard, (ii) to develop reliable Josephson junctions

which are impervious to the effects of room-temperature aging and of thermal

cycling between liquid-helium and room temperatures, and (iii) to develop

Josephson junctions from h i g

h -

T

c superconducting materials. The objective of

the SRM Josephson-Devi ce Project is to produce, for distribution through the

Office of Standard Reference Materials, well characterized Josephson devices

which can be repeatedly cycled, stored and shipped unrefri gerated, and packaged

to be compatible with commercial Josephson voltage standards. The objectives of

the NASA Josephson-Device Research Project are to produce low-T c films,

fabricate devices from these low-T c films, and to investigate their microwave

response (0.1-40 GHz) in order to evaluate the high-frequency and

non-equilibrium limitations of these devices in radiation-detection and

vo 1 tage -standard apppl icati ons

.

Current Activities

The NBS Josephson voltage standard is used to assign new emf values to two

NBS reference groups of standard cells, which are then used to assign values to

customer standard cells. Evaluation of the al 1 -cryogeni c voltage standard is

underway, with present efforts directed toward resolving a significant

systematic error between this system and the room-temperature voltage standard.

Five commercial Josephson-ef feet voltage standards are undergoing acceptance

testing in the EMSD, and will be delivered in turn as they are made to meet

specifications. Development of techniques for producing niobium-based junctions

is nearing completion. Thin-film Josephson devices fabricated from the low-T c

i ntermetal 1 ic compounds AuAl2 and Auln2 are being studied, and an investigation

of microwave enhancement of superconductivity of Al films is continuing.

Accompl i shments

In FY 81, there were eight comparisons of the Josephson voltage standard

against NBS reference groups of saturated standard cells. The results of these

measurements indicate the primary reference group NBS- 1 3 is drifting at the rate

33
of -0.15 ppm/month. Major improvements in the al 1 -cryogenic voltage standard

include the upgrading of the constant-current source, construction of a microwave generation system, modification of the switching arrangement and the

use of a thermal superconducting switch for the preliminary junction voltage

balances. Josephson voltage comparisons to standard cells using this system

have started.

Niobium/Nb oxide/Pb Josephson devices for the commercial voltage standards

have been produced in both thin-film deposition systems using different

oxidation techniques (glow discharge and sputter-oxidation). Thin-film

Josephson junctions of AuA^/oxide/Al and Al /oxi de/AuIn? have been used to

measure the temperature dependence of the energy gaps or these i ntermetal 1 i

c

compounds, and an all-low-Tc material tunnel junction ( AuAl2/oxi de/AuIng ) has

been fabricated for study. Investigations of microwave enhancement of

superconductivity in Al using the double resonator configuration of the

commercial and al 1 -cryogenic voltage standards has yielded additional results

that will be discussed at the 16th International Conference on Lew-Temperature

Physics. Results of the AuAl 2 and Aulng work will also be presented.

Future Plans

Comparisons of the Josephson voltage standard against NBS standard-cel 1 reference groups will continue. The testing of Nb-based junctions will continue

until a suitable device is found for the al 1 -cryogenic Josephson voltage

standard. Then a thorough investigation of possible sources of systematic error

will continue in oraer to resolve the discrepancies between this system and the

room-temperature voltage standard. The commercial Josephson voltage standards

will be delivered in turn as they are brought into specification. The study of

microwave enhancement of superconductivity will be continued in order to

increase the understanding of the phenomenon, and the investigation of low-Tc thin-film devices will continue with the goal of obtaining devices with

identical electrodes and direct observation of radiation at the Riedell

singularity.

Nb-based SRM Josephson devices will be produced for distribution through the

Office of Standard Reference Materials. Using stripline techniques and Al

tunnel junctions with sharp gaps, we will be able to investigate predictions

( e . g . , mixing with gain) of a recent quantum general ization of microwave-mi xer theory as well as new predictions in the theory of non-equilibrium

superconducti vi ty (e.g., the role of the distribution function in

photon-assisted tunneling). Finally, if time permits, a study will be initiated

of zero current Josephson junction arrays for possible use as a "high voltage

( i . e . , ^1 V) Josephson standard.

34
QUANTIZED HALL RESISTANCE

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

Objectives

The ultimate project goals are to determine the fi ne-structure constant, a,

to the unprecedented accuracy of a few parts in 10 s

, and to establish an absolute, highly reproducible resistance standard of the same accuracy based on fundamental constants of nature.

The method for achieving these goals involves measurements of the Hall

resistance, Rh, of metal -oxi de-semiconductor field-effect transistors (MOSFET's)

and of GaAs-Al x Ga^ As heterojunctions at temperatures less than or equal to 4.2

K in large magnetic xfi el ds

.

When a positive voltage is applied to the gate electrode of a MOSFET, a thin

layer of electrons (called the inversion layer) accumulates beneath the oxide.

This layer approximates a two-dimensional gas of electrons. The number of

electrons in the inversion layer can be varied over two orders of magnitude by

changing the gate voltage, and thus the Fermi level of the electron gas is an experimental variable. A magnetic field B applied perpendicul ar to the

inversion layer constrains the electron motion to Quantized orbits with discrete

energy levels (Landau levels).

At sufficiently low temperatures , the Fermi level can be adjusted so that a given Landau level is completely filled while higher levels are completely

empty, so that an inversion layer electron cannot be scattered if the spacing

between Landau levels (which is proportional to B) is sufficiently large. Under

these conditions, a current flows between source and drain without a voltage

drop within the inversion layer, and the Hall resistance (the ratio between the

Hall voltage and source-to-drai n current I ^

p) is given by

R

H SD

V _ 25,813 — « -—

;

2ai i

(

1 )

where y 0 is the permeability of vacuum (exactly equal to 4 tt x 10 H/m), c is

the speed of light in vacuum, a is the fine-structure constant and i is an

i nteger.

Current Activities

We are continuing 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. The experiments

on GaAs heterojunctions, being done with D. C. Tsui and A. C. Gossard of

Bell Labs, have been so successful that Bell Labs is loaning us a 9 T superconducting magnet system, and we are preparing an experimental area for it.

35
Accompl i shments

A sensitive measurement system was developed, in which the Hall resistance

is compared to a nominal ly-equal room temperature reference resistor via a potentiometer adjusted to within a few ppm of the Hall voltage. This system is

100 times more sensitive than the digital voltmeter method used by v. Klitzing,

10 times more sensitive than the Japanese potentiometric method, and twice as sensitive as the complex cryogenic current comparator systems being constructed

in West Germany and England. The Si MOSFET experiments at NRL have yielded Hall

steps flat to within at least 1 ppm at 1.5 K and 13 T, and the increased

sensitivity revealed new features near the edges of the Hall steps. Most of our efforts were directed towards these new features (which we suspect are due to

inhomogenities across the samples).

We have determined the value of a to within ±0.16 ppm using

GaAs-Al xGa]

_

xAs heterojunctions. This uncertaingy is comparable to the ±0.11

ppm NBS a determi nation by E. R. Williams and P. T. Olsen from the

gyrornagnetic ratio of the proton, and the ±0.095 ppm QED theory-dependent value

from the anomalous moment of the electron. Our result, or±= 137.035968 ±0.16

ppm, is in excellent agreement with these two experiments. It is the first

precision measurement for GaAs heterojunctions, and the uncertainty is 5.5 times

smaller than the best previous quantized Hall resistance measurements.

Future Plans

The appearance of features on the sides of Hall steps has led to a host of

questions, some of which we hope can be answered by using a newly designed mask

set which includes a selection of Si MOSFET samples with different lengths,

widths and length/width ratios -- as well as a variety of Hall probe

configurations. We will begin a program at NRL to investigate these questions,

and will determine a to the same level of accuracy that we have just achieved

for GaAs heterojunctions. We will also collaborate with P. J. Stiles of Brown

University in studies of Si MOSFETs cooled to mK temperatures with a dilution

refri gerator. These experiments will be done on superconducting magnets at the

National Magnet Laboratory. Our major effort will be directed towards

GaAs-Al xGa l

xAs heterojunction measurements at NBS. We will use two measurement

systems: a modified version of the present system for studying the Hall step

shapes, and a new automated system for precision measurements, including a more stable set of reference resistors. With this system we will be able to make

comprehensive investigations of the flatness of Hall steps, carry out controlled

high precision measurements of the Hall resistance, and test the device

independence of the Hall resistance to the parts in 10° level of accuracy.

36
ADVANCED IMPEDANCE-MEASUREMENTS RESEARCH

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

Objectives

The objectives of this project are to conceive and investigate new techniques for making various electrical measurements, and to develop and

construct the instrumentation and physical standards necessary to carry out and

support these measurements.

A significant number of electrical measurement problems are not encountered

often enough to attract commercial development of appropriate instrumentation,

yet are of considerable importance to persons providing measurement services and

persons engaged in exploratory research or in the measurement of fundamental

constants. Those engaged in such activities are generally best situated for

connecting established techniques with new problems, and consequently a project

of this kind must be closely linked with projects involving research activities.

Current Activities and Accomplishments

An automatic resi stance-thermometer bridge suitable for small-scale

production was constructed last year. This year six of the automatic resistance

bridges were constructed in the Temperature and Pressure Measurements and

Standards Division (TPMSD, 522). Most of the further development of the

automatic resistance bridge (e.g. ,devel opment of a 100 ft version) was carried

out in TPMSD and will be described in that division's section of the Annual

Report.

This is the first year of a three year program to develop an automatic

capacitance bridge. Most of the logic circuits have been completed, and designs

have been produced for the transformer and the internal conductance standard.

The internal capacitance standard was scheduled for completion by the end of the

second year, but much of the development work for it has already been completed,

including the construction of a simple and compact temperature enclosure that

maintains temperatures to 100 microkelvin or so for respectable lengths of time.

The electronic portion of the regulator is the subject of a paper co-authored by

R. Davis of the Length and Mass Measurements and Standards Division that is to

be published in the Review of Scientific Instruments this fall. The capacitance

standard itself, although well along, will not be in a publication stage until

at least a year of stability data has been obtained.

Future Plans

Development of the automatic capacitance bridge will continue.

37
EDDY-CURRENT NONDESTRUCTIVE EVALUATION

(G. M. Free, B. F. Field)

Objectives

The eddy-current project has two principal objectives: the development of a calibration service for electrical conductivity standards in the range 10%-100%

IACS (international annealed copper standard); and the production of electrical

conductivity standards which will become MBS Standard Reference Materials.

Eddy-current testing of metal components 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 will meet the need for accurate

calibration of conductivity test systems.

Current Activities

The electrical conductivity calibration service and the electrical

conductivity standard reference materials have as a common factor the

instrumentation developed to measure electrical conductivity. This consists of

a direct-current measuring system by which the resistivity of metal bars of

rectangular cross section will be determined. These metal bars will then become

the primary conductivity standards at MBS. Using an eddy-current bridge

developed at NBS that is based on a new concept in eddy-current measurement,

comparison will be maae between the primary conductivity standards and either

customer samples or SRM's to determine their electrical conductivity.

The dc measurement system is being improved to increase the sensitivity of

the measurements and the signal to noise ratio to the nanovolt level. This is

being done through filters and impedance matching in various parts of the

circuit. Calibration of the primary standards using various separations of the

potential contacts is being done do determine more accurately the slope of the

line for resistance vs. potential contact separation.

The eddy current bridge is continually being improved. The goal of this

work is improved accuracy and simplicity of operation. Differences in measured

values of coils of different geometry are being resolved. These differences

appear to be caused primarily by coil temperature coefficients. The computer

algorithm used to correct measured values for sensing coi 1 -to-metal separation

is being refined and tested.

The logistics of the electrical conductivity calibration service are being

established. It is expected that the initial demands for this service will be

quite high. Computer programs which calculate the inductance and resistance of

a coil on metal are still being developed. The present effort is two-fold.

First the calculation of the parameters for metals with varying conductivity and

38
secondly for calculating performance of coils which contain separate driving and

sensing coils in different configurations.

Accompl i shments

The following was accomplished during FY 81: (1) The new eddy current

bridge has been completed and tested. A method of balancing ground circuits

simultaneously with the main circuit was completed and tested. The accuracy and

precision of the bridge have also been improved. (2) Two metal bars have been

calibrated dimensionally and electrically and the resistivity of the bars have

been determined. (3) The temperature coefficients for the two primary standards

have been determined. (4) Some of the SRM's in the range 30% - 60% IACS have

received final calibration. (5) Temperature coefficients for all test coils

have been determined. (6) A computer algorithm has been written which corrects

measurement reading for varying amounts of coi 1 -to-metal separation and

variations in temperature of the coil. (7) The book "Eddy Current

Characterization of Materials and Structures" an ASTM STP has been published and

distributed to attendees of the conference. (8) The third draft of a proposed

ASTM Standard on measuring electrical conductivity by eddy current methods has

been written. (9) The defect characterizati on system has been set aside for the

moment due to problems in making matched sensing coils. Consultations with

experts within and outside the Division have been held on the anomalies in test

results. No solution to the problem has been found.

Future Plans

Plans for FY 82 include the following: (1) Completion of the calibration of

the current set of SRM's (30% - 60% IACS). (2) Formal announcement of the

calibration service for electrical conductivity standards. (3) Manufacture and

testing of two new primary standards of high resistivity, that is, in the range

10% - 30% IACS. These will serve as a check on Eddy current transfer techniques

and possibly lower the uncertainty in the dc measurement. (4) Several new coil

geometries will be tested. Their purpose will be to improve lift-off

di scrimi nati on and reduce effects due to variations in coil temperature. (5)

The feasibility of several new approaches for determining electrical

conductivity using eddy currents will be tested. (6) A joint project with

Division 564 will be directed at producing SRM's in the range 60% - 100% IACS.

39
ELECTRICAL MEASUREMENTS FOR CORROSION

(W. G. Eicke, J. E. Sims)

Objectives

The objectives of this project are to improve, both in quality and

techniques, the electrical measurements requisite to the study of underground

corrosi on

.

Each year, tons of various metals are buried underground for various purposes:

pipelines carrying oil, gas, or water; transmission lines for communications or electrical power; and support pilings, to mention a few. Corrosion of all

kinds has been estimated to cost the United States billions of dollars annually,

with underground galvanic corrosion responsible for a significant fraction of

this loss. A variety of methods for inhibiting underground corrosion have been

developed, but in order to evaluate these methods in the field, and to develop

new protection methods, an i_n si tu measurement of the rate at which metals

corrode is essential.

One approach is to use electrical techniques to measure the rate of

corrosion. In this approach, a current I is applied to the structure under

study, and the change in electrochemical potential V is observed by using a standard reference electrode. By varying I, a curve V(I) is obtained. The rate

of corrosion can be calculated from this measured current-vol tage relationship.

Since the measurements are made manually, this approach is tedious and time

consuming. Therefore the immediate objectives of this project are to improve

the above approach through automation or semi automation.

Current Activities

Two distinct tasks are being carried out in collaboration with the staff of

the Chemical Stability and Corrosion Division (CSCD, 561). Task A involves the

development of a Fourier analysis program by the EMSD to process data resulting

from the superposition of alternating current on an applied direct current as a means of improving corrosion measurements of specimens in the laboratory. Task

B is directed to automating the measurements of corrosion rates of buried

cab! es

.

Accompl i shments

Task A. The completed computer software package performs harmonic (Fourier)

analysis ana is essentially machine independent. The package is comprised of

three BASIC subroutines - PERIOD, DFT, and FFT. The BASIC program (PERIOD)

determines the period of an arbitrary set of data. A subset of the data is used

as a "window". This window is characteri zed by a minimum, a maximum, and the numoer of points in the subset. The rest of the data is searched until the

window is located twice. This defines an estimate of the period. An error

function is used to vary the estimate until the minimum error is located and an accurate value for the period is obtained. Analysis of the results obtained

from running the program using a group of simulated data sets, indicates this

40
method is accurate to 0.1%. The input and search portions of the program are written in assembly language to substantially reduce the execution time.

Another BASIC program (DFT) calculates the discrete Fourier coefficients

using standard techniques. Although accurate values are obtained from this

program, usually several hours of execution time per data set is required.

Another program (FFT) employs fast Fourier transform methods to reduce the

number of computations such that only several minutes are required to run a data

set. Analysis of the results from running the FFT program using simulated data

sets indicate this method has an accuracy of 0.15%.

An NBSIR is currently being written to document this effort. It is

anticipated that this report will be completed in early FY 82.

Reconfiguration of the operating system and rewiring of some of the hardware

appear to have corrected most of the serious problems encountered with the 7/32

computer used in the Volt Facility. Delivery of a new operating system and new hardware resulted in an inordinate amount of time being spent in changing the

system, altering some of the old software, and writing new software.

Task B. Efforts begun in FY 80 to automate the NBS underground corrosion

test site using the HP 9830 as the controlling computer continued. Because of

the variety of instruments required for this project, it was necessary to design

a controller to serve as the interface between the various instruments and the

9830 ' s 8 bit parallel interface. Several possible methods were considered and

the most attractive, from the stand point of both hardware and programming,

required that the controller put out 12 bits to the various instrument control

cards. The 12 bits were divided into a 4 bit address and 8 bits of data. This

approach leads to simple programming; only two bytes are required to "talk" to

the instruments. Reading is accomplished by simply addressing the instrument to

be i nterrogated. Although not particularly efficient, it is the best technique

of those studied. In principle the design of a controller to do the above is

very simple. Several versions were designed and constructed early in the FY and none worked. Because of a lack of auxilary equipment such as a logic analyzer,

progress was very slow. After several months of effort we found

problems with the HP 9830 and the interface card that insured that our original

designs were all doomed to failure. Because of these problems, it was not

until well into the second quarter and the acquisition of a logic analyzer

that we were able to get an interface design to work more or less properly,

and it was not until July that all bugs were removed.

We reviewed with CSCD their needs for monitoring the various reference

electrodes at the site and decided that it would be desireable to develop a scanner to permit the random selection of any two electrodes similar to the

random access switch we designed and constructed last FY. Because of the

possible use of such a scanner in a microprocessor based system in CSD, we decided to look at solid state devices. A prototype board with 16 random access

41
SPST channels was designed and constructed. In addition, a control board that

allows expansion to 120 lines was also built. Preliminary tests indicate

unresolved emfs (probably thermal) of less than 10 microvolts which is more than

adequate for these measurements. Some data indicate that with the proper

selection of the FET switches, it may be possible to reduce this figure to less

than one microvolt.

In addition to the switch cards, cards have been designed and constructed

for the DVM and programmable current source. By the end of FY 81, we should

have the system at the field side for testing and evaluation.

Work has also continued on methods for resistance compensation. Several

possible designs were evaluated and a method using two operational amplifiers

and one multiplying DAC looks very promising. A prototype that is 9830 compatible

will be constructed and evaluated in the next month or so. It is expected that

all hardware will be in place by the end of FY 81.

Future Plans

This work was terminated during FY 81. Mrs. Sims was assigned new duties

associated with the dissemination of the volt. Initially she will have

operational responsibi 1 ity for the Volt Transfer Program (a MAP activity) and as she gains experience and current problems with the existing program are solved,

she will assume additional responsibilities in the area of volt dissemination

(especially documentation).

Mr. Eicke has been reassigned to (1) complete the Volt Facility (a task

suspended with his reprogrammi ng to corrosion research two years ago); and (2)

collaborate with other division personnel in improving existing electrical

dissemination services. In FY 82 the major thrust will be directed to

completing the Volt Facility. Specific tasks identified to date are (i) the

design and construction of an automated comparator using the Interdata 7/16 and

the IEEE 488 bus to control the various components; and (ii) development of

software to control the process. The plan is to develop a single system with

two independent or nearly independent measurement methods that will handle both

VTP and regular calibrations.

Some effort will also be made in FY 82 to prepare documentation describing

the VTP and the related regional voltage MAP.

42
GAMMA-P AND THE FINE-STRUCTURE CONSTANT

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

Objecti ves

To extend the precision with which quantum electrodynamics (QED), the

Josephson effect, and the von Klitzing effect (quantized Hall Resistance) can be

tested by parrying out an improved measurement of the proton gyromagnetic ratio

in H 2O, T p. This should yield a value of the fine structure constant, a, that

is accurate to 0.01 - 0.02 ppm.

The present approach to redetermi nati ng a is based on improving the

inductive method developed in our laboratory and used to carry out a 0.2 ppm

experiment reported in 1979. The NPL in England and the VNIIM in the USSR have

recently reported values of y' that are in complete disagreement with our 1979

result (10-15 standard deviations). The Chinese value obtained at NIM, Beijing,

agrees with our value. We expect a new determination of y p will resolve this

major discrepancy.

Current Activities

The gyromagnetic ratio of the proton is defined as the ratio of the angular

precession frequency con of a proton in a magnetic field B to the magnitude of

the field, Yp = «p/B. The precession frequency is measured by standard nuclear

magnetic resonance methods. The magnetic field is calculated from the measured

physical dimensions of a single-layer solenoid, wound on a preci sion-ground

quartz form, with a known 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 this 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

straight edge 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 determi nati on

The new von Klitzing effect provides additional incentive for completing the

Yp measurement in the near future. The quantized Hall resistance, the absolute

ohm, 2e/h from the Josephson effect, and Yp form an over determined set of

constants which allows a to be calculated by three different paths. The

consistency of these three paths tests a great deal of physics as well as the

quality with which the electrical standards are being maintained.

43
Accompl ishments

The latest theoretical calculations of the sixth and eighth order

corrections to the electron anomalous moment by Levine and Roskies and by

Kinoshita and Lindquist have eliminated the discrepancy between QED theory and

experiment. In other words, the NBS value of a using Yp is now in good

agreement with QED (i.e., within 0.15 ppm). Also, the value of a determined by

the von Klitzing effect shows excellent agreement with our a value (i.e.,

within 0.04 ppm).

The USSR and England have, however, published values of Yp that are in

complete disagreement with ours. NPL is (7 ± 0.5) ppm lower than NBS, while

VNIIM is (5 ± 0.6) ppm lower. The Chinese/NIM value is (1.0 ± 0.8) ppm higher.

These large discrepancies are very disturbing ana graphically demonstrate how

careful one must be in making an accurate Yp measurement.

The new 2.5 m precision solenoid has been lapped with a helical grove and

wound with copper wire. It should soon be rewound with gold plated copper wire

and the tedious, time consuming, construction of the new solenoid will be

completed. A 3 m straight edge has been polished and is straight to about 10“ ^ m, completing that tedious job. A new and very simple method to detect the

leakage between turns of the solenoid has been demonstrated on the old one-meter

solenoid. This technique will eliminate any significant uncertainty in Yp due

to leakage.

Future Plans

Assembly of the apparatus will occupy most of our time during FY 82. We

have chosen to concentrate on this approach rather than the new Ampere's Law

approach because we feel confident that an improved value can be obtained within

two years.

The special solenoid for measuring the susceptibility of the precision

solenoid will be assembled. This solenoid will stand on end with a shower of

cooling water to control the temperature to 0.01 °C with 2.5 kW of power in the

windings. A current source with short term stability of a part in 10° must be

built to produce a constant magnetic field. The smaller precision solenoid will

be lowered into this uniform field and the field change due to the

susceptibility of the precision solenoid will be measured with an NMR

magnetometer.

With the recent advances in the theory of the electron anaalous moment ana with the new quantized Hall resistance, the need for immediate new results for

Yp has greatly increased. Now that the tedious construction phase of our experiment nears completion, we can respond to this added pressure by spending a larger percentage of our time on the Yp experiment itself.

44
LASER COOLING AND TRAPPING OF NEUTRAL ATOMS

(W. D. Phillips)

Objecti ves

The fundamental objective of this experiment is to use tunable lasers to

cool and possibly confine neutral atoms. These atoms, cooled to as low as

10 -4 K, could be used for high-resolution spectroscopy in a number of

appl i cations.

Because spectroscopic techniques form the basis for the most precise

physical measurements made today, NBS continues to work on extending the

resolution of spectroscopy. Maintenance of time, frequency, and length

standards has benefited from advances in spectroscopy. Recent advances in

non-linear optical spectroscopy indicate that attempts to achieve higher

resolution must address the problems of second order Doppler shift and

broadening due to finite observation time. Cooling and confinement of atoms are

an answer to these problems.

This work is complementary to the trapped ion work of the Time and Frequency

Division in that, while directed toward the same aim of improved spectroscopy,

the use of neutral atoms presents different opportunities. For example, cooled

neutral atoms in highly excited (Rydberg) states could be used for precision

tests of theories of the Stark effect, precise measurement of electric fields,

or the determination of the fi ne-structure constant from Stark splittings.

Cooled neutral cesium atoms could be used in conventional atomic clocks to

improve their performance. High resolution spectroscopy of neutral atoms also

has other possible applications in atomic physics and fundamental constants,

such as Lamb shift or Rydberg determination.

Current Activities

Atoms which interact with laser light that is resonant with an atomic

transition will experience forces due to the absorption and emission of light.

These forces can in theory be used to confine and cool the atoms. The forces

are weak enough, however, that with present technology, atoms hotter than about

1 K cannot be confined. Therefore, we need to cool the atoms considerably

before trapping is possible.

We are now attempting to use the light from a tunable dye laser to slow down

a beam of sodium atoms. The slow atoms could be trapped by another laser beam,

or used as a cold atomic beam for high resolution spectroscopy. We are also

considering confinement in static magnetic or electric fields.

Accompl i shments

During FY 81 we have observed for the first time clear effects of laser

cooling of an atomic beam. The earliest indications were from some experiments

where a rapidly scanned, circularly polarized laser was used in conjunction with

an axial magnetic field to both cool and detect atoms. Since this arrangement

45
leads to ambiguities, we developed a two laser system for separate cooling and

detection processes. The velocity distribution is measured from Doppler shifts

using a very weak probe beam which neither saturates nor optically pumps the

atoms, while the cooling is accomplished with a strong fixed frequency laser

which is turned off during the observation time. Using a differential

technique, we have seen clearly the effects of optical pumping and of cooling.

The cooling process produces a monochromoti zation of the velocity distribution

as well as a shift to lower velocity, as has been predicted by theory.

We have seen that the cooling process improves consideraly as a stronger

magnetic field (up to 250 gauss) is used to better define a quantization axis

and to separate different quantum states so as to avoid the optical pumping

which limits the number of times atoms can interact with the laser. We have

constructed a solenoid that will provide fields in excess of 1000 gauss, and

that better separates the cooling and detection regions. This should allow ofr more effective cooling and easier analysis of the results.

Future Plans

During FY 82 we will be concentrating on optimizing the cooling effect. One

way in which this will be done is with a stronger magnetic field, which varies

spatially so as to keep the atoms on resonance with the fixed frequency laser.

We will also consider a fast scanned cooling laser using the new time resolved

analysis technique. Other schemes such as multiple lasers, or mul ti -frequency

lasers are being planned to overcome some of the effects of optical pumping. We

may make use of time-of-f 1 ight velocity analysis to further separate our experimental observation of optical pumping and cooling effects.

We will also attempt to fit our experimental results to a theoretical model

which includes the effects of optical pumping as well as cooling. We may also

use our new observation techniques to provide more insight into some unexplained

long-time optical pumping effects seen in the early stages of this work. Our

immediate objective will be to determine what experimental factors affect the

efficiency and limits of the cooling and how they can be manipulated to maximize

the cooling. We expect to be able to produce a beam of atoms of significantly

reduced energy in the near future and eventually to apply this achievement to

trapping, spectroscopy, and standards.

46
FUNDAMENTAL CONSTANTS DATA CENTER

(B. N. Taylor)

Objecti ves

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 scientific

fields, and to obtain recommended values of these constants for international

use.

The close relationships that exist between the fundamental constants and

precision measurements, basic measurement units, fundamental physics, and

state-of-the-art measurement technology makes the subject a natural one for NBS

to be deeply involved in. One of the purposes of this project is to provide

assistance and guidance in the general area of precision measurement and

fundamental constants for both NBS staff and university scientists, and in

particular, to advise them as to which experiments should be carried out and

what work is currently underway in various laboratories throughout the world.

Self-consistent "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 reporducible , 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; (3)

participating in the work of national and international groups (for example, the

CODATA Task Group on Fundamental Constants and the NAS/NRC 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 i nternational conferences on PMFC and visiting

laboratories carrying out work in this field; (6) serving as an editor of

Metrologia in the area of Electrical Measurements and Fundamental Constants;

(7) carrying out collaborative work with Soviet colleagues under the joint

NBS-Gosstandart cooparative agreement in metrology; and (8) answering numerous inquiries from both within and without NBS relating to the PMFC field.

47
Accompl ishments

The following was accomplished in FY 81: (i) published four quarterly

issues of PPMFC; (ii) responded to numerous written and oral inquiries

regarding the fundamental constants; (iii) attended the April meeting of the

NAS/NRC Fundamental Constants Committee and contributed to the preparation of a report documenting the importance of the PMFC field to physics and the need for

continued, strong support of the field; (iv) organized and held the Second

International Conference on Precision Measurement and Fundamental Constants

( PMFC- II), 8-12 June 1981. This was a highly successful meeting which brought

together over 250 workers in the PMFC field from all over the world and laid the

groundwork for the 1981 Least-Squares Adjustment of the Fundamental Constants

(LSAFC); (v) began work on the 1981 LSAFC, in particular, developed the

necessary computer programs required to analyze discrepant data and prepared a NBS-IR in which various algorithms for treating discrepant data are numerically

compared; (vi) participated in the work of the CODATA Task Group on Fundamental

Constants related to the 1981 LSAFC, in particular, attended a meeting in June

1981 during which the problems associated with the adjustment were discussed in

detail (hosted the latter meeting); (vii) worked with Keith Eberhart, Center

for Applied Mathematics, on a new method for analyzing the data relating to the

determination of atomic weights using dilution mass spectrometry (applicable to

the Faraday constant); and (viii) participated in NESS' Ad Hoc Committee on Uncertainties, in particular, helped Ronald Col 1 e prepare the MBS position prior

to the BIPM Uncertainty Committee meeting in October, 1980.

Future Plans

The following is planned for FY 82: (i) publish as usual the quarterly

PPMFC; (ii) respond to inquiries as received; and (iii) attend the April 1982

meeting of the NAS/NRC Fundamental Constants Committee. The main objectives in

FY 82 will be (iv) to complete the 1981 least-squares adjustment of the

constants, to oversee its adoption for international use by CODATA, and to

prepare several brief reports summarizing the adjustment for NBS, CODATA, and

other organizations; and (v) to complete the editing of the proceedings of the

Second International Conference on Precision Measurement and Fundamental

Constants and oversee its publication (the target publication date is late FY

82).

48
PRECISION MEASUREMENTS GRANTS

( NBS Precision Measurements Grants Committee; B. N. Taylor, Chairman)

Objectives

The annual objectives are to award two to four new Precision Measurement

Grants of $30K (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 (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 by awarding grants to a selected number of

outstandingly qualified, creative experimentalists. Only those individuals

working in areas of immediate or potential future benefit to ongoing NBS

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, and thus to increase their productivity. 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 determi nation 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.

49
Accompl ishments

A request was sent to and was approved by the NBS Director to increase each new PMG from $25 K to $30 K to partially compensate for inflation (the 525 K level had been in effect since 1977). A proposal to NSF requesting their

participation in the NBS PMG program was approved and NSF gave NBS sufficient

funds to award two additional new grants. The procedures outlined above for

selecting candidates, which were first instituted in FY 77, were again used

successfully in FY 81. Proposals were openly solicited via an advertisement in

Physics Today, announcements in appropriate trade journals and newsletters, and

the mailing of a brochure to all of the college and university physics

departments in the U.S. (about 950). Proposals were received from 30

candidates, five of whom were chosen to submit final, full proposals. The four

grantees selected from these five were:

David F. Bartlett, University of Colorado;

Proposal Title: Eotvos Experiment -- a Cryogenic Version

David A. Church, Texas A & M University;

Proposal Title: Low Energy, Highly Charged Ion Precision Spectroscopy

Charles E. Johnson, North Carolina State University;

Proposal Title: RF Spectroscopy of Atomic and Molecular Ions

Michael G. Littman, Princeton University;

Proposal Title: Fi ne-Structure Constant Determination Using Precision Stark

Spectroscopy

For FY 81, the NBS Precision Measurement Grants Committee consisted of Drs.

Deslattes, Hall, Taylor and Wineland; the Outside Advisory Committee of

Professors Kleppner, Pipkin, Robinson, and Schuessler.

The following four $25K Grants were also renewed during FY 81: W. H. Wing, U. Ariz., Electrostatic Trapping of Neutral Atomic Particles; W. C.

Oelfke, U. Central Florida, Quantum Limited Measurement of a Harmonic

Oscillator; C. E. Wieman, U. Mich., Measurement of Fundamental Constants

Using Three-Level Resonances in Hydrogen; and W. C. Sauder, Virginia Military

Institute, Precise Determination of the Gas Constant: First Applications of the

Ultrasonic Michel son Interferometer

Fifteen of the 30 past or present PMG recipients attended the June 8-12,

1981 Second International Conference on Precision Measurement and Fundamental

Constants at NBS, and 13 of these presented papers. The most significant

accomplishment under PMG sponsorship this FY was undoubtedly the measurement of

the proton to electron mass ratio by R. S. Van Dyck, U. Washington [P.R.L.

47, 395 (1981)] using a Penning trap.

PI ans

FY 82 plans naturally focus on renewing the 6 current grants and awarding

four new grants. It should be noted, however, that NSF support is not automatic

-- it is NSF policy not to give regranting authority. This means that NSF

50
retains the right to approve the two Grants for which they supply the funds; if

they are not satisfied the work proposed and the P.I. is NSF quality, they will

decline to support the project. However, no distinction is made between the

PMG's supported by MBS funds and those supported by NSF funds — to the PMG

recipient, it is an NBS Precision Measurement Grant (there is absolutely no contact between the recipient and NSF).

51
DISSEMINATION SERVICES: SUPPORT AND OPERATION INCLUDING MAP DEVELOPMENT

(N. B. Belecki, C. R. Childers R. F. Dziuba. R. C. Fronk

J. Hastings. C. R. Levy. R. E. Long. T. P. Moore D. D. Prather.

J. Sims A. R. Wi se)

Objecti ves

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 needed levels of accuracy. The legal units

are provided to the user community by means of 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's and calibrations ultimately hinges 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 world

-- and indirectly through them by industry for the quality control of 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 safety-barrier crash tests performed by automobile

companies in compliance with National Highway Traffic Safety Administration

(DOT) regulations. 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 high because they have not been limited by measurement

constraints such as the nonavail abil ity of electrical instruments of adequate

accuracy. This condition can only occur if NBS maintains a strong R&D program

to ensure the availablity 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 resistance. Some measurements

are also done on ac ratio standards of the highest accuracy.

Measurement-service support activities are STRS-funded projects directed toward

continuing the viable operation of the measurement services above, developing

improved quality control procedures for them, making both evolutionary and

revol utionary improvements in technique and equipment, and increasing their

efficiency to ensure that the services offered are sufficient in type and

accuracy to fulfill the most stringent requirements for measurements support

52
from industry, government- and the scientific community. The bulk of the effort

is going toward automation and MAP development.

The professional manpower situation has been considerably improved by the

addition of John Hastings to the staff in December. 1980. and the reprogrammi ng

of Eicke and Sims from corrosion work back into this program. Hastings, who came from the Thermopnysics Division, has been in training to assume

responsibil ity for the ac-dc difference area. He has already proven to be of

significant help in reviewing calibration reports and, as his grasp of the field

improves, is expected to contribute significantly in the areas of improved

qua! i ty-control procedures , documentati on , advanced standards, and MAP

devel opment

Sims, whose background is that of computer science and electrical

engineering, has had some experience in precision voltage measurements and

considerable experience in the area of data reduction. She has been given

responsibil ity for operations in the Volt Facility and for the voltage MAP. She

has already made inroads into the MAP backlog and has been working on bringing

the transport standards up to an acceptable level. It is anticipated that with

her efforts, the voltage MAP will be a much mere viable and timely service

starting in FY 82.

Eicke, a senior professional with an international reputation in the area of

standard cell metrology and MAP applications, will be responsible for

completely automating the Volt Facility and for setting up proper operating

procedures for both the regular voltage calibration services and the MAP

services. He has worked out an improved approach for the automation and much of

the hardware needed for its implementation has been ordered. His work should go

a long way towards relieving the manpower shortage in this technical area by

significantly reducing the 0.7 MY/year effort now required to calibrate customer

voltage standards manually.

A great deal of support was also obtained in FY 81 from three co-op

students, all working under the supervision of R. Dziuba. K. Baker spent two

semesters working in the resistance area where he made major contributions to our automation effort and made precision resistance intercompari sons which

enabled us to continue to offer MAP services at a high level of quality. P. Boynton spent the summer working in the high-resistance laboratory, where he

performed the hardware modifications and wrote the software necessary to

automate the digital teraohm meter. This can now be used to calibrate

resistance standards in the range 10? to 1

1 3 ohms, freeing some technician

time.

Finally. J. Glenn spent the summer evaluating Josephson junctions designed

for use in the all-cryogenic Josephson apparatus and making measurements on solid-state voltage standards, thus reducing the burden of five senior people in

these areas.

53
Accompl i shments

1. A Technical Note describing in detail the calibration and use of thermal

transfer converters has been written under contract by E. S. Williams and will

be published in the next few months. (Belecki, Hastings)

2. A pilot experiment with the intent of establishing do- i t-yoursel f MAP's

in the resistance area has been started with six southern California companies - Autonetics, Beckman, ESRS, Ford Aerospace, Lockheed California, and TRW Space

Systems. (Dziuba, Belecki)

3. Voltage MAP data were analyzed to determine criteria for deletion of bad

data and to establish long-term behavior statistics for transport standards.

This resulted in rebuilding several standards [Sims, Belecki. Kefadar. Reeves

(Div. 714)]

4. A photocell amplifier has been modified to permit the use of a digital

voltmeter to balance the ampere-turn potentiometer for one-ohm resistor

intercompari sons . The system has been tested and found to work sat i sfactori ly.

(Dziuba, Baker)

5. A microprocessor system has been implemented in the resistance

laboratory to facilitate data collection from the one-ohm resistance calibration

facility. (Dziuba, Baker)

6. An automated system for the measurement of high-valued resistors, based

on the use of a commercial teraohm meter as a transfer device between NBS

standards and unknown resistors, has been implemented and tested. (Dziuba,

Boynton, Childers)

7. By the end of August, the group had calibrated 1050 electrical

standards, with no technical errors reported and generally on time. A detailed

breakdown of this activity is given in the Summary of Calibration Activities.

(Baker, Childers, Fronk, Levy, Long, Moore, Prather. Wise)

Future Plans

In addition to continuing the the Division's SP 250 calibration services at a high quality level, our objectives for FY 82 include:

1. The generation of a detailed set of instructions for the Volt Transfer

Program, our voltage MAP.

2. The construction and testing of a prototype system for automatically

measuring standard cells, and

3. The completion of a study on the primary standards for ac current and

voltage measurements. This includes assessing their accuracies and detailing

the uncertainties in the calibration process for thermal transfer standards.

54
IMPROVED STANDARDS FOR WIDE RANGING ENVIRONMENTS

(B. F. Field)

Objectives

The overall objective of this project is to develop new electrical standards

with state-of-the-art performance for use outside the standards laboratory

envi ronment

.

Voltage and resistance references presently available for use as secondary

standards (i.e., for use in a production-line environment) are from 10 to 100

times less accurate than their standards laboratory equivalents (so-called

"primary standards"). This project will identify problems with existing

secondary standards ana attempt to develop improved voltage and resistance

standards with accuracies comparable to "delicate" primary standards.

For voltage standards, where the need is greatest, we will develop

measurement systems to characterize reference devices, establish liaison with

appropriate industrial companies, characterize presently-avai 1 abl e reference

devices, and explore the physical phenomena underlying solid state references.

In addition we will investigate semiconductor processing parameters that affect

long term device stability, with the eventual goal of developing an improved

solid-state standard with stability performance comparable to a standard cell.

To minimize the effect of transportati on on resistance standards, we will

design improved and ruggized wi rewound standards, and explore modern circuit

technology as a potential source of new standards. This will include

investigating the use of cryoresi stors as new primary standards.

Current Activities

We are proceeding in the construction of an IEEE 488-based system for fully

automatic measurement of any voltage in the range 1 to 10 volts, with an initial

design accuracy of 0.2 ppm. The instrument consists of a resistance network of

10 series connected 1000 resistors fed by a constant current source. This

arrangement produces 10 volts across the resistor string with ten taps at one volt increments. The unit under test is compared to a voltage produced by the

10 V tapped source that most nearly equals the voltage of the unit under test.

The difference voltage is read by a high accuracy digital voltmeter. A low

thermal -emf cross bar switch is used to connect up to 80 devices to the

measuring circuit.

High measurement accuracy (0.2 ppm) is expected as a result of a careful

evaluation of all the system components and a measurement design technique that

compensates for systematic errors in the measuring system. The desktop computer

which controls the measuring system is programmed to evaluate and correct the

data for all the major sources of error of the digital voltmeter, including

offset, gain, and nonlinearity errors.

55
We have been in contact with several of the leading voltage reference device

manufacturers such as National Semiconductor and Standard Reference Labs, as well as instrument manufacturers such as John Fluke Mfg. Co. We are presently

exchanging information and evaluating some prototype and production standards

submitted by various manufacturers. Full scale testing of devices will begin

when the automated measuring system is completed.

Accompl i shments

While the automated system described above is under construction, a manual

measurement system (designed and constructed by N. B. Belecki) is being

employed to do limited testing of some voltage standards. This system, accurate

to approximately 0.3 ppm, has been used to evaluate a 3 "cell" Zener reference

that was transported and calibrated at four national 1 aboratories . Agreement

between the laboratories was within 2 ppm.

Future Plans

The automated voltage measuring system will be completed and tested.

Appropriate software is being written to measure up to 80 voltage references and

analyze the measurement data. A 20 Mbyte disk with removeable cartridges has

been installed on the desktop computer to provide storage for the large volume

of data expected. The effect on voltage references of changing temperature and

humidity conditions will be studied using a large environmental chamber located

nearby. We also plan to build a system to analyze the noise spectrum of

selected references. Transportation of standard cells requires special

handling, whereas some voltage references may oe moved with much less care. Therefore we will determine the transport standard capabilities of present

references under field use conditions.

Improved resistance standards will be constructed possibly using a new CSIRO

(National Measurement Laboratory, Australia) design. New packaging and mounting

structures will be designed and incorporated into prototypes of new generation

one ohm and 10 k ohm standards. We also eventually intend to investigate the

use of cryoresi stors as new primary standards.

56
Conferences Sponsored

Second International Conference on Precision Measurement and Fundamental

Constants, 8-12 June 1981. Over 250 individuals from around the world (40% from

abroad) participated. The Conference provided an international forum for

scientists engaged in experimental and theoretical research on precision

measurements relating to the fundamental physical constants, and on the testing

of related fundamental theory. It also laid the foundation for the 1981

least-squares adjustment of the fundamental constants.

Invited Talks

M. E. Cage, "Determination of the Fine-Structure Constant and an Atomic

Standard of Resistance Based on the Quantized Hall Effect", Baltimore Meeting of

the American Physical Society, 20-23 April, 1981.

W. G. Eicke, "Ten Years of the Regional Measurement Assurance Program", Joint

Meeting of the Greater Los Angeles Chapters of the Precision Measurement

Association, Los Angeles, California, February, 1981.

E. R. Williams, "The Proton Gyromagnetic Ratio in HjO - A Problem in

Dimensional Metrology", Second International Conference on Precision Measurement

and Fundamental Constants, NBS Gai thersburg , 8-12 June, 1981.

57
Publications

1. _In Print .

M. E. Cage, An Analysis of the Effects of Dynamic and Static Forces Present in

the MBS SI Volt Experiment, NBS IR80-2143 , September, 1980.

G. M. Free, High-Accuracy Conductivity Measurements in Nonferrous Metals, in

Eddy - Current Characterization of Material s and Structures , ASTM Special

Technical Publication 722, Ed. by G. Birnbaum and G. M. Free (American

Society for Testing and Materials, 1981) p. 121.

G. M. Free, L. K. Ives, R. Mehrabian, and L. J. Swartzendruber

,

Nondestructive Evaluation of Monuniformities in Aluminum Alloy Plate, in

Proceedings of the American Society for Nondestructive Testing Fall Conference,

1980, p. 39.

0. P. Galakhova, S. Harkness, F. L. Hermach, H. Hirayama, P. Martin, T.

H. Rozdestvenskaya , and E. S. Williams, An International Comparison of

Thermal Converters as AC-DC Transfer Standards, IEEE Trans. Instrum. Meas.

_IM-29 , 396 ( 1980).

L. B. Holdeman, James T. Hall, D. Van Vechten, and R. J. Soulen, Jr., Gap

Enhancement in Aluminum Tunnel Junctions Coupled to Microstrip Resonators,

Physica 108B, 827 (1981).

R. L. Kautz and G. Costabile, A Josephson Voltage Standard Using a Series

Array of 100 Junctions, IEEE Trans. Mag. MAG-JL7, 780 ( 1981).

H. J. Metcalf and W. D. Phillips, Time Resolved Subnatural -Width

Spectroscopy, Opt. Lett. 5, 540 (1980).

P. T. Olsen, M. E. Cage, W. D. Phillips, and E. R. Williams, The

Realization of the Ampere at NBS, IEEE Trans. Instrum. Meas. IM-29, 234

(1980).

R. J. Soulen, Jr., D. Van Vechten, G. Costabile, Terrence Jach, and L. B. Holdeman, The Superconductive Energy Gap of AuAl^ , Physica 108B, 823 (1981).

E. S. Williams, A Thermoelement Comparator for Automatic AC-DC Difference

Measurements, IEEE Trans. Instrum. Meas. _IM-29, 405 (1980).

2. _In press , i_n Review , or Neari ng Compl eti on .

M. E. Cage and R. S. Davis, An Analysis of Read-Out Perturbations Seen on an Analytical Balance with a Swinging Pan, NBS J. Research.

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 Proceedings of the Second International

58
Conference on Precision Measurement and Fundamental Constants (hereafter

reffered to as NBS Spec- Publ . 617).

M. Littman and W. D. Phillips, A New Method for Measuring the Fi ne-Structure

Constant Using Stark Spectroscopy, NBS Spec. Publ. 617.

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.

B. N. Taylor, Numerical Comparisons of Several Algorithms for Treating

Inconsistent Data in a Least-Squares Adjustment of the Fundamental Constants,

NBS- IR.

B. N. Taylor and W. D. Phillips, Eds. of Preci si on Measurement and

Fundamental Constants II, Nat. Bur. Stand. (U.S.) Spec. Publ. 617, in press

(to appear late FY 82).

D. C. Tsui, A. C. Gossard, B. F. Field, M. E. Cage and R. F. Dziuba, A

Preliminary Determination of the Fi ne-Structure Constant Using GaAs-Al

x

Gd| _ x As

Heterostructures , Phys. Rev. Lett.

R. J. Wagner, C. F. Levine, M. E. Cage, R. F. Dziuba, and B. F. Field,

Measurements of Quantized Hall Steps in Si at the PPM Level, Surface Science.

59
Technical and Professional Committee Participation and Leadership

N. B. Belecki, member, ANSI C39/100, American National Standards

Institute Committee on Electrical Standards, Insturmentation , and

Devices; and SC. I, 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); and E7,Sc.9, Materials Inspection and

Testing Laboratories.

G. M. Free, member, American Society for Nondestructive Testing, C2,

Electrical and Magnetic Methods Committee.

G. M. Free, Secretary, American Society for Nondestructive Testing,

Cl, Research Promotion Committee.

G. M. Free, member, American Society for Nondestructive Testing,

Electronic Components 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.

B. N. Taylor, Chairman, NBS Precision Measurement Grants Committee.

60
B. N. Taylor, MBS 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 Verification.

B. N. Taylor, member, TC-2, DC and LF Standards, Instrumentation and

Measurements Committee of the Instrumentation and Measurement Society,

Institute of Electrical and Electronics Engineers (IEEE).

61
Collaborations, Consulting, Miscellaneous Activities

N. B. Belecki consulted throughout the year with the staff of the Office of

Measurement Services on MAP activities at NBS and in industry. He is also

serving as a member of MBS' Calibration Advisory Group.

N. B. Belecki reviewed the proposed syllabus for a two-year metrology course

at Butler County Community College in Pennsylvania under the auspices of NCSL.

N. B. Belecki and R. F. Dziuba are collaborating with metrologists from six

Southern California companies (Beckman Instruments, Electrical Standards Repair

Service, Ford Aerospace & Communications, Lockheed of California, Rockwell

International Anaheim, and TRW) in a pilot experiment to develop methodology for

a "self-help" group MAP in resistance. The goal is a procedure by which

companies could set up and run their own MAP, including data reduction and error

analysis, using NBS ' s calibration services and their own transport standards.

Some of the equipment is being furnished by the NCSL Measurement Assurance

Committee.

M. E. Cage collaborated with R. S. Davis of the Length and Mass Measurements

and Standards Division (523) in obtaining analytical solutions to the equations

of motion of a single-pan balance for the freely-swinging, the unaerdamped, the

critically damped, and the electronical ly-servoed cases.

M. E. Cage, R, F. Dziuba, and B. F. Field are collaborating with S. M.

Girvin of the Surface Science Division (541) and R. W. Rendell of the

Radiation Physics Division (533) on the theoretical aspects of the quantized

Hall resistance experiment.

M. E. Cage, R. F. Dziuba, and B. F. Field collaborated with P. J. Stiles

of Brown Univeristy, R. J. Wagner and C. F. Lavine of the Electronics

Technology Division of the Naval Research Laboratory, and with the staff of the

Research Device Facility of the Naval Research Laboratory, in the design and

fabrication of a new mask set for Si MOSFETs.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with R. J.

Wagner and C. F. Lavine of B. D. McCombe's Electronics Technology Division

the Naval Research Laboratory, on quantized Hall resistance measurements using

the 15 T NRL superconducting magnet and Si MOSFET devices.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with D. C.

Tsui and A. C. Gossard, Bell Laboratories , on quantized Hall resistance

measurements using a Bell Labs 10.5 T superconducting magnet and GaAs-Al Ga, As

heterojunctions.

M. E. Cage, R. F. Dziuba, and B. F. Field are collaborating with P. J.

Stiles of Brown University on quantized Hall resistance experiments with Si

MOSFET devices cooled to mK temperatures. These experiments are being done

using a superconducting magnet at the National Magnet Laboratory.

62
G. Costabile collaborated with R. L. Kautz of the Electromagnetic Technology

Division (724) on the application of arrays of hysteretic junctions to a zero-current bias Josephson voltage standard.

R. F. Dziuba consulted with Hughes Aircraft Co. on problems involving

qualification of high-power precision resistors for inertial guidance

appl ications.

R. F. Dziuba provided consulting support to approximately twenty five

companies on problems in precision resistance measurements and standards

applications.

R. F. Dziuba collaborated with K. Harmans, Van Swinden Laboratory, the

Netherlands, on improving the performance on an NBS al 1 -cryogenic Josephson

voltage standard system.

R. F. Dziuba has collaborated in the training of George Gillies, newly hired

as an electrical metrologist by the International Bureau of Weights and Measures

(BIPM)

.

R. F. Dziuba and J. Q. Shields are collaborating with A. M. Thompson,

CSIRO, 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,

transportabl e resistance stanaard.

W. G. Eicke has provided consulting services to personnel in the Office of

Energy-Real ated Inventions in the area of electrochemical power.

W. G. Eicke is collaborating with E. Escalante of the Chemical Stability and

Corrosion Division (561) on improvement of electrical measurements in the field

of corrosion.

B. F. Field and L. B. Hoi deman are 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.

G. M. Free is collaborating with L. Schwartzendruber of the Metal Science and

Standards Division (564) on a program to correlate electrical conductivity

(determined using eddy-current testing) wit-h the tensile strength of aluminum

al 1 oys.

G. M. Free Collaborated with Caius Dodd of Oak Ridge National Laboratories on

an experiment to determine the electrical conductivity of metals directly by

eddy current methods.

G. M. Free Collaborated with Jeff Bailey of Kaiser Aluminum in a round-robin

measurement of aluminum electrical conductivity standards . The information

gathered will be used to evaluate the accuracy and precision with which members

of the aluminum manufacturers association measure this quantity.

63
L. B. Hoi deman and J. Toots are collaborating with P. N. Peters of NASA's

Marchall Space Flight Center in an investigation of microbridge-type Josephson

junctions for voltage standard and radiation detection applications.

L. B. Holdeman is collaborating with R. J. Soulen, Jr., and D. YanVechten

of the Temperature and Pressure Measurements and Standards Division (TPMSD, 522)

in an investigation of low-T superconductors (Ir, AuAl , Auln ) and low-T

superconducting devices. c 22c

L. B. Holdeman collaborated with R. J. Soulen, Jr., and D. YanVechten

(TPMSD, 522) in an investigation of enhancement of the superconducting

properties of thin aluminum films by microwave radiation.

L.- B. Holdeman and T. J. Jach of the Surface Science Division (541) are collaborating on an investigation of the oxidation of AuAl^

.

L. B. Holdeman and J. Toots made numerous thin-film depositions as an informal service to various research groups within MBS: e.g., deposition of

gold contacts onto carbon wafers for low- temperature thermometry (B. Dove, R. Soulen, H. Marshak, 522); fabricated large-area platinum-silicon

Schottky-barrier diodes as prototype soft x-ray detectors for the NBS beam line

at the Brookhaven National Synchrotron Light Source (T. Jach, 541); deposited

a series of gold films onto suspended formvar films for calibrating the Mott

scattering apparatus built by the Electron Physics Group to detect electron spin

polarization (D. Pierce, S. Mielczarek, 533); and fabricated a thin-film platinum

bolometer (K. C. Harvey, 520).

W. D. Phillips is col 1 aborati ng with M. G. Littman of Princeton University

on the spectroscopy of Rydberg atoms in electric fields and applications to the

measurement of the fi ne-structure constant.

W. D. Phillips is collaborating with H. J. Metcalf, SUMY, Stony Brook, on the use of magnetic fields in the laser cooling of neutral atomic beams; and

collaborated with Metcalf on the analysis of subnatural Doppler-width

spectroscopy.

W. D. Phillips is collaborating with R. J. Santoro of the Thermal Processes

Division (566) on the application of rapid laser frequency scanning to the study

of transient systems.

J. Q. Shields is collaborating in the training of Ho Chaolai, an electrical

metrologist from NIM, Beijing, PRC.

J. E. Sims collaborated with U. Bertocci of the Chemical Stability and

Corrosion Division (561) on development of a Fourier analysis computer program

to process electrochemical data in corrosion studies.

B. N. Taylor is collaborating with E. R. Cohen, Rockwell International, and

the CODATA Task Group on Fundamental Constants, on a new least-squares

adjustment of the fundamental physical constants to be completed in late 1981 or

64
early 1982 for international adoption by CODATA in 1982. This work is also part

of a collaborative effort with Soviet scientists from VNIIM under the Joint

NBS-Gosstandart collaboration in metrology.

B. N. Taylor is serving on the NML's Merit Pay Performance Review Board, and

served on the NBS director's Task Force on Calibration and Related Measurement

Services.

B. N. Taylor served as Chairman of the Conference Committee which organized

the Second International Conference on Precision Measurement and Fundamental

Constants held at NBS/Gai thersburg, June 8-12, 1981.

B. N. Taylor serves as a member of the Editorial Review Board of the IEEE

Transactions on Instrumentation and Measurement, as an Editor of Metrologia in

the area of Electrical Measurements and Fundamental Constants, and as Editor

with D. R. Lide of MBS' quarterly Preprints on Precision Measurement and

Fundamental Constants.

B. N. Taylor is NBS representati ve to and member of the Executive Committee of

the Conference on Precision Electromagnetic Measurements.

B. N. Taylor and W. D. Phillips are editing the Proceedings of the Second

International Conference on Precision Measurement and Fundamental Constants.

J. Toots is collaborating with D. W. Braudaway, Sandia, on the implementation

of a Josephson voltage standard at Sandia by producing Josephson tunnel

junctions for Sandia.

E. R. Williams, P. T. Olsen, and W. D. Phillips are collaborating with K.

A. Krasnov, VNIIM, USSR, on the theoretical investigation of various new techniques for realizing the ampere using superconductivity and/or cryogenics.

This is part of a collaboration between NBS scientists and Soviet scientists

from VNIIM under the joint NBS-Gosstandard collaboration in metrology.

E. R. Williams is col 1 aborati ng with G. L. Greene, Yale University, on testing Greene's new technique (Ramsey separated oscillatory field magnetic

resonance) to determine the proton gyromagnetic ratio.

E. R. Williams is collaborating with G. T. Gillies, BIPM, on the development

of a new approach to detecting free quarks.

65
EMSD Calibration Summary for FY 81

(as of 8/31/81)

SP 250 - 3.1 Resistance Measurements

523 Standard resistors and shunts

3 MAP Transfers

3.2 Precision Apparatus

28 Inductive Voltage Dividers

3.3 Impedance Measurements

185 Standard Inductors

218 Standard Capacitors

3.4 Voltage Measurements

106 Standard Cell Enclosures

(402) Standard cells)

22 MAP transfers

3.5 Electrical Instruments (AC-DC)

53 Standard Thermal Converter Instruments

(773 points)

Estimated FY 81 Billing $375,000

66

MEASUREMENTS AND STANDARDS DIVISION

"'F ACTIVITIES

" 1981

*• into three major areas

temperature and

emperature

">es of

-tand-

TEMPERATURE AND PRESSURE MEASUREMENTS AND STANDARDS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1981

I. INTRODUCTION

The activities of the TPMSD can be divided into three major areas

of responsibility. These are:

1. Providing access to the national scales of temperature and

pressure for technical groups throughout the U.S.;

2. Developing new standards for the measurement of temperature

and pressure which are more accurate or more useful; and

3. Performing scientific research which may lead to new types of

high-precision temperature or pressure sensors or to a better understanding of temperature or pressure measurement.

During the past year, the TPMSD staff was active in each of these

areas. In the following narrative, we note the names of staff members

who have done the work under discussion. Often, a staff member contributed in all three areas; this situation is a natural consequence of the

close connection between the calibration and research responsibilities

of the Division. In some instances, substantial portions of the work

were done by Guest Workers, Summer Academic staff, or visiting scientists; we have tried to acknowledge this assistance as well.

II. CALIBRATION, INSTRUCTION, AND CONSULTATION

In setting the original charter for the NBS, Congress decreed that

the Bureau should disseminate to U.S. science and industry the means of

measurement of physical quantities. The TPMSD still regards this responsibility as providing for its most direct contribution to American productivity; the resulting activity is certainly the Bureau's most visible

from the point of view of American industry.

The Division discharges its responsibility to provide access to

standard measurements of temperature and pressure through three activities:

^Calibration of "standard" sensors for temperature and pressure;

^Formal instruction in the techniques of precision measurement of

temperature and pressure; and

^Consultation on an individual basis with personnel from U. S. scientific or industrial organizations.

67
A. Cal ibrations

The NBS Special Publication 250 provides the basic information

by which the majority of requests for calibration of temperature or pressure instruments reach NBS. It contains a listing of the procedures

most frequently needed along with their prices, and it also refers to the

availability of specialized calibration services available on an "at

cost" basis. Here we summarize the fee-paid services performed during

the past year:

^Laboratory thermometers (liquid-in-glass type) - J. A. Wise, calibrator. 661 liquid-in-glass thermometers, 25 thermocouples, and 24

platinum resistance, thermistor, digital or other temperature sensors calibrated for 166 customers representing major manufacturers of thermometers; U.S., state, and local governments; manufacturers of consumables

and durable goods; utilities; and universities and hospitals.

*Thermomcouple thermometers - M. G. Scroger, calibrator. 300 thermometers calibrated for 95 customers representing major manufacturers of

thermometers ; U.S. government agencies; manufacturers of durable goods;

utilities; and universities.

^Platinum resistance thermometers - W. R. Bigge, calibrator. 77

thermometers calibrated for 64 customers representing major thermometer

manufacturers ; U. S. government agencies; durable goods manufacturers;

utilities; and universities.

^Germanium-based cryogenic thermometers - E. R. Pfeiffer, calibrator

5 thermometers calibrated for NASA and thermometer manufacturers.

^Gas-operated piston gages - R. G. Driver, 26 multiple-range gages

calibrated for major gage manufacturers, for utilities, industrial

users, and U.S. government agencies;

*0i 1-operated piston gages - W. Markus, calibrator. 20 multiplerange gages calibrated for manufacturers, utilities, NOAA, NASA, military

and private industry.

*Mercury manometers - B. E. Welch, calibrator. 4 manometers calibrated for manufacturers, auto industry, and chemical industries.

*Low-range Ball gages - R. W. Hyland, calibrator. One calibrated

for Ametek, Inc.

^Capacitance diaphragm manometers - R. W. Hyland, calibrator. 11 gages calibrated for a variety of government laboratories and private

corporations.

’’'Ionization vacuum gages - K. E. McCulloh and C. R. Tilford, calibra

tors. 3 gages calibrated for NASA and U. S. government contractors. 6

gages calibrated under DoE sponsorship (not for fee) for LASL.

68
Besides the relatively frequent calibrations of the types noted

above, the calibration staff provide many calibrations as participants

in international comparisons of laboratory standards or of laboratory

techniques. During the past year, an international piston gage interlaboratory comparison continued [4].

An additional calibration activity is known as a "Measurement

Assurance Program" (MAP) calibration; in this case the intention of the

activity is to ascertain the overall level of accuracy currently being

achieved by a participating laboratory. The TPMSD MAP activity is

directed by the NBS Office of Measurement Services. Two general areas

are involved — thermometry in the range covered by the new Provisional

0.5 K to 30 K Temperature Scale (EPT-76), and the PRT range (14 K to

904 K). Three major suppliers of cryogenic thermometers have requested

that NBS provide a MAP in the EPT-76 range; therefore, the 1 ow- temperature

MAP is addressed to their needs. E. R. Pfeiffer and R. S. Kaeser accom- plished the following results:

*Compari son of thermometers incorporating the IPTS-68; the NBS 2-20 K Acoustic Scale; the NPL-1975 Gas Thermometry Scale; and the SRM 767

superconducting fixed point device from 0.5 K to 30 K;

^Calibration of 9 germanium thermometers over the same range;

^Completion of an automatic data acquisition and processing program

known as "MOOSE"; and

^Development of interpolation relations for the germanium thermometers.

In the PRT range, the capabilities of two additional laboratories

were evaluated with respect to calibration accuracy of standard IPTS

PRT's [5]. In addition, work was continued through ASTM committee E-20

on an evaluation of the calibration capabilities of industrial thermometer

manufacturers.

The calibration of ionization- type vacuum gages mentioned above is

a new service of NBS, just instituted during the past year. The calibration of liquid manometers is discouraged because the accuracy of these

instruments is quite sensitive to user procedures.

B. Precision Measurement Seminars

The TPMSD offers two formal instructional seminars to the

public on a fee-paid basis. One of these, the Precision Thermometry

Seminar, consists of theoretical and laboratory instruction in the use of

platinum resistance thermometers, liquid-in-glass thermometers, thermocouple thermometers, and thermistor thermometers. The instructions are given by the calibration staff and their supervisors. The Precision

Thermometry Seminars are presented twice yearly and last four and one-half

days. Attendance generally is limited to 25 people so that an effective

69
level of instruction is maintained. The roster of students usually represents the same types of organizations that make up the lists of calibration customers, except that often there are attendees from foreign

countries whose own national laboratories cannot offer such instruction.

The Division offers instruction in pressure measurement as well,

through the seminar on Calibration and Use of Piston Gages. This seminar

is offered twice yearly to a maximum of 15 people at each session.

B. E. Welch is the prinicpal instructor.

C. Consultations

Frequently it happens that the Division is asked for advice on measurement problems that are very specifically related to a particular

company or industry. Such requests can be resolved many times during a telephone conversation or by a visit to NBS by the scientist or engineer

making the request, but occasionally effective help can be given only

through a longer-term effort on behalf of the caller. As examples of

such assistance by the Division, we can cite the following activities

from the past year:

*A one-day visit to the Orton Foundation by an NBS measurement

consulting team which included G. W. Burns. The Orton Foundation is a major supplier of pyrometric cones used in heat treating;

^Development of a level sensor by V. E. Bean and F. G. Long for the

Bruceton, Pennsylvania, DoE facility [16]. Originally thought to be a pressure measurement problem in the handling of liquid coal derivatives,

this effort took the form of a magnetic level sensor in the output line

of a coal reactor. The design has been described in a report to sponsor

and is under patent consideration;

*Conti nuation of a long-term effort on behalf of the heavy metals

industry by G. W. Burns and G. A. Evans. The principal objective of

this project is the development of a test method for disposable thermocouple thermometers used in preparing melts of heavy metals. Currently

the work involves an effort to measure the melt temperature for continuous periods of 20 minutes or more. This work is described more fully in

a later section of this report;

*Advice to a manufacturer of piston gages on technical design; and

*A one-day visit by G. W. Burns to the Owens-Corni ng Corporation to

review plant temperature measurement techniques.

70
III. DEVELOPMENT OF NEW STANDARDS FOR TEMPERATURE AND PRESSURE MEASUREMENT

At the present time there is an intense effort on the part of the

TPMSD to develop new standards for temperature measurement. This work

is part of a world-wide effort to replace the International Practical

Temperature Scale of 1968 with a scale which is both improved and

extended in range. The international Consultative Committee for

Thermometry, acting under the direction of the International Committee

for Weights and Measures, is monitoring the progress of the current

research and has the responsibility for preparing the text of a replacement scale. Discussions of this international thermometry effort have

been published in the NBS Dimensions magazine (September 1978 and

November 1980 [32]); these articles have been circulated to many

interested persons during the past two years.

Besides the effort in international standards for temperature, the

Division staff also is active in U.S. industrial and medical temperature

standards.

International standards of pressure exist primarily in the form of

standard instruments; however, there is a growing interest in the

establishment of a pressure scale. As with temperature, the development

of industrial standards of pressure continues to be actively pursued.

A. Work Towards A New Temperature Scale

The IPTS-68 provides for the measurement of temperature over

the range 13.8 K to 904 K (-259 °C to 630 °C) by use of a standard platinum

resistance thermometer (sPRT) calibrated at prescribed reference temperatures. The main objective in formulating the IPTS-68 was to provide

reproducible, precise temperature measurements for the use of science

and industry; in the sPRT range this objective has been realized rather

well. In the hands of careful workers, the typical level of imprecision

for sPRT's over most of their range does not exceed a few tenths of a mi Hi degree, which amounts to about one part per million at room temperature. Much larger temperature errors are introduced by differences in

the IPTS-68 fixed-point realizations in different laboratories. For

this reason, the major research on thermometry in this range is focused

on more reproducible fixed-point devices [22].

1. Sealed Triple-Point Cells

Outstanding among improved temperature fixed-point devices

is the sealed cell for realizing the triple points of 1 ow- temperature

gases. At the NBS, this type of cell is under study by G. T. Furukawa.

His work is part of an international effort to develop transportable,

precise, and practical cells for use below room temperature. Cells

containing Ar, 0 2 , CH 4 , H 2 , Kr, and Xe have been prepared in various

71
countries as part of this program. Shown below are results obtained

with two sPRT's by Furukawa on melting a sample of Ar in a sealed cell.

This figure shows that the sPRT measurement precision, as well as the

cell temperature stability, approaches 0.01 millikelvins.

o

o

<

S

UJu

z

<

VS

V)

>

<

1

—

qo [>

o

_ j

!

0

A

1 1 1 r~ * 0 *

° 6 A & * t>0

J

1

<2r g

0.1 mK

A —

J2

x

10'

7W

"

PRT S/N

17740 92 0

1774095 A - &*iii 1

1 1 ! 1 I 0 10 20 30 40 50 60 70 80 90 100 PERCENT OF SAMPLE MELTED

Fig. 1: Melting curve of Ar in a sealed

cell. The curve was measured with two

thermometers.

Measurements made on Ar cells prepared by several different laboratories show a mean value of 83.8003 K and a spread of about 0.2 mK.

These results indicate that such a cell can provide a very precise

reference temperature without the usual problems associated with contamin

ation and manometry that are found using open cells.

Using a sample of 99.9995% pure 0 2 , Furukawa found an IPTS-68

triple-point temperature of 54.3619 K. The melting curve showed discernible effects of impurities, however, so that Furukawa plans to prepare

more pure oxygen by decomposing KMn0 4 during the coming year.

Furukawa has obtained samples of Kr and Xe for similar studies. In

addition, he is modifying a calorimetric cryostat for measurements below

50 K.

2. Triple Point of Water

The triple point of water is the primary defining point

of the Kelvin thermodynamic temperature scale and of the IPTS-68. This

temperature is ordinarily realized using sealed re-entrant cells of

borosilicate glass. It is difficult to exclude air, however, during the

72
construction of water triple-point cells. In order to determine the

effects of air or impurities leached from the glass by the water,

Furukawa tested a collection of 16 cells ranging in age from newly

purchased to more than 20 years. The triple-point temperature of 15 of

the cells agreed within ±0.03 millidegrees Celsius. The 16th cell

showed a triple-point temperature some 0.15 millidegrees lower, probably

as a result of contamination with air; examination of the cell revealed

a noncondensible bubble about 2 cc in volume. Thus Furukawa estimates

that triple point of water cells are capable of thermometric precision

within about 30 microdegrees Celsius (about 2 parts in ten million).

3. Gallium triple point

In an earlier report, B. W. Mangum noted that the melting

curves of high-purity samples of Ga showed stability at the 1 microkelvin

level when the samples had been prepared for determination of the triplepoint temperature. During the past year, Mangum experimented with the

use of teflon-coated stainless steel cells on the ground that they would

be more safely transported than the all-nylon cells used originally.

Both ac and dc resistance bridges were used to measure the sPRT's. Final

results are not available, but the preliminary findings indicate the

presence of pinholes in the teflon coating of some of the cells and that

the mean triple-point temperature of the newly-prepared cells agrees well

with the earlier determination.

4. Resistance Thermometer Bridges

The IPTS-68 text does not prescribe the measurement

method to be used in realizing the scale. In various laboratories,

measurements of sPRT resistances are made with potentiometers, current

comparators, dc resistance bridges, and ac resistance bridges. The NBS

issues sPRT calibrations based upon dc Meuller bridge measurements,

although a 400-Hz ac bridge designed by R. D. Cutkosky and a commercial

current comparator are under study as well.

Recently, Cutkosky has designed a new resistance bridge [2]. It uses 15 Hz or 30 Hz square wave excitation, is self-balancing, and incorporates a microprocessor control for full compatibility with computerbased, automatic operation. Several measuring currents are available, and

the bridge has been modified for use with guarded thermometers [3] and

resistances as high as 100 ohms.

During the past year, three bridges of this design were built under

the direction of Cutkosky and R. S. Kaeser, bringing the total number in

the Division to six.

73
5. Temperature Scale Improvement above 900 K (630 °C).

In the IPTS-68, temperatures between 900 K and 1337 K

(respectively the Sb and Au freezing points) are determined by use of

thermocouple thermometers , resulting in a marked deterioration of the

scale precision. To improve thermometry in this range, J. P. Evans has

spent many years in an effort to design and fabricate platinum resistance

thermometers capable of the greatest stability and precision at temperatures as high as 1370 K (1100 °C). During 1980, with the help of

R. D. Cutkosky, Evans designed a guarded-lead thermometer in an attempt

to reduce the effect of leakage currents in the 2.5-ohm configuration.

The guarding technique proved to be effective, but most of the 1980

thermometers were unsatisfactory in stability, apparently because of

contamination of the platinum resistor during construction.

During 1981, an additional 25 thermometers were built, including

five by H. Nubbemeyer of the PTB in Berlin and ten by N. Bass of the

CSIR0 in Sydney. In general, the alpha coefficient was found to decrease

on heating to 1100 °C from an initial value above 0.003926 to a value

lower than 0.003925 (the lower limit of alpha for a sPRT). Elimination

of a teflon separator in the thermometer head, replacing the argon- 10%

oxygen filling gas with dry air, and prolonged annealing at 900 °C all

proved ineffective in correcting this decline in the alpha coefficient.

Chemical testing of the affected thermometers has indicated the presence

of copper; accordingly, the glass-cleaning procedure has been modified

slightly, and a second bake-out system has been installed for use with

newer thermometers. Results are not yet sufficient to judge the efficacy

of these steps.

Several modifications to the thermometer geometry have been made as well. One thermometer resistor was fabricated in a coiled helix configur

ation; its alpha value remained above 0.003925 after 700 h above 1100 °C.

In another change, two thermometers were made with grooved cylindrical

fused silica resistor mounts; however, the rate of change of the triplepoint resistance was anomalously large for these thermometers. Finally,

several thermometers were prepared using crosses with 20% deeper notches

for the windings, again with no improvement in characteristics.

During the past year, the NIM in Peking gave the NBS a 0.25-ohm

high-temperature PRT of Chinese construction. Preliminary examination

shows an alpha value of 0.003927 and essential agreement with the

resistance-temperature relation of the NBS thermometers up to 660 °C.

J. P. Evans also has been working on the problem of improving the

precision obtainable with Ag and Au freezing points. He has fitted a silver point cell with a heat pipe; a recent modification of this arrange

ment has produced a cell with a 5-cm length uniform within 0.1 mK except

for the hydrostatic head gradient.

74
6. Temperature Scale Improvement Below 30 K

NBS contributions to the extension of the IPTS-68 to

lower temperatures include the development of superconductive temperature

reference points, the evaluation of the 0.5 K to 30 K Provisional Temperature Scale (EPT-76), development and evaluation of cryogenic thermometers,

and the evaluation of thermodynamic temperatures [20],

Little progress was made in renewing the SRM 767 0.5 K to 7 K superconductive fixed point device during the past year; G. A. Evans has

been returned to the project on a half-time basis to prepare singlecrystal samples and J. F. Schooley has rebuilt a cryostat in which the

devices can be tested at the 0.1 mK level of resolution.

The SRM 768 device continues to be produced by R. J. Soulen and

R. B. Dove. The principal activity during the past year in this regard

has been the use of the SRM 768 to resolve a controversy about the He-3

phase diagram. This work took place in Finland; essentially, the Be and

W points of the SRM 768 were employed to calibrate a Pt nuclear magnetic

resonance thermometer and verify within 2% the assignment of 1.04 mK as the temperature of the zero pressure point on the phase diagram [34].

E. R. Pfeiffer and R. S. Kaeser compared values on the EPT-76

obtained from several sources; two capsule PRT's calibrated on the

IPTS-68, four germanium resistance thermometers calibrated on the NBS

Provisional 2-20 K acoustic temperature scale of 1965, two Rh-Fe resistance thermometers calibrated on the NPL-75 gas thermometer scale, and

two NBS SRM 767 devices augmented by a paramagnetic salt thermometer

containing cerous magnesium nitrate. The results obtained in this study

indicate agreement between the various realizations of the EPT-76 within

about 1 mK. A novel feature of this work is the use of a computer-based

system for control of the experiment as well as for obtaining and processing the data.

No practical thermometry technique capable of 0.1 mK reproducibi 1 i ty

at all temperatures between 0.5 and 30 K has yet been demonstrated. In

principle, gas thermometry should be appropriate in this range, since

the ideal gas law would permit relatively accurate interpolation between

relatively few fixed reference temperatures; in practice, however, the

problems in performing manometric measurements have been a sufficiently

strong disadvantage to discourage use of this method. C. T. Van Degrift

recently devised a new type of gas thermometer in which a single electrical lead conveys information on the resonant frequency of an LC oscillator

circuit employing a cryogenic tunnel diode. During the past year, six

copies of a successful prototype gas thermometer have been fabricated

from coin silver. The thermometers have been made with capacitor diaphragm

thicknesses varying from 0.1 mm to 9.25 mm. The corresponding predicted

temperature resolutions of these units vary from 3 to 50 microkelvins.

75
Evaluation of thermodynamic temperatures by noise thermometry and gammaray anisotropy thermometry at the NBS has permitted the evolution of a new

1 ow- temperature scale, the NBS-CTS-1, from 0.01 K to 0.5 K [13,34,35],

During the past year, R. J. Soulen, with the assistance of H. Seppa, a Finnish Guest Worker, and of W. S. Hurst, has succeeded in accelerating

the acquisition of data by about a factor 100. This improvement should

materially reduce the uncertainty of noise temperatures obtained in

Soulen 1 s laboratory. In a neighboring laboratory, H. Marshak has performed many of the preliminary measurements necessary to use Ho-166m [8] as a gamma- ray thermometer in the range 35 mK to 1.2 K.

Most of the projects reported in this section will be the subjects

of papers to be presented to the 6th Symposium on Temperature, Its

Measurement and Control in Science and Industry.

B. Industrial and Medical Temperature Standards

Besides work on research leading to a replacement for the

IPTS-68, the Division is involved in the work of industrial and medical

standards of temperature. Much of this work occurs at the behest of

Committee E-20, Temperature Measurement, of the American Society for

Testing and Materials or of the National Committee for Clinical Laboratory Standards.

At the request of the resistance thermometry subcommittee of the

ASTM E-20 Committee, G. T. Furukawa has undertaken a round-robin series

of evaluations of the calibration capabilities of industrial laboratories.

Results of the first year's measurements indicate that an sPRT is the

most satisfactory thermometer for this evaluation. Although the sPRT's

receive sufficiently rough handling in the tests that the thermometer

resistance changes by amounts corresponding to 0.05 K to 1 K, the resistance ratio W changes only by relatively small amounts, 3 mK to 5 mK.

To obtain information on the behavior of industrial PRT's, some 40

thermometers were obtained from different manufacturers for tests at the

triple point of water and at the Sn and Zn freezing points. Furukawa

also serves the ASTM E-20 as secretary of the New Thermometers Subcommittee, and he has written a draft standard on fixed points and assisted in

the preparation of a standard on industrial PRT's. In addition, Furukawa

has agreed to help write a handbook on resistance thermometry.

On behalf of a Task Group on Immersion Thermocouples for Molten

Metals, G. W. Burns, with the assistance of G. A. Evans, has designed

new thermocouple thermometer probes intended to function for 15-20 min

in molten metal at temperatures of 1400 °C and 1650 °C. During the past

year, two such probes were built. These probes incorporate Type B thermocouples (Pt-30% Rh vs. Pt-6% Rh) insulated with high-purity A1 2 03

and protected by a self-bonded Type KT SiC sheath 13 mm o.d. and 0.6 m

long. The SiC sheath is joined to a 2.2 m long stainless steel sheath

which itself is protected by multiple wrapping of "Fiberfrax 800" paper.

76
Burns also designed and constructed a crucible for preliminary testing,

and found that the SiC suffered severe attack after only 3-6 minutes in

molten iron. As a consequence of these tests, the protective sheath has

been redesigned to incorporate Mo tubing which is spray coated with

MgAl 2 0 4.

During the past year, also, the second edition of the ASTM STP 470B

"Manual for the Use of Thermocouples" was issued. Mr. Burns again

served as a co-editor for this work.

The Temperature and Pressure Measurements and Standards Division

staff is participating in the development of measurement standards in

support of resource recovery, under the direction of the NBS Office of

Recycled Materials. The role of the Division is to provide assistance

in the development of thermometry for use in high-temperature industrial

combustion. M. L. Reilly, in collaboration with colleagues in the NBS

Center for Chemical Physics, has made considerable progress toward the

development of a large scale calorimeter for use in evaluating the calorific

value of industrial waste. This device is a flow calorimeter designed for

2.5 kg samples. The first draft of a manuscript describing experiments with

a prototype combustor and the analysis of the experimental data was finished

during the past year. Other Division staff members contributed to the

project by providing advice on materials, thermometry, and data acquisition

techniques for the large-scale calorimeter, and by work on ancillary hightemperature instrumentation involving thermocouples, high-temperature

resistance thermometers, and temperature reference devices.

The Division's Medical Thermometry project, led by B. W. Mangum,

showed accomplishments in several areas during the past year. Characteristics of about 80 small platinum RTD's (resistance temperature

detectors) from 5 companies were studied over the range 0-100 °C; the

stability of the thermometers ' resistances following thermal cycling to

250 °C was evaluated. In another study, the behavior of Rb as a temperature fixed point was examined. Rb proved to be a difficult substance to

handle in the NBS laboratory, so that the assistance of a commercial

firm was obtained to fill some of the stainless steel cells used to hold

Rb samples. Preliminary results indicate that a temperature accuracy of

±0.01 °C can be obtained with the use of cells such as these. Other

fixed points in the range of interest for medical thermometry include

transitions in hydrated salts [7], succinonitrile (triple point about

58 °C), and In (melting point 156 °C); samples of both these latter

substances are under study. The Medical Thermometry project benefitted

this year from the work of G. A. Evans and of J. M. Figueroa, a Guest

Worker from the Polytechnical University in Mexico City.

C. International Standards of Pressure and Vacuum

During the past year, a new consultative committee was formed

under the auspices of the International Committee for Weights and Measures.

77
It is called the Consultative Committee for Mass and Related Quantities.

Its initial meeting at the International Bureau of Weights and Measures

took place in June 1981. This Committee discussed current and proposed

activities involving international standards for pressure and vacuum,

including the following:

^International comparison of piston gages in the range of atmospheric pressure. This comparison will use 50-psi CEC gas-operated gages

provided by the NBS;

^International comparison of piston gages in the 100 MPa range

(15,000 psi), using an oil-operated gage from France;

^International comparison of low pressure gages; NBS is the pilot

laboratory for this work, which will involve the use of capacitance

diaphragm gages.

The Division staff members responsible for coordinating CCM work in

pressure and vacuum are respectively, V. E. Bean and C. R. Til ford.

Several years ago, the International Association for the Advancement

of High Pressure Science and Technology (AIRAPT) organized a task group

with the responsibility for studying an international high pressure

scale. V. E. Bean is the chairman of this task group. This year he

wrote a review of high pressure metrology with recommendations regarding

a high pressure scale, and circulated it within the committee for discussion during the August 1981 meeting in Uppsala [17].

D. New NBS Pressure and Vacuum Standards

The principal activity in the improvement of pressure standards

at the NBS is the calibration of 3 CEC gas-operated piston gages against

the NBS Gas Thermometer manometer. It is expected that the 1.5 ppm

pressure accuracy of the latter can be utilized to improve substantially

the primary piston gage accuracy at pressures near one atmosphere. Subsequent cross-checking among the CEC gages should preserve the improved

accuracy, and it is hoped that cross-calibration with higher-pressure

gages will improve their accuracy ratings as well [29]. The gages have

been acquired for this experiment, and mounting hardware to operate them

in the absolute mode is nearly complete. B. E. Welch, R. G. Driver, and

L. A. Guildner are working on this project.

New 3000 psi controlled-clearance primary standard piston gages

have been ordered. These gages will be used in the calibration service

once they have been characterized.

Results obtained over the past two years by B. E. Welch on a heavilyinstrumented piston gage cylinder have given a great deal of information

on fluid properties in the annular crevice between the piston and cylinder.

A typical plot of some of this data is shown at the top of the next page.

78
TEMPERATURE GRADIENT

Spme**o No. 34 *

/

» 23 KPo

* 7 MPa

o 1 4 MPa

= 21 MPa

a i6 Crevic* Length (mm)

Fig. 2: Temperature gradient in the annular space

between a piston and cylinder of an oil -operated

piston gage using “Spinesso No. 34“ as the working

fluid. The temperature anomalies appear to be

related to dimensional changes in the annulus.

A paper discussing these results is in preparation. This experiment

is the first of its kind; it has yielded the following interesting

i nformati on:

*The data support a model proposed by Bass of the NRC in Canada;

*The elastic distortion coefficient probably can be calculated from

dimensional measurements;

*The position of the effective seal in a piston and cylinder can be

located by dimensional measurements; and

*Data were obtained on the effect of viscosity on the temperature

and pressure profiles in the annular gage crevice.

A project originated some time ago on the measurement of pressure

by capacitance has been reactivited following the rejoining of J. H. Colwell to the Pressure Group. A major difficulty of using capacitors

for pressure transduction lies in their large temperature sensitivity.

Progress to the present time has followed the use of two capacitors in

opposite arms of a capacitance bridge; if the dielectric materials of

the two capacitors have nearly identical temperature dependences but

different pressure dependences, a workable gage can result. One such

79
pair of dielectric materials is composed of two different orientations

of crystalline calcite; a second pair results from the use of bismuth

germanium oxide and arsenic trisulfide. The value of this work lies in

the possible applications as a stable transfer standard to save wear on the primary pressure standards and as a sensitive pressure monitor in

the characterization of controlled clearance gages.

Effort was made this year to improve the ultrasonic interferometer

manometer, which is used for calibration in the 0.1 Pa to 0.1 MPa range.

R. W. Hyland has incorporated an on-line computer capability to reduce

the time spent on data analysis and to speed diagnostics, and F. W. Long

and Hyland have modified the rf electronics and microprocessor control

circuitry to improve control of the instrument. The manometer was used

for more than twenty calibrations this year. It also served to evaluate

a low-range dead-weight ball gage, confirming a significant non-linearity

noted previously. The usefulness of the ultrasonic manometer was recognized by the presentation of a 1981 IR-100 Award to the NBS staff,

including P. L. M. Heydemann, C. R. Tilford, R. W. Hyland, D. F. Martin,

and F. G. Long.

A new gage comparator for the high vacuum range (0.1 mPa to 0.1 Pa) was completed during the past year by K. E. McCulloh, D. F. Martin, and

C. R. Tilford. A service in the calibration of ion gages was begun

using this device in conjunction with standard gages from the NPL in

England and from the PTB in Germany. Work is under way to develop a primary vacuum standard for this range by constructing a flowmeter for

use with the vacuum comparator.

A major effort in the characterization of high vacuum gages was begun this year by C. R. Tilford and K. E. McCulloh. The problem with

these gages is that their metrological properties have not been adequately

determined. The first step in evaluating the factors that affect gage

accuracy was to observe the response of several commercial gages to

nitrogen gas; a paper on this topic was published this year [11]. With

the assistance of an NBS Research Associate from Korea and of a summer

student, further examination of widely-used commercial gages was accomplished. Shown at the top of the next page is a graph of some of these

results.

A further problem in the use of ion gages has been the relatively

unstable performance of commercial ion gage controllers. McCulloh and

F. G. Long have designed and built a new controller. It is now in

routine use in the project; when the final design is fixed, it will be

publ i shed.

E. Thermodynamic Properties of Moist Air

R. W. Hyland had considerable experience in the field of humidity

measurement prior to joining the Pressure Group. An outgrowth of that work

80
Log Pressure (Toit) -6 -5 -4 -3

Fig. 3: Nitrogen sensitivities for seven different

ion gages as a function of pressure.

has been the development of comprehensive formulations for the properties

of the air-water system under the auspices of the American Society for

Heating, Refrigeration, and Air Conditioning Engineers. Writing has been

completed during this year for three publications on this work [24,25,26].

F. Industrial, Medical, and Fusion Pressure and Vacuum Standards

The Division staff serves the pressure and vacuum industrial

standardization community by participating in the work of the American

Society of Mechanical Engineers and the American Vacuum Society. V. E. Bean attended a meeting of an ad hoc committee on High Pressure Vessels

and Piping of the ASME during the past year; C. R. Til ford currently is

the chairman of the Standards Committee of the AVS and consults with the

ASTM Committee E-21.04 on Space Simulation; R. W. Hyland is chairman of

the Gaging Subcommittee of the AVS Standards Committee.

The Vacuum Group has made some progress during the past year toward

completing a vapor pressure apparatus for use in research at the National

Institutes of Health.

The Vacuum Group is involved in a substantial collaborative project

on behalf of the DoE Magnetic Fusion program. This year the NBS work

included calibration of vacuum gages used in vacuum pumping speed measurements at the Los Alamos Scientific Lab and the evaluation of the LASL

measurement techniques. The NBS analysis showed several problem areas in

these measurements. Solutions to these problems will be pursued, since

an improperly-designed pumping system can lead to major financial and

technical penalties. A co-op student has been added to this project.

81
IV. RESEARCH IN TEMPERATURE, PRESSURE AND VACUUM PHYSICS

The Division supports considerable laboratory work in which the

typical output is a scientific paper on the properties of matter or demonstration of a new measurement technique rather than a calibration

or a new standard device or procedure. It is felt that the scientific

growth of the Division staff accompanying such broadly-based and un- directed research enables staff members to develop or understand new principles for the precise measurement of temperature, pressure, and

vacuum. This approach has been proven useful over a long period of time

during which NBS has made major contributions to the development of

precision measurement in these areas.

Because the staff involved is inevitably aware of the close relationship of their work to the development of new standards, it is often

difficult to categorize specific projects as "basic" or "undirected".

Nevertheless, the existence of such projects is demonstrably of fundamental

importance to the long-term success of a metrological division, so that

work not specifically devoted to the development of new standards is

encouraged to the extent that flexibility in the program permits it.

A. Optical Measurements of Temperature and Pressure

G. J. Rosasco, with assistance from W. S. Hurst and R. B. Dove,

is preparing the apparatus necessary to measure the shifts and widths of

the levels of molecules such as N2 , 02 , CO, and C0 2 as functions of

pressure at room temperature. These data are not available, and they

are fundamental to the use of such information to characterize the

temperature and pressure of gaseous systems at high speed and without

the imposition of contact sensors. The project plan is to measure these

properties with very stable, narrow-frequency cw-laser sources.

The experimental apparatus involves several sub-systems which are

in various stages of construction. Among them are a frequency-stabilized

continuous krypton ion laser to be used as a "pump" — to prepare a population of molecules in excited states; a single-frequency continuous

ring dye laser to be used as a probe of the excited population (states

are selected by adjusting the pump-probe frequency difference); a frequency

measurement system; an optical detection system for use in wide-band

detection; opti cally-resonant sample cells; a computer-based data acquisition and control system; and, for use in future high-temperature experiments, a pulsed dye laser.

Work on this project during the past year has focussed on the

design of the first experiments and the acquisition and construction of

the basic instruments to be used. Considerable benefit is expected from

the contiguity of this laboratory to that occupied by collaborating

staff of the Molecular Spectroscopy Division.

82
B. Physics of Superconducting Films and Josephson Junctions

R. J. Soulen, with the assistance of R. B. Dove and collaborating with D. Van Vechten, an NBS Postdoctoral Research Associate, and with

L. B. Hoi deman of the NBS Electrical Measurements and Standards Division,

is involved in several projects besides the evaluation of thermodynamic

temperatures by Johnson noise measurement described elsewhere in this

report.

Considerable progress has been made in understanding the impedance

of resi sti vely-shunted superconducting quantum interference detectors

(SQUID's). Van Vechten has studied the dependence of the impedance upon

the impressed dc current, the bias amplitude, and the frequency of an rf

bias; and H. Seppa, a Guest Worker from the VTT laboratory in Helsinki,

has succeeded in correlating these results with an improved model of the

R-SQUID. These results are shown below.

; RAW VS PREDICTED

i.ee

N

o5 0.99

IIA

L

: 0.98

,1P£

0 0.97

S0

u 0.96

A

RE

D 0.95

20 22 2A 26 28 30

RF FREQUENCY

RES FREQ* 24. 86 SHUNT RESIS-12.904 Fig. 4: Fit of the impedance of an R-SQUID to the

RF input frequency. The circles show the data and

the dashed line represents the calculated impedance.

In another project, which receives partial support from NASA,

Soulen, Van Vechten, Hoi deman and J. T. Hall, a former NBS Postdoctoral

Research Associate, are investigating the effect of microwave radiation

on tunnel junctions [39]. Last year's short report on microwave enhancement

of the superconducting energy gap [6] has been followed during this year by

measurements on high-quality tunnel junctions of aluminum and Auln2 or

AuAl 2

. The current measurements were of the energy gap as a function of

temperature; the fit to that calculated from the BCS theory was quite

good. It was reported during the 16th Low Temperature Conference [36].

Microwave irradiation experiments are inhibited by substantial heating

of the cryostat, indicating the necessity for improved microwave leads.

83
Soulen, P. H. E. Meijer, and R. D. Mountain, of the NBS Thermophysics Division, conducted the 6th International Conference on Noise in

Physical Systems in April of this year. The proceedings will be published

as an NBS Special Publication during September of 1981 [28].

C. Nuclear and Magnetic Studies in Hoi mi urn

Single crystals of holmium are used by H. Marshak in the

development of nuclear orientation thermometry, as is described elsewhere

in this report. The generation of Ho- 166m nuclei by neutron capture

within such a crystal is straightforward because holmium has only one stable isotope, mass 165. The nuclear decay scheme of Ho-166m has not

been completely determined, so that this isotope cannot be used at present

to obtain thermodynamically meaningful temperatures. To develop Ho-166m

in holmium as a fundamental thermometer, Marshak has undertaken the

problem of determining the multipolarity mixing ratios for some 27 gammarays in this nuclide [8]. By measuring gamma-ray anistropies in a Ho

single crystal under conditions of nearly complete nuclear ordering,

Marshak can assign mixing ratios with unprecedented accuracy (by perhaps

a factor of ten better than previous assignments). These results will

be prepared for publication during the coming months.

The study of the magnetic structure of holmium is complete [10]. A

paper entitled "Nuclear Orientation Studies of Multi axial Nuclear Spin

Systems: Ho-166m Ho" will be published soon in the journal Hyperfine

Interactions [27].

D. Thermodynamic Measurements on Solid He-3

C. T. Van Degrift, with the assistance of W. J. Bowers, has

been engaged for some time in a study of the thermodynamic properties of

solid He-3. The apparatus in use is a pulsed tunnel diode oscillator

pressure cell contained in a He-3-He-4 dilution refrigerator.

Progress during the past year included measurements of the pressure

of solid He-3 at temperatures as low as 30 mK and pressures as high as 3.2 MPa in magnetic fields up to 8 tesla; measurements of the magnetothermal conductivity of coin silver (a useful material for many lowtemperature, high-field applications) [38]; and measurements of the

melting curve of He-3. Partial phase diagrams for He-3 and He-4 are shown at the top of the next page.

A significant improvement in the tunnel diode oscillator sensor [14] was required for the He-3 work. By operating the resonator in a pulsed

mode (0.03 sec per pulse), its power dissipation was reduced by a factor

of 100 while the frequency resolution remained at one part in 10s [37].

This modification also demonstrated the practicality of rapid scanning of

a large number of such sensors. In addition, the detailed behavior of the

pulsed oscillator was examined by use of a full computer simulation, and

84
general rules_were developed governing the fundamental limits of the

technique (10 8 parts resolution in 100 ps).

A calibration of the low temperature sensor against a room temperature piston gage with the assistance of G. Driver led to a paper describing the present utility of this project for assisting pressure standards

work by providing stable sensors and reproducible fixed points and the

prospects for future pressure standards based on cryogenics.

E. Properties of Materials at High pressures

Several experiments on the properties of materials at high

pressures [15] are in progress, all involving V. E. Bean and S. D. Wood.

One of these is a study of the compressibility of fluids — a good understanding of this property is necessary for all materials to be used in

fluid-operated piston gages. During the past year, new sample cells

designed for use at pressures up to 1.4 GPa were constructed. The design

was intended to permit direct evaluation of the fluid compressibility by

simultaneous measurement of the capacitances of two samples of the test

fluid, one held at constant volume and the other maintained with a constant number of molecules.

A secondary cell was especially designed for use with CC1 4 , which

has been shown to possess two metastable phases. In this cell, the CC1 4 is contained in a stainless steel bellows, the length of which is measured

by capacitance. Preliminary analysis of the experimental data indicates

that an equation of state for CC1 4 can be constructed to cover the range

of temperature from -19 °C to 25 °C and pressures up to 200 GPa. In

addition, information has been collected on the CC1 4 compressibility

85
over the same ranges; the changes of volume accompanying the fccrhombohedral , the liquid- fee, and 1 iquid-rhombohedral phase transitions

and their enthalpies and entropies; and on other anomalies in the CC1 4

properties. The compressibility of CC1 4 at -19 °C is shown below.

CompresaiDliity at -19 °C. 7/7/81

2. Of

o . :

• - « - » - - — •*— —— .... . q 5000 10000 12000 20C00 25000 Pressure, osi Fig. 6: Compressibility of CC1 4 at -19 °C for

pressures up to 20000 psi. The curve I refers to

the face-centered cubic phase and the curve I, refers to the rhombohedral phase.

Also constructed during the past year was a viscometer designed for

use up to 1.4 GPa at room temperature. The work of a summer student,

M. Turner, was utilized in a search for a fluid possessing a usefully high

low-pressure viscosity in conjunction with a pressure dependence of viscosity which is lower than logarithmic. Initial choices for study have

been glycerine and several alcohols.

A three-year cooperative research program between the NBS Pressure

Group and researchers at the U. S. Naval Academy, J. Fontanel la and M. Wintersgill, was completed during the past year. Among the results of

this collaboration are the following:

^Dielectric properties of CCL4 from -14 °C to 21 °C and up to

200 MPa [1]. This study provided information on the normal fluid, the

metastable fluid, and both of the solid phases, and preliminary analysis

indicates that the Clausius-Mosotti equation holds not only for the

dielectric properties of the normal fluid state but also for the superpressed, metastable fluid state;

*Study of the dielectric properties of another plastic crystal

system, cyclohexane in the fee solid phase. Unlike CC1 4 , cyclohexane

appears not to possess a super-pressed fluid phase;

86
*Study of the rotator-nonrotator phase transition in cycl ohexanol

,

under examination as a possible pressure fixed point. Preliminary

results indicate that the transition is not reproducible;

^Development of a solid dielectric material for use in pressure transducers. As noted elsewhere in this report, such a material should possess

a large pressure coefficient and a small or zero temperature coefficient

of capacitance. By adding Er to CaF 2 , its usual temperature coefficient

was markedly diminished, while its dielectric constant and the pressure

coefficient were increased by factors of three and 1.16, respectively.

Further work will be done on this material by J. H. Colwell.

V. GENERAL DIVISION ACTIVITIES

A. Laboratory Automation

During the past few years it has been possible for the Division

to spend substantially more funds for capital equipment. Much of these

funds have been utilized for the purchase of laboratory minicomputers

and the associated components, as well as for computer-compatible measuring instruments. As a result, the Division has made considerable progress

in the use of computer-based data acquisition and control equipment both

for research and for calibration.

W. S. Hurst has provided much of the concentrated effort needed to

establish the requirements for a given application and to assist the

affected staff members in acquiring suitable systems, although by no means

has he worked alone on this problem. Other staff members contributing to

the generation of hardware and software requirements within the Division

include R. S. Kaeser, F. G. Long, M. L. Reilly, and S. D. Wood.

During the past year, several new computer applications have been

introduced. These include:

*Use of a computer to record and analyze data on the compressibility

of CC1 4 and the introduction of real-time plotting to that experiment;

introduction of a minicomputer to control the operation of in the

ultrasonic manometer and to record the data from this instrument;

introduction of a minicomputer-based data acquisition system into

the thermocouple calibration laboratory;

*Full use of a minicomputer to control fixed-point equipment in the

high-temperature resistance thermometer laboratory, and automatic measurement and processing of thermometer resistances using the new 15-Hz

Cutkosky resistance bridge;

87
^Acquisition of a minicomputer in conjunction with a 100-ohm

Cutkosky resistance bridge for evaluation in the sPRT calibration

laboratory;

*Ref inement of the automatic temperature control and data acquisition

and processing system in use in the low-temperature scale laboratory. The

"MOOSE" control program was improved and expanded to allow 50 different

measurement tasks, and a new 15-Hz Cutkosky bridge was coupled to the

apparatus

;

^Installation of a computer-based data acquisition and control

system in the optical temperature and pressure measurements laboratory;

and

^Installation of a new computer and frequency counter system in the

noise thermometry laboratory.

B. 6th Temperature Symposium

Serious work was begun during the past year to prepare for the

6th Symposium on Temperature, Its Measurement and Control in Science and

Industry, scheduled for the week of 14-18 March 1982 in Washington, DC.

This decennial symposium will be co-sponsored by the NBS, the Instrument

Society of America, and the American Institute of Physics. The NBS

responsibility is for the technical quality of the program and of the

resulting proceedings, the ISA is responsible for facilities management

of the symposium and the attendant instrument exhibit, and the AIP

intends to publish the proceedings of the symposium.

Eleven members of the Division staff help to comprise the symposium

program committee; J. School ey is the Program Chairman. Activities thus

far include the evaluation of about 200 abstracts of contributed papers

and tentative assignment of these topics into symposium sessions.

The preparation of their own technical papers for the symposium,

technical review of a substantial portion of the contributed papers, and

activities during the symposium itself will occupy much of the Division

Temperature group's time during the coming year. However, no comparable

source of information on new research in thermometry exists; thus,

participation in the 6th Temperature Symposium will provide an excellent

opportunity for the Division staff to grow scientifically.

88
Conferences Sponsored

A joint General Committee and Program Committee meeting was held at the

Washington Hilton on 22 June 1981. These committees are planning the

6th Symposium on Temperature which will be held at the Washington Hilton

on 14-18 March 1982.

R. J. Soulen, Jr. and P.H.E. Meijer were involved in the Sixth International Conference on Noise in Physical Systems sponsored by the National

Bureau of Standards, The Catholic University of America, and the National

Science Foundation. The proceedings of this Conference will be published

as an NBS Special Publication in September 1981.

Invited Talks

Vern E. Bean, "Metastability in Tetrahidral ly Bonded Molecules," Institute

of Materials Science, Cornell University, Ithica, NY, 23 July 1981.

Vern E. Bean, "Toward an International Practical Pressure Scale," 8th

AIRAPT (International Association for the Advancement of High Pressure

Sciences and Technology) Conference, Uppsala, Sweden, 18 August 1981.

J. P. Evans presented an invited talk on high temperature platinum

resistance thermometry at a symposium given by the Dayton Section of ISA

(Instrument Society of America) at Yellow Springs, OH, November 1980.

G. T. Furukawa, "Temperature Measurements," Symposium for Innovation in

Measurement Science (sponsored by ISA), Geneva, NY, 9-14 August 1981.

K. E. McCulloh (C. R. Til ford, co-author), "Nitrogen Sensitivities of a Sample of Commercial Hot Cathode Ionization Gage Tubes," American Vacuum

Society 27th National Symposium, Detroit, MI, 14 October 1980.

R. J. Soulen, Jr., "Millikelvin Temperature Standards," 16th International

Low Temperature Physics Conference, Los Angeles, CA, 19-26 August 1981.

C. R. Tilford gave a talk on vacuum gaging at the 10th Annual Symposium

on Applied Vacuum Science and Technology, Tampa, FL, February 1981.

Seminars Organized

Two Precision Thermometry Seminars -- 9-13 March 1981 and 14-18 September

1981

Two Seminars on Calibration and Use of Piston Gages -- 15-16 May 1981

and 19-20 November 1981.

89
Publications - Division 522

In Print:

1. Joseph Link, Mary C. Wintersgill, John J. Fontanella, Vern E. Bean,

and Carl G. Andeen, "Pressure variation of the 1 ow-frequency dielectric constants of some anisotropic crystals, J. Appl . Phys. _52,

No. 2, 936-939 (Feb. 1981).

2. Robert D. Cutkosky, "An Automatic Resistance Thermometer Bridge,

IEEE Trans. Instrum. Meas. IM-29 , No. 4, 330-333 (Dec. 1980).

3. Robert D. Cutkosky, "Guarding Techniques for Resistance Thermometers ,"

IEEE Trans. Instrum. Meas. IM-30 , No. 3, 21 7-220 (Sept. 1981).

4. R. G. Driver, J. C. Houck, and B. E. Welch, "An Intercomparison of

Pressure Standards Between LNE and NBS," J. Res. NBS 84_ (5), 277

279 (May-June 1 981 )

.

5. G. T. Furukawa and W. R. Bigge, "A Measurement Assurance Program - Thermometer Calibration," Testing Laboratory Performance: Evaluation and Accreditation, pp. 137-145, NBS SP-591 , August 1980.

6. James T. Hall, L. B. Holdeman, Robert J. Soulen, Jr., "Microwave

Enhancement of Superconductivity in Aluminum Tunnel Junctions,"

Phys. Rev. Lett. 45, No. 12, 1011-1014 (Sept. 1980).

7. R. L. Magin, B. W. Mangum, J. A. Statler, and D. D. Thornton,

"Transition Temperatures of the Hydrates of Na2S0^, Na^HPO^, and

KF as Fixed Points in Biomedical Thermometry, J. Res. NBS 86_ (2),

181-192 (Mar. -Apr. 1981).

8. H. Marshak, "Nuclear Orientation of 16& Ho in 165 Ho Single Crystal ,"

Hyperfine Interactions, 1_0 (1-4), 1183-1188 (June 1981).

9. A. L. Allsop, N. J. Stone, H. Marshak and 0. G. Symko, "Nuclear

Orientation Studies of 54 Mn in Zn," Hyperfine Interactions, 9/10 , 839 (1 981 ).

10. B. G. Turrell and H. Marshak, "Magnetic Structure Determined by

Nuclear Orientation," Hyperfine Interactions 1_0, 1 231 -1 236 (1 981 ).

11. K. E. McCulloh and C. R. Til ford, "Nitrogen Sensitivities of a Sample of Commercial Hot Cathode Ionization Gage Tubes," J. Vac.

Sci. Technol . 18, 994 (1981).

12. J. J. Blaha and G. J. Rosasco, "Raman Microprobe Characterization

of Urea: n-Paraffin Inclusion Compounds," J. Raman Spectrosc. VT_,

No. 2 , 75-80 (1 981 ).

90
13. E. Lhota, M. T. Manninen, J. P. Pekola, A. T. Soinne, and R. J. Soulen, Jr., "Comparison of the NBS and Helsinki Temperature Scales

and Its Effect on the Heat Capacity of Liquid J He Below 10 mK,"

Phys. Rev. Lett. 47_, No. 8, 590-592 (Aug. 1981).

14. Craig T. Van Degrift and David P. Love, "Modeling of tunnel diode

oscillators," Rev. Sc i . Instrum. 52_ (5), 71 2-723 (May 1981).

14a. J. F. Schooley, "Progress Toward a New Scale of Temperature," NBS

Dimensions, November 1980, pp. 10-15.

In Press, in Review, or Nearing Completion:

15. Vincent J. Fratello and Vern E. Bean, "Melting Curve of 0_-terphenyl ,

to be published in J. Phys. Chem.

16. Vern E. Bean and Frederick G. Long, Jr., "Coal Slurry Level Monitor

Developed," to appear in NBS Dimensions.

17. Vern E. Bean, "Toward an International Practical Pressure Scale," to

be published in the Proceedings of the 8th AIRAPT Conference,

Uppsala, Sweden, 16-21 August 1981.

18. H. P. R. Frederikse, P. K. Schenck, G. W. Burns, R. R. Dils, and

J. R. Whetstone, "Materials for Instrumentation in Fossil Energy,"

to be published as NBSIR 81 -2348.

19. R. D. Cutkosky and R. S. Davis, "A Simple Control Circuit for

Temperature Regulation and Other Bridge Applications," to be published in the September issue of Review of Scientific Instruments.

20. G. T. Furukawa, R. S. Kaeser, H. Marshak, E. R. Pfeiffer, J. F. Schooley, R. J. Soulen, and C. T. Van Degrift, "Thermometric Fixed

Points Below 0 °C at the National Bureau of Standards," to be

published in the Proceedings of Temperature Measurement in Industry

and Science, IMEK0 TC 12 Symposium, Karlovv Vary, Czechoslovakia,

20-22 October 1 981

.

21. Furukawa, G. W. Burns, R. D. Cutkosky, R. E. Edsinger, J. P. Evans,

L. A. Guildner, and B. W. Mangum, "Temperature Research Above 0 °C

at the National Bureau of Standards," to be published in the Proceedings of Temperature Measurement in Industry and Science, I ME K0

TC 12 Symposium, Karlovv Vary, Czechoslovakia, 20-22 October 1931.

22. George T. Furukawa, John L. Riddle, William G. Bigge, and Earl R.

Pfeiffer, "Application of Some Metal SRM's as Thermometric Fixed

Points," to be published as an NBS SP.

91
23 . Leslie A. Guildner and Martin L. Reilly, "Proposed Method for

Determination of the Molar Gas Constant, R," to be published in the

Proceedings of the Second International Conference on Precision

Measurement and Fundamental Constants, Gaithersburg, MD, 7-12 June

1981.

24. Arnold Wexler and Richard W. Hyland, "Formulations for the Thermodynamic Properties of Dry Air from 173.15 to 473.1 5 K, and of

Saturated Noise Air from 173.15 to 372.15 K, at Pressures to 5 MPa,

to be published in ASHRAE Transactions.

25. Arnold Wexler and Richard W. Hyland, "A Formulation for the Thermodyanmic Properties of the Saturated Pure Ordinary Water-Substance

from 173.15 to 473.15 K," to be published in ASHRAE Transactions

.

26. R. W. Hyland, "Estimates of Uncertainties in Calorimetric Parameters

for Pure Water-Substance Determined by Osborne, Stimson, Ginnings,

and Fiock in the 1930's," to be published in ASHRAE Transactions.

27. H. Marshak and B. G. Turrell, "Nuclear Orientation Studies of

Multiaxial Nuclear Spin Systems: 166m Ho Hid," to be published in

Hyperfine Interactions.

28. P. H. E. Meijer, R. D. Mountain and R. J. Soulen, Jr., Proceedings

of the 6th International Conference on Noise in Physical Systems3 " to be published as NBS Spec. Pub! . 614.

29. C. R. Til ford and Donald Martin, "High Sensitivities Gas/Oil Pressure

Separator," to be published in Review of Scientific Instruments.

30. R. B. Strem, B. K. Das, W. T. Angel, J. T. Siewick, S. C. Greer and

C. T. Van Degrift, "A Digital Temperature Control and Measurement

System," to be published in Review of Scientific Instruments.

31. Deborah Van Vechten and Joel F. Liebman, "Number and Novelty in

Approaches to the Calculation of Strainless Group Increments," to be

published in the Israeli Journal of Chemistry.

32. J. F. Schooley - See Item 14a.

33. K. L. Churney, M. L. Reilly, A. E. Ledford, R. V. Ryan, and E. S.

Domalski, "An Oxygen Flow Calorimeter for Solid Fuels", to be published in the Proceedings of the 28th Congress of the International

Union of Pure and Applied Chemistry.

92
The following papers are to be published in the Proceedings of the 16th

International Low Temperature Physics Conference, Los Angeles, CA, 19-26

August 1 981

:

34. E. Lhota, M. T. Manninen, J. P. Pekola, A. T. Soinne and R. J. Soulen, Jr., "Intercomparison of NBS and Helsinki Temperature

Scales in the Mill ikelvin Region".

35. R. J. Soulen, Jr., "Mill ikelvin Temperature Standards" (Invited

paper)

.

36. Robert J. Soulen, Jr., D. Van Vechten, G. Costabile, Terrence Jach,

and L. B. Holdeman, "The Superconductive Energy Gap of AuA^"-

37. Craig T. Van Degrift, "A Pulsing of Tunnel Diode LC Oscillator

Sensors"

.

38. Craig T. Van Degrift, "Coin Silver as a Construction Material in

Low-Temperature Experiments".

39. L. B. Holdeman, J. T. Hall, D. Van Vechten, and R. J. Soulen, Jr.,

"Gap Enhancement in Aluminum Tunnel Junctions Coupled to Microstrip

Resonators"

.

93
Technical and Professional Committee Participation and Leadership

Vern E. Bean, Chairman, AIRAPT C002 , International Association for the

Advancement of High Pressure Science and Technology Committee on International Practical Pressure Scale.

G. W. Burns, Member, ANSI C096, American National Standards Institute

Committee on Temperature Measurement Thermocouples.

G. W. Burns, Member, ASTM E020, American Society for Testing and Materials

Committee on Temperature Measurement, Subcommittee SC. 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 E020, American Society for Testing and

Materials Temperature Measurement Committee, Subcommittee SC. 03, Resistance Thermometers; Subcommittee SC. 04, Thermocouples; Secretary, Subcommittee SC. 06, New Thermometers ; and Member, Subcommittee SC. 07, Fundamentals in Thermometry.

W. S. Hurst, Member, ANSI MC088, American National Standards Institute

Committee on Calibration of Instruments, Subcommittee SC. 03, Temperature.

Richard W. Hyland, Member, AVS C004, American Vacuum Society Committee on Standards, Subcommittee SC. 01 , Gaging.

B. W. Mangum, Member, ASTM E020, American Society for Testing and Materials

Temperature Measurement Committee, Subcommittee SC. 03, Resistance Thermometers; Chairman, Subcommittee SC. 06, New Thermometers; Member, Subcommittee SC. 07, Fundamentals in Thermometry; Subcommittee SC. 08, Medical

Thermometry, Working Group GS.02, 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 SC. 09,

Advisory Committee.

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,

Subcommittee SC. 01, Temperature.

James F. School ey. Member ANSI MC088, .American National Standards Institute Committee on Calibration of Instruments.

94
James F. Schooley, Member, CIPM CCT, International Committee on Weights

and Measures Consultative Committee on Thermometry ; and Delegate, Subcommittee SC. 01, Replacement of IPTS-68.

James F. Schooley, Delegate, OIML PS12, International Organization of

Legal Metrology Committee on Measurement of Temperature and Calorific

Energy.

James F. Schooley, Program Chairman, The 6th Symposium on Temperature:

Its Measurement and Control in Science and Industry.

Robert J. Soulen, Member, ASTM B001 , American Society for Testing and

Materials Committee on Wires for Electrical Conductors, Subcommittee

SC. 08, Superconductors

.

Charles R. Til ford, Technical Advisor, 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.

Charles R. Tilford, Assistant Chairman, AVS C004, American Vacuum Society

Standards Committee; and Chairman, Subcommittee SC. 01, Gaging.

Charles R. Tilford, Member, BIPM C002, International Bureau of Weights

and Measures Committee on Pressure Standards; Member, WG.01, Working

Group on High Pressures; Chairman, WG.02, Working Group on Low Pressures;

and Member, WG.03, Working Group on Barometric Pressures.

Jacquelyn A. Wise, Member, ASTM E020, American Society for Testing and

Materials Temperature and Measurement Committee, Subcommittee, SC. 01 , Editorial and Nomenclature; and Secretary, Subcommittee SC. 05, Liquid-inGlass Thermometers and Hydrometers.

95
Consulting and Advisory Centers

G. W. Burns, working in collaboration with H.P.R. Frederikse and P. K. Schenck of the NBS Center for Materials Science and with R. R. Dils and

J. R. Whetstone of the NBS Center for Chemical Engineering, conducted a study of materials needed to solve instrumentation problems existing in

various fossil energy technologies. The study was carried out at the

request of the DoE Fossil Energy Program. A comprehensive report summarizing the findings of the study and giving recommendations for needed R&D

programs was prepared for DoE by the NBS team and soon will be published

as an NBSIR.

G. W. Burns, at the request and expense of the Owens-Corni ng Fiberglass

Corporation, spent a day at the Technical Center of the Corporation in

Granville, OH, and at a fiberglass manufacturing plant in Newark, OH,

where he provided consultation on suitable thermometry to use for production. Comments and recommendations were offered regarding the selection,

thermocouple thermometers for such applications.

Dr. Harvey Marshak was appointed a visiting Professor of nuclear and

nuclear orientation physics at the Katholieke Uni versi tei t , Leuven,

Belgium, for a period of five months during 1981. His duties are to help

them in their experimental program in the above fields and assist them in

their low-temperature thermometry measurements.

96
LENGTH AND MASS MEASUREMENTS AND STANDARDS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1981

I. OVERVIEW

Measurements and Standards Division (LMMSD) has

*ain the U.S. primary standards, to transfer

secondary standards, and to improve the

' and applied research.

y't of these responsibilities. Compari-

•ith the International Bureau of

her national laboratories to

->se working relationship is

nnal Engineering Laboratory

Vibration services to other

-ooperation not only

"ies but also includes

the portable laser

[h of which were

‘de institutions,

ure that our

nmmuni ty

.

v, am of

^s and

~al
Consulting and Advisory Centers

G. W. Burns, working in collaboration with H.P.R. Frederikse and p S chenck of the NBS Center for Materials Science and with R. R. r J. R. Whetstone of the NBS Center for Chemical Engineering, c

r study of materials needed to solve instrumentation problems

various fossil energy technologies. The study was carris

request of the DoE Fossil Energy Program. A comprehen r izing the findings of the study and giving recommend*

programs was prepared for DoE by the NBS team and

as an NBSIR.

G. W. Burns, at the request and expense of + Corporation, spent a day at the Technical

Granville, OH, and at a fiberglass mani 1 where he provided consultation on su 1

’ tion. Comments and recommendation r thermocouple thermometers for sir

Dr. Harvey Marshak was appo 1

' nuclear orientation physi r Belgium, for a period

them in their experim

their 1 ow-temperati 1
LENGTH AND MASS MEASUREMENTS AND STANDARDS DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1981

I. OVERVIEW

The Length and Mass Measurements and Standards Division (LMMSD) has

the responsibility to maintain the U.S. primary standards, to transfer

the U.S. primary standards to secondary standards, and to improve the

primary standards 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 compatibility. A close working relationship is

maintained with those divisions in the National Engineering Laboratory

which have the responsibility for providing calibration services to other

governmental agencies and to the public. This cooperation not only

concerns the first transfer of dimensional quantities but also includes

the transfer techniques and of instruments, such as the portable laser

length standard and the load cell mass comparator, both of which were developed in the LMMSD. Cooperative projects with outside institutions,

such as state standards laboratories and universities, ensure that our activities are revel ant to the problems of the measurement community.

Solutions to these problems are sought through a vigorous program of

research which strives to develop improved measurement instruments and

techniques through a better understanding of the fundamental physical

principles upon which the primary standards are based. Finally, the

LMMSD is frequently called upon to offer information and assistance to

private and public organizations who have the responsibility for stateof-the-art length and mass measurements but who cannot get adequate

support from the private sector.

The Division has completed several long-term projects during the past

year including: development of the Portable Laser Length Standard, modifications of the Voland balance which serves as the NBS Primary Kilogram

Comparator, the Load Cell Mass Comparator, and the submersible balance for

solid-object density comparisons. Significant progress has been made on

the stabilization of the mercury laser and the certification of the silicon

density standards for the Standard Reference Materials Program. Work this

coming year will focus on completing these latter two projects, initiating

international comparisons of the Kilogram and the new density standards,

and on a major new project to design and construct an evacuable servo- controlled kilogram mass comparator.

97
II. TECHNICAL ACTIVITIES

Portable Laser Length Standard

The portable iodine stabilized helium-neon laser length standard

developed in the Division has received an IR-100 award for being con- sidered one of the 100 most significant products introduced in 1981.

This award will provide significant impetus to the commercialization of

this instrument by providing very high quality publicity. Frequency and

Time Systems, Inc. (Beverly, MA), which has shown very strong interest

in adding the portable laser length standard to its product line of

quartz crystal and cesium oscillators, is encouraging organizations to

place orders in the anticipation of manufacture and sale. The strong

development effort which we have put into the intracavity iodine stabilized helium-neon laser has now concluded with the design and fabrication of a housing which provides personnel protection and graceful

appearance. Some activity in evaluating the performance of the commercial

version is anticipated, however, when the first models are built.

The design and construction of an external cell iodine stabilized

helium-neon laser has been completed and initial measurements have been

made, however, definitive statements regarding its performance are premature. At least an order of magnitude improvement in absolute resetability is anticipated as a consequence of deconvolution of the neon gain

and iodine absorption mechanisms. The external cell system will become

the LMMSD laboratory standard against which internal cell instruments can

be compared.

Stabilized Mercury Laser

The optically pumped mercury laser was stabilized to an iodine

transition in an internal cell laser. This is the first time this stabilization has been reported and portends a system similar to the portable

helium-neon length standard but at a higher level of performance. Significant data has been collected about the mercury spectrum (four suitable

isotopes) and the iodine absorption spectrum (diatomic, two isotopes) in an effort to select the optimum combination. Several months of this

study remain. During the course of this investigation four wave conjugate

mixing was observed and is the first such observation reported for mercury.

Although this is interesting from a scientific point of view, no metrological benefits are anticipated. While the four lamp close-coupled pump

lamp configuration has worked reliably, other pump lamp configurations

are being investigated in an effort to reduce complexity and size of the

laser head while maintaining good performance. At the appropriate time,

the frequency of this laser will be measured relative to the cesium

oscillator at the Boulder laboratories.

98
Primary Kilogram Comparator

A number of modifications have been made to the Voland balance so that it now achieves a routine standard deviation of 3-6 micrograms when

intercomparing four stainless steel kilograms. In addition, two 500-g

platinum-iridium (Pt-Ir) counterweights have been fabricated, which will

allow us to intercompare Pt-Ir kilograms either with stainless steel or other Pt-Ir kilograms.

The balance performance would probably benefit from further modifications: new knives, air-tight enclosure, mechanically driven weight

changer, and automatic readout. Each of these would be very costly of

either personnel or resources. We believe, however, that the Voland

balance in its present state will be adequate for our needs until the

servo-control! ed balance now under development becomes operational.

In the next year there are three projects which will make use of our primary comparator: 1) recalibration of U.S. prototype kilogram K-20

against international standards maintained at B I PM (last done in 1948);

2) recalibration of U.S. working standards N1 and N2; 3) participation

next summer in a round robin between NBS, NRC (Canada) and B I PM to intercompare the same stainless steel and Pt-Ir kilograms.

Servo-Control 1 ed Kilogram Mass Comparator

A new project has been started which will focus on the theory and

practice of servo-controlled, single pan, knife-edge mass comparators.

The motivation for this endeavor is several fold. Modern servo technology

combined with new modes of balance operation (constant load, static beam)

portend unprecedented accuracy coupled with total computer control. This

system will permit, for the first time, analytical studies on beam dynamics

and allow balance optimization through a comparison of theory and performance. The balance will eventually be mounted in an evacuable enclosure

to permit accurate measurements of air buoyancy effects without recourse

to a semi -empi rical equation-of-state for moist air. Errors in air

buoyancy corrections presently dominate the uncertainty when platinum and

stainless-steel kilograms are compared on the best balances. The program

is in the planning stage although some optical equipment has been purchased

for the angle i nterferometer which will measure the beam position. Initial

studies will focus on servo elements, beam motor and position indicator,

and on knife loading and geometry. Completion of this project is expected

in three years.

Load Cell Mass Comparator

The Division activities relating to development of the load cell mass comparator, its acceptance by the measurement community, and manufacture by an independent company are culminated with success in all areas. The need to continue this activity on any basis other than

occasional consulting no longer exists.

99
The Office of Weights and Measures supported the Division's effort

to complete a 50 pound instrument designed to tolerance test weights in

the State laboratories. This device is to be loaned to several states to

acquaint them with the advantages of the instrument. Texas was the first

state to receive the mass comparator and is now performing weekly tests

to determine its efficiency.

Extensive consulting with White Sands Missile Range Mass Laboratory

has lead to their success in fabricating a load cell comparator with a range from 500 to 1500 pounds with a precision of 1 ppm. Their success

besides being an independent confirmation (to be reported at the next ISA

Conference) of the load cell mass comparator has made available for the

White Sands Laboratory automatic data acquisition that was not possible

with the mechanical balance employed by them.

This year three additional papers were prepared for publication; two

dealing with the mechanics and electronics of the mass comparator and a third presented to the annual conference of the Institute for Nuclear

Materials Management in San Francisco, CA. This latter paper described

to the nuclear industry the advantages of incorporating the load cell mass comparator in their production weighing and safeguard programs.

A significant advance in the acceptance of the load cell mass comparator has been the decision of the Frazier Precision Instrument Company,

an old line balance manufacturer, to manufacture the mass comparator in

several ranges from 50 pounds to 10,000 pounds. Personnel of the Division

have given the Frazier engineers assistance on request to ensure the

transfer of technology from NBS to the private sector.

Submersible Balance and Density SRM

The project to deliver 70 solid-object density standards to the

Office of Standard Reference Materials (0SRM) is nearing completion. The

fabrication of all 70 artifacts, fashioned from single-crystal silicon,

is now finished. It only remains to certify the density of these objects

against our working standards. The latter endeavor will be completed

very early in FY'82 thanks to an innovative submersible balance, developed

within the Division, which allows density certification to one part per

million in a fraction of the time required by traditional techniques.

Development and testing of the high-precision submersible balance is

complete. The rapid measurement capabilities of this new balance become

extremely valuable given the number of objects to be certified for the

0SRM. The submersible balance has also proven useful for 1) screening a large number of materials for use in experiments where density is an important factor, such as the measurement of the gravitational constant

being conducted elsewhere in the Center; and 2) determining the volume of

working mass standards such as those of Sandia Laboratories in Albuquerque,

NM. (The altitude of this laboratory is high enough that buoyancy

corrections in air weighings are significantly different from those of

100
laboratories near sea level, hence their interest in accurate knowledge

of the volumes of their standards).

The unique feature of the SRM is that it will provide the purchaser

with a highly homogeneous object whose density is extremely well known,

being directly traceable to base units of mass and length. In practice,

this means we must compare hydrostatically the newly fabricated artifacts

against our existing working standards of density. The completion of

this project will enable the public to obtain density reference standards

which have a higher degree of permanance and stability than distilled

water, the usual density reference. Another attractive feature is that

purchasers can further shape and etch the SRM to fit their experimental

needs without changing the certified density.

The expertise developed in this work will be useful in projected

international intercomparisons of solid density standards. These will

occur as a part of NBS participation in the activities of a newly organized

working group of the Consultative Conmittee for Mass and Related Quantities.

101
INVITED TALKS

Length & Mass Measurements & Standards Division (523)

H. P. Layer, "The Laser Length Standard: The Definition of the Meter,"

January 7, 1981, National Association for the Advancement of Science,

Toronto, Canada.

H. P. Layer, "The Length Standard and Fundamental Constants," January 20,

1981, Yale University Physics Department, New Haven, Connecticut.

H. P. Layer, "The Length Standard and Fundamental Constants," January 21,

1981, Frequency and Time Systems, Boston, Massachusetts.

102
PUBLICATIONS

Length & Mass Measurements & Standards Division (523)

In Print:

R. M. Schoonover, "A simple gravimetric method to determine barometer

corrections J. Res. Nat. Bur. Stand. 85(5) , 341-345, Sept-Oct 1980.

Howard Layer, "A portable iodine stabilized helium-neon laser," IEEE Trans,

on Instrumentation and Measurements, IM-29 , No. 4, 358-361, December 1980.

Fielding Ogburn, Randall M. Schoonover, and Christian E. Johnson, "Density

of autocatalytic nickel -phosphorus deposits," Plating and Surface Finishing, p. 45, March 1981

.

H. P. Layer, W. R. C. Rowley, and B. R. Marx, National Physical LaboratoryNational Bureau of Standards iodine-stabilized helium-neon laser intercomparison," Opt. Lett. 6(4) , 188-190, April 1980.

R. Schoonover and Frank Jones, "Air buoyancy correction in high-accuracy

weighing," Anal. Chem. 53_, 900-902, May 1981.

A. L. Cummings, H. P. Layer and R. J. Hocken, "Lasers and Analytical

Polarimetry ," Chapter 15 in Lasers in Chemical Analysis , ed. by Gary M.

Hieftje, John C. Travis, and Fred E. Blytle, The Humana Press, 1981.

p 291-302.

In Press, in Review, or Nearing Completion:

R. D. Cutkosky and R. S. Davis, "Simple control circuit for temperature

regulation and other bridge applications," Rev. Sci . Instrum, (to be

published in the September 1981 issue).

Marvin E. Cage and Richard S. Davis, "An analysis of read-out perturbations

seen on an analytical balance with a swinging pan," (accepted for publication in NBS. J. Res.)

.

Randall Schoonover, "A 30 Kg capacity high precision load cell mass comparator," (accepted for publication in NBS J. Res.).

S. Suda, P. Pontius, and R. Schoonover, "Improved mass measurement

accuracy using the PNB load cell scale," Proc. of Institute of Nuclear

Materials Management 22nd Annual Meeting in San Francisco, CA, July 13-17,

1981.

V. E. Bower, R. S. Davis, T. J. Murphy, P. J. Paulsen, J. W. Gramlich,

and L. J. Powell, "Recalculation of the Faraday Constant due to a new value for the atomic weight of silver," (in preparation)

.

103
SEMINARS ORGANIZED

Length & Mass Measurements & Standards Division (523)

R. S. Davis, an informal meeting of mass metro! ogists held during the

PMFC-II Conference, June 9, 1981.

R. M. Schoonover, George Washington University Engineering Seminar,

"Operation and Management of Standards Laboratories."

R. M. Schoonover, taught a two-week course for the Office of Weights

and Measures on Basic Metrology. This course covered in total, lab

management, mass calibration, volumetric, length calibrations and

associated statistics.

104
COMMITTEES

Length & Mass Measurements & Standards 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.

105
TRIPS SPONSORED BY OTHERS

Length & Mass Measurements & Standards Division (523)

H. P. Layer January 6-8, 1981 - Toronto, Canada

Presented an invited talk to the American Association

of Advanced Science to help disseminate basic standards

to the scientific community and to meet and confer with

scientists with matters of Bureau interest.

Sponsor: AAAS

H. P. Layer January 18-20, 1981 - New Haven, Connecticut

Presented an invited talk at Yale University and calibrated a Rydberg constant experiment.

Sponsor: Yale University

106
J

jm

dial , the

o' primary

lient on new

^e frequency

.'iBS standards and

i y; and provides

ation services. The

lied to related problems

ernment agencies.

ch the smallest percentage

erformance than currently avail

.cise and accurate time and frequency

television, electric power system

che operation of the telephone system,

.curate and precise standards is so ed performance of oscillators and clocks.

1 in the development of the Global Positioning

.urrent design goals for GPS require routine

.xceeding the present state-of-the-art in the

les. Also, standards laboratories of other nations

.ndards equal to or better than the present NBS

.ere is significant pressure on the Division not only to

jt to provide new developments and measurement methods in the

j frequency. Over the past several years the Division has

„ne feasibility of redefining the unit of length, the meter, in

_ unit of time. In effect, the meter could be defined as the

-raversed by a light wave in some specified fraction of a second.

u\t would be both an improvement in the standard of length and a conceprefinement of the International System (S.I.) of units. Currently, the

.Sion has committed itself to the performance of a measurement which is

rucial to the practical realization of the redefinition of the meter'. This

measurement, which is the precise determination of the frequency of a particular

107

TIME AND FREQUENCY DIVISION

SUMMARY OF ACTIVITIES

FISCAL YEAR 1981

I. Overview

The Time and Frequency Division provides the basic standards for the

country in the areas of frequency and time interval. These standards must be

coordinated both nationally and international ly in order to ensure compatibility of all measurements. By international agreement, the definition of the

unit of time, the second, is in terms of the cesium beam frequency standard.

Currently three countries (U.S., Canada, and West Germany) have primary cesium

beam frequency standards of sufficient quality for inclusion into the official,

i nternational ly cordinated time scales. The U.S. standard is provided by the

Di vi sion

.

To ensure the Division's effectiveness, the Division maintains primary

cesium beam frequency standards; undertakes research and development on new

and improved standards and measurement methods; extends accurate frequency

measurements into the visible region; actively compares the NBS standards and

time scales with others, both nationally and internationally; and provides

access to the coordinated standards via various dissemination services. The

skills and knowledge developed in this process are applied to related problems

of national interest and made available to other government agencies.

While time and frequency can be measured with the smallest percentage

error of any physical quantity, even greater performance than currently available is demanded of these measurements. Precise and accurate time and frequency

signals are essential for such things as television, electric power system

control, navigation, communication, and the operation of the telephone system.

Because the potential for even more accurate and precise standards is so great, many laboratories seek improved performance of oscillators and clocks.

One significant example of this is in the development of the Global Positioning

System (GPS) by the military. Current design goals for GPS require routine

performance of devices at or exceeding the present state-of-the-art in the

most sophisticated laboratories. Also, standards laboratories of other nations

are perfecting primary standards equal to or better than the present NBS

standard, NBS-6.

As a result, there is significant pressure on the Division not only to

remain current, but to provide new developments and measurement methods in the area of time and frequency. Over the past several years the Division has

demonstrated the feasibility of redefining the unit of length, the meter, in

terms of the unit of time. In effect, the meter could be defined as the

distance traversed by a light wave in some specified fraction of a second.

The result would be both an improvement in the standard of length and a conceptual refinement of the International System (S.I.) of units. Currently, the

Division has committed itself to the performance of a measurement which is

crucial to the practical realization of the redefinition of the meter. This

measurement, which is the precise determination of the frequency of a particular

107
optical transition in iodine relative to the NBS primary frequency standard,

will be both the most accurate optical frequency ever measured and the highest

frequency ever measured directly. It is scheduled for completion in FY 82.

The Division has begun to design and plan for the next generation of

primary frequency standard, NBS-7. The present standard, NBS-6, has served

well at an accuracy of about 8 parts in ten to the 14th, but laboratories of

other nations specify finer tolerances, newer systems demand ever increasing

accuracies, and the means of building a better standard are now known. The new standard will still be based on cesium, but new techniques of state selection and detection, developed by the Division, will allow improvement by a factor of about ten in accuracy and stability over NBS-6. The budgeting

process will be initiated in FY 82 and research on techniques to improve

primary standards will continue. The final design and construction of NBS-7

will begin in FY 84 with the availability of the funds. Research on other

more advanced standards concepts (such as stored, cooled ions) will continue.

A radio navigation system, Loran-C, currently provides the means of

comparing standards and time scales international ly . Unfortunately , the

accuracy attainable with Loran-C is a severe limitation and more accurate

means of comparison are badly needed. Satellite systems provide the best

current hope for improvement and have demonstrated accuracies of time transfer

about a hundred times better than possible with Loran-C. What is still needed

is an operational system performing at these higher accuracies. One significant,

possible system is GPS. The Division has devised and tested a GPS receiver

based on common-mode reception of GPS signals. This system allows time comparisons with a precision of a few nanoseconds and frequency comparisons to a few

parts in ten to the 15th in a period of several weeks. Plans are under way to

make comparisons of frequency and time using these GPS receivers with a few

key national and international laboratories. Since the future of GPS is

uncertain, other options are also being studied.

Various services provide general access to the NBS standards of frequency

and time. Radio stations WWV, Ft. Collins, Colo., and WWVH, Kauai, Hawaii,

provide continuous broadcasts of standard time and frequency in the short-wave

bands. These broadcasts are probably the primary references for standard time

at modest accuracies (greater than a millisecond) for most of the U.S. and the

surrounding oceans. Somewhat better accuracies can be obtained from the

broadcasts of WWVB, Ft. Collins, Colo., and from the satellite broadcasts from

NOAA's GOES satellites. The Division provides the time signals for the GOES

broadcasts and these services are receiving increased attention, primarily by

electric power companies.

Approximately one quarter of the Division's funding support comes from

other government agencies. The Division has been able to foster contracts

which both augment our efforts on the primary mission and provide useful

services and data to the funding agencies. These other agencies have been

interested in supporting such efforts as the development of clocks with

improved stability (e.g., passive hydrogen masers), and research on future

frequency standards options (e.g., stored ions).

108
II. Technical Activities

1. Primary Standards

During the last several years the Division has pursued a specific strategy

which can be summarized as follows:

A. Primary Group effort on research and development of new standards options.

B. Maintain "adequate" primary frequency calibrations by

evaluating NBS-6 about once per year.

The rationale for this strategy has been that the accuracy attainable

with NBS-6 was adequate for commercially available clocks and oscillators.

Operating NBS-6 as a "standard clock", as other laboratories have done, provides

little improvement at the cost of much effort which could more profitably be

directed toward advanced research on improved primary frequency standards.

More recently, two new directions have been added to the strategy. These

are:

C. Construct a new time scale hardware and control system and develop a new time scale algorithm.

D. Develop specific plans to build the next generation of primary frequency standard, NBS-7.

The old time scale control system was based on 1967-vintage computer

systems and time measurement hardware with accuracies of about one nanosecond.

The system severely limited the abililty to evaluate new devices (such as the

passive hydrogen maser), provided no opportunity to increase the number of

clocks contributing to the time scale, and provided no opportunity to develop

and test new time scale algorithms with real clocks. The new system includes

a totally new computer (PDP 11/70) for control and newly designed measurement

hardware (developed by the Group) which is capable of sub-picosecond resolution

and time stability of a few picoseconds over periods of months. This is an improvement of nearly two orders of magnitude over the previous state-of-theart. Most of the hardware now exists and has been tested and verified. The

new computer now computes the official time scale (using essentially the old

algorithm adapted to the new computer), and both hardware and software are being assembled to make automatic clock comparisons with the new hardware.

Final assembly and testing should be completed in the next few months.

A new time scale algorithm (based on Kalman filters) is under development.

We have been fortunate in interesting some people in the Statistical Engineering

Division in the problem. This turns out to be a most fruitful collaboration

and some significant progress has been made on the problems of adaptive parameter

estimation. While the implementation of a Kalman filter algorithm is reasonably

strai ghtforward , the estimation of the model parameters for the filter is more

subtle. A complete time scale algorithm should be under test by the end of FY

82 and a paper prepared for the Second International Symposium on Time Scale

Algorithms, hosted by the Division next June.

109
We have begun the process of acquiring funds to design and know that

NBS-7 will be a cesium beam device and will probably employ optical pumping

techniques for state selection and detection. The presently stated goal is to

build a device with an absolute accuracy of one part in ten to the 14th, and a frequency stability of about (3 E-13/root-tau) improving out to averaging

times of at least one day. Optical state selection can increase signal-tonoise by pumping all atoms into the desired state. This should result in a factor of 16 enhancement in the usable beam and greatly reduce the background

as compared to present cesium beam designs. Moreover, the lack of population

in the other hyperfine sublevels should permit a study of Majorana transitions.

These transitions occur between the magnetic state selection region and the

Ramsey cavity region in current cesium beam design and are a concern in the

accuracy of cesium standards. Optical pumping and laser fluorescence detection

of the cesium atoms will permit the use of smaller, more symmetric atomic

beams, which will decrease sensitivity of the standard to distributed phase

shifts across the openings of the cavity. We have demonstrated the necessary

selection rules for this process and are testing laser diodes for a practical

implementation. We are also developing a more efficient, high-flux oven and

investigating the electronics required for an adequate servo for the standard.

NBS-7 will have to be a totally new device, separate from NBS-6. During

the design and construction phases of NBS-7, we will continue to operate NBS-6

in its present mode of about one complete evaluation per year. The intent is

to submit a budget initiative for FY 1984. To meet that schedule, the paperwork

is due this coming Spring.

Passive hydrogen masers have been perfected to the point where they now demonstrate a frequency stability of a few parts in ten to the 15th for aver- aging times of a few days, which is comparable to the entire present time

scale. This is at least ten times better than active masers. One passive

maser has been incorporated into the NBS time scale and data is accumulating.

In addition to work specifically directed toward NBS-7, work has con- tinued on concepts for more advanced frequency standards (i.e. , for a generation of standards following NBS-7). A major limitation of all atomic standards

is due to Doppler effects. When ions stored in an electromagnetic trap are cooled with laser radiation within the Doppler linewidth, but at a frequency

below the line center, kinetic energy is removed from the ion system by radiation. In addition to the radiatively selected ion, other ions in the trap

will also be cooled because of Coulomb interactions. The result is the con- finement of ions which are nearly at rest (i.e., at a temperature of only a few millikelvin). Magnetic hyperfine linewidths of a few millihertz (the

linewidth of NBS-6 is 30 Hz) have been observed with the system. Furthermore,

the effects of the confinement on the ions is both very small and calculable,

so that potential use with primary frequency standards operation is good.

Cooled ions have potential stability and accuracy advantages over cesium

beams. The ions can be stored for long periods in a "container" which has

small, calculable perturbations to the energy levels; first and second-order

Doppler effects can be essentially eliminated; and once trapped and cooled,

either microwave or optical transitions (or both) can be used as frequency and

length standards. Projected frequency stability of a cooled ion microwave

standard is of the order of 1.0 E-12 to 1.0 E-16 divided by root-tau, and the

stability of the device will be limited by the available local oscillators to

110
drive the transition, while for optical frequency standards, projected frequency

stabilities are of the order of 1.0 E- 14 to 1.0 E- 16 divided by root-tau.

Work on more stable laser flywheel oscillators is also being pursued in conjunction with the stored ion effort. Absolute accuracies of 1.0 E- 15 and frequency

stability in the low 1.0 E- 16 range for days to weeks are anticipated (again

limited by the local oscillator, i.e., the laser). In addition to the advantages for standards, the cooled ion technique is ideal for spectroscopic

research on ions. Because of its broad impact on high precision metrology, it

is anticipated that cooled ion technology will be an active Division program

for at least the next 10 years.

A prime obstacle to an optical time standard has been the inability to

develop an operational means to run a one pulse per second clock from an optical frequency laser. Frequency division using a one-electron synchrotron

may remove this obstacle. This concept, developed in the Division, is based

on the cyclotron, synchrocycl otron, and the synchrotron method to accelerate

charged particles. Instead of using a localized microwave field to drive the

charged particle, a wel 1 -col 1 imated, Gaussian laser beam, focused to a spot

diameter of approximately one wavelength, will be used to drive an electron in

a Penning trap. The electron should absorb energy from the laser radiation

field, and will cycle at and be phase locked to a very small subharmonic of

the laser frequency if the electron spends on the order of one-half cycle of

the laser radiation in the laser beam. The subharmonic frequency is observed

by an image current, hence a single electron is required to precisely define

the phase of the output signal.

2. Coordination

Time and frequency are quantities which must be actively and closely

coordinated both nationally and internationally . This is currently accom- plished by monitoring signals of the Loran-C navigation system and communicating the results to the International Time Bureau (BIH), which acts as the

central "clearing-house" for time and frequency data. In turn, the BIH

constructs the official time scales TAI and UTC (International Atomic Time

and Coordinated Universal Time, respecti vely) . All standard time in the world

is referenced to UTC.

The NBS contributes to the formation of TAI and UTC by supplying data on accurate frequency relative to NBS-6 and by supplying data on the stable

clocks of the NBS Time Scale. The accuracy and precision of the data are degraded by the comparison link, Loran-C, sufficiently that even after a year's average, uncertainties of nearly one part in ten to the 13th remain.

This is comparable to the absolute accuracy of NBS-6. Because of the variability in the comparison links, meaningful comparisons of the world's primary

frequency standards are severely limited and comparison results are very

unsatisfying.

In recent years, numerous laboratories (including NBS) have demonstrated

that improved accuracy and precision of comparison can be obtained from satellite systems. Not only can these satellite systems provide improved time

comparisons, they need accurate and stable frequency and time references.

They provide both a means of improved comparison and a demand for better and more accurate clocks.

Ill
In addition to the routine monitoring of Loran-C, the Division has a program devoted to the development of a time comparison technique based on the

use of the Global Positioning System (GPS), which is under development by the

Department of Defense. The Time and Frequency Division devised a technique of

using GPS satellites in common view of two time laboratories for extremely

precise time transfer. We have developed and are now in the testing phase of

a GPS receiver which has demonstrated time transfer precisions in the nano- second range and frequency measurement consistencies a hundred fold better

than possible with Loran-C. These tests have been carried out in cooperation

with the U.S. Naval Observatory (USNO). Other governmental agencies have

shown significant interest in these GPS receivers and have helped fund the

development. Because of uncertainties in the future of the entire GPS system,

the Division continues to investigate other satellite options also.

3. Laser Frequency Metrology

The current definition of the unit of length, the meter, is in terms of

the orange-red line of the krypton lamp. This standard is practically limited

at about four parts in ten to the 10th. The possibility exists (and has been

demonstrated by the Division) to measure the frequency of a very stable and

reproducible laser in the optical region and effectively transfer the accuracy

of the cesium beam frequency standard to a new length standard. In effect, one defines the speed of light in this process. This possibility has been

recognized for some time and the organizations of the Treaty of the Meter are expected to take specific action in the summer of 1982 to redefine the meter.

The Consultative Committee for the Definition of the Meter (CCDM) is a technical

advisory committee to the International Committee of Weights and Measures

(CIPM). At its meeting next June, the CCDM is expected to recommend to the

CIPM that the meter be redefined as the distance traversed by a light wave in

a specified fraction of a second.

In preparation for this CCDM meeting the Division has undertaken the

accurate measurement of the 520 THz line of iodine relative to the cesium

primary frequency standard. This measurement involves the construction of a "chain 11 of lasers from the far infrared to the visible region. Each laser's

frequency is measured in terms of a lower frequency laser or the primary

frequency standard at the beginning of the chain. Knowing the exact frequency

of the 520 THz line of iodine establishes a link between optical wavelength

standards and the primary frequency standard.

Current efforts involve the perfection of a color-center laser operating

in the infrared region. With the completion of this task, all elements of the

chain will have been proven. The remaining task will be the operation of the

complete chain and the exact determination of the iodine frequency.

For practical purposes, there is still significant value in determining a few key "benchmark" frequencies in the infrared region relative to cesium.

Some work continues in this area.

The Division's expertise in lasers and atomic and molecular physics has

been applied to related problems also. Laser Magnetic Resonance (LMR) spectroscopy was initiated in a 1966 experiment at NBS. During the last year, LMR has

112
proceeded with the operation of a new spectrometer with a larger magnet and a more homogeneous field. This new spectrometer has demonstrated about a fivefold improvement in sensitivity. The LMR program continues to be a cooperative

effort with NOAA and largely funded by other agencies. Most recent studies

include spectra of oxygen molecules with mixed isotopes. During the next few

months, we plan completion of the analysis of the CH frequencies for radio

astronomy and completion of spectra and identification of CH2.

Another major area of frequency application is the laser geodimeter.

This instrument is an outgrowth of previous work on laser strai nmeters . In the early 1970's, a 30-meter i nterferometer was constructed in the Poor Man

Mine in Boulder Canyon as part of the measurement of the velocity of light.

During the past year, the geodimeter has undergone testing over short ranges,

mainly within the lab. The geodimeter is a three-frequency device designed to

allow the calculation of the integrated water vapor content along a path

of up to 50 kilometers. The water vapor content is the primary limiting

effect on the determination of the index of refraction of the air along the

path. Knowing the integrated correction allows one to determine real variations of the path length rather than variations in the water vapor content.

This device has potential application in forecasting earthquakes. Also significant interest has developed in a device which is capable of determining water

vapor content along a path.

During the present Fiscal Year (FY82) the geodimeter will undergo more extensive field tests. Initial tests will be done locally and later the

geodimeter will be tested in earthquake-active areas in California. Much of

this work has been supported with other agency funds.

An outgrowth of our precision measurement work and our interests in

geophysics is the work on tiltmeters, which is almost entirely funded by other

agencies. A group of very accurate tiltmeters has been built and installed in

wells at a site near the Boulder Labs. Each tiltmeter is in a 100 foot deep

well and is equipped with its own data telemetering system. Data has been

accumulating for the past several months and verifies both the high sensitivity of the tiltmeters and the very high consistency of the tiltmeters between

each other. The next phase will be to install the tiltmeters in a seismically

active area.

4. Time and Frequency Services

Access to the NBS standards of time and frequency is via 2.5, 5, 10, 15,

and 20 (at WWV only) MHz services from two radio stations located at Ft.

Collins, Colorado and Kauai, Hawaii; a 60 kHz service from Ft. Collins, WWVB;

a satellite time code from the NOAA GOES satellite; and non-NBS broadcasts

usable as transfer standards (such as calibrations of the color subcarriers of

major East and West Coast TV networks and Loran-C and Omega Navigation System

transmissions); and occasional portable clock trips.

The broadcast services of WWV, WWVH, and WWVB operate with downtimes of

less than 0.1%. These services continue to be a major source of time and

frequency information in the Western Hemisphere.

During the past few years, a modernization program has been under way at

WWVB. Nearly 20 years ago, the WWVB transmitters were constructed from

113
surplus military transmitters and the WWVB antennas and drivers were installed

at Ft. Collins. A couple years ago equipment funds were made available to

renovate WWVB. This has just been completed and the WWVB system should be

good for another ten to fifteen years.

The GOES time code, transmitted at 468 MHz from two NOAA satellites and

fed from an uplink from Wallops Island, VA, has been operational for four

years. This time code was the first routine time broadcast from a satellite,

but because it was established mainly to serve the NOAA data bouy system, the

transmission frequency is in the satellite meteorology band, not in the 400 MHz

time and frequency allocated band. Two manufacturers currently market GOES

time code receivers. The more sophisticated version, with automatic path

delay compensation, is priced at $3500 each. The second supplier markets

several models of a simpler version for $2200. Nearly a thousand receivers

now exist and are used by the electric power industry, the military, scientific

applications and more.

Increasing interest is evident in adding a compatible time code to the

European METE0SAT and the Japanese GMS components of the overall meteorological

satellite system, of which GOES is the U.S. component. Such an extension to

other satellites is being requested by European and Japanese timekeeping

organizations and will not directly involve NBS, except possibly in an informal

consulting role.

114
INVITED TALKS

Time and Frequency Division (524)

K. M. Evenson, "Far Infrared Laser Magnetic Resonance," Non Linear

Laser Spectroscopy Conference. Joint Japan-U.S. participation, Kauai,

Hawaii, September 10, 1980.

D. J. Wineland, "Atoms at Rest in Space; The Spectroscopists Ideal,"

Physics Department, University of North Carolina, January 25, 1981.

D.. J. Wineland, "Laser Cooling of Stored Ions," American Physical Society

and American Association of Physics Teachers, New York, N.Y., January

28, 1981.

D. W. Allan, "Some Methods of Maintaining and/or Generating Time and

Frequency at Arbitrary Points on the Surface of the Earth," International

Symposium on Time and Frequency, National Physical Laboratory, New

Delhi, India, February 10, 1981.

R. E. Beehler, "Time/Frequency Dissemination Services from NBS and Some

Alternatives for Future Improvements," International Symposium on Time

and Frequency National Physical Laboratory, New Delhi, India, February

11, 1981.

L. L. Lewis, "Use of Diode Lasers in Cesium Frequency Standards,"

Electro-Optics Group McDonnel 1 -Dougl as Aircraft Corp. St. Louis, MO.,

February 19, 1981.

D. J. Wineland, "Cesium and Rubidum Atomic Clocks," Seminar on: Frequency

Standards Measurement and' Usage, Laboratoire de Physique et Metrologie

des Osci 1 1 ateurs , Besancon, France, March 23, 1981.

D. J. Wineland, "Ion Storage and the Future of Atomic Clocks," Seminar

on: Frequency Standards Measurement and Usage, Laboratoire de Physique

et Metrologie des Oscillateurs, Besancon, France, March 24, 1981.

F. R. Petersen, "Laser Frequency Measurements and Molecular Spectroscopy,"

NBS - Gaithersburg, April 22, 1981.

F. R. Petersen, "Frequency Measurements in the Visible: Are We Close to

a Unified Time and Length Standard?," American Physical Society, Baltimore,

Maryland, April 23, 1981.

K. M. Evenson, "Laser Magnetic Resonance of Free Radicals Important in

Radio Astronomy," MIT, Boston, MA, April 28, 1981.

K. M. Evenson, "Laser Magnetic Resonance of Free Radicals Important in

Radio Astronomy," Georgia Tech, Atalanta, GA, April 29, 1981.

115
K. M. Evenson, "Laser Magnetic Resonance of Free Radicals Important in

Radio Astronomy," Physics Department, Colorado State University, Fort

Collins, CO, May 5, 1981.

K. M. Evenson, "Laser Magnetic Resonance of Free Radicals Important in

Radio Astronomy," Physics Department, University of Colorado, Boulder,

CO, May 8, 1981.

K. M. Evenson, "Laser Magnetic Resonance of Free Radicals Important in

Radio Astronomy," Physics Bldg., University of Arizona, Tucson, AZ, May

11, 1981.

D. A. Howe, "Properties of Signal Sources," 35th Annual Symposium on Frequency Control, Marriott Hotel, Philadelphia, PA, May 27, 1981

D. W. Allan, "Construction and Performance Character!' sties of a Prototype

NBS/GPS Receiver," 35th Annual Symposium on Frequency Control, Marriott

Hotel, Philadelphia, PA, May 28, 1981.

L. L. Lewis, "Optical Pumping by Lasers in Atomic Frequency Standards,"

35th Annual Symposium on Frequency Control, Marriott Hotel, Philadelphia,

PA, May 28, 1981.

D. J. Wineland, "Proposed Stored Ion Primary Frequency and Time Standard,"

35th Annual Symposium on Frequency Control, Marriott Hotel, Philadelphia,

PA May 28, 1981.

D. W. Allan, "A Modified 'Allan Variance' with Increased Oscillator

Characterization," 35th Annual Symposium on Frequency Control, Marriott

Hotel, Philadelphia, PA, May 29, 1981.

W. M. Itano, "Progress Toward a Stored Ion Frequency Standard at the

National Bureau of Standards," Second International Conference on Precision

Measurements and Fundamental Constants, Holiday Inn, Bethesda, MD, June

8, 1981.

D. J. Wineland, "Spectroscopy of Stored Ions," Second International

Conference on Precision Measurements and Fundamental Constants, Holiday

Inn, Bethesda, MD, June 8, 1981.

L. L. Lewis, "Prospects for Cesium Primary Standards at the National

Bureau of Standards," Second International Conference on Precision

Measurement and Fundamental Constants, Holiday Inn, Bethesda, MD, June

8, 1981.

D. J. Wineland, "Ion Storage and Optically Pumped Standards," XXth

General Assembly of the International Union of Radio Science, Hyatt

Regency Hotel, Washington, DC, August 12, 1981.

116
R. E. Beehler, "General Review of Time Coordination and Dissemination by

Satellite," XXth General Assembly of the International Union of Radio

Science, Hyatt Regency Hotel, Washington, DC, August 12, 1981.

F. L. Walls, "Timekeeping with Passive Hydrogen Masers," XXth General

Assembly of the International Union of Radio Science URSI, Washington,

DC. , August 12, 1981.

117
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, Program Chairman, 1982 CEPM.

D. W. Allan, Consultative Committee for the Definition of the Second

(CCDS).

D. W. Allan, IEEE IM TC-3 Frequency and Time.

D. W. Allan, 1981 PTTI Program Committee.

J. A. Barnes, Consultative Committee for the Definition of the Second

(CCDS), CCIR..

J. A. Barnes, Delegate USRI.

J. A. Barnes, Professor Adjunct, University of Denver.

J. A. Barnes, IEEE Technical Committee on Frequency and Time: Subcommittee

on Frequency Stability.

J. A. Barnes, JPL, Hydrogen Maser Comparison Test Formal Review Board.

R. E. Beehler, CCIR Study Group VII; International Chairman of Interim

Working Party 7/4 on "Improved Time Coordination and Dissemination Using

Satel 1 i tes

.

K. M. Evenson, URSI Commission D.

D. W. Hanson, Member Technical Advisory Committee for TDRSS, NASA Satellite

Program.

J. L. Jespersen, Chairman I RIG Timing Committee.

J. L. Jespersen, CCIR.

G. Kamas, Measurement Assurance Subcommittee, National Conference of

Standards Laboratories.

S. L. Howe, PTTI Editorial Committee.

F. L. Walls, Steering Committee, 3rd Symposium on Frequency Standards

and Metrology.

D. J. Wine! and, Committee for NBS Precision Measurements Grants.

118
PUBLICATIONS

Time and Frequency Division (524)

(R. Decher) , D. W. Allan, (C. 0- Alley, R. F. C. Vessot, and G. M. R. Winkler), A Space System for Hi gh-Accuracy Global Time and Frequency

Comparison, Proc. 12th Annual PTTI Applications and Planning Meeting

NASA Publication 2175 , 99 (1980).

R. L. Barger, Simple Interferometric Technique for Alignment of Segmented

Retroreflectors , Appl . Opt. 19_, 2088 (1980).

J. A. Barnes, H. H. Sargent III, and P. V. Tryon, Sunspot Cycle Simulation

Using Random Noise, Proc. Conf. Ancient Sun, 159 (1980).

J. A. Barnes, Clocks, Atomic and Molecular, Encyclopedia of Physics, 124

(1980).

K. M. Evenson, (R. J. Saykally), D. A. Jennings, (R. F. Curl, Jr., and

J. M. Brown), Far Infrared Laser Magnetic Resonance, Chemical and Biochemical Applications of Lasers 5_, 95-138 (1980).

(Richard J. Saykally, Karen G. Lubic), and Kenneth M. Evenson, Structures

of Molecular Ions from Laser Magnetic Resonance Spectroscopy, Proc. NATO

Advanced Study Institute on Structures of Molecular Ions, Kos, Greece

(1980).

Wayne M. Itano, D. J. Wineland, R. E. Drullinger, an£ J. C. Bergquist,

High-Resolution RF Spectroscopy of Laser-Cooled 25 Mg Ions, Proc. International

Conf. on Atomic Physics (1980).

L. L. Lewis, D. A. Howe, S. R. Stein, C. Manney, M. Mohler, J. C. Bergquist,

D. J. Wineland, and F. L. Walls, Experiments to Reduce Cavity Phase

Shift Errors in the Cs Beam Tube, Proc. Conf. of Precision Electromagnetic

Measurements (CPEM) (1980).

A. Risley, S. Jarvis, Jr., and (J. Vanier), The Dependence of

upon Microwave Power of Wall -Coated and Buffer-Gas-Fi 11 ed Gas

Frequency Standards, J. Appl. Phys. 51_, 4571 (1980).

D. J. Wineland, J. C. Bergquist, Wayne M. Itano, and R. E. Drullinger,

Optical Pumping and Double Resonance Experiments on Laser Cooled Ions,

Proc. IEEE International Quantum Electronics Conf. (IQEC) (1980).

David W. Allan, Some Methods of Maintaining and/or Generating Time and

Frequency at Arbitrary Points on the Surface of the Earth, Proc. International Symposium on Time and Frequency, New Delhi, India (1981).

NOTE : Names in parentheses ( ) are non-NBS authors.

Frequency

Cell RB 8

2

119
David W. Allan and James A. Barnes, A Modified "Allan Variance" with

Increased Oscillator Characterization Ability, Proc. 35th Annual Symposium

on Frequency Control (SFC) (1981).

R. L. Barger, Influence of Second-Order Doppler Effect on Optical Ramsey

Fringe Profiles, Opt. Lett. 6_, 145 (1981).

R. E. Beehler, Time/Frequency Services of the U.S. National Bureau of

Standards and Some Alternatives for Future Improvement, Proc. International

Symposium on Time and Frequency, New Delhi, India (1981).

Dick D. Davis, Marc Weiss, Alvin Clements, and D. W. Allan, Construction

and Performance Characteristics of a Prototype NBS/GPS Receiver, Proc.

35th Annual Symposium on Frequency Control (SFC) (1981).

(J. M. Brown, C. M. L. Kerr, F. D. Wayne), K. M. Evenson, and (H. E. Radford), The Far Infrared Laser Magnetic Resonance Spectrum of the OH

Radical, J. Mol. Spectrosc. 86, 544 (1981).

(H. E. Radford), K. M. Evenson, and D. A. Jennings, Far-Infrared LMR

Detection of Hydroxymethyl, Chem. Phys. Lett. 78_, 589 (1981).

(Artemio Scalabrin, Richard J. Saykally), Kenneth M. Evenson, (H. E. Radford, and Masataka Mizushima), Laser Magnetic Resonance Measurement

of Rotational Transitions in the Metastable a *A State of Oxygen, J. Mol. Spectrosc. 89_, (1981). ^

K. M. Evenson, Far Infrared Laser Magnetic Resonance, Proc. Roy. Soc.

(1981).

Mark Feldman, J. C. Bergquist, L. L. Lewis, and F. L. Walls, Preliminary

Investigation of a New Optically Pumped Atomic Rubidium Standard, Proc.

35th Annual Symposium on Frequency Control (SFC) (1981).

D. A. Howe, D. W. Allan, and J. A. Barnes, Properties of Signal Sources

and Measurement Methods, Proc. 35th Annual Symposium on Frequency Control

(SFC) (1981).

Wayne M. Itano and D. J. Wineland, Precision Measurement of the GroundState Hyperfine Constant of 25Mg , Phys. Rev. A 24_, 1364 (1981).

Wayne M. Itano and D. J. Wineland, Laser Cooling and Double Resonance

Spectroscopy of Stored Ions, Proc. 5th International Conference on Laser

Spectroscopy (1981)

.

Wayne M. Itano, D. J. Wineland, J. C. Bergquist, and F. L. Walls, Progress

Toward a Stored Ion Frequency Standard at the National Bureau of Standards,

Proc. 2nd International Conf. on Precision Measurement and Fundamental

Constants (PMFC II) (1981).

120
Bokuji Komiyama, Quartz Crystal Oscillator at Cryogenic Temperature,

Proc. 35th Annual Symposium on Frequency Control (SFC) (1981).

(J. C. Harrison), J. Levine, and (C. M. Meertens), Design of a Deep

Borehole Tiltmeter, Proc. 9th International Symposium on Earths Tides

(1981).

J. Levine, (J. C. Harrison, and C. M. Meertens), Performance of a Deep

Borehole Tiltmeter, Proc. 9th International Sypmposium on Earth Tides

(1981).

(J. H. Hollister, G. R. Apperson), L. L. Lewis, (T. P. Emmons, T. G.

Void, and E. N. Fortson), Measurement of Parity Nonconservation in

Atomic Bismuth, Phys. Rev. Lett. 46, 643 (1981).

L. L. Lewis, F. L. Walls, and D. A. Howe, Prospects for Cesium Primary

Standards at the National Bureau of Standards, Proc. 2nd International

Conf. on Precision Measurments and Fundamental Constants (PMFC II)

(1981).

L. L. Lewis and M. Feldman, Optical Pumping by Lasers in Atomic Frequency

Standards, Proc. 35th Annual Symposium on Frequency Control (SFC) (1981).

(E. C. C. Vasconcel los , A. Scalabrin), F. R. Petersen, and K. M. Evenson,

New FIR Laser Lines and Frequency Measurements in CD3OD, Int. J. Infrared

and Millimeter Waves 2 , 533 (1981).

(Robin S. McDowell, Chris W. Patterson, Norris G. Nereson), F. R. Petersen,

and J. S. Wells, CO, Laser Coincidences with v 3 of Si near 9.7 pm,

Opt. Lett. 6, 1981.

Earl W. Smith, Absorption and Dispersion in the 0, Microwave Spectrum at

Atmospheric Pressures, J. Chem. Phys. 74_, 6658 (1981).

Earl W. Smith, An Analysis of Markovian Model Microfield Methods for

Stark Broadening, J. Quant. Spectrosc. Radiat. Transfer 26_, 229 (1981).

F. L. Walls and D. A. Howe, Precision Timekeeping Using a Small Passive

Hydrogen Maser, Proc. 12th Annual PTTI (1981).

J. S. Wells, F. R. Petersen, (A. G. Maki, and D. J. Sukle), Heterodyne

Frequency Measurements on the 11.6 ym Band of QCS: New Frequency/

Wavelength Calibration Tables for 11.6 and 5.8 ym OCS Bands, Appl . Opt.

20, 1676 (1981)

David J. Wineland and Wayne M. Itano, Spectroscopy of a Single Mg

+ Ion,

Phys. Lett. 82A , 75 (1981).

121
D. J. Wineland, Future Atomic Frequency and Time Standards, Proc. Frequency

Standards Measurement and Usage Seminar (1981).

D. J. Wineland, Field Usable Rb and Cs Frequency Standards, Proc. Frequency

Standards Measurement and Usage Seminar (1981).

D. J. Winelaijd, Wayne M. Itano, J. C. Bergquist, and F. L. Walls, Proposed

Stored 201 Hg Frequency Standards, Proc. 35th Annual Symposium on Frquency

Control ( SFC) (1981).

D. J. Wineland, Spectroscopy of Stored Ions, Proc. 2nd International

Conf. on Precision Measurement and Fundamental Constants (PMFC II)

(1981).

122
SEMINARS

Time and Frequency Division (524)

Time and Frequency Users' Seminar, Boulder, CO, August 26-27, 1981

Seminar on Properties of Signal Sources, US Army ERADCOM, 35th Annual

Symposium on Frequency Control, Phildadel phia, PA, May 27, 1981.

SPECIAL REPORTS

Final Report - NBS Contract NB80RAA02404, "Relativistic Kepler Problem

and Construction of A Local Inertial Frame," Neil Ashby, Principal

Investigator, September 1980.

CCIR Report - 23 March 1981, "Inclusion of Relativistic Effects in

International Time Comparisons, David W. Allan, Contributor.

Final Report - U.S. Army Proposal Number DRXR0-PP-L-16399-P, "A Study of

Clustering in Water Vapor at Ultraviolet Wavelengths," Jerry C. Wyss,

R. E. Drullinger, E. W. Smith, and J. Cooper, Investigators. Submitted

to U.S. Army Research Office, 10 April 1981.

123
CONSULTING AND ADVISORY PARTICIPATION

Time and Frequency Division (524)

D. W. Allan consulting with Air Force Space Division.

D. W. Allan consulting with Jet Propulsion Laboratory.

J. A. Barnes consulting with IAU, Commission 31.

A. J. D. Clements consulting with National Oceanic and Atmospheric

Administration on maintenance and operation of GOES equipment.

D. D. Davis consulting with National Oceanic and Atmospheric Administration

on maintenance and operation of GOES equipment.

G. Kamas consulting with Rome Air Development Command.

L. L. Lewis consulting with GPS Steering Committee, Air Force Space

Di vision.

F. L. Walls consulting with Air Force Space Division.

F. L. Walls consulting with Jet Propulsion Laboratory.

F. L. Walls consulting with Naval Research Laboratory.

F. L. Walls consulting with Rome Air Development Command.

124
TRIPS SPONSORED BY OTHERS

Time and Frequency Division (524)

D. W. Allan February 5-20, 1981 - New Delhi, India.

Attended and gave invited paper at the International

Symposium on Time and Frequency. Also served as consultant for India and underdeveloped countries

in regard to time and frequency matters.

Sponsor: National Physical Laboratory

F. R. Petersen February 21-28, 1981 - Trondheim, Norway.

Presented invited lectures and consulted with

Norwegian Defense Research Establishment and at

University of Trondheim on laser frequency

measurements with MINI diodes.

Sponsor: Advisory Group for Aerospace Research

and Development, NATO

D. J. Wineland March 22-28, 1981 - Besancon, France.

Attended Seminar "Frequency Standards, Measurement

and Usage" and presented two invited papers, "Cs

and Rb Atomic Clocks: and "Ion Storage and the Future

of Atomic Clocks.

Sponsor: Centre National de la Recherche.

K. M. Evenson April 27-30, 1981 - Boston, MA and Atlanta, GA.

Presented invited talks at Massachusetts Institute

of Technology and Georgia Tech entited "Laser Magnetic

Resonance of Free Radicals Important in Radio

Astronomy .

Sponsor: MIT and Georgia Tech.

May 10-12,1981 - Tucson, Arizona.

Presented invited talk at University of Arizona

entitled "Laser Magnetic Resonance of Free Radicals

Important in Radio Astonomy."

Sponsor: University of Arizona.

125
R. E. Drullinger

D. J. Wineland

May 15, 1980 - May 16, 1981 - Munich, West Germany.

Spent one year at Max Planck University to further

develop the technique of using spectral shifts in

electronic transitions to study small clusters.

Sponsor: Max Planck University

July 5-11, 1981 - Wolfboro, New Hampshire.

Presented invited talk at Gordon Conference on Atomic Physics.

Sponsor: Brewster Academy.

126
jn

earch

i later:

j interactions .

personnel in JILA distributed ac- jctuates substantially over a year's

ienti f ic turnover of 40 to 50 persons.

127

QUANTUM PHYSICS DIVISION

SUMMARY OF ACTIVITIES

Fiscal Year 1980

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.

When JILA was formed in 1962, "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

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, to be discussed in more detail later:

1 . Fundamental and precision measurements.

2. Geophysical measurement methods.

3. Astrophysical measurement.

4. Atomic and molecular physics and interactions.

5. Chemical physics.

Currently, there are 162 total personnel in JILA distributed ac- cording to Fig. 1. This figure fluctuates substantial ly over a year's

time, since there is an annual scientific turnover of 40 to 50 persons.

127
J I LA STAFFING

1981-82

(162 Total)

128
The permanent Ph.D. Staff or "Fellows of JILA" of which there are

26 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-ennially as the principal officer of the Institute, and is

responsible for operating the Institute within the limits of policy set

forth by the Fellows. An Executive Committee assists the Chairman with

policy matters of shorter duration or lesser moment that would command

attention of the Fellows, and the Executive Officer deals with most administrative matters as delegated by the Chairman. Of the 26 Fellows,

11 are CU full-time faculty from the Departments of Physics, Chemistry,

and Astro-Geophysics, 14 are MBS employees in the QPD, and 1 is an NBS

employee in the Time and Frequency Division. MBS Fellows hold adjoint

appointments in one of the three academic departments. While sharing

responsibility for the success of the Institute, the MBS 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 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.

As a result of the recent Reduction in Force at MBS, a senior scientist at JILA (Fellow) is being transferred to Division 524 (Time and

Frequency). Two other Fellows of JILA on the CU Faculty are currently

on leave for employment elsewhere and it is highly probable that this

will result in resignation after a year's time. This is probably the

largest decrease in number of Fellows in a single year during JILA's

history.

One notes from the figure that of the 128 research scientists in

JILA, that 84 (or 66%) are postdoctoral s and students. Another 18 are visitors, for a total of 102 (or 80%) students, postdoctoral s, 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. Five

Ph.D.'s have been awarded with MBS thesis supervisors, and MBS Fellows

have supervised 31 Ph.D. students during the past year as well as 33

postdoctoral s (many have left, accounting for discrepancy of numbers

with figure).

Visiting Fellows Program

The Visiting Fellows Program is perhaps one of the main components

of "glue" that holds this unique partnership together. This program is

funded by MBS by a contract with CU, and provides for the order of 10

senior level scientists to spend from 6 months to 1 year in the Institute. The participants are chosen competitively from a large number of

applicants, and the program which has operated for 17 years now has been

a spectacular success. Scientific productivity of this group who come with no duties has been very high. For example, of the 471 publications

129
listed in the last three years' annual reports by QPD staff and Visiting

Fellows, approximately 40% were by Visiting Fellows. This program again

provided tremendous amplification of NBS staff. Visiting Fellows for

1980-81 and for 1981-82 are listed in Sec. III.

The program has managed to stay healthy and viable over the years,

as MBS management (with support from the Evaluation Panels) has recognized the value of the program and given budget increases to help offset

inflation. Specifically, $100 K is being added to the VF Program budget

in October 1981 to make up inflationary losses in the regular Visiting

Fellows Program. Further, in October 1982 an additional $100 K will be

made available for exchange of scientists between JILA and Gaithersburg.

It is expected that the "direction of visit" will alternate each year,

with a JILA person going to Washington in 1982-83. This new program

should enhance the communication and collaboration between JILA and

MSBG — a long sought goal often emphasized by our evaluation panels.

130
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

Simple Stabilized Laser System . J . L. Hall, T. Baer and D. Bass

continued development of a stabilized laser system at the simple, rugged

and inexpensive end of the performance spectrum. Such devices are in

great demand as laser sources of stable wavelength for dye laser wavelength interferometers (the <<Lambdameter>> invented by S. A. Lee and

J . L. Hall) , for the JILA gravity-measuring apparatus ( J . Fal ler and M.

Zumberge) , for all routine interferometric testing, and for a variety of

precision applications in astronomy, including calibration of high reso- lution astronomical spectrographs, and alignment of sophisticated polarization (Lyot) filters, etc. The JILA laser device is based on a frequency-pulling effect in a single mode HeNe laser in a longitudinal

Zeeman field. The JILA approach is to measure the beat frequency between the two oscillating modes of opposite senses of circular polarization and servo-control the laser to the minimum. Although the beat

frequency only changes by ~10“4 of the optical frequency change, the

beat signal has a very high information content since most perturbations

affect the two polarization modes equally. The intermode beat is continuously counted into a reversible counter whose sense is switched

synchronously with the applied square wave laser frequency modulation.

Error information is strobed once per modulation cycle into a DAC for

the servo. Performance of the system is remarkable, providing a frequency stability (Allan variance) well below 10“ 9 for only 1 second av- eraging time, and below 10” 10

at 100 seconds. The drift of the system

over time and with exchange of laser tubes is below 10" 9

. A systematic

o shift of ~10" over the laser tube's life is expected due to pressure

changes. The concept is to work with appropriate commeri cal ly-avail able

tubes — which have been designed and optimized for long life — by attaching our piezo electric tuning control element with epoxy cement.

Some useful experience is being obtained by building six of these units

for projects in JILA and NBSB, NBSG (J. Faller, S. Smith, A. Gallagher,

J. Bergquist, D. A. Jennings, and J. J . Snyder) . The published work has

attracted wide interest and requests for assistance. A patent application through NBS is being prepared ( J L. Hall, T. Baer and F. Kowalski).

Optical Heterodyne Saturation Spectroscopy . A major breakthrough

in laser spectroscopy has come from the work of J . Hall, L. Hollberg,

T. Baer, and Visiting Fellow, H. G. Robinson. In this new technique

(Fig. 1), called Optical Heterodyne Saturation Spectroscopy, they use phase-modulation techniques to encode the resonance information of interest to a modulation frequency at which the laser noise has dropped to

131
Fig. 1. Optical Heterodyne Saturation Spectroscopy. The frequencystabilized single frequency laser output is divided into probe

and saturating beams by a beam splitter. The probe beam is

phase modulated by an Electro-Optic Modulator and passed

through the Iodine cell whose pressure is controlled by the

Peltier Cooler. The saturating beam, frequency offset and

chopped by the Acousto-Optic Modulator, is collimated and

aligned coaxial and anti parallel to the probe beam in the I 2 cell. The signal -bearing probe beam is detected by a fast

photodiode (D) whose output is filtered for the rf component

at frequency w and applied to the signal port of an rf DoublyBalanced Mixer. The rf reference signal is phase shifted by an adjustable delay line. The dc output of DBM-1 may be further

processed by a lockin amplifier to recover the signal (output

2) synchronous with the saturation chopping.

132
near the theoretical minimum value associated with the photoelectron

shot noise. For example, in demonstration experiments with dye laser

measurement in I 2 vapor, the noise was reduced by about 10,000-fold in

comparison to conventional saturation spectroscopy. They have shown

that under realizable conditions, the sensitivity of measurement approaches the limit associated with the intrinsic quantum fluctuation

of the signal itself. Experiments to confirm this result are under way.

A very important aspect of this technique is that the absorption signal

is received by an optical heterodyne process. The "local oscilator"

signal provides "conversion gain," in the language of the radio engineers. The result is that quantum-counting spectroscopic sensitivity

should be available well into the infrared where detector limitations

would otherwise totally prevail. T. Baer and J. L. Hall have already

applied the technique to stabilizing a cw color center laser at 2.6 urn with which excellent high resolution hyperfine-resol ved spectra of HF

were obtained for several P-branch lines. Application of our "traditional" {= state of the art) frequency offset lock techniques for longterm control and scanning of this color center laser will allow precision measurement of all the hyperfine interaction constants. Their

variation with vibrational and rotational excitation carries important

signature information about deviations from the Born-Oppenheimer limit

of electronic-vibrational separability. Such information could well

have a synergistic effect with direct investigations of intramolecular

energy transfer processes that influence selectivity in laser isotope

separation and bond-specific laser chemistry schemes. Interaction with

the ion spectroscopy interests of S. R. Leone and D. Nesbitt is planned.

From the standards point of view, the new optical heterodyne spectroscopy technique is the most exciting development since the introduction of saturated molecular absorption spectroscopy (Barger and Hall,

1968). Robinson and Hall have shown theoretically that the resonance

profiles in optical heterodyne spectroscopy should be based on a simple

dispersion shape and should be rigorously odd-symmetric with respect to

their center frequency. The experiments of L. Hollberg, T. Baer and

J. L. Hall confirm the line shape prediction and pure symmetry to within

1 part in 500. New experiments on the metrologically-important I 2 line

at 612 nm are being conducted by Ma Leung Sheng and J. L. Hall. The

high sensitivity of the method has a side benefit in that one :an work

at much lower light intensities than those conventionally employed in

I 2 -stabil ized lasers, thus avoiding the disastrous light shifts that

dominate the reproducibil ity of these devices. Detailed information on this new technique has been provided to Alan Pine (NBSG) to facilitate

his search for Se 2 and Te 2 resonances useful for stabilizing the argon

green and blue laser lines.

Relativistic Time Dilation . Progress on the longitudinal interaction experiment of J. L. Hall, P. Nachman, and M. Rayman to remeasure

the Relativistic Time Dilation is good, but has been seriously hampered

by inadequate funding. A funding initiative which would have allowed

this work to go forth in an aggressive manner now appears doomed to be

cut out. Hal 1

1 s group does in fact have the fast ion beam up and running, and they have studied the formation of well-focused ion beam

133
images using a phosphor screen. The next step is to load the Na charge

transfer over and measure the collimation of the resulting metastable

beam via resonant laser excitation. After the laser, ion beam/fast

neutral beam, and interaction techniques are developed and proved out,

they will be measuring the absolute optical resonance wavelength for

transitions of the fast-moving metastable atoms (Ne first, then He ).

This will provide vastly improved spectral information for both atoms.

At 50 keV, the first order Doppler shifts are ~20 A (2.5 THz) which they

expect to be able to measure to ~10 kHz, a fractional accuracy approaching 10" 9

. The second order shift associated with Relativistic Time

Dilation for He will be 6.8 GHz which should be measurable to ~10” 6

. This will represent a 10 3 -fold improvement over the present limit inferred from muon decay. The metrological technique to be employed is

high resolution Fabry Perot Interferometry , using a free spectral range

=100 MHz a finesse of ~75 (silver mirrors). The little Lambdameter has

enough accuracy to identify the order number uniquely without tedious

counting. In locking to Fabry Perots of similar line width they have

already demonstrated a 20 Hz/mi n drift rate, made possible by the new fm

sideband locking technique. Finally, it should be possible to set a new and very tight limit ~10" 9 on any vector dependence of the speed of

light. If sufficient linear distance can be obtained in a laboratory to

provide an attractive interaction time, it will be interesting to make

the same measurements with the faster moving H* atoms.

New Limits for Lambdameter Accuracy . A major breakthrough in frequency metrology has recently been made by J. J. Snyder (NBSG) and applied to the high resolution JILA Lambdameter by J. J. Snyder, J. L.

Hall, T. Baer, and L. Hollberg. In the JILA Lambdameter, the idea basically amounts to computing the wavelength average over a large number

of overlapping but independent measurement intervals. The available /n

enhancement is quite interesting when the number of fringe measurements

is ~106 -10 7. A first hybrid software/software version was tried with

the JILA Lambdameter and showed real promise. The main consequence is

that the high data rate will make feasible a detailed clarification and

(hopefully) removal of the interferometric errors of the system. Repeatability and resolution above 10 10 were easily demonstrated, and wavelength accuracy of 10 -9 was achieved. The intention is to pursue this

real-time interferometric wavelength measurement technique to new limits.

Gravitational Waves . A new conceptual design for a gravitational

wave detection experiment in space has been developed by J. E. Faller and

P. L. Bender . It utilizes the equivalent of a Michel son interferometer,

with spacecraft A at the center and spacecraft B and C about 10 6 km away

at the ends of the two arms (see Fig. 2). Doppler measurements are made

over each arm, using roughly 50 cm diameter transmit/receive optics and

visible helium-neon lasers with output powers of a milliwatt or less.

The lasers at B and C are phase-locked to the received signals from A,

and the phase of the received signals at A with respect to the lasers at

A are recorded.

134
Spacecraft A

Fig. 2. Schematic diagram of gravitational wave detection experiment in

space

.

135
The orbital geometry is chosen so that each arm will stay constant

in length over a year to 0.1%. Spacecraft A is placed about 2 x io 7 km

ahead of the earth in a coplanar circular orbit around the sun with one year period. Spacecraft B and C are placed in similar one-year period

orbits about the sun, with e = 0.003, i = /J e, and nodes differing by

90%. With proper initial longitudes, spacecraft B and C will stay in a reference plane through spacecraft A which is defined by having the normal to the plane always point 30° below the direction to the sun. The

directions to B and C from A will be orthogonal, as shown in Fig. 2, and

they will appear to rotate in the reference plance with annual period.

The main limitation on the constancy of the arm lengths is due to orbital perturbations by Jupiter and Venus.

There are two main objectives for the experiment. One is to search

for gravitational wave pulses with periods of minutes to a few hours and

with fractional strain amplitudes of roughly IO” 20 or 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 10" 21 in a one-day measurement interval.

The main factor that makes the achievement of such sensitivities

possible is the absence of substantial gravitational forces due to the

sun and planets with periods in the range of interest. For this reason,

the apparent changes in the length of one arm of the interferometer can

be used to determine changes in the laser frequency for periods considerably longer than the 6 sec round-trip travel time but less than days.

It appears feasible to correct for such laser frequency variations with

an accuracy of better than 10" 18

, so that the effect of laser instability on determining the difference in length of the two arms of the interferometer can be reduced to below 10" 21

.

Conceptual studies are now being started on the problem of shielding the test masses between which the distances are being measured from

solar radiation and the solar wind without introducing other disturbances. The major forces of importance acting on test masses inside

their shields are likely to be the following: fluctuating gradients in

the thermal radiation pressure due to temperature variations in the

shield; varying gravitational forces due to gradients in the gravitational field from the shield and relative motion of the shield due to

time-varying forces on it; and fluctuating electrical and magnetic

forces. It appears that such effects can be reduced to acceptable

levels, but substantial studies of the associated problems are needed.

136
J. L. Hall has established a working level cooperation with the Cal

Tech and Glasgow groups interested in gravitational antenna research

( K. S. Thorne, R. W. P. Drever, S. A. Lee, and J. Hough). They have had numerous discussions about fundamental principle limits and ways to

avoid them; although, of course, the strongest interaction has been in

the area of laser stabilization. A paper in the final stages of preparation will describe the joint experiment at JILA in which a dye laser

line width below 100 Hz was demonstrated.

Efltvfls Experiment. P. Keyser and J. Faller have under construction

a large (bU" diam) torsion pendulum apparatus (see Fig. 3) with which to

test for the equivalence of gravitational and inertial mass. This large

Efltvtfs apparatus utilizes the surrogate fluid fiber which was developed

at JILA, and which was used in the earlier (and smaller - 0.25 m diam)

Efltvds apparatus of M. Keiser and Fal 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. This apparatus is now in the final stages of construction.

During the past year a number of practical problems have arisen as a result of having increased the size of the apparatus. For example, a hy

draulic jack was used to deform the top of the float just past its elastic limit so as to improve its roundness from the "as received" ±0.014"

to ±0.004". Also the 95 lb. Zn test mass castings proved to be not near

ly as non-magnetic as the Zn sample had led us to expect; as a result

they were rejected and we are replacing them with 0FHC Cu test masses.

Of the various noise sources identified in the earlier experiment

of Keiser and Faller, only the effect of the residual mass-quadrupole

moments can be expected to be substantially worse in the new apparatus.

These effects can be ameliorated by measuring the quadrupole moments

of the float and systematically tuning them out (as they did) by mass

tuning; or one can remove their effect on the data by directly measuring

the changes in the gradients of the external gravitational field and

then correcting the float's response for these changes. In the case of

the new float, it is planned to use both methods.

Geophysical Measurement Development

Gravity Gradiometer . Recognizing the needs of the Efltvds experiment lIsTweTTlisHEfie

-^^ of this type of fluid supported pendulum

apparatus as a gradiometer, Faller is proceeding at present with the

testing of two 0.25 m diam (see Fig. 4) fluid gradiometers. This development — in addition to its importance for our Edtvtts work — is seen to have application to tunnel and intrusion detection as well as security for nuclear stockpiles.

This group has developed a new optical angle-detecting system (Fig.

5) for use both with the gradiometer and on the large Efltvfls apparatus.

This "internal" sensing system promises to have a much higher mechanical

integrity — the sensing optics are a part of the container lid on which

the zero-determining electrode array is located -- then the external

auto-collimator approach used in the earlier work.

137
Masses

and

Float

138

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3

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(1.3

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apparatus

to

test

equivalence

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Centering

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139

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gravity

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.
Optical

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The sensing system consists of an infrared light emitting diodeIR LED (whose output light is focused into a line image by a cylindrical

glass "lens" attached to the type of the float) and a split photodiode

detector. As the float turns, the cylindrical lens moves with respect

to the LED-photodiode pair causing the line image to move its position

in the split photodiode giving rise to a rotation-dependent voltage as shown on the right half of Fig. 5. Locating detection systems on opposite sides and using their outputs properly summed makes this detection

system insensitive to sideways motion of the float without sacrificing

its sensitivity to rotation.

Absolute Gravimeter (g). Over this past year, J. Faller has con- tinued 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. At JILA,

M. Zumberge, J. Faller, and R. Rinker have developed a new absolute gravimeter which was designed to be portable so that it could be used in

field applications (see Fig. 6, photograph of apparatus).

Three innovations have contributed to the successful development of

the new JILA apparatus that has been developed over the past few years:

(1) the addition of a coaccelerating chamber which drops with the corner

cube, (2) the development of the "super spring" that provides a compact,

stable long period spring for isolation purposes, and (3) a newly implemented Zeeman stabilization scheme devised at JILA which has been used

to stabilize the He-Ne laser that serves as the light source in the interferometer .

Questions relating to the accuracy of this new instrument have been

for some time and continue to be under study at JILA. At this time the

best estimate of the error budget is given in Table 1.

This past year 400 sets of 150 drops were made, during which the

system appeared to be operating correctly (e.g. the apparatus was not

being subjected to any special test conditions). The standard deviation

of the results of these 400 data sets is 5.9 ^gal or about 6 parts in

10 9

, while the standard error associated with a single 150 drop data set

ranges from 3 to 7 iigal . This coming October an intercomparison of absolute gravimeters (Sakuma's stationary apparatus, the new instrument

developed at JILA, the absolute gravimeter of the USSR Academy of

Sciences, and the AFGL instrument of Dr. Hammond) is planned at the

Bureau International des Poids et Mesures ( B I PM ) in Sevres, France.

The results of this intercomparison should help to further clarify the

issue of instrumental accuracy.

Recognizing that broadly based usage is the one and only way to answer questions of geophysical import as well as actual instrumental

field performance, it is planned to follow-on this development by seeing

that this new type of gravity instrument is both widely used and field

141
142
Table 1 Known Systematic Errors

Source Error

Differential Pressure 1.0 ugal

Differential Temperature 1.0

Magnetic Field Gradient 0.5

Electrostatics 1.2

Attraction of Apparatus 0.5

Vertical Reference * 0.8

Optical Path Changes 3.8

Laser Wavelength 1.0

Rotation 1.0

Transl ation 1.0

Floor Recoil 1.0

Phase Shift 1.0

Frequency Standard 0.5

R.M.S. Total 4.2 ij.gal

This error is primarily due to problems

associated with the pelicle on the bottom

of the drag-free chamber having a finite

wedge angle. At the present time we are exploring a number of possibilities (including the possibility of completely

eliminating the pelicle) with the aim

of reducing or eliminating this error

source.

tested in as many different geophysical settings as possible. Hopefully

we can look forward to an era in which precision measurements of g will

prove to be an exciting new tool for furthering our understanding of the

world on which we live.

Short Wavelength Variation in "g ." The problem of using satellite

measurements to determine variations in the earth's gravitational field

with wavelengths of about 100 km and somewhat shorter has been studied

by Bender and Faller . The NASA Office of Space and Terrestrial Applications is considering requesting a new start in FY/83 or FY/84 for a mission called GRAVSAT, which involves microwave Doppler measurements

between two spacecraft in the same low polar orbit around the earth and

separated by up to about 300 km. Gravity gradients in the along track

direction would change the relative motion of the two spacecraft, and

worldwide measurements of the velocity data would determine the global

gravity field for wavelengths of longer than 100 km. The approach suggested for consideration by Bender and Faller is the use of laser Doppler

143
measurements between the spacecraft to improve the accuracy, and therefore the short wavelength gravity field resolution. This also would

require improvements in the systems aboard the spacecraft for avoiding

spurious accelerations due to atmospheric drag and other effects.

Deep Borehole Tiltmeter. J. Levine (Fellow of JILA rostered in NBS

Div. 524) , in collaboration with J. C. Harrison and C. Meertens of CIRES

and the University of Colorado, have developed a deep borehole tiltmeter

which can be operated below the near surface layers so as to reduce the

influence of meteorological effects and which is relatively inexpensive

to build and to install. A depth of 33 m is normally used, although

this is not a critical aspect of the design, as the electronics are inside the instrument capsule. The instruments are capable of operating

unattended for long periods of time at tidal sensitivity. Six of these

instruments have been installed at two sites near Boulder, Colorado.

One site is at the edge of the foothills with closely spaced holes 6 m,

16 m, and 33 m deep. The other site is 24 km to the east in the flat

plains where five holes, each 33 m deep have been drilled spaced from

30 m to 120 m apart. Using an observation time of 28 days, earth tides

are observed with a signal-to-noise ratio of almost 40 db and with an apparent secular tilt of about 0.1 micro-radian/month. Data from the

instruments are used to construct the tidal admittance and to study the

coherence among the instruments. The semi-diurnal tidal admittance

shows very good agreement with theory. Consecutive monthly admittances

average 0.984, show a standard deviation of approximately 6% and have no secular trend. The instruments show no nonlinear behavior. They are currently requesting permission to deploy approximately ten additional

instruments in Yellowstone National Park to study the known low-velocity

anomaly there and along the Wasatch Fault near Ogden, Utah to investigate a possible seismic gap in that area.

Mul tiple Wavelength Geodimeter . J. Levine and J. Magyar of the

Time and Frequency Division are developing a multiple-wavelength distance measuring system designed to measure distances of order 40-50 km

with an uncertainty of about 0.02 ppm. The instrument is currently

undergoing laboratory tests, with the first field tests planned for this

winter. The first field tests will be made over short baselines in

Colorado. These tests will be used to test the phase-measuring system

in the presence of realistic levels of atmospheric turbulence. They

will also be studying the degradation in the microwave system due to

spurious reflections ("ground-swing"). (Levine is a physicist in the

Time and Frequency Division and is also involved in other projects in

collaboration with others in that division including various problems

involved with the NBS time scale and with time coordination. In particular he has been responsible for generating UTC(NBS) and is currently

developing software and hardware for a new NBS time scale system.)

Astrophysical Measurement

Diagnostic Techniques for Stellar Atmospheres . Astronomers have

been developing powerful techniques for inferring such physical properties as temperatures, densities, and departures from excitation and

144
ionization equilibrium in the hot plasmas found in the outer atmospheres

of the Sun and stars. These techniques involve comparing observed spectral lines and line ratios primarily in the ultraviolet with profiles

computed by solving the equations of radiative transfer and statistical

equilibrium for a realistic model of stellar atmospheres. During the

last year Linsky and his colleagues have derived physical models for the

chromospheres of different types of stars by analyzing ultraviolet emission lines of Mg +

, C +, Si +, C ++, and C +++

. They have also found that

the ultraviolet A-X bands of the molecule CO can fluoresce in the chromospheres of cool stars when pumped by the resonance lines of neutral H,

C, and 0 (see Fig. 7). They found that the relative line intensities

among the intersystem lines of C + near 232 nm are useful density diagnostics for stellar chromospheres, and that the 164 nm subordinate line

of He+is formed primarily by recombination in the solar chromosphere

and thus is a good indicator of the photoionizing flux of X-rays. An

important problem for next year will be the study of the La, Lp, and Ha

lines of hydrogen using the theory for frequency redistribution in this

coupled system of lines being developed by J. Cooper .

What Types of Stars are Solar-Like? The outer atmosphere of the

Sun is now known to consist of a chromosphere (T * 10 4 K) , a 10 6 K corona with a very small mass loss rate, and a geometrically thin transition

region between the chromosphere and corona. Based on X-ray observations

with the Einstein X-ray Observatory and ultraviolet spectra from the

International Ultraviolet Explorer satellites, Linsky and his colleagues

are now able to determine the range of stellar effective temperatures

and gravities in which stars have outer atmospheres similar to the Sun.

They also found that stars with somewhat lower effective temperatures

and gravities no longer have hot coronae and transition regions, but

rather have only cool chromospheres and large rates of mass loss (see

Fig. 8). During the next year they will study the energy balance in

stellar chromospheres and coronae.

Measurement of Stellar Magnetic Fields . Linsky and his colleagues

are now pursuing two methods for measuring magnetic fields in stars.

The first method involves measuring the Zeeman triplet splitting directly on the extra width of spectral lines with large Lands

g factors

compared to lines with small g factors in high resolution unpolarized

spectra. The second method involves the analysis of 6 cm radio emission

from stars formed by the gyroresonance emission process (low order harmonics of the cyclotron frequency of electrons spiraling in coronal

magnetic fields). This second technique became feasible when Gary and

Linsky discovered radio emission from solar-like stars for the first

time (see Fig. 9) using the Very Large Array radio interferometer of the

National Radio Astronomy Observatory.

Solar and Stellar Flares . Linsky and his colleagues are studying

flares on the Sun using experiments on the Solar Maximum Mission satellite and stellar flares using the Einstein X-ray Observatory and the

International Ultraviolet Explorer satellites. The principle question

they are trying to answer is whether flares cool primarily by radiation

(X-rays and ultraviolet), thermal conduction, or expansion.

145
cm ia

30N30S3aomj

3AllV“l3d

to s uuo

I- 2 - T

O

cvi s 6 j 0 ) ooo

CMoo0) oo

COoo

r*- ooU3 oooooo

rooo

CM

h-Z

LlI -J

Lli ><5

-o

O) I CL <J E cu 3 Cl

CL oO

00 +J

<0 0) o 'o O -t->

<4- (O O i- 4-> T3C 3

<T3 JO -o

OJ

X > I i- < <u00

<D jC

-SC

Oc1- M 5 O

<U ^Cl "O

00 c

03

CLo

4->

*oc

03

03

O

U

21 0) S- <4- o o

<D -C WO

4-> 0Jc

03 t- O CDu c c O 03 t/1 c

TO

i_ oo

03 0) Q. S- EO >, O JC

CTi

146

trum

of

the

star

Arcturus

(bottom

band).

Many

of

the

heretofore

unidentified

features

In

the

ultraviolet

spectrum

of

Arcturus

and

other

stars

can

now

be

Identified

as

due

to

fluorescence

of

CO.
OBSERVED

FLUX

AT

EARTH

(10

13

ergs

10

Lh

r 4 L

7

|_ W i- E oo r

4 (-

[r 3 r

1 T

’ " '

I

1 T -l ~rT1

HI

-r—n— —7- --t 0 Dra (G 2 E)

-t-.

01

NZ

V MuiajUTV

C3Z

<- 1

: T-H'-t nt-r- H 1 1

j

' i m j

i h .

e Gem (G8Ib)

SI

01 Fe II S-L.

| Cl

j

l J j i 1

1

I

1 ‘ A I

I *

I \l\ J L i<vS/r!

* i — y ,

1 j , .1

<

If-t-r4 '

| < '1 t r

I ^ « W*- P\ . "

Si Z

n

Si: * r e il

I ,/l

< - n ' W

2

rt

i h

I

o Ori (M2 lab)

SI

Sii EL

r-i i

I I

N I

Feu S i I Cl

[ISill

i I j FeSL’

, ATJW< l

*% /

‘ .

1 Fe El

I

:

|

(

1

I Ii , T Ai /•/

I ,\v

J*' I » V ; V \ J v v V

1100 1200 1300 1400 1500 1600 1700 1300 1900 2000

WAVELENGTH (A)

Fig. 8 . Ultraviolet spectra of the stars 3 Dra, s Gem, and a Ori obtained with the International Ultraviolet Explorer satellite.

Note that £ Dra shows emission lines of highly ionized species

such as N V (N +T and C IV (C +++

), indicating a solar-like

outer atmosphere. On the other hand, both e Gem and 2 Ori show

no evidence of highly ionized species and thus have only cool

matter in their chromospheres

147
DECLINATION

(1950.0)

20°I6’40"

zo°\6'zou 'r

20° 16' 00" -

20° 1 5' 40"

C?

vA OR!

6 cm

I960 OCT 2

\

!"Vj N

half power

BEAM PATTERN -

5

h 5l

m

2S s 5

n 5l m

24 s RIGHT ASCENSION (1950.0)

Fiq. 9. First discovery of radio emission from a solar-like star

with the Very Large Array radio i nterferometer of the

National Radio Astronomy Observatory. This is a map at

6 cm wavelength indicating that the x

1 Ori is a radio

source (* marks the optical position of the star). The

emission is almost certainly due to the qyroresonance

process indicating coronal magnetic fields of about

300 gauss.

148
Steady Flows in the Quiet Solar Transition Region . K. B. Gebbie , J. Toomre, F. Hill, In collaboration with L. J. November and 6. W. Simon

(SPO), have carried out an observational study of steady flows in the

quiet solar transition region, as a guest investigator program on the

Ultraviolet Spectrometer and Polarimeter (UVSP) experiment on the Solar

Maximum Mission (SMM) satellite. Two dimensional images of intensity

and Doppler velocity in spectral lines of C II, S IV and C IV were typically repeated for an entire orbit and the data time averaged to yield

the steady component of the velocity field over a range of heights. The

main results of this work are that: (1) the patterns of steady velocity

in the three spectral lines are similar, suggesting not only that the same flow pattern extends from 2 x 104 K to 10 5 K, but also that it persists without apparent evolution for a period of at least three hours.

(2) Seen at disk center, regions of relative downflow tend to coincide

with regions of bright network emission, while relative upflow occurs

more often in the darker areas. (3) Histograms showing the numbers of

spatial points with given velocity amplitudes are close to Gaussian with

only a slight asymmetry toward higher amplitude downflows. (4) The real

surprise in these data is revealed in scatter diagrams of steady vertical velocity versus intensity (Fig. 10), where the brightest points

appear to form a separate branch with substantially lower velocity am- plitudes than those of the primary branch. The presence of the two

branches suggests that the downflow has at least two components. Since

the primary branch is associated with the network as a whole, it

seemingly includes both supergranulation and magnetic downflow; the

secondary branch may form a separate, lower amplitude component of the

magnetic downflow in the brighter sites. We are hardpressed to offer an interpretation of the two classes, largely because theoretical models of mean flows and waves along magnetic flux tubes are still in the early

stages of development, as are the theories of penetrative convection re- lating to supergranul ation.

Mesogranulation . The same research group has continued their study

of the lifetimes, topology and height dependence of mesogranulation, in

order to shed light on its origin and relation to other discrete scales

of motion in the Sun. Further, it is now clear that these 5-10 Mm con- vective flows will make a significant contribution to all the photospheric and chromospheric velocity fields to be measured with the Solar

Optical Universal Polarimeter (UVSP) on Spacelab 2 and with many of the

proposed experiments on the Solar Optical Telescope (SOT). For any real

advance in the understanding of mesogranulation, it is essential to obtain observations with good seeing for periods of 8 to 10 consecutive

hours. In an attempt to improve the consistency of the data over such

long periods, a number of substantial improvements have been made in

both the observing strategy and the software. Sixty-minute running

means of data obtained during such continuous observing runs indicate

that the mesogranular lifetime is of order 3 hours.

Analysis of the Ultra-hot Wolf-Rayet Star Sand 3 . D. H. Hummer has

continued his analysis of the OVI star Sanduleak 3 with M. J. Barlow

(London), using two IUE spectra and five AAT visual spectra. Hummer and

Barlow have merged the spectra to obtain continuous coverage from 1145 A

149
ORBIT

2119

(b)

CIV

ORBIT

2120

(c)

CIV

ORBIT

3103 o __ oinoinOusom I P TO

<v c

in jOO •

<T3 I>Oo o

in

—

p

0) r— P <v

10 c

<e (O p cl

p

O T3 CO

CTi

C

«—• O C P O 3 o 'o

a <e O)

m

at cl

m c > <U o £ CM i- P p - o P C 0J » . . C\J O f Cl fl m a; . - <P CP JO =

fl 1- fO o *r“ >, p cn *o P P H3 « a> -o p > s- -a

</» <d i—i ai c CfO > 3 <e 1) Oi fl o •LJ CO I £ VI C 0) Ot O O

i- e sz i- it- P- -C P m > P 3 m 3 t—• t— m >, " * . A M P t- JO m <e 001 - - <u 00 p p

z: > TO >1 a;

m

ZD a) a>

p 0 >,£= c 3 m c 0 p p* •*- D <e 0

•r— fOp

p

U P O 0 >- O • JO CO — JO

I— rC

O o^ in a. 0) 3 «—

CO >1/15)

p z: P c X 0/ uj 1— p a/ 0 p h- « U) 2 — p 2: 0 f- -a 0 <D

•—

t- 3 — a> CM P O’ JO > f—

p p

C

a> <d a> P •»— >£i- m a» re P 0) JO (— p

«= 0 r— £3

a c <e <e

O

<T3

O CL <rs S

0)

O

m

O P P C P P m <u t- re O p in P P C fl 3 <v OOP 0 L- -0 0 r<3 CSJ 0 p m "O r*H 0 £ -* 0

fl 1/1 CO

X 01 c p 1- «sr re ova in a p O a» co

1- 4-> CM > Q <e 1—1 <e

p 5» <v P m 0) .Q 0 c JZ s= POO CD P 0) p 1— c P

<T3 P O) T— 0 CL O *3 .C p p O

LO > P 0) <e OO O ( T .SW>0 A1 1 3013 A

150

the

expense

of

spatial

coverage.

The

two

distinct

branches

In

each

of

these

plots

suggests

that

the

downflow

has

at

least

two

components.
to 7300 A, and have dereddened the resulting composite spectrum by removing the 2200 A feature, to obtain E(B-V) = 0.5. The resulting spectrum,

shown in Fig. 11, shows no signs of deviation from a pure Rayl eigh-Jeans

(F^ ~ \" 4

) throughout the spectral range of the observations. The very

high temperature implied by this observation, together with the presence

of emission lines of 0 VI, VII, and VIII, which Hummer and Barlow identified in 1979, and the absence of hydrogen and visual nitrogen lines

implies that one may be seeing the bare core of a highly-evolved star

that has recently blown off its atmosphere; the presence of the NV resonance line with a strong P-Cygni profile suggests that the ejected material is still relatively close to the star. Barlow and Hummer will be

reporting at the IAU Symposium on Wolf-Rayet stars for September 1931

on this object as a prototype of a new stellar class, W0, which have

evolved from WC stars.

The main effort at present is to determine the relative abundances

of He, C and 0 using the emission lines of various ions of the elements;

for this purpose radiative recombination coefficients and relative line

intensities, allowing for collisions, are being computed for one, two

and three electron systems. These codes have been written and largely

debugged in collaboration with Dr. P. J. Storey (London) and will be

used to prepare extensive tabulations of effective recombination coefficients, which will be invaluable in interpreting the high n ( <.20 ) re- combination lines now being observed more and more frequently in the near infrared spectra of many types of stars and nebulae.

Analysis of Hydrogen Spectrum of Dwarf Novae . The escapeprobability treatment of radiative transfer in spectral lines in a gas

with a general three-dimensional flow field, which was developed several

years ago by D. G. Hummer and G. B. Rybicki (Center for Astrophysics) is

being used to calculate hydrogen line profiles formed in the accretion

discs of dwarf novae. Although accretion discs are found in a wide va- riety of astronomical systems, the basic physics of viscous dissipation

of Keplerian motion by which they are heated remains obscure. Dwarf

novae are thought to be the most favorable system to study in order to

understand this phenomenon; from a detailed study of the hydrogen spectrum it should be possible to estimate the heat input into the disc as

a function of radius. This work is being carried out by a graduate student, Mr. Douglas Carroll, under the supervision of D. G. Hummer .

External Blanketing of Stellar Atmospheres . In view of the accumulating evidence that the ultraviolet color temperatures of hot stars is

essentially lower than the effective temperature inferred from visual

fluxes, D. G. Hummer is investigating the effect of stellar flux distributions 3T~raHTatTorT either emitted or scattered back into the stellar

photosphere by overlying material. As a first step, this mechanism was investigated schematically by considering a gray model atmosphere with a partially reflecting outer boundary with a wavelength dependent reflectance function. For certain simple forms of the reflectance function,

this problem can be solved numerically with little effort; the results

show that quite moderate back scattering by the winds in the ultraviolet

151
I / a

07

COa

cn

-<

a

zfarj

cn e c •r-

*r*2 x: O *-> jz os

vs c

a>

A

ron a>>

T3 <9 c 2 3

on <1> x:

M— 4-> o

<4- E o 3

S- E 4-> sz

<J 4-> a> •1—

CL i. VI 3

3)

0) o

4-4 • J- V) o 1 o J=

CL 4-> s • 5 <4- 4-4 u o VSC c o

s_ o CJ a> T— O. 4-> <4- CL CJ o 3 c3 4-» 4— *p— *3 <4- 04 ITS c p—

<u VS r— o i3 3

•c X3

a>X 1 s_ 3 0)

a; r— >> a •*- CJ a 04 VI c jC 3 4->

CJ

IL- e

s_ o —

<D r— 2 = O -C 4-> f— 4J JZ

•p- os

L. •t— r— 3 3 3 os i- C o 4-> ,— VO

cn o

S- jC • O

JfIil oo

CO

aa

fM

Oo oa

CD

li

152 PP
can make the visual flux appear characteristic of hotter models, so that

ignoring this effect would lead one to assign too high an effective temperature to the star. Typical results are shown in Fig. 12. A brief

account of this work is being prepared for publication, and a more

realistic calculation, using monochromatic wind opacities from David

Abbott's wind models and the Auer-Mihalas non-LTE atmosphere code, is

under way in collaboration with Drs. Castor and Abbott.

Escape-Probability Theory of Spectral -Line Formation . The general i zeT'escape^proljaFrrTtythe^^ year by D. G.

Hummer and G. B. Rybicki (Center for Astrophysics) is valid for veloci ty

f i el ds of arbitrary amplitude, goes to known low- and high-velocity limits, and for the first time yields necessary conditions for the validity

of the high-velocity (Sobolev) limit. This work has been submitted for

publication. Hummer has recently generalized this theory to include,

for the first time, the effects of continuous opacity on the line, and

has obtained simple analytical results for several limiting cases most

applicable to astrophysical modeling. This extension of the theory is

important because it allows the use of escape-probability approximations

in dealing with optically-thick media. In the next year, extensive com- parison of the results of escape-probability calculations with accurate

numerical solution of the transfer equation for a wide range of flowspeed gradients and optical thicknesses will be made to further refine

our understanding of conditions for validity and of typical errors in

the approximation.

Frequency Redistribution in Scattering. D. G. Hummer is continuing

his long-standing research in the effects of partial redi stribution on spectral line formation. A new formulation of colli si onal redistribution for non-general levels that has been developed by Ballagh, Burnett,

and Cooper is being carried through, in collaboration with D. G. Hummer , to the point that it is computationally useful in astrophysical problems. A preliminary draft of this paper has been written.

The effects of partial redistribution on transfer in multi pi ets and

in molecular bands will be investigated by Dr. Hummer, in collaboration

with Dr. A. A. Kutepov, an exchange scholar from the Department of Atmospheric Science, Leningrad State University. The multiplet calculation

is intended to examine the anomalous multiplet ratios caused by the differential effect of continuous opacity on strong and weak components.

The molecular band theory will be applied to modeling of the 15 \x bands

of C0 2 in the earth's atmosphere; this band will be observed by a satellite to be flown shortly carrying LASP instrumentation.

Festschrift for Professor M, J. Seaton . D. G. Hummer has been

named a co-editor, along with P. G. Burke (Daresbury) and Ian Percival

(London), of a book on atomic physics and astrophysics in honor of

Professor Seaton's 60th birthday, which occurs in 1983. Contributions

have been promised by a number of Seaton's colleagues and former students; Hummer is writing a chapter on "The Role of Atomc Physics in

Stellar Atmospheres."

153
Fig. 12. The normalized flux distribution vs. 5 = hv/kTe ff for

a stellar atmosphere in which a fraction p of the

emerging radiation is reflected back into the atmosphere for 5 > 4, for purely absorbing (e = 1.0) and

primarily scattering (e = 0 . 1 ) media.

154
Atomic and Molecular Physics and Interactions

Excitation of He-Like Ions. A. K. Pradhan, D. G. Hummer and D. W.

Norcross have computed detailed and exhaustive rate coefficients for

electron-impact excitation of seven helium-like ions from Be III to

Fe XXV. These calculations involved the ten possible transitions involving the ground and n=2 excited states, and included the effects of resonances in Rydberg series converging on both the n=2 and n=3 levels

of the ions. These were found to significantly enhance the rate co- efficients for most of the transitions. Typical results are shown in

Fig. 13.

These new rate coefficients were then used by A. K. Pradhan and

J. M. Shull to produce improved values of the ratios of spectral lines

that are routinely used as diagnostics of temperature and electron density in high temperature plasmas. The comparison with earlier results

shown in Fig. 14 is typical. The accuracy of the present results is

supported by solar observations, for which the temperature can be independently estimated.

The next stage of this study involves evaluation of the effect of

dielectronic recombination on the excitation cross sections and rate co- efficients. A. K. Pradhan has shown that this effect may significantly

reduce the enhancement of the effective contribution due to resonances

found earlier, and that this process is likely to be of importance in

analyzing line emission from high temperature plasmas. The effect on the excitation cross section contributing most directly to the ratio G

of Fig. 14 is shown in Fig. 15. A similar sequence of calculations on magnesium-like ions is in progress.

R. Christensen and D. W. Norcross have completed a more elaborate

set of calculations for Li +

in order to explore sensitivity to specification of the target wave function, and to test the techniques used to

include resonance structure, in the more extensive calculations for the

helium-like ions. This ion is particularly interesting, as it is the

only case for which a spin-forbidden transition has been measured (by

W. T. Rogers, J. 0. Olsen and G. H. Dunn ) , and the only simple ion for

which resonance structure has been observed. The results of these calculations are shown in Fig. 16. Agreement with the measured data is

remarkably good, and provides a partial identification of the resonant

feature at ~66 eV as an excitation of a combination of the l$3s3p 2 R°

and ls3p 2 2 D states of lithium.

Electron Collisions with Polar Molecules . N. T. Padial and D. W.

Norcross are continuing to study aspects of electron collisions with polar molecules. Recent advances in formal aspects include: the derivation

of a new sum rule for Clebsch-Gordan coefficients; generalization of the

expression relating body-frame (fixed-nuclei) and laboratory-frame cross sections for linear and symmetric-top molecules to asymmetric-top molecules, and the demonstration that for this case also the cross section

155
156

Fig.

13.

The

log

10

of

the

Maxwell

Ian-averaged

collision

strength

(cross

section

x

collision

energy)

for

four

He-llke

levels

excited

from

the

ground

(

1

1S)

state.

The

filled

circles

mark

the

temperature

corresponding

to

the

Ionization

energy

of

the

species,

for

convenience

In

Isoelectronic

sequence

extrapolation.
157

Fig.

14.

Line

ratios

G(T)

and R

0

(T)

for

0

VII,

as

computed

in

this

work

and

by

others

(BDT,

MS,

AB).

G

0

bs

Is

the

ratio

observed

in

the

sun

(Acton

and

Catura

1976)

at

the

temperature

T

m

of

maximum

emission.
III

*o </> a) c c a> jc x: 3 > 40 40 o s_

4. 3 C <4- ci U 0) O

4> c X 5 40 JZ 40 40 e

40

O 4) 4> O X) E E £ 4> . o on a) U C

s_ o c o

4- a; c ns •<- jC <D JC 40 M 1— 4_ C «

w—

0) 4)

C

5» <4- *T— • <4- 4> X O cn n— <J E

4J "O e o

<4- 40 o o <T3 4) C 4)

-•-> x: o s4> cn t— cn 40 4> u « a. 4- n40 • C U1 CM 0) <4- O

4-

O 4. to -a 3 +0

cn e 4-> 40

a

CM o U 4) 3 <v •— 0) 00 i- <4- 4) x: 40 4- **-

+-> CM cn QJ "O

<4- 0) <v 4) x: o X <J JC Cl

40

C 40 3 c <T3 o o e e cn 4. T—

at o 40

r 40 4) cn C 40

<T3 3 <D 4; 40 40 $- 01 40

•T— 4) 4) Ol o _C 4) 4- O X x: Cli— a 4) +> 4) cn 4- Cl

4_ c 4.

C

O (O 4) a;

— <4- i- > > 4) o 4. j3

U1 cl cn 3

CJ -X

4. a; 40 cn 4) Cl'C CJ1 e C <9 n- C a> 4' 4- i— 4)

4- 4)

O 4- 40 4) > cn -to CO x: « cn

4-> -c c 40 c e o c c <e o

*T~ i- a>

t/1 cn *o i/i *T“ <v o 4) n—

f— 40 4. JC f—

(O Q. cn r— o 40 0) « o o cn 4. *C o

IT)

ci IIIIIJI1\\I)

fi[

158 t
65 75 80

25

CM£

0

1 2 20

2

o

h*O

u

cn

COCOo

c:o

15

10

£ (eV)

60

3or“

70

- 9 / \

3’s 3

? D

t i 4.4

i . i . t 5.0 5.5

E (Ryd)

6.0

Fig. 16. Cross section for excitation of the 2

3 P state of Li from the

ground state. The solid and dashed curves are the results of

the present work, the latter being an average over the Rydberg

series of resonances converging on the 2

l P state. The points

mark the measured results (Rogers, Olsen and Dunn 1978), and

the squares the present results folded with the experimental

energy resolution.

159
for transitions between any rotational states can be written as a simple

linear combination of those for the ground rotational state; and the

derivation of a general expression for the energy-loss, or stopping,

cross section for particles incident on all three classes of molecules,

within the context of the adiabatic-nuclei approximation. They also

developed an extension of this approximation appropriate to electron

collisions with polar molecules, for which it ordinarily has limited

applicability due to the long-range nature of the intraction. The es- sence of the method consists of extracting the effects of the long-range

interactions from the usual body-frame (fixed-nuclei) expressions and

reintroducing them in the laboratory-frame in a consistent manner.

These formal developments have been incorporated in computer programs and applied in an extensive set of calculations for HCl. One set

of scattering calculations, which may be quite elaborate and expensive,

can be used to generate cross sections for arbitrary initial and final

rotational states. This is illustrated for the third rotational state

of HCji in Fig. 17a. Agreement of the results with measured data, over

the energy range 0.3 to 11 eV, for which Fig. 17b is typical, is generally excellent. These calculations are being pushed to lower energies

with the aim of exploring near-threshol d vibrational excitation.

Ionization of Ions: Excitation-Autoionization. R. A. Falk and

G. H. Dunn, along with col laborators at Oak Ridge National Laboratory,

showed the possible dominance of excitation-autoionization in electron

impact ionization of ions. Using crossed beams of ions ( T

+ 3

, Zr +3, Hf+3

) and electrons, their experimental measurements shown in Fig. 18

demonstrate dramatically that excitation of an inner-shell electron to a level above the next ionization continuum, followed by autoionization

(excitation-autoionization) increases the cross sections by more than an order of magnitude over that anticipated for direct ionization. Their

theoretical predictions of both the energies and approximate magnitudes

of these excitation cross sections provide confidence that this important indirect contribution to the total ionization can be estimated for

many cases important in fusion and other hot plasmas. G. Dunn, A. Falk

and D. Bel id, along with ORNL col 1 aborators also made measurements on ions in the Na isoelectronic sequence (Mg+

, A£ 2+, Si 3+

), finding several

anomalies (compared with theory) in both the direct and indirect processes. The work on the Na sequence complements other work they are com- pleting on the Be and Li sequences.

Excitation of Ions . Crossed beams of Aji + 2 and electrons were used

by Falk, Belie and Dunn to measure the cross section for the 3S-3P excitation of this Na-like ion, observing the resultant 186 nm radiation.

Analysis of the data is still under way, but comparisons with theories

indicate some interesting and possibly important effects. All successful measurements on ion excitation which have been made to date have

used the fluorescence technique, and most have been made over the past

decade by Dunn's group. However, limitations on detector sensitivity,

160
c * 0 1 * u a; to

•*-> a> > r— 7^

O

u r— S_ <13 O0 +>

0) <U 3 <D

M 1—1 • to U sz r“ 73 S

tt- 4-> aJ

A

O to 0 -a = i- N to

to **—A CL) 1- 0 31 «— to 73 r- LJ

S_

CO -M 0)

C 03 <3

O r- tO r— Cl •r—

— 3 X _! S- to

MC

a>

s-<u

0) <U to <U o

-t-> x: <d -a c

*-> i— i- a> c « j: 15 c

CJ 4-> -M <V

tO • 3 1) =* a> x: n cj o <0 i_ o

<— ic a) <13 a. 3j M— 4-> S- = —« >

r: ^ aT5 <13 .Q <— <U r* 4) «1 r <13 3 +>

•*-> i. o O O 1- to co

to

a>

i_Cl

to to j:

0) +-> to r- x:

to 3 U O to •—

i- a> .c

_

U i- 3 +->

a;

j3I

a>

toco

•m

a>

to

to

too

i-o

4-> ca

s.

0)

fO

a> —

toc 1 O 3

i- -Q

+J •*- U i~

OJ 4-> I— c

0) ou

u_o +-> 00 a> a> c ao

T- S»

5- <13 <U r-

-s-> 0) « x: u f—

tou • cV •M OtO ~

<13 <— >1

a>n

SC I O 10

•«- 4->

+->

O

O i-

<Kto <D J=

to

toO £

iO o 1-

<70I <mo• 1 •*-) <70

03 0)

•*-> S_ O 03

0) CJ x: >

*-> i_3 o u w o

to *<— C r- o o

•»— to

toco I uo I I — CO

to cm -3

r. 1 3

00 <fl i.

03 -—

c 1 O

1- I I M ^ m

161
cm

ELECTRON ENERGY (eV)

Fig. 18. Experimental results for electron-impact ionization of Ti +3

, Zr +3

, and Hf+3

. Error bars are one standard deviation of the

mean statistical uncertainty. Dashed curves are calculated

estimates of the direct ionization process.

162
wavelength dispersion, lifetimes, etc. preclude measurements on many important systems and transitions using this technique. Dunn and Bel id

have under design a new technique which will detect i nel astical ly scattered electrons. A bonus of the new method may be the possibility of

measuring cross sections for di electronic recombination. It is anticipated that construction of apparatus to do this will begin this year.

Ion-Molecule Reactions Near 4 K . J. Luine and G. Dunn used their

newly developed and unique ion-trap technique for measuring ion-molecule

reaction rates at temperatures near 4 K to study several important pro- cesses at low temperatures. The reaction probabilities for the hydrogen

abstraction reaction sequence

+

H +H +

H +H +

N + NH + NH

2 + NH^ * NHj

were mesaured in the 11 to 20 K temperature range, and results for the

first process are shown in Fig. 19. The mesaurements have direct and

important consequences in the modeling of ammonia formation in the interstellar medium. The radiative association, C +

+ H 2 * CH 2 + hv, has

received extensive experimental and theoretical attention recently, as

it has been proposed as a critical, rate limiting step in the formation

of hydrocarbon molecules in interstellar space. Luine and Dunn measured

a new upper limit of k^ < 2 x 10' 15 cm

3 s _1 for the rate for this pro- cess. The limit is more than an order of magnitude less than previous

measurements, and is the first at the very low temperatures characteristic of dark interstellar clouds. A stronger magnetic field (~60 T)

should allow pushing the limit another order of magnitude — to the

range predicted by the most recent theories and "needed" in the models

of interstellar hydrocarbon molecule formation.

Free-Free Transitions: Theoretical . The project initiated last year

by $. Geltman and M. J. Conneely (visitor from the University of Galway,

Ireland) on free-free transitions at electron-hydrogen atom scattering

resonances has been completed. They used the el ectron-hydrogen atom

scattering wave functions in the ls-2s-2p close-coupling approximation to

evaluate the appropriate free-free dipole matrix elements. They studied

the differential cross sections associated with the absorption of C0 2 laser radiation (0.117 eV) for electrons whose initial or final scattering energies coincided with one of the Feshbach resonances below the n=2

threshold, as well as free-free transitions between two Feshbach resonances. For higher photon energies, say those from a Nd laser (1.17 eV),

a free-free transition originating in a Feshbach resonance below n=2 may

also produce the simultaneous excitation of the hydrogen atom to the 2s

and 2p states. The differential cross sections for these processes were studied and the forward scattering result is shown in Fig. 20. The two

peaks in each curve are due to the 2s 2 : S and 2s2p 3 P scattering reso- nances. The latter resonance is seen to give enhancements of ~10 3 over

the nonresonant background. There is as yet very little experimental

data, and none involving hydrogen atoms, on these processes, and it is

hoped that the present results will help stimulate such measurements.

163
Reaction

Probability,

P(T)

Fig. 19. Standard Arhenius plot. Solid curve represents the expression

P ( T ) = (0.41±0.1) e“( 85 t

10 )/ T deduced as the reaction probability for the process N + + H 2

-*• NH

+

+ H from present mea- surements. The dashed curve represents the rate coefficient

from these measurements, k(T) = 1.28 * 10” 9 (T_i /

6 + 0.117)

e-as/T cm

3 s1

.

164

Rate

Coefficient

(cm 3

s

M
dcr

ab

(i-f

)/d£2.

(a

^/sr)

Fig. 20. Differential free-free cross sections per unit electron density in the forward direction for the absorption of a 1.17 eV

photon as a function of the initial electron energy k

n

- 2

( Ry d ) .

165
Free-Free Radiation: Experiments . A. V. Phelps, in collaboration

with Dr. C. Yamabe of Nagoya University, has succeeded in mesauring the

absolute intensity of free-free radiation or bremsstrahlung produced in

the collisions of free electrons with argon atoms using the electron

drift tube technique. This measurement is particularly noteworthy be- cause of the very small cross section for IR or visible photon production, i.e., about 10 -26 m

2

, the very small power density input used in

the drift tube, i.e., ~10-12 W/m 3

, and the ease with which the electron

energy can be varied. Most previous measurements have been made using

shock tubes or electric arcs. These measurements are a significant ad- vance in that they yield quantitative values of the rates of free-free

emission for comparison with theory, such as that of $. Gel tman, and for

use in the quantitative diagnostics of high pressure, weakly ionized

plasmas, such as the ionosphere, discharge lasers and charged particle

beam plasmas. Preliminary results of these measurements for electrons

in argon are shown in Fig. 21, where the excitation coefficient appropriate to drift tube experiments is compared to the results of a calculation based on one of the simpler theories.

Electrons in N 2

. A. V. Phelps, in collaboration with L. C.

Pitchford of Sandia National Laboratories, has extended the calculation

of the electron energy distribution functions and transport coefficients

for electrons in N 2 to high electric field to gas density ratios E/N,

where anisotropies in the electron collisions with N 2 molecules and in

the electron energy distribution become appreciable. This project included an analysis of the available experimental and theoretical elastic

and inelastic scattering cross section data for electrons by N 2 so as to

express the data as energy dependent coefficients of a spherical harmonic expansion. Figure 22 shows a portion of the results of this analysis

for elastically scattered electrons between 0.1 and 104 eV. These re- sults and the previously developed techniques for the solution of the

electron Boltzmann equation make possible for the first time a meaningful calculation of the effects of anisotropic scattering on electron

transport and reaction coefficients at high E/N. The results of these

calculations show that to a good approximation the transport and reaction coefficients depend only on the momentum transfer cross sections

and the total inelastic cross sections and not on other details of the

differential scattering cross sections.

Oxygen Dissociation. A. V. Phelps, in collaboration with M. A.

Islam, has reactivated an experiment designed to yield rate coefficients

and cross sections for the dissociation of oxygen molecules by electron

impact. These data are needed for the modeling of electrical discharges

for ozone production, charged particle beam systems, and switching devices. The initial phase of the project is the development of a well

characterized source of oxygen resonance radiation, e.g., the control of

the oxygen concentration through the use of a silver leak to admit small

amounts of oxygen into the resonance lamp.

Effects of Fluctuations on Nonlinear Processes in Atoms. As the

first step in an experimental study directed to providing benchmark data

166
Fig. 21. Free-free emission from argon vs. electric field to gas den

sity ratios for various wavelengths.

167
Ratio

of

Cross

Sections

Q^/Q

Fig. 22. Ratios of spherical harmonic components from elastic differ

ential scattering cross section data for electrons on N 2

.

168
for theoreticians investigating the effects of fluctuations on nonlinear

processes in atoms, D. Elliott, R. Roy and S. J. Smith have developed a method of controlling the bandwidth and bandshape of a single mode laser

power spectrum by superimposing freqency fluctuations onto the laser

beam. This process is external to the laser cavity, and the method is

applicable to a laser beam with no modifications to the laser.

The major components used for superimposing frequency fluctuations

on the laser are a noise module (NM), voltage controlled oscillator (VCO)

and an acousto-optic modulator (AOM) . The VCO transforms the Gaussian

voltage fluctuations of the NM into frequency fluctuations, yielding a constant amplitude, frequency -modul ated RF signal. The acousto-optic

modulator then effectively adds the RF frequency to the laser frequency,

resulting in a broadened laser power spectrum. The width of this power

spectrum is controlled by changing the rms amplitude of the output of

the NM, and the "slew rate" of the frequency fluctuations is controlled

by changing the cut-off frequency of the output of the NM. The shape

of RF power spectrum is strongly dependent on the power spectrum of the

white noise with which the VCO is frequency modulated.

Figure 23 shows an example of the RF power spectrum of the VCO

output. Figure 23b is a logarithmic display and 23c a square-root display which result from frequency modulation derived from the white noise

power spectrum shown in Fig. 23a. The central portion of the RF power

spectrum is nearly Lorentzian, with a Gaussian character dominating the

wings. The crossover frequency between these two shapes is the cut-off

frequency of the white noise spectrum. Improvements under consideration

include a method of increasing the white-noise cut-off frequency limit,

and of obtaining an acousto-optic modulator with a wider and more symmetric response than the one which we are currently using. The system

is operational, and the study of the atom-fluctuating laser interaction

problem is being implemented. Bandwidth and bandshape control of the

laser power spectrum is attractive for a variety of other reasons. For

an inhomogeneously broadened transition in a sample of atoms or molecules, instead of saturating the transition for only one subgroup, the

laser spectrum can be broadened to be in resonance with all the atoms or molecules in the sample. In the study of laser-atom interactions which

do not involve the hyperfine structure of the atom, the laser spectrum

can be made broader than the hyperfine splitting, eliminating effects

due to this atomic structure.

Photoionization of Excited State Atoms . Studies of photoionization

out of highly excited and aligned states of atomic sodium have been carried out by G. Leuchs (Visiting Fellow), D. Elliott, R. Roy, and S. J.

Smi th . These are among the first studies of photoionization out oT

level s higher than n=10 and are the first such to include careful mea- surement and analysis of photoelectron angular distributions. Atoms

are resonantly excited by linearly polarized pulses from two nitrogen

pumped dye lasers, one tuned to a component of the resonance line and

the second to the appropriate 3P+nD or 3P+nS transition. Photoionization is accomplished with a 12 nsec pulse at 1.06 ^m generated by a YAG

169
Fig. 23. A white (Gaussian) noise spectrum cut-off at 90 MHz

(a) produces the F.M. power spectra shown in (b)

(logarithmic ordinate) and (c) (square-root ordinate)

for use in controlling the bandwidth of a laser by

means of an acousto-optic modulator. The shoulders

on (b) and (c) occur ~90 MHz from the central frequency. The inner portion is Lorentzian in character

while the wings are Gaussian.

’

170
oscillator and amplifier system. Delayed field ionization is used to

monitor upper state populations. Angular distributions are measured by

using a fixed position detector and rotating the plane of linear polarization with a \/2 plate.

Figure 24 shows curves of the form

1(9) =

I a

n cos 9 , n fit to experimental points (x) for photoionization from aligned 20D

states of sodium. Alignment derives from excitation with parallel lin- ear polarizations. Photoionization with the linear polarization of the

1.06 ^m radiation set orthogonal to the exciting radiation yields the

butterfly pattern shown on the right. Parallel polarization yields the

left-hand pattern. Analysis of such parallel patterns, for the analogous process but through the 3P X / 2 state, shows that at n=20 a cos 6 9

component is present, in apparent violation of the dipole approximation.

This is consistent with the fact that the optical phase (£*r) variation

across the radial dimension of the n=20 orbital is ~0.2 (for a hydrogenic orbital) and the dipole approximation should begin to fail. Measurements at n=25, 30 and 35 emphasize that by n=30 and 35 the failure

seems complete.

In contradiction to this interpretation, however, recent theoretical calculations (Dixit and Lambropoulos, private communication; and

Christensen-Dalsgaard, private communication) show that quadrupole con- tributions, even if present, should not appear at the angle of observation used in the measurements. Possible contributions by higher order

poles or by such terms as might be due to dipole-octopole interference

have not yet been examined theoretically . Finite collection angles

could permit observation of small quadrupole contributions, but probably

not as large as were observed. Electric field mixing estimates seem to

preclude mixing as a source of error. An additional possibility requiring further investigation is the pickup of additional photons by the

outgoing electron, in the extremely intense (-10 10 watts/cm2

) ionizing

laser field. This would modify angular distributions.

At these intensities three-photon nonresonant ionization out of the

3P state, and five-photon nonresonant ionization out of the ground state

are also observed and are found to require significant corrections to

the n=25 and n=3Q results respectively.

Heavy Symmetry Molecules . F. Pipkin (Visiting Fellow), R. Roy,

D. Elliott and S. J. Smith are continuing with the development of a stimulated Raman gain experiment, using a unique high-intensity narrowband pulsed laser system, to examine rotational spectra of heavy symmetric molecules in a search for the "spectral clustering" predicted by

former Visiting Fellow W. Harter on the basis of higher symmetries of

these molecules.

171
Fig. 24. Measured angular distributions (x) of Dhotoelectrons from

the 20 2 D excited state of atomic sodium, aligned by stepwise excitation to 20 2 D with parallel linearly polarized

pulsed lasers. The two patterns result from orienting

the linear polarization of the photoionizing laser beam

a) parallel and b) perpendicul ar to the axis of alignment

The solid curves represent fits of expansions in cos 2 9,

where 0 is measured with respect to the axis of alignment

172
Long Range Atom-Atom Interactions . W. Kamke, B. Kamke, and A.

Gallagher are continuing their studies of mixed-alkali interactions,

which are of particular interest as diagnostics of colli si onal lineshape theories. They have been measuring the colli si onal broadening of

the Na resonance lines by Rb. Combined with previous measurements of

the line wings in FY 79 this provides detailed insights into these ex- ceptionally long-range atom-atom interactions. They have also obtained

preliminary measurements of the extreme-wing intensities of the Na resonance lines due to perturbation by N

2

. This radiation is due to the NaN 2 triatomic collision complex, so that its interpretation is much more

complex than the atom-atom case and much more data and theory are needed

to build a detailed understanding of the process. This problem is directly analogous to observing the interaction surfaces in chemical reactions, so that extensive measurements and diagnostics over an extended

period are planned.

J. Huennekens and A. Gallagher , as part of their study of highdensity Na vapor in strong laser fields, have measured the colli si onal

absorption in the wings of the D 1 and D 2 resonance lines. This absorption, due to the Na-Na resonance interaction, is observed in this optically thick vapor by measuring the Rayleigh scattering at the laser

frequency and the fluorescence at the atomic frequencies. The 3P

3 j 2 3Pi/ 2 excitation transfer cross section has been obtained at the same

time from the ratio of D* to D 2 lines, with the Rayleigh light separated

out, and a complementary measurement of the radiative decay rate for the

trapped radiation. Preliminary data have also been taken on cross sec- tions for collisions between two excited sodium atoms; these measurements will be continued in FY 82.

Electron Collisions with Excited State Atoms . R. Dang and A.

Gallagher have measured the cross section for electron colli si onal ex- citation of Na(3P) atoms to the 3D state (Na(3P) + e Na ( 3D ) + e) . Results are shown in Fig. 25. Additional measurements in the threshold

energy region are planned, as are measurements of the polarization of

the 3D decay radiation.

Atomic Processes in Silane Discharges . H. Chatham, R. Robertson,

and A. Gallagher have studied the ion and neutral species arriving at

the surface of electric discharges in silane gas, of the types used in

the production of amorphous silicon solar cells. As an example, the ion

species from rf, dc, and dc-proximity discharges are shown in Fig. 26.

Qualitative models have been developed for the plasma processes leading

to these constituents from the initial SiH 4 , and these models are being

compared to the data in an iterative manner to improve understanding of

the discharge chemistry. Many of the reaction rate-coefficients needed

in the models are unknown or poorly known, and an apparatus has been

constructed to measure some of the ion-molecule rate coefficients.

Multiphoton Ionization. S. Haan and S. Gel tman have completed

their theoretical study of the time development of the resonant (3s-3p)

three-photon ionization of Na with linearly polarize.', monochromatic

173
2

Q^oCwao

Fig. 25. Cross section for electron excitation of Na(3P) atoms to

the 3D state. A polarization correction, so far unknown,

must be applied to obtain the total cross section.

174
Fig. 26. Ratios of SixHy ion fluxes from three types of low-power discharges in silane. Silane pressures in mTorr are indicated.

175
radiation. The theoretical method they have used is to take the

strongly-coupled 3s-3p rotating-wave-approximation as the lowest order

solution, and to apply second order perturbation theory to obtain the

ionization probabilities. The photoelectron energy spectrum and total

ionization probability have been studied for various laser detunings

and turn-on forms. Processes which are forbidden at long times by the

energy conservation condition for monochromatic photons are found to

be important at short times (t < 10“ 9 s for laser intensities of order

MW/cm2

) because of the transient photon distribution associated with

the turn-on of the laser pulse. The ionization probability is found to

exhibit plateau-like behavior at times much less than the 3s-3p Rabi

period, and subsequently to oscillate with the 3p population before

reaching rate behavior in the long-time limit. The use of the limiting

rate to predict very short-time ionization probabilities gives results

which can be too low by several orders of magnitude for t < 10- 9 s.

Gel tman, in cooperation with D. Normand of Sac! ay, is in the process of completing a theoretical study of the two-photon ionization of

Cs in the region of the interference minimum {near the 7p L / 2 state).

Additional recent experimental work at Saclay (D. Normand and J.

Morellec, J. Phys. B _14_, L401 (1981)) has yielded more precise values

for the magnitudes of the cross section in the region of the minimum as well as the ratio of cross sections due to linearly and circularly polarized light. Their calculation to date takes complete account of all

the discrete intermediate npi/ 2 and np 3 / 2 states. The agreement with

the location and magnitude of the mesaured result for linearly polarized

light is quite good: within 70 cm” 1 for the position of the minimum and

within the error bars of the measured magnitude (6±2) x 10" 51 cm

4 s. For the ratio of cross sections with the two light polarizations the

agreement is also quite good and is shown in Fig. 27. The theory shows

quite explicitly that the ratio a 2 c/a 2 |_ has a maximum value of 3/2 in

the vicinity of the interference minimum, and this is very well con- firmed by the experimental points. All that remains to be done in this

study is to calculate the contribution of continuum intermediate states,

and this is not expected to be large. The present theoretical results

are in much closer agreement with experiment than other theoretical calculations in the literature.

Laser-Induced Collisional Ionization . Work on the theory of laserinduced collisional ionization is being continued by S. Gel tman . Some

progress has been made on understanding the measurements made on the

process

SrCSp

1 ?) + Cs ( 6 s 2

S ) + hoj -*• Sr(5s 1 S) + Cs+

+ e by Brechignac et al ., J. Phys. B _13, L383 (1980). A separated-atom approach in which the Sr 5s-5p Rabi oscillation serves as the basis of a perturbation treatment of the atom-atom interaction gives a satisfactory

explanation of the spectral width which was observed as a function of

176
C\i i-^ O

lzx)/oz

x> = a

i E

o

>CJs

<35 C.

LlI

CL

r-.

C\J

• CT> *»• U_

177

Calculation

ofR

=

02C/02L

for

Cs

in

the

vicinity

of

the

Interference

minimum

(solid

line).

The

points

are

the

measurements

of

Normand

and

Morellec.
laser intensity. However, the observed strong asymmetry of the line

does not come out of the lowest order perturbation treatment. A very

approximate higher order perturbation calculation did exhibit asymmetries in qualitative agreement with the experiment. This problem will

be studied from a quasimolecul ar point of view to see if the observed

line asymmetry can be understood in a simpler way. Also being studied,

in collaboration with a Saclay program on laser-induced ionization in Na

vapor, is the effect of a laser field on the rate of associative ionization

Na ( 3p ) + Na ( 3p ) - Na

2

+ + e

This process goes via a curve-crossing and photons are not needed for

energy conservation, but their presence may enhance the effective rate

by providing alternate channels.

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 JILA 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's work

listed here as part of the QPD program.

Translation-to-Vibration Excitation Transfer . F. Magnotta ( NRC

Postdoc), D. Nesbitt, and S. Leone have developed a new method to study

transl ation-to-vibration (T-V) excitation transfer. T-V processes are important in plasmas and shock-heated gases, and can be related to emissions observed from the upper atmosphere and interstellar media. The

new technique utilizes a short wavelength (193 nm) pulsed excimer laser

to produce transl ational ly "hot" D and H-atoms by photodissociation of

HQ, HBr, or H 2 S. The atoms have energies between 2 and 3 eV. Upon

collision of these atoms with other molecules, emission is observed from

vibrational states excited by T-V transfer. For example, collision of a fast H with HQ results in vibrational excitation in the HQ as high as v=5. Precision measurements have been made on the translational slowing

or moderator efficiency, of the H-atoms by rare gases (Fig. 28). The

distribution of vibrationally excited states and atom exchange cross sec tions have been obtained for collisions of H + HQ, H + DQ, D + HQ,

and D + DQ . The results show that both inelastic and reactive collisions are responsible for the excitation.

T^n-Molecule Reaction Dynamics . T. Zwier, J. Weisshaar, and S

.

Leone are studying ion-molecule reaction dynamics via infrared chemiluminescence in a flowing afterglow. Complete vibrational state distributions have been obtained for the products of the reactions:

F" + HX -> HF( v) + X“ (X = Q, Br and I) and F“ + H + HF(v) + e". The

results show that a substantial fraction of the reaction energy is

deposited into product vibration. The populations observed in the

H + F” associative detachment reaction are in good agreement with

178
T-V

Moderator

Efficiency

O

05

U5O

A

crq:oH

179

Fig.

28.

Experimental

ly

observed

T-V

excited

IIBr(v)

signal

intensity

asa

function

of

moderator

buffer

gas

pressure.

The

ratio

of

pressures

required

to

reduce

the

peak

signal

intensity

toa

fixed

level

(0.4

is

shown

by

the

horizontal

dotted

line)

is

the

inverse

of

the

inert

gas

moderating

efficiencies

(see

table

inset).
recent calculations in the literature which use virtual state models

and consider dynamical transitions induced by the nuclear motion.

These methods are presently being extended by M. Smith, V. Bierbaum,

and S. Leone to study the associative ionization processes Ar , Ne* + H + ArH+

( v) , NeH+ (v) + e-

.

Recently, two major new developments have been introduced to the

study of ion-molecule reaction dynamics. Laser-induced fluorescence has

been used by T. Zwier, J. Weisshaar, and S. Leone to probe the C0

+

(v)

product states in the thermal energy charge transfer reaction: N + + CO -> H + C0+ (v=0,l,2) . The results are similar to, but quantitatively different from predictions based on simple Franck-Condon models of the

charge transfer. The laser probe method allows some of the first mea- surements on vibrational deactivation to be made. Preliminary estimates

show that deactivation of C0 + (v=l) by symmetric charge transfer with CO

is ~0.5 Langevin. Near resonant vibration-to-vibration energy transfer

of C0

+ (v=l) to N 2 is also extremely rapid, >0.1 Langevin. This work

will be continued by C. Hamilton (NSF predoctoral fellow) and M. Duncan

( NRC Postdoc). A second major development involves the completion and

successful operation of a low pressure ion-reaction apparatus, in which

both vibrational and rotational state distributions of ion-molecule re- actions will be obtained. D. Guyer, L. Hilwel (Max-Planck fellowship),

and S. Leone have obtained the first laser-induced fluorescence spectra

of thermal i zed ions cooled in a mild supersonic jet. The jet of ions

will be crossed with other reagents and the products of ion-molecule re- actions interrogated. The first reactions to be studied will be charge

transfer (e.g., Ar +

+ N 2

-* Ar + N 2 + (v,J)) and associative detachment

(e.g., 0" + H - 0H(v,J) + e"). Important information about the reactive

dynamics will be obtained for the first time especially from the rotational state information in the products.

Laser-Initiated Chain Reactions. D. Nesbitt, D. Dolson (NRC Postdoc ) ,~lmT3T2n[onFlire

-Tu chain reactions. The

development of these methods have taken on tremendous commercial importance with the discovery in Germany of a laser-initiated chain reaction

synthesis of the industrially important vinyl chloride molecule. The

work at JILA, which has pioneered this field, has progressed into the

study of complex hydrocarbon chlorination chain reactions and the detection of extremely slow chain reactions that often go unnoticed. An offshoot of this work involves the recent development by L. Kovalenko and

$. Leone of a method to make absolute reaction rate constant determinations for methyl radical reactions.

Photofragmentation Dynamics . Basic photofragmentation dynamics of

CH 3I has been studied by H. Hermann (DFG fellowship) and S. Leone to

determine potential constants and vibrational state distribution for the

CH 3 out-of-plane ("umbrella") vibration. Figure 29 shows the low reso- lution spectrum of CH 3 obtained in emission after the photolysis of CH

3

I

180
CH

3

"Umbrella"

Mode

Emission

CH3I

—

CH3

(v)

+I

(

I

w)

266

nm

Slit

33

cm' 1

€&

1116cm

- '

05

CD OD OO f—; CD uO <3*. i-O CNJ CD

Apsua|U| SAjjCjsy

CM

cn

Ll.

131

Experimentally

observed

low

resolution

infrared

emission

spectrum

of

CH3

(

v

2)

immediately

after

the

photolysis

pulse.

The

dots

•

are

data

points.

The

solid

line

is

the

best

fit

to

the

data,

giving

the

nascent

populations

shown

(solid

bars).
at 266 nm. Each peak in the spectrum corresponds to a Q-branch feature

of a vibrational band. The positions of three bands were obtained

di rectly

i from the data: v = 3-2 (727 cm" 1 ), 4-3 (770 cm" 1 ), and 5-4

(810 cm" -1 ). From these frequencies and an earlier determination in the

literature of the v = 1-0 position at -605 cm" 1

, the harmonic + quartic

potential function for the umbrella mode was derived. From the amplitudes of the emission bands, the vibrational populations produced in the

dissociation were obtained and have been compared to accurate theoretical calculations on the dissociation dynamics. The study of photofragmentation dynamics is being expanded with new work by J. Smedley and S.

Leone to understand dissociation in molecules which yield excited state

species suitable for direct solar pumping of lasers.

Spin Changing Collisions . Spin changing collisions in atomic calcium vapor are being studied by M. Hale and S. Leone using fully timeresolved kinetic methods. Thus far buffer gas induced transfer from the

4s5p 1 P

1 > 4s5p 3 P2 j i j0 levels has been measured. The cross sections

for He, Ne, Ar, Kr, and Xe are -34 A

2

, 6 A

2

, 4 A

2

, 17 A

2 and 38 A2 re- spectively. The results do not follow the expected trend, with helium

being anomalously high. One explanation involves the possibility that

helium can penetrate the 5p orbital to interact with the Ca

+ ionic core.

The perturbation of the charge symmetry could then induce the spin change

more efficiently. The mechanism of these spin changing collisions will

be investigated by further examination of the spherically symmetric

4s6s

1 S

0 orbital which is near resonant with the 4s6s

3 S

X level.

JILA Atomic Collisions Data Center

The year 1981 has been one of very great change in the Center —

changes which are continuing and will be in progress for sometime.

Prominent in the changes is the departure of Dr. Earl Beaty, Director

of the Center, who as a result of the large (10*) reduction in force at

NBS is now on duty in the Time and Frequency Division of NBS.

In January 1981, a change of philosophy and direction was determined for the Center. The advisory committee of JILA staff scientists

formed in 1980 became very active in the Center and its expertise utilized in the choice and planning of projects. Evaluated compilations

and reviews will be emphasized, while published bibliographies will be

deemphasized. Projects of well-defined scope will be planned, so that

the amount of data concerned is manageable by the available facilities

and projects can be started and completed in intervals of a few months.

Appropriate scientists from outside JILA will be invited to work at the

Data Center on the evaluation and review of data, and the JILA scientific staff, both permanent and visiting, will be urged to participate in

these activities.

182
With this policy in mind, several compilation-review type projects

have been started. In collaboration with J. Dutton (University of

Swansea, Wales), work was started in August 1980, on a review of swarm

data in electronegative gases, and this project is nearing completion.

J. Alan Rees (University of Liverpool, United Kingdom) spent the interval of October 1980 to April 1981 at the Data Center working on a review

of differential elastic scattering cross sections for atoms. Y.-K. Kim

(Argonne National Laboratory) is spending July and August 1981 on review

and analysis of data on secondary electron spectra of atoms and molecules.

Steve Leone (JILA) embarked on a compilation of vibrational energy transfer rates of hydrogen halides in June 1981. W. Carl Lineberger (JILA)

began work in July 1981 on an update to his review of electron affinities in atoms. All of these projects have involved the Information Center Staff in bibliographic search, collection of related publications,

and compilation of numerical data. In early 1980 Ara Chutjian expressed

interest in reviewing data on vibrational excitation of molecules by

electron impact. Publications and data for this project were collected

and sent to Dr. Chutjian, who is considering spending a month (November

1981) at JILA to complete the manuscript for his review. All of these

projects are scheduled for completion in FY 1982.

In the spirit of change in direction of the Information Center

efforts, arrangements were made in June 1981 to do computer searches

of bibliographic data bases using the Lockheed Dialog System. We are

now on-line to this system and expect to employ it for all compilation

projects.

In the area of modernizing operating procedures, the bibliographic

data base was moved from the now-defunct XDS 940 computer (NOAA) to

indexed sequential files on the CDC 750. Programs were completed for

dependable read/write of ASCII tapes on the CDC 750. Programs were com- pleted to make camera-ready tables and multi -curve graphs using our inhouse microcomputer system. Work is in progress on interrogation of our bibliographic data base on various descripters and comprehensive handling of numerical data using the CDC 750. The latter item would include data manipulation and preparation of camera-ready figures and

tables. Exploration has begun on the feasibility of use of the CDC 750

Data Base Management System, initially for loading numerical data into a data base.

A search for a manager-director of the Information Center to

fill the gap left by the departure of Dr. Beaty was begun in June

1981. The advisory committee, with a few additions, is forming the

Search Committee.

Various publications have been completed in FY 1981. They include:

1. "Data Index for Energy Transfer Collisions of Atoms and

Molecules, 1970-1979," NBS Special Publication 593, J. W.

Gallagher, Janet Van Blerkom, E. C. Beaty, and J. R. Rumble,

Jr. (April 1981).

183
2. "Bibliography of Low Energy Electron and Photon Cross Section

Data (1979)," Jean W. Gallagher and Earl C. Beaty, JILA

Information Center Report No. 21 (January 1981).

3. "Multiphoton Bibliography 1979," NBS Publication LP-92,

Suppl . 2, 51 pages, J. H. Eberly, J. W. Gallagher, and E. C.

Beaty (October 1980).

FY 1982 Plans . Plans for FY 1982 are in keeping with the newlyestablished direction of producing more evaluated compilations and re- views. The projects mentioned above, all scheduled for completion in

FY 1982, are itemized under Milestones below. Plans are, of course,

subject to revision — particularly if the new Director of the Center

sees better directions to take.

Additional similar projects are planned. Mike Shull (JILA) will

continue his work in compiling collision strengths for electron- impact

excitation of ions in high-temperature plasmas and, with the help of the

Information Center staff, will compile tables by isoelectronic sequence

and describe temperature dependences of the collision strengths.

Work has been ongoing at the Data Center to compile elastic, momentum transfer, and electronic excitation cross sections for electron collisions with atoms. J. Gallagher and J. R. Rumble will produce a series

of compilations of these data, divided by atomic species. This series

will be started in early 1982.

A. V. Phelps (JILA) will evaluate and compile a recommended set of

electron collision cross sections for N 2 beginning in the summer of 1982.

Some projects are tentative, depending on uncertain schedules and

commitments of scientists outside of JILA. These include a compilation

and review by Robert Bernheim of the Pennsylvania State University of

the molecular structure and spectral data for the ground and excited

electronic states of the alkali metal diatomic molecules and a compilation and review by Jeffrey I. SteinfBld of MIT of state-specific collisional energy transfer rates in the diatomic halogens. Presumably

Bernheim' s work might be done between September 1981 and June 1982 and

Steinf eld's during the suimner of 1982. Both of these projects would

deal with timely topics and be conducted by well -recognized experts.

Both would place heavy demands on Information Center staff, but are predicted to produce very worthwhile results. An alternate project, should

either of these scientists be unavailable, would be a compilation of data

on photoabsorption and photoionization in the vacuum ultraviolet with

minimal advisory participation by Anthony F. Starace and J. A. R. Samson

of the University of Nebraska.

In the area of operating procedures, plans are to continue the

work in progress on computer programs for handling numerical data,

possible implementation of the CDC Data Base Management System, to

interface the Lockheed output with the local machine-readable medium,

to provide program support for editing the Lockheed output, and to

184
I;

establish working procedures for information exchange with other data

centers

.

There are topics adjacent to the areas historically covered by the

Center in which research activity is currently high and which are not now within the established subject area of existing data centers. Though

there are currently no plans to specifically expand into these areas,

for the purpose of planning a timely evolution of the JILA Information

Center, the possibility of extending our activities into one or more of

these will be reviewed with the advisory committee, staff scientists and

outside experts. These topics include: (1) astrophysics; i.e., processes involving highly ionized species and interstellar molecules; (2)

chemical physics; e.g., electronic potential surfaces in excimers, population distributions in chemical reactions, and radiationless processes

represented by lifetime tables; (3) laser related physics; e.g., absorption coefficients, lifetimes and <j>f's of laser dyes, nonlinear optical

coefficients, data describing laser-induced collision phenomena, and

multi photon absorption, ionization and dissociation; (4) applied physics; e.g., parameters describing supersonic jet technology.

Milestones FY 1982

1. "A Survey of Electron Swarm Data in Electronegative Gases," Beaty,

Dutton, Gallagher and Pitchford, to be submitted to JCPRD, 10/81.

2. "A Review of Differential Elastic Scattering Cross Sections," J. A.

Rees and E. C. Beaty, to be submitted to JCPRD, 11/81.

3. "An Update to the Review of Atomic Electron Affinities," W. C.

Lineberger, to be submitted to JCPRD, 12/81.

4. "A Compilation of Vibration Relaxation Rates in Hydrogen Halides,"

S. Leone, to be submitted to Atomic and Nuclear Data Tables or JCPRD, 12/81.

5. "Recommended Electron Scattering Cross Sections for Vibrational

Excitation of Diatomic and Polyatomic Molecules," A. Chutjian, to

be submitted to JCPRD, 2/82.

6. "A Review of Secondary Photoelectron Spectra: I. He, N 2 ," Y.-K.

Kim, JILA Information Center Report, 3/82. To be submitted with

subsequent sections, but without extensive tables, to JPCRD or Reviews of Modern Physics.

7. "A Review of Secondary Photoelectron Spectra: I. 0 2 , H 2 ," Y.-K.

Kim, JILA Information Center Report, 10/82. (See Milestone 6).

8. "Collision Strengths for the He Isoelectronic Sequence," M. Shull.

9. "A Compilation of Elastic, Momentum Transfer, and Electronic Excitation Cross Sections for the Rare Gases," J. Gallagher and J. R.

Rumble, to be submitted to JCPRD, 7/82.

10.

Computer programs described above to be completed, 6/82.

185
III. PUBLICATIONS AND INTERACTIONS

Included in the following pages of this section are tables of

• JILA Visiting Fellows for 1980-81 and 1981-82.

• 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.

186
III.

PUBLICATIONS

AND

INTERACTIONS

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OO

zz. 3 +-> cn CD fO E CO 03 E 03 co CQ c= 4-3 4-> (—1 +-> 3 p— 4-> i. p— 4-> -r- >, — 3 P 3 03 03

•r- 0) • i 1 co i- a> 03 S- 03 3 O 4-3 i- -r- <J

U

LlJ 4-> o o o o 03 > X 03 <13 r— 03 o 03 03 3 3 3

s: co 3 o DO CL-.- ia ax 03 3 03 cl -a •r- r— o c 4-> • r-H 3 ai 3 03 03 E D 3 O 03 03 S_ S- a: 1—

00 CL r-H >- CD CD CQ CD • DC O' 1 CD CD -Q CL CL

CM

CO

cr.

>-Ll

i—

1 .—t 3O

00 03 pi CO 3 L. 03 3 o > O 1- •r— _J 03 O O 3 s: o r—

LlJ 03 s: •f— Ll 'Q >> 3

03 • C3 • p— cc • z T3 1— M 03 p—

1—

O S- 03 T3

t—

CQ •r— p—

oo 4-> 3 >

1—

03 • 03 03 > QC O CD Q

190
PUBLICATIONS

Quantum Physics Division (525)

E. C. Beaty, J. Dutton, and L. Pitchford, Electron Swarm Data

Relevant to High-Voltage Insulation, in Gaseous Dielectronics II,

Proceedings of the Second International Symposium on Gaseous Dielectronics, Knoxville, Tenn. , March 9-13, 1980 (Pergamon, Oxford,

1980), pp. 25-31.

(J. H. Eberly), J. W. Gallagher, and E. C. Beaty, Multiphoton Bibliography 1979, NBS LP-92, Suppl. 2 (1980).

J. W. Gallagher and E. C. Beaty, Bibliography of Low Eneryg Electron

and Photon Cross Section Data (1979), J I LA Information Center Report

No. 21, January 1, 1981.

J. W. Gallagher, J. Van Blerkom, E. C. Beaty, and J. R. Rumble, Jr.,

Data Index for Energy Transfer Collisions of Atoms and Molecules--

1970-1979, NBS Spec. Publ . 593 (U. S. Government Printing Office,

Washington, DC, 1981).

P. L. Bender, Improved Methods for Measuring Present Crustal Movements, in Dynamics of PLAIE Interiors, Geodynamics Series, Vol. 1 (American Geophysical Union, 1980), pp. 155-162.

P. L. Bender, Establishment of Terrestrial Reference Frames by New

Observational Techniques, On Reference Coordinate Systems for Earth

Dynamics , Vol. II (D. Reidel, Dordrecht, 1981), pp. 23-3 6.

(J. D. Bossier, C. C. Goad), and P. L. Bender, Using the Global Positioning System for Geodetic Positioning, Bull. Geodesique 54, 553-563

(1980).

(R. Decher, J. L. Randall), P. L. Bender, and J. E. Faller, Design

Aspects of a Laser Gravitational Wave Detector in Space, in Active

Optical Devices and Applications , SPIE Vol. 228 (1980), pp. 149-153.

* (Y. Rabin, M. Berman), and A. Ben-Reuven, Theory of Double Resonance

Raman Amplifier, J. Phys. B: Atom. Molec. Phys. _L3, 2127-2136 (1980).

* (Y. Rabin) and A. Ben-Reuven, Resonance Fluorescence and Resonance

Raman Line Shapes in Strong Radiation Fields, J. Phys. B: Atom.

Molec. Phys. 13, 2011-2025 (1980).

* Entries with stars are those resulting from the work of J I LA Visiting

Fel lows.

NOTE: Names in parentheses are authors who are not connected with

JILA—NBS or CU.

191
PUBLICATIONS

Quantum Physics Division (525)

A. Ben-Reuven, Theory of Two-Atom Coherence in Gases. I. Master Equations, Phys. Rev. A 22_, 2572-2584 (1980).

A. Ben-Reuven, Theory of Two-Atom Coherence in Gases. II. ContinuousWave Spectra, Phys. Rev. A 22_, 2585-2597 (1980).

A. Ben-Reuven, Recent Developments in Line Shape Theory, in Spectral

Line Shapes, Proceedings Fifth International Conference, Berlin

(West) July 7-11, 1980 (B. Wende, Ed., De Gruyter, Berlin, New York,

1981), pp. 867-884.

A. Ben-Reuven, Resonance Absorption and Scattering of Strong Coherent

Radiation in Thermally Relaxing Systems, in Lectures on Biological

and Chemical Physics: A Symposium in Honour of Shneior Li f son on His

65th Birthday (in press).

B. Bertotti, Statistics of Narrow Structures of the Gravity Field of

the Earth. I. General Theory, J. Geophys. Res. (in press).

G. Chanmugam, Cyclotron Absorption in Accreting Magnetic White

Dwarfs, Astrophys. J. 241, 1122-1130 (1980).

G. Chanmugam and (G. A. Dulk), Polarized Radiation from Hot Plasmas

and Applications to AM Herculis Binaries, Astrophys. J. 244, 569-578

(1981).

S. H. Langer, G. Chanmugam, and G. Shaviv, Thermal Instability in

Accretion Flows Onto Stellar Atmospheres, Astrophys. J. (Letters)

245, L23-26 (1981).

G. Chanmugam, Cyclotron Emission From AM Herculis, in The Universe at

Ultraviolet Wavelengths: The First Two Years of International Ultraviolet Explorer (NASA Conference Publication 2171, 1981), pp. 515-519.

(H. C. Brayman, D. R. Fischell), and T. A. Cool, Spectroscopic

Studies of the Products of Reactions of Yttrium and Scandium Atoms

with Halogen Molecules. I. The Origin of Chemiluminescence, J. Chem.

Phys. 73_, 4247-4259 (1980).

(D. R. Fischell, H. C. Brayman), and T. A. Cool, Spectroscopic

Studies of the Products of Reactions of Yttrium and Scandium Atoms

with Halogen Molecules. II. Laser Induced Fluorescence from Yttrium

and Scandium Monohalides, J. Chem. Phys. _73> 4260-4272 (1980).

T. A. Cool and J. B. Koffend, Two-Photon Excitation of Indium Atoms

by Photodissociation of InQ and InBr, J. Chem. Phys. 74, 2287-2292

(1981).
PUBLICATIONS

Quantum Physics Division (525)

* K. Davidson and R. McCray, SS 433 as a Prototype of Astrophysical

"Jets," Astrophys. J. 241, 1082-1089 (1980).

G. H. Dunn, Electron-Ion Collisions, in The Physics of Ionized Gases,

(ed. M. Matic, Boris Kidric, Institute of Nuclear Sciences, Belgrade,

1980), pp. 49-95.

(B. Van Zyl ) , G. H. Dunn, (G. Chamberlain, and D. W. 0. Heddle),

Benchmark Cross Sections for Electron Impact Excitation of n

: S Levels

of He, Phys. Rev. A 22 , 1916 (1980).

R. A. Falk, G. H. Dunn, (D. C. Griffin, C. Bottcher, D. C. Gregory,

D. H. Crandall, and M. S. Pindzola), Excitation-Autoionization Contributions to Electron Impact Ionization, Phys. Rev. Lett. _£7_, 494

(1981).

W. T. Rogers, G. H. Dunn, J. 0. Olsen, M. Reading, and G. Stefani

,

Absolute Emission Cross Sections for Electron Impact Excitation of

Zn+(4p 2 P) and (5s 2 S) Terms, Phys. Rev. A (in press).

(D. H. Crandall, R. A. Phaneuf), R. A. Falk, D. S. Belid, and G. H.

Dunn, Absolute Cross Section Measurements for Electron Impact Ionization of He-like Ions — Mg+

, Aji

+2

, Si + 3

, Phys. Rev. A (in press).

J. E. Faller, R. L. Rinker, and M. A. Zumberge, Absolute Gravity as a Reconnaissance Tool for Vertical Height Changes and for Studying Density Changes, in Proceedings of the Second International Symposium on Problems Related to the Redefinition of North American Vertical Geodetic Networks (The Canadian Institute of Surveying, Ottawa, 1980),

pp. 919-932.

(R. Decher, J. L. Randall), P. L. Bender, and J. E. Faller, Design

Aspects of a Laser Gravitational Wave Detector in Space, in Acti ve Optical Devices and Applications , SPIE Vol . 228 (1980), pp. 149-153.

G. M. Keiser and J. E. Faller, Efltvds Experiment with a Fluid Fiber,

in Proceedings, Second Marcel Grossman Meeting on Recent Developments

of General Relativity, Miramare, Trieste, July 5-11, 1979 (in press).

M. A. Zumberge, J. E. Faller, and R. L. Rinker, A New, Portable,

Absolute Gravimeter, in Second International Conference on Precision

Measurement and Fundamental Constants (in press).

J. E. Faller, Tunnel Detection Utilizing Field-Stationary Gravity

Gradiometers, in Proceedings, Symposium on Tunnel Detection, July El23, 1981, Colorado School of Mines, Golden, Colorado (in press).

193
PUBLICATIONS

Quantum Physics Division (525)

(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).

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).

J. E. Faller, M. Zumberge, and R. L. Rinker, The JILA Absolute Gravimeter, in Proceedings, Ninth International Symposium on Earth Tides,

New York City, August 17-22, 1981 (in press).

W-U L. Brillet and A. Gallagher, Inert Gas Collisional Broadening and

Shifts of Rb Rydberg States, Phys. Rev. A _22, 1012-1017 (1980).

R. E. Kennerly, R. J. Van Brunt, and A. C. Gallagher, High-Resolution

Measurement of the Helium (ls2s 2

) 2 S Resonance Profile, Phys. Rev. A

23_, 2430-2442 (1981).

D. W. Wildman, L. W. Schumann, and A. C. Gallagher, Electric Discharge Excited Til-Xe Mixtures, J. Appl . Phys. (published).

(W. J. Sandle) and A. Gallagher, Optical Bistability by an Atomic

Vapor in a Focusing Fabry Perot Cavity, Phys. Rev. A (in press).

(VI. J. Sandle, R. J. Ballagh), and A. Gallagher, Optical Bistability

Experiments and Mean Field Theories, in Proceedings, International

Conference and Workshop on Optical Bistability (in press).

K. B. Gebbie, F. Hill, J. Toomre, (L. J. November, G. W. Simon, R. G.

Athay, E. C. Bruner, R. A. Rehse, J. B. Gurman, R. A. Shine, B. E.

Woodgate, E. A. Tandberg-Hanssen), Steady Flows in the Solar Transition Region Observed with the UVSP Experiment on SMM, B.A.A.S., 12 , 907 (1980).

(L. J. November), J. Toomre, K. B. Gebbie, F. Hill, and (G. W. Simon),

The Lifetime of Solar Mesogranulation, B.A.A.S., jJ_, 895 (1980).

(L. J. November), J. Toomre, K. B. Gebbie, and (G. W. Simon), The

Detection of Mesogranulation on the Sun, Astrophys. J. (Letters) 245,

L123-126 (1981).

K. B. Gebbie, F. Hill, J. Toomre, (L. J. November, G. W. Simon, R. G.

Athay, E. C. Bruner, R. A. Rehse, J. B. Gurman, R. A. Shine, B. E.

Woodgate, and E. A. Tandberg-Hanssen), Steady Flows in the Solar Transition Region Observed with SMM, Astrophys. J. (Letters) (in press).

194
PUBLICATIONS

Quantum Physics Division (525)

(F. Roussel, P. Breger, C. Manus), and S. Geltman, Evidence of SuperElastic Effects in Laser-Induced Ionization of Na Vapor, J. Phys. B: Atom. Molec. Phys. 13, L631-636 (1980).

S. Geltman, Approximate Response of a Two-Level System to Intense

Multimode Radiation, Phys. Lett. 81A, 27-30 (1981).

M. J. Conneely and S. Geltman, Resonance Effects in Multichannel

Free-Free Transitions of an Electron Scattering from a Hydrogen Atom,

J. Phys. B: Atom. Molec. Phys. (accepted).

T. Baer, F. V. Kowalski, and J. L. Hall, Frequency Stabilization of a 0.633 pm HeNe Longitudinal Zeeman Laser, Appl . Opt. 19, 3173-3177

(1980)

.

J. L. Hall, Tunable Laser Stabilization Techniques for Ultrahigh

Resolution Spectroscopy, in Proceedings, International Conference on Lasers, Beijing, China, June 1980 (in press).

J. L. Hall, Stable Lasers and Optical Frequency Standards for Testing

the Postulates of Physics, in Proceedings, Seventh International Conference on Atomic Physics (in press).

T. Baer and J. L. Hall, Stabilized Lasers, in Solar Instrumentation--

What's Next? (in press).

* C. S. Feigerle, Z. Herman, and W. C. Lineberger, Laser Photoelectron

Spectormetry of Sc" and Y". A Determination of the Order of Electron

Filling in Transition Metal Anions, J. Electron Spectrosc. Relat.

Phenom. (in press).

(M. J. Barlow, J. C. Blades), and D. G. Hummer, Optical Observations

of the U1 trahigh-Excitation Wolf-Rayet Star Sanduleak 3, Astrophys.

J. (Letters) 241, L27-31 (1980).

J. Katriel and D. G. Hummer, Analytic Solutions for Three- and FourWave Mixing via Generalized Bose Operators, J. Phys. A: Math. Gen.

_14, 1211-1224 (1981).

A. K. Pradhan, D. W. Norcross, and D. G. Hummer, Cross Sections and

Excitation Rates for Electron Collisions with Helium-Like Ions, Phys.

Rev. A 23, 619-631 (1981).

A. K. Pradhan, D. W. Norcross, and D. G. Hummer, Rate Coefficients

for Electron Impact Excitation of Helium-Like Ions, Astrophys. J.

246, 1031-1039 (1981).

195
PUBLICATIONS

Quantum Physics Division (525)

D. G. Hummer, Expressions for the Computer-Evaluation of the Four

Kernel Functions for Doppler and Lorentz Profiles, J. Quant. Spectrosc. Radiat. Transfer (in press).

* J. Katriel and D. G. Hummer, Analytic Solutions for Three- and FourWave Mixing via Generalized Bose Operators, J. Phys. A: Math. Gen.

_U, 1211-1224 (1981).

* P. L. Jones, R. D. Mead, B. E. Kohler, D. R. Rosner, and W. C.

Lineberger, Photodetachment Spectroscopy of C

2

” Autodetaching

Resonances, J. Chem. Phys. 73^, 4419-4432 (1980).

* H. J. G. L. M. Lamers, Mass Loss from 0 and B Stars, Astrophys. J. 245, 593-608 (1981).

D. J. Nesbitt and S. R. Leone, Br*( 2 P 1 / 2

) + H

2 (v=0,l): Laser Studies

of the Competition Between Reactive Pathways and Inelastic Energy

Transfer Channels, J. Chem. Phys. 73_, 6182-6190 (1980).

W. H. Pence and S. R. Leone, "Laser Studies of Electronic Excitation

Transfer in Atomic Calcium: Ca(4s5p 1 P

1

) + Ar ^ Ca(4s5p 3 P

2 l 0

) + Ar,

J. Chem. Phys. 74, 5707-5717 (1981).

* ’

S. R. Leone, Photofragment Dynamics, in Dynamics of the Excited State

(K. Lawley, Ed., Wiley, New York) (in press)

J. B. Koffend and S. R. Leone, Tunable Laser Photodissociation: Quantum Yield of I*

(

2 Pi

/

2

) from CH

2

I 2

, Chem. Phys. Letters (in press).

J. C. Weisshaar, T. S. Zwier, and S. R. Leone, Nascent Product Vibrational State Distributions of Ion-Molecule Reactions: The Proton

Transfer Reactions F“ + HX - HF(v) + X", X = Cl, Br, I, J. Chem.

Phys. (in press).

T. S. Zwier, J. C. Weisshaar, and S. R. Leone, Nascent Product Vibrational State Distributions of Ion-Molecule Reactions: The H + F” -

HF(v) + e“ Associative Detachment Reaction, J. Chem. Phys. (in

press).

W. H. Pence, S. L. Baughcum, and S. R. Leone, Laser UV Photofragmentation of Halogenated Molecules: Selective Bond

? Dissociation and Wavelength Specific Quantum Yields for Excited K

2 P

1 / 2

) and Br( 2 P

x / 2

) Atoms, J. Phys. Chem. (in press).

D. J. Nesbitt and S. R. Leone, Laser Initiated Chain Reactions: A

Generalized Extension to Complex Chemical Chain Systems, J. Chem.

Phys. (in press).

196
PUBLICATIONS

Quantum Physics Division (525)

F. Magnotta, D, J. Nesbitt, and S. R. Leone, Excimer Laser Photolysis

Studies of Translational -to-Vibrational Energy Transfer, Chem., Phys.

Lett, (in press).

* D. E. Nitz, A. V. Smith, M. D. Levenson, and S. J. Smith, BandwidthInduced Reversal of Asymmetry in Optical Double Resonance Amplitudes,

Phys. Rev. A 24, 288-293 (1981).

* M. D. Levenson and (J. J. Song), Coherent Raman Spectroscopy, in Ad- vances in Coherent Nonlinear Optics (M. S. Feld and V. S. Letckhov,

Eds., Springer, New York) (in press)

.

T. R. Ayres and J. L. Linsky, Outer Atmospheres of Cool Stars. V. IUE

Observations of Capella: The Rotation-Activity Connection, Astrophys. J. 241, 279-299 (1980).

J. L. Linsky, Stellar Chromospheres , in Stellar Turbulence , IAU Colloq. 51 (D. F. Gray and J. L. Linsky, Eds., Springer-Verl ag, New

York, 1980), pp. 248-277.

J. L. Linsky, Stellar Chromospheres , in Annual Review of Astronomy

and Astrophysics (Annual Reviews, Inc., Pal o A1 to, CA, 1980) , Vol . l&_, pp. 439-488.

T. Simon, J. L. Linsky, and (F. H. Schiffer), IUE Spectra of a Flare

in the RS Canum Venati corum-Type System UX Arietis, Astrophys. J.

239, 911-918 (1980).

J. L. Linsky, On the Differences at Chromospheric Levels Between

RS CVn-Type Binaries, Active and Quiet Chromospheric Single Stars,

and Active and Quiet Regions in the Sun, in Highlights of Astronomy

(P. A. Wayman, Ed., Reidel, Dordrecht, 1980), pp. 861-862.

R. E. Stencel , (D. J. Mullan), J. L. Linsky, (G. S. Basri , and S. P.

Worden), Outer Atmospheres of Cool Stars. VII. High Resolution, Absolute Flux Profiles of the Mg II h and k Lines in Stars of Spectral

Types F8 to M5, Astrophys. J. Suppl . 44_, 383-402 (1980).

T. Simon and J. L. Linsky, IUE Ultraviolet Spectra and Chromospheric

Models of HR 1099 and UX Arietis, Astrophys. J. 241, 759-773 (1980).

B. M. Haisch, J. L. Linsky, (F. R. Harnden, R. Rosner, F. D. Seward,

and G. S. Vaiana), Einstein X-ray Observations of Proxima Centauri

and the Surrounding Region, Astrophys. J. (Letters) 242, L99-103

(1980).

197
PUBLICATIONS

Quantum Physics Division (525)

J. L. Linsky, Theory of Stellar Coronae: An Interpretation of X-ray

Emission from Non-Degenerate Stellar Sources, in X-ray Astronomy With

the Einstein Satellite, (R. Giacconi, Ed., Reidel, Boston, 1981), pp. T^W.

B. M. Haisch, J. L. Linsky, (0. B. Slee, B. C. Siegman, I. Nikoloff,

M. Candy, D. Harwood, A. Verveer, P. J. Quinn, I. Wilson, A. A. Page,

P. Higson, and F. D. Seward), Simultaneous X-ray, Ultraviolet, Optical, and Radio Observations of the Flare Star Proxima Centauri,

Astrophys. J. 245, 1009-1017 (1981).

(G. S. Vaiana, J. P. Cassinelli, G. Fabbiano, R. Giacconi, L. Golub,

P. Gorenstein), B. M. Haisch, (F. R. Harnden, Jr., H. M. Johnson),

J. L. Linsky, (C. F. Maxson, R. Mewe, R. Rosner, F. Seward, K. Topka,

and C. ztoaan), Results from an Extensive Einstein Stellar Survey,

Astrophys. J. 244, 163-182 (1981).

T. Simon, J. L. Linsky, and (F. H. Schiffer III), IUE Spectra of a Flare in HR 5110: A Flaring RS CVn or ALGOL System? in The Universe

in Ultraviolet Wavelengths, The First Two Years of Internati onal

Ultraviolet Explorer (R. D. Chapman, Ld., NASA Conference Publication

2l7l, 1981), pp. 435-442

.

R. E. Stencel , (D. J. Mull an, G. S. Basri ) , and J. L. Linsky, High

Resolution Absolute Flux Profiles of the Mg II h and k Lines in

Evolved F8 to M5 Stars, in The Universe in Ultraviolet Wavelengths,

The First Two Years of International Ultraviolet Explorer (R. D.

Chapman, Ed., NASA Conference Publication 2171, 1981), pp. 317-324.

(M. S. Giampapa, P. L. Bornmann), T. R. Ayres, J. L. Linsky, and

(S. P. Worden), The Mg II h and k Lines in a Sample of dMe and dM

Stars, in The Universe in Ultraviolet Wavelengths , The First Two

Years of International Ultraviolet Explorer (R. D. Chapman, Ed.,

NASA Conference Publication 2l7l, 1981), pp. 279-286.

J. L. Linsky and N. C. Marstad, IUE Spectra of F and Late A Stars,

in The Universe in Ultraviolet Wavelengths, The First Two Years of

I n ternational Ultraviolet Explorer (R. D. Chapman, Ed., NASA Conference Publication 21/1, 1981), pp. 287-295.

J. L. Linsky, Evidence for Chromospheres and Coronae in Stars, Recent

Observations, Some Unanswered Theoretical Questions, and a Speculative Scenario, in Proc., NATO Advanced Study Institute, Solar Phenomena in Stars and Stellar Systems (M. Bonnet and A. K. Dupree, Eds.,

Kei del , 1981), pp. 99-122.

198
PUBLICATIONS

Quantum Physics Division (525)

J. L. Linsky, Outer Atmospheres of Late-Type Stars, in Physical Pro- cesses in Red Giants (I. Iben, Jr. and A. Renzini, Eds . , Rei del

,

Boston, 1981), pp. 247-261 .

J. L. Linsky, Stellar Chromospheres, Coronae, and Winds: Present

Status and Implications for Solar Astrophysics, in Solar Instrumentation--What' s Next? , pp. 180-190 (1981).

G. S. Basri, J. L. Linsky, and K. Eriksson, Outer Atmospheres of Cool

Stars. VIII. IUE Observations and Chromospheric Models for the Supergiant Stars p Draconis, e Gemi norum, and a Orionis, Astrophys. J. (in

press)

.

T. R. Ayres, N. C. Marstad, and J. L. Linsky, Outer Atmospheres of

Cool Stars. IX. A Survey of Ultraviolet Emission from F-K Dwarfs and

Giants with IUE, Astrophys. J. (in press).

(T. R. Ayres), J. L. Linsky, (G. S. Vaiana, L. Golub, and R. Rosner)

,

The Cool Half of the H-R Diagram in Soft X-rays, Astrophys. J. (in

press)

.

(R. Pallavicini, L. Golub, R. Rosner, G. S. Vaiana, T. R. Ayres), and

J. L. Linsky, Relations Among Stellar X-ray Emission Observed from

Einstein: Stellar Rotation and Bolometric Luminosity, Astrophys. J.

(in press)

.

(D. E. Gary) and J. L. Linsky, First Detection of Nonflare Microwave

Emission from the Coronae of Single Late-type Dwarf Stars, Astrophys.

J . (in press)

.

(T. R. Ayres) and J. L. Linsky, Outer Atmospheres of Cool Stars. X.

HR 1099 at Quadrature, Astrophys. J. (in press).

J. L. Linsky, Winds in Late-Type Stars, Mechanisms of Mass Outflow,

in Effects of Mass loss on Stellar Evolution, I All Co Hog. 59 (C.

Chi osi and R. Stalio, Eds., Rei del, Boston) (in press).

R. E. Stencel , J. L. Linsky, (A. Brown, C. Jordan, K. G. Karpenter,

R. F. Wing, and S. Czyzak), Density Sensitive C II Lines in Cool

Stars of Low Gravity, Monthly Notices Roy. Astron. Soc. (in press).

* (T. R. Ayres), H. W. Moos, and J. L. Linsky, Far-Ul travi ol et Fluorescence of Carbon Monoxide in the Red Giant Arcturus, Astrophys. J.

(Letters) (in press).

199
PUBLICATIONS

Quantum Physics Division (525)

* H. W. Moos (Ed.), The Study of Solar System Objects from Earth Orbit,

A Workshop Held at Goddard Space Flight Center, October 9 and 10,

1980, NASA Special Report (1981), 25 pp.

* (J. T. Clarke), H. W. Moos, (S. K. Atreya and A. L. Lane), IUE Detection of Bursts of H Ly -Alpha Emission from Saturn, Nature, 290, 226-

227 (1981).

* H. W. Moos and (J . T. Clarke), Ultraviolet Observations of the Io

Torus from Earth Orbit Using the IUE Observatory, Astrophys. J. (in

press)

* (T. R. Ayres), H. W. Moos and J. L. Linsky, Far-Ul traviolet Fluorescence of Carbon Monoxide in the Red Giant Arcturus, Astrophys. J.

(Letters) (in press).

E. R. Mosburg, Jr., The Effect of Ion Current in the Collisionless

Theory of Floating ac Probe Measurements, Rev. Sci . Instrum, (in

press)

G. B. Schmid, D. W. Norcross, and (L. A. Collins), VLAM, A Program

for Computing the Electron-Molecule Static Interaction Potential from

a Legendre Expansion of the Molecular Charge Density, Comp. Phys.

Commun. _21_, 79-90 (1980).

A. K. Pradhan, D. W. Norcross, and D. G. Hummer, Cross Sections and

Excitation Rates for Electron Collisions with Helium-Like Ions, Phys.

Rev. A_23, 619-631 (1981).

A. K. Pradhan, D. W. Norcross, and D. G. Hummer, Rate Coefficients

for Electron Impact Excitation of Helium-Like Ions, Astrophys. J. (in

press)

N. T. Padial, D. W. Norcross, and (L. A. Collins), On the Use of the

Unitarized Born Approximation in Electron Collisions with Polar Molecules, J. Phys. B: Atom. Molec. Phys. (in press).

D. W. Norcross, Application of the Adiabatic-Nuclei Approximation to

Energy-Loss Cross Sections for Collisions with Molecules, Phys. Rev.

A (in press)

D. W. Norcross, Magnetohydrodynamic Electrical Power Generation, in

Applied Atomic Collision Physics (H. S. W. Massey, B. Bederson, E. W.

McDaniel, Eds., Academic, hew York), Vol . II, Chap. 13 (in press).

200
PUBLICATIONS

Quantum Physics Division (525)

D. W. Norcross and N. T. Padial, A Multipole-Extracted AdiabaticNuclei Approximation for Electron-Molecule Collisions, Phys. Rev. A

( i n press)

* S. J. Peale, (P. Cassen, and R. T. Reynolds), Tidal Dissipation,

Orbital Evolution and the Nature of Saturn's Inner Satellites, Icarus

43, 65-72 (1980).

* (R. T. Reynolds), S. J. Peale, and (P. Cassen), Io: Energy Constraints and Plume Volcanism, Icarus (in press).

C. H. Muller, III and A. V. Phelps, Low Current ELectric Discharges

in H

2 -He Mixtures, J. Appl . Phys. _51_, 6141-6148 (1980).

A. G. Zajonc and A. V. Phelps, Nonradiative Transport of Atomic Excitation in Na Vapor, Phys. Rev. A 23 , 2479-2487 (1981).

K. Tachibana and A. V. Phelps, Excitation of the 0

2 (a^g) State by

Low Energy Electrons, J. Chem. Phys. (in press).

:

L. C. Pitchford and A. V. Phelps, On the Calculation of Electron

Swarm Properties in N

2 at Moderate E/N, Phys. Rev. A (in press).

A. K. Pradhan, The Effect of Di -El ectroni c ecombination on ElectronIon Scattering Cross Sections, Phys. Rev. Letters 47_, 79 (1981).

A. K. Pradhan and J. M. Shull, Density and Temperature Diagnostics of

X-ray Sources: Live Ratios for Helium-Like Ions, Astrophys. J. (in

press)

* H. G. Robinson and (C. E. Johnson), Measured gj Factor Ratio of

4 He +

(l

2 S 1 / 2

) and 4 He(2 3 S 1 ), in Second International Conference on Precision Measurement and Fundamental Constants (in press).

* P. L. Jones, R. D. Mead, B. E. Kohler, D. R. Rosner, and W. C.

Lineberger, Photodetachment Spectroscopy of C

2 ” Autodetaching

Resonances, J. Chem. Phys. _73_, 4419-4432 (1986).

* (M. Contini, B. Z. Kozlovsky), and G. Shaviv, The Calculation of the

Optical Spectra of the Cygnus Loop, Astron. Astrophys. 92, 273-280

(1980). —

* (M. Livio, 0. Regev), and G. Shaviv, Kel vi n-Helmhol tz Instability in

Clusters of Galaxies, Astrophys. J. (Letters) 240, L83-86 (1980).

* (M. M. Shara, D. Prialnik), and G. Shaviv, What Determines the Speed

Class of Novae? Astrophys. J . 239, 586-591 (1980).

201
PUBLICATIONS

Quantum Physics Division (525)

(D. Prialnik) and G. Shaviv, The Relationship Between the Envelope

Composition of a 6 Mg Red-Giant Model and Its Future Evolution,

Astron. Astrophys. 88, 127-134 (1980).

(M. Livio) and G. Shaviv, The Stability of Accretion Disks to Short

Wavelength Perturbations, Astrophys. J. 244, 290-298 (1981).

(0. Regev) and G. Shaviv, Formation of Protostars in Collapsing,

Rotating, Turbulent Clouds, Astrophys. J. 245, 934-959 (1981).

S. H. Langer, G. Chanmugam, and G. Shaviv, Thermal Instability in

Accretion Flows Onto Stellar Atmospheres, Astrophys. J. (Letters),

245, L23-26 (1981).

(A. N. Cox), G. Shaviv, and (S. W. Hodson), On the Ratio of Mixing

Length to Scale Height in Red Dwarfs, Astrophys. J. 245, L37-40

(1981)

(D. Prialnik), G. Shaviv, and (A. Kovetz), The Effect of Diffusion on Asymptotic Branching Evolution, Astrophys. J. (in press).

(T. Hellmuth, G. Leuchs), S. J. Smith, and (H. Walther), Angular Distribution of Photoelectrons in Multiphoton Ionization, in Proc., 2nd

International Conference on Multiphoton Processes , Budapest, 14-1*5

April 1980 (N. Krao and Z. Gg. Horvath, Eds., Hungarian Academy of

Science, Budapest, 1981), pp. 1-15.

(T. Hellmuth, G. Leuchs), S. J. Smith, and (H. Walther), Multi photon

Ionization of Atoms, in Laser and Applications, Proceedings of the

Sergio Porto Memorial Symposium, Rio de Janeiro, Brazil, June 29-

July 3, 1980 (W. 0. N. Guimaraes, C.-T. Lin, and A. Mooradian, Eds.,

Springer-Verlag, Berlin, Heidelberg, 1981), Springer Series in Optical Sciences Vol . 26 , pp. 194-203.

D. E. Nitz, A. V. Smith, M. D. Levenson, and S. J. Smith, BandwidthInduced Reversal of Asymmetry in Optical Double Resonance Amplitudes,

Phys. Rev. A 24, 288-293 (1981).

(M. A. Dillon) and D. Spence, The Angular Dependence of Scattered

Electron Spectra of Neon and Argon in the Region of Quasi discrete

Autoionizing States, J. C’nem. Phys. 74, 2654-2655 (1981).

D. Spence, On Resonances in HF, J. Phys. B: Atom. Molec. Phys. _14_, L107-114 (1981).

D. Spence, Studies of the 0 2

3 llg(V) Valence States and 3 rig(R)

Rydberg State in the Schumann-Runge Continuum from Ejected and

Scattered Electron Spectra, J. Chem. Phys. 74, 3898-3904 (1981).
PUBLICATIONS

Quantum Physics Division (525)

(M. A. Dillon) and D. Spence, A New Optically Forbidden Rydberg

Series in 0 2 Converging to 0 2 +

c

4 £y Limit, J. Chem. Phys. 74_, 6070-

6074 (1981).

D. F. Walls, (P. Zeller, and M. L. Steyn-Ross), Optical Bistability

from Three-Level Atoms, IEEE J. Quantum Electron. QE-17, 380-384

(1981).

D. F. Walls, (P. D. Drummond, and K. J. McNeil), Bistable Systems in

Nonlinear Optics, in Proceedings, International Conference and Workshop on Optical Bistability (in press).

(P. D. Drummond, C. W. Gardiner), and D. F. Walls, Quasi probabi 1 i ty

Methods for Nonlinear Chemical and Optical Systems, Phys. Rev. A (in

press)

.

D. F. Walls, C. V. Kunasz, (P. D. Drummond, and P. Zoller), Bifurcations and Multi stability in Two-Photon Processes, Phys. Rev. Letters

( i n press)

.

(M. Reid, K. J. McNeil), and D. F. Walls, A Unified Approach to

Multi photon Lasers and Multi photon Bistability, Phys. Rev. A (in

press)

.

H. Saio and J. C. Wheeler, The Evolution of Mixed Long-Lived Stars,

Astrophys. J. 242, 1176-1182 (1980).

J. P. Cox, (D. S. King, A. N. Cox), J. C. Wheeler, C. J. Hansen and

(S. W. Hodson), Pulsations of the R Coronae Borealis Stars, in IAU

Colloq. 58, Stellar Hydrodynamics, Space Sci . Rev._27_, 529-585

(1980)

.

W. H. Wing, Electrostatic Trapping of Neutral Atomic Particles, Phys.

Rev. Letters 4^_, 631-634 (1980).

(J . T. Shy, J. W. Farley, W. E. Lamb, Jr.), and W. H. Wing, Observation of the Infrared Spectrum of the Tri atomic Deuterium Molecular

Ion D

3 +

, Phys. Rev. Letters _45_, 535-537 (1980).

(J . W. Farley) and W. H. Wing, Accurate Calculation of Dynamic Stark

Shifts and Depopulation Rates of Rydberg Energy Levels Induced by

Blackbody Radiation: Hydrogen, Helium and Alkali -Metal Atoms, Phys.

Rev. A 23, 2397-2424 (1981) .
PUBLICATIONS

("in preparation" or "submitted")

Quantum Physics Division (525)

R. A. Falk and G. H. Dunn, Electron-Impact Ionization of Be

+

, Phys.

Rev. A (submitted).

W. T. Rogers, G. Stefani, R. Camilloni, G. H. Dunn, (A. Z. Msezane,

and R. J. W. Henry), Electron-Impact Ionization of Zn+ and Ga+, Phys.

Rev. A (submitted).

R. A. Falk, G. Stefani, R. Camilloni, G. H. Dunn, R. A. Phaneuf,

D. C. Gregory, and D. H. Crandall, Experimental Measurements of Electron Impact Ionization: Cross Sections for Be-Like Ions, B, C +

, N , and 0+4 (in preparation)

G. Stefani, R. Camilloni, G. H. Dunn, and W. T. Rogers, Absolute

Emission Cross Section for Electron Impact Excitation of Ga

+ to the

{

1 P ) Level (in preparation)

J. A. Luine and G. H. Dunn, Ion-Molecule Reactions Near 10 K (in

preparation)

J. B. Jeffries, S. E. Barlow, W. P. Allis, and G. H. Dunn, SelfOrganization of a Nonequilibrium Gas (in preparation).

J. B. Jeffries, S. E. Barlow, and G. H. Dunn, Space Charge Effects on Ion Resonance Frequencies in Ion Traps (in preparation)

R. A. Falk, G. H. Dunn, (D. C. Gregory, and D. H. Crandall),

Excitation-Autoionization in Electron Impact Ionization of Metal

Ions: Ti 3+

, Zr , Hf 3+

, Ta 3+ (in preparation)

K. B. Gebbie, (L. J. November), F. Hill, J. Toomre, and (G. W.

Simon), The Height Dependence of Steady Flows in the Solar Photosphere, Chromosphere and Transition Region Determined from Simultaneous SMM Satellite and Ground-Based Observations (in preparation).

(L. J. November), K. B. Gebbie, J. Toomre, and (G. W. Simon), The

Vertical Component of Supergranular Motions Observed in the Solar

Photosphere and Chromosphere (in preparation)

S. L. Haan and S. Geltman, Time Development of Resonant Multiphoton

Ionization of Sodium, J. Phys. B: Atom. Molec. Phys. (submitted).

(B. A. Palmer, R. A. Keller), F. V. Kowalski, and J. L. Hall, Accurate Wavenumber Measurements of Uranium Spectral Lines, J. Opt. Soc.

Am. (submitted).

204
PUBLICATIONS

("in preparation" or "submitted")

Quantum Physics Division (525)

J. L. Hall, L. Hollberg, T. Baer, and H. G. Robinson, Optical Heterodyne Saturation Spectroscopy, Appl . Phys. Lett, (submitted).

J. Cooper, R. J. Ballagh, K. Burnett, and D. G. Hummer, On Redistribution and the Equations for Radiative Transfer, Astrophys. J. (in

preparation)

.

D. G. Hummer and G. B. Rybicki, A Unified Treatment of Escape Probabilities in Static and Moving Media. I. Plane Geometry, Astrophys. J.

(in preparation)

.

D. G. Hummer, The Effect of Reflected and External Radiation on Stellar Flux Distribution, Monthly Notices Roy. Astron. Soc. (in preparation) .

(S. L. Bernasek) and S. R. Leone, Direct Detection of Vibrational

Excitation in the C0 2 Product of the Oxidation of CO on a Platinum

Surface, Chem. Phys. Lett, (submitted).

* (T. R. Ayres), J. L. Linsky, (G. S. Basri , W. Landsman, R. C. Henry),

H. W. Moos, and R. E. Stencel , Outer Atmospheres of Cool Stars. XII.

High-Dispersion IUE Spectra of Five Late-Type Dwarfs and Giants,

Astrophys. J. (submitted).

* (J. T. Clarke), H. W. Moos, and (P. D. Feldman), The Far Ultraviolet

Spectra and Geometric Albedos of Jupiter and Saturn, Astrophys. J.

(submitted)

.

* (C. F. Yoder) and S. J. Peale, The Tides of Io, Icarus (submitted).

T. Fujimoto and A. V. Phelps, Transport of Resonance Excitation in Na

Vapor Excited by White Light, Phys. Rev. A (submitted).

* S. Rappaport, (P. C. Joss and R. Webbink), The Evolution of Highly

Compact Binary Stellar Systems, Astrophys. J. (submitted).

* (R. L. Kelley), S. Rappaport, (M. J. Brodheim and L. Cominsky), A

Search for Apsidal Motion in 4U0115+63, Astrophys. J. (submitted).

* S. H. Langer and S. Rappaport, Low-Luminosity Accretion onto Magnetized Neutron Stars, Astrophys. J. (submitted).

* (S. D. Kepler), E. L. Robinson, (R. E. Nather and J. T. McGraw), The

Pulsation Periods of the Pulsating White Dwarf G117-B15A, Astrophys.

J. (submitted).

205
PUBLICATIONS

("in preparation" or "submitted")

Quantum Physics Division (525)

* E. L. Robinson, (E. S. Barker, A. Cochran, W. D. Cochran, and R. E.

Nather), MV Lyrae: Spectrophotometric Properties of Minimum Light or

on MV Lyrae Off, Astrophys. J. (submitted).

* E. L. Robinson, (R. E. Nather, and S. 0. Kepler), BT Monocerotis: A

New and Unusual Eclipsing Nova, Astrophys. J. (submitted).

* E. L. Robinson, (S. 0. Kepler, and R. E. Nather), Multicolor Variations of the ZZ Ceti Stars, Astrophys. J. (submitted).

* J. L. Hall, L. Hollberg, T. Baer, and H. G. Robinson, Optical Heterodyne Saturation Spectroscopy, Appl . Phys. Lett, (submitted).

* (M. Conti ni) and G. Shaviv, The Calculation of the UV Spectra of the

Cygnus Loop, Astrophys. J. (submitted).

* (N. Brosch) and G. Shaviv, Mul tiaperture Photometry of Isolated

Galaxies, Astrophys. J. (submitted).

* (VI. P. Blair), R. E. Stencel , G. Shaviv, and (W. A. Feibelman),

HM Sagittae: Symbiotic Cousin of the RS CVn Stars, Astron. Astrophys.

(submitted)

* D. Spence, (W. A. Chupka, and C. M. Stevens), Search for Long-Lived

Doubly Charged Atomic Negative Ions, Phys. Rev. A (submitted).

206
INVITED TALKS

Quantum Physics Division (525)

G. H. Dunn, "Experimental Results for Electron Impact Excitation and

Ionization of Ions," Conference on Atomic Processes in High Temperature

Plasmas, topical conference of the American Physical Society by the

Division of Electron and Atomic Physics, Louisiana State University,

Baton Rouge, Louisiana, February 27, 1981.

A. C. Gallagher, "Molecular Continuum Radiation as a Reaction Diagnostic," University of Toronto, Physics and Chemistry Colloquium, April

20, 1981.

A. C. Gallagher, "The Absorption and Emission of Radiation by the Collision Complex," XII ICPEAC, July 16, 1981.

S. Geltman, "Separated-Atom Theory of Laser Induced Colli si onal Excitation Transfer and Ionization," (two talks), Conference on PhotonAssisted Collisions, June 22-24, 1981, Instituto di Chimica Quantistica,

Pisa, Italy.

S. R. Leone, "Nascent Product Vibrational State Distributions of Simple

Ion-Molecule Reactions," Dept, of Chemistry, Colorado State Univ., Fort

Collins, Colorado, October 1980.

S. R. Leone, "Simple A+BC Reaction Dynamics with a Negative Ion Twist,"

Department of Chemistry, University of Denver, Denver, Colorado,

November 1980.

S. R. Leone, "Vibrational Product State Distributions of Ion-Molecule

Reactions, Symposium on "Chemistry and Dynamics of Ions and Molecules in

the Gas Phase," 16th Midwest Regional American Chemical Society Meeting,

Lincoln, Nebraska, November 1980.

S. R. Leone, "Ion Molecule Reaction Dynamics in the Gas Phase," The

James Franck Institute, University of Chicago, February 1981.

S. R. Leone, "Dynamics of Negative Ion Reactions," Department of

Chemistry, Illinois Institute of Technology, February 1981.

S. R. Leone, "Infrared Emission Studies of Laser-Produced Free Radicals

and Chain Reactions," General Motors Research Laboratory, Warren,

Michigan, February 1981.

S. R. Leone, "Photofragmentation Infrared Emission Spectroscopy," Workshop on Far UV Spectroscopy and Photochemistry, MOlheim, West Germany,

March 1981.

S. R. Leone, "Dynamics of Gaseous Ion-Molecule Reactions," Max-PlanckInstitut fiir Strtimungsforschung, Gottingen, West Germany, March 1981.

207
INVITED TALKS

Quantum Physics Division (525)

S. R. Leone, “Properties of Laser Radiation," "Detection of Radiation,"

"V-V, V-RT Small Molecules," and "Laser-Induced Chain Reactions," Lectures for Lasers in Chemistry Workshop, University of Utah, held at

Snowbird, Utah, September 1981.

J. L. Linsky, "Stellar Chromospheres , Coronae, and Winds," Invited re- view paper presented at the Meeting on Solar Instrumentation, Sacramento

Peak National Observatory, Sunspot, New Mexico, October 16, 1980.

J. L. Linsky, "The Solar Physics of Nearby Stars," Invited colloquium

presented at an Astro-Geophysics Departmental Meeting, University of

Colorado, Boulder, Colorado, October 27, 1980.

J. L. Linsky, "Chromospheres and Coronae of Stars," Invited colloquiums:

Physics Department, Gettysburg College, Gettysburg, Pennsylvania,

October 29, 1980.

NASA Goddard Space Flight Center, Greenbelt, Maryland, October 31,

1980.

J. L. Linsky, "Stellar Chromospheres and Coronae: Recent Results from

Einstein and IUE," Invited colloquiums:

NASA Ames Research Center, Moffett Field, California, February 17,

1981.

Astronomy Department, Penn State University, University Park,

Pennsylvania, February 23, 1981.

Astronomy Department, University of Toronto, West Hill, Ontario,

Canada, March 4, 1981.

High Altitude Observatory, National Center for Atmospheric Research,

Boulder, Colorado, April 9, 1981.

J. L. Linsky, "Stellar Chromospheres and Coronae: Recent Results from

the Einstein X-ray Observatory and the International Ultraviolet Explorer Satellites," Invited colloquium presented at the NOAA Space

Environment Lab, Boulder, Colorado, March 31, 1981.

D. W. Norcross, "The Theory of Inelastic Electron-Atomic Collisions,"

Invited review paper to be presented at the 14th National Atomic and

Molecular Physics Conference, Newcastle upon Tyne, England, March 30,

1982.

D. W. Norcross, "The Theory of Electron Collisions with Polar

Molecules," Invited paper to be presented at the Electron Collisions

Workshop, Newcastle upon Tyne, England, April 2, 1982.

208
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

P. L. Bender, Member, Ad Hoc Committee on Gravitational Physics of the

Space Science Board, National Research Council.

P. L. Bender, Member, Panel on Crustal Movement Measurement, Committee

on Geodesy, National Academy of Science and National Research Council.

P. L. Bender, Member, Laser Geodynamics Satellite (LAGEOS) Working

Group, NASA.

P. L. Bender, Member, Physics Department Advisory Council, Princeton

University

P. L. Bender, Internal University of Colorado Review Panel for the

Astro-Geophysics Department.

G. H. Dunn, Chairman, Organizing Committee, Conference on Atomic Pro- cesses in High Temperature Plasmas. Held in Baton Rouge, Louisiana,

February 1981. A Topical Conference of the American Physical Society.

G. H. Dunn, Member, Committee for Davi sson-Germer Prize.

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.

A. C. Gallagher, Member, ICPEAC Organizing Committee.

K. B. Gebbie, Vice Chairman, Colorado Passenger Tramway Safety Board.

K. B. Gebbie, Member, Electorate Nominating Committee, Section D,

American Association for the Advancement of Science.

J. L. Hall, Member, National Research Committee on Fundamental Constants, National Research Council /National Academy of Sciences, July 1,

1976 - June 30, 1979, extended to June 30, 1982.

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.

209
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

J. L. Hall, Member, NBS Committee for NBS Precision Measurement Grants.

J. L. Hall, Di rector-at-Large, Optical Society of America.

D. G. Hummer, Member, Editorial Board, Computer Physics Communications.

S. R. Leone, Organizer of Symposium on New Techniques in Chemical

Kinetics, American Chemical Society Meeting, New York City, August 1981.

S. R. Leone, Co-Chairman, Gordon Conference on Molecular Energy Transfer

for 1985.

S. R. Leone, Associate Editor, Optics Letters.

J. L. Linsky, Member, Solar Physics Working Group of the Astronomy Survey

Committee, National Academy of Sciences and National Research Council.

J. L. Linsky, Co-Investigator, ST (Space Telescope) High Resolution

Spectrograph Experiment.

J. L. Linsky, Member, NSF Astronomy Research Section Oversight Committee, National Science Foundation.

J. L. Linsky, Member, Committee to Evaluate the Future of the Cloudcraft

48-inch Telescope of Sacramento Peak Observatory, AURA (Association of

Universities for Research in Astronomy).

J. L. Linsky, Member, Committee on Space Astronomy and Astrophysics of

the Space Science Board, National Academy of Sciences and National

Research Council.

J. L. Linsky, Member, Panel on Ultraviolet, Optical, and Infrared

Astronomy of the Astronomy Survey Committee, National Academy of

Sciences and National Research Council. -

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.

A. V. Phelps, DARPA Committee on Beam-Generated Air Chemistry.

A. V. Phelps, Steering Committee for Workshop on Glow Discharge Opening

Switches, January 1982.

210
TECHNICAL AND PROFESSIONAL COMMITTEE PARTICIPATION AND LEADERSHIP

Quantum Physics Division (525)

A. V. Phelps, Advisory Committee, NATO Advanced Study Institute on Electrical Breakdown and Discharges in Gases.

S. J. Smith, Member, Committee on Atomic and Molecular Sciences,

National Academy of Sciences.

S. J. Smith, Co-Chairman, NAS-NRC Survey of Atomic and Molecular

Science.

S. J. Smith, Member, Organizing Committee, Eighth International

Conference on Atomic Physics, Gtttteburg, Sweden, 1982.

S. J. Smith, Member, Local Committee for Annual Meeting of Division of

Electron and Atomic Physics, Boulder, Colorado, 1982.

S. J. Smith, Co-Chairman, JILA Workshop on Photoionization from Excited

States of Atoms and Molecules, Boulder, Colorado, March 1981.

211
CONSULTING

Quantum Physics Division (525)

A. Gallagher

Dr. Gallagher is consulting with a group studying the production of

hydrogenated amorphous silicon films at the Solar Energy Research

Institute in Golden, Colorado.

S. Geltman

Dr. Geltman does consulting and advising with the Service de

Physique Atomique, CEN de Saclay, 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.

D. G. Hummer

Dr. Hummer consults for the X-ray laser project at Livermore 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 does informal consulting with Texaco and Martin Marietta

on laser chemistry and collaborates with General Motors Research

Laboratories

.

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 lasers and

charged particle beam devices.

212
TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

P. L. Bender January 14-15, 1981 - Washington, D.C.

Attended the meeting of ad hoc Gravity Gradiometer

Review Panel at NASA Headquarters.

Sponsor: Science Applications, Inc.

January 20-22, 1981 - Clear Lake, Texas.

Attended the meeting of the Committee on Earth Sciences

of the Space Science Board, National Academy of

Sciences.

Sponsor: National Research Council.

March 3-5, 1981 - Washington, D.C.

Attended the meeting of the Committee on Earth Sciences

of the Space Science Board, National Academy of

Sciences.

Sponsor: National Research Council.

April 9-11, 1981 - Washington, D.C.

Attended meeting of the Committee on Earth Sciences of

the Space Science Board, National Academy of Sciences.

Sponsor: National Research Council.

June 1-4, 1981 - Greenbelt, Maryland.

Participated in NASA Panel to review Crustal Dynamics

projects proposals.

Sponsor: NASA

July 7-8, 1981 - Boston, Massachusetts.

Assisted in editing of the report of the Panel on Crustal Movement Measurements of the Committee on Geodesy, National Academy of Sciences.

Sponsor: National Research Council.

A. C. Gallagher April 20-21, 1981 - Toronto, Ontario, Canada.

Presented a seminar on molecular continuum radiation as

a diagnostic of chemical reactions and visited labs at

the University of Toronto.

Sponsor: University of Toronto.

K. B. Gebbie November 23-26, 1981 - Greenbelt, Maryland.

Worked at NASA Goddard Space Flight Center as a Guest

Investigator on the SMM/UVSP Experiment.

Sponsor: NASA.

213
K. B. Gebbie

D. G. Hummer

S. R. Leone

TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

January 6-10, 1981 - Taos, New Mexico.

Attended 1981 annual meeting of the Solar Physics Division of the American Astronomical Society and presented

a contributed paper entitled, "Steady Flows in the

Solar Transition Region Observed with UVSP Experiment

on SMM.

Sponsor: NASA.

January 30 - February 5, 1981 - Greenbelt, Maryland.

At NASA/Goddard Space Flight Center analyzed data

obtained with Solar Maximum Mission Satellite.

Sponsor: NASA.

January 21 - February 1, 1981 - Cambridge,

Massachusetts.

Collaborated with Dr. G. B. Rybicki on calculation of

hydrogen line profile in accretion disks.

Sponsor: Smithsonian Institute.

April 19-22, 1981 - Livermore, California.

Participated in workshop on calcul ational methods in

dynamic line transport held at Livermore and discussed

with Livermore personnel the possibility of a contract

for research in radiation transport in moving media.

Sponsor: Lawrence Livermore Laboratory.

July 9-19, 1981 - London, England and Gregynog, Wales.

Attended a four-day planning meeting of the UK Collaborative Computational Project on Stellar Atmospheres, a nation-wide collaborative project supported by the UK

Science Research Council in Gregynog, Wales.

Worked with Dr. Peter Storey at University College on the discrepancies between results of recombination

programs recently transferred from University College

to JILA.

Sponsor: UK Collaborative Computational Project on Stellar Atmospheres.

November 5-6, 1980 - Lincoln, Nebraska.

Attended the 16th Midwest Regional American Chemical

Society Meeting and gave a talk entitled, "Vibrational

Product State Distributions of Ion-Molecule Reactions,"

at invited symposium on Chemistry and Dynamics of Ions

and Molecules in the Gas Phase.

Sponsor: 16th Midwest Regional ACS Meeting.

214
S. R. Leone

J. L. Linsky

TRIPS SPONSORED BY OTHERS

Quantum Physics Division (525)

February 3, 1981 - Chicago, Illinois.

Visited the James Franck Institute at the University of

Chicago and gave a colloquium on "Ion Molecule Reaction

Dynamics in the Gas Phase."

Sponsor: The University of Chicago

February 4, 1981 - Chicago, Illinois.

Visited the Illinois Institute of Technology and gave a colloquium on "Dynamics of Negative Ion Reactions."

Sponsor: Illinois Institute of Technology.

February 5, 1981 - Detroit, Michigan.

Visited General Motors Research Lab and gave a colloquium on "Infrared Emission Studies of Laser-Produced

Free Radicals and Chain Reactions."

Sponsor: General Motors Corporation.

February 20 - March 6, 1981 - West Germany.

Visited with Hubert Hoffman of Battel le Institute in

Frankfurt, West Germany.

Attended workshop on "Far Ultraviolet Spectroscopy and

Photochemistry," and gave an invited lecture on "Photofragmentation Infrared Emission Spectroscopy," in

Mulheim, West Germany.

Visited labs in Kaiserslautern, West Germany.

Visited labs at Max Planck Institutes in Munich and

Gdttingen, West Germany.

Sponsors: National Science Foundation

Max-Planck-Institut fUr Stromungsforschung.

September 20-25, 1981 - Snowbird, Utah.

University of Utah, Workshop on "Lasers in Chemistry."

Sponsor: University of Utah.

October 29, 1980 - Gettysburg, Pennsylvania.

Gave invited colloquium at the Department of Physics,

Gettysburg College on the topic "Recent Work on the

Study of Stellar Chromospheres and Coronae."

Sponsor: Gettysburg College.

October 30-31, 1980 - Greenbelt, Maryland.

Attended a meeting at Goddard Space Flight Center of

the Space Telescope High Resolution Spectrograph

Instrument Development Team, and

215
TRIPS SPONSORED BY OTHERS

J. L. Linsky

Quantum Physics Division (525)

October 31, 1980 - Greenbelt, Maryland.

Gave NASA Goddard Space Flight Center Scientific

Colloquium on "Recent Work on the Study of Stellar

Chromospheres & Coronae."

Sponsor: NASA.

February 17, 1981 - San Francisco, California.

Discussed with colleagues at Lockheed the x-ray spectroscopic observation of the sun and presented an invited colloquium at NASA, Ames Space Flight Center.

Sponsor: NASA.

February 18-20, 1981 - San Francisco, California.

Attended meeting of Committee on Space Astronomy & Astrophysics of National Academy of Science at Stanford

University.

Sponsor: National Academy of Sciences.

February 23, 1981 - State College, Pennsylvania.

Consulted with members of the Astronomy Department at

Penn State and gave a colloquium.

Sponsor: Pennsylvania State University.

February 24-26, 1981 - Washington, D. C.

Participated as a member of the Review Committee for

Astronomy Research Section of National Science Foundati on

.

Sponsor: National Science Foundation.

April 24, 1981 - Washington, D. C.

Attended a meeting of the Committee on Space Astronomy

and Astrophysics.

Sponsor: National Academy of Sciences.

May 14-15, 1981 - Greenbelt, Maryland.

Attended a meeting at Goddard Space Flight Center of

the Space Telescope High Resolution Spectrograph Instrument Development Team.

Sponsor: NASA.

June 29 - July 2, 1981 - Calgary, Alberta, Canada.

Attended a meeting of the American Astronomical

Society, and presented a paper.

Sponsor: NASA.

216
TRIPS SPONSORED BY OTHERS

D. W. Norcross

A. V. Phelps

S. J. Smith

Quantum Physics Division (525)

August 1980 - August 1981 - Cambridge, Massachusetts.

Extended travel to Smithsonian Center for Astrophysics.

Sponsor: Smithsonian Institute.

December 4-5, 1980 - Los Alamos, New Mexico.

Consulted at Los Alamos Scientific Laboratory on atomic

collision problems.

Sponsor: Los Alamos Scientific Laboratory.

June 27 - July 11, 1981 - Les Arcs, France.

Participated in the NATO Advanced Study Institute.

Presented lectures and learned of the European work

on gas discharges for use in JILA/NBS and contract

research.

Sponsor: NATO Advanced Study Institute.

May 27 - June 2, 1981 - Lenox, Massachusetts.

Worked with group on writing report for the Committee

on Atomic and Molecular Science, National Academy of

Science.

Sponsor: National Academy of Science.

217
SPONSORED CONFERENCES

Quantum Physics Division (525)

North American Workshop on Symbiotic Stars, June 22-24, 1981, at JILA.

J. L. Linsky and R. E. Stencel were co-organizers.

Fifth Workshop on the Vacuum Ultraviolet Radiometric Calibration of

Space Experiments, March 22-23, 1981, at NCAR in Boulder.

J. L. Linsky was the organizer.

A JILA Workshop on photoionization of excited atomic and molecular

states, including cross-sections, angular distributions, spin polarization and wavelength dependence was held in March 1981.

S. J. Smith and G. Leuchs (Visiting Fellow) were co-organizers.

218
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Informal Seminars

Name/Aff i 1 i ati on/Ti tl e/Date

R. Stencel (Research Associate) and G. Shaviv (JILA Visiting Fellow) - A Short Period Binary Model for HM Sge, November 7, 1980.

L. A. Willson (Univ. of Iowa) and G. Wallerstein (JILA Visitor) - A Long

Period Binary Model for Eruptive Symbiotics, November 7, 1980.

B. W. Bopp (JILA Visitor) - Recent IR Observations of Symbiotic and

Related Stars, November 7, 1980.

L. A. Willson (Univ. of Iowa) - Miras, Modes, and Mass Loss and Simple

Symbiotic Systems, November 17, 1980.

D. M. Gibson (New Mexico Tech.) - Radio Stars: Making the Solar Connection, November 26, 1980.

J. Chri stensen-Dal sgaard (Inst. Chemia, Sart-Tilman, Liege, Belgium) - Radiative Transfer in Linear Stellar Oscillations, December 10, 1980.

J. L. Beauchamp (Cal. Tech.) - Infrared Laser Photochemistry , December

12, 1980.

M. Rodono, (Catania Univ. Observatory) - Observations of Close Binary

Systems: Studies of RS CVn and BY Dra Systems Under Way at Catania

Observatory , February 10, 1981.

R. Roy (Univ. of Rochester) - Spontaneous Switching and Quantum Fluctuations in Dye Lasers, February 18, 1981.

W. Raith (Yale Univ.) - e-Li Impact Ionization with Polarized Particles,

June 17, 1981.

H. Taylor (Univ. of Southern California) - Special Experimental Effects

in Electron Scattering on Atoms and Molecules in Strong Laser Fields,

June 23, 1981.

B. L. Moiseiwitsch (The Queen's University of Belfast) - What is the

Behaviour of Ionization and Electron Capture Cross Sections at Very High

Impact Energies?, July 22, 1981.

J. Kimman (F.O.M. Institute for Atomic and Molecular Physics, Amsterdam,

The Netherlands) - Absorption of Additional Photons in the Multiphoton

Ionization Continuum of Xenon--Experimental Study, July 24, 1981.

219
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Informal Seminars on Atomic and Radiation Theory

Name/Affil iation/Title/Date

W. P. Allis (JILA Visitor) - Asymptotic Limits of the Boltzmann Equation

for Electrons, October 14, 1980.

C. W. Gardiner (Univ. of Waikato) - New Treatment of Laser Phase and

Amplitude Fluctuations in Atomic Fluorescence Experiments, October 21,

1980.

B. Chri stensen-Dal sgaard (JILA Visitor) - Application of the FiniteElement Method in Electron-Atom Scattering, October 28, 1980.

S. Haan (Research Assistant) - Time Evolution of Resonant Multiphoton

Ionization of Sodium, November 4, 1980.

A. Tip (F.O.M. Inst., Amsterdam) - Hydrogen Atoms Interacting with a Quantized Radiation Mode, November 18, 1980.

L. Pitchford (LASL) - Comparison of Methods for Electron Swarm Analysis,

November 25, 1980.

D. F. Walls (JILA Visiting Fellow) - Quantum Analysis of Fluctuations in

Nonlinear Optics, December 9, 1980.

J. H. Eberly (Univ. of Rochester) - The Transition to Chaos in an Exactly Soluble Quantum Model, March 10, 1981.

B. Carre (Service de Physique Atomique, Saclay) - Laser-induced Ionization in Sodium Vapour, August 6, 1981.

220
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Seminars

Name/Af f i 1 i ati on/T i tl e/Date

J. Leventhal (Univ. of Missouri) - Energy Transfer in Collisions Involving Laser Excited Sodium Atoms, October 3, 1980.

D. A. Dixon (Univ. of Minnesota) - Applications of Molecular Orbital

Theory--The Electronic States of Trimethylene-methane and Theoretical

Determination of Proton Affinities, October 10,1980.

J. C. Weisshaar (JILA Postdoc) - Formaldehyde Photochemistry: The Decay

Mechanism of Single Rotational Levels of S^, October 17, 1980.

D. F. Walls (JILA Visiting Fellow) - Order and Chaos in Non-Equilibrium

Systems, October 24, 1980.

S. Chapman (Columbia University) - Reaction Dynamics of 0

3

+N0 - O^+NO^,

October 31, 1980.

J. R. Taylor (Univ. of Colorado, Physics) - Three-body Scattering Rates,

November 7, 1980.

J. D. Harvey (Univ. of Auckland) - Recent Developments in Dynamic Light

Scattering, November 14, 1980.

N. Clark (Univ. of Colorado, Physics) - Ferro-electric Liquids, November

21, 1980.

J. T. Hynes (Univ. of Colorado, Chemistry) - Along the Reaction

Coordinate in Liquids, December 5, 1980.

G. B. Ellison (Univ. of Colorado, Chemistry) - Photo-electron Spectroscopy and Reaction Dynamics of Ions, December 12, 1980.

R. Mead (Graduate Student), P. Schulz, C. Feigerle (Research

Associates), and K. Burnett (JILA Member) - Chemical Physics Christmas

Special, December 19, 1980.

P. Schulz (Research Associate) - Photodetachment of OH", March 6, 1981.

E. W. Smith (NBS, Boulder) - Model Microfield Methods: An Introduction,

March 20, 1981.

D. McMahon (JILA Visiting Scientist) - Dielectric Friction in Polar

Liquids and Gases, April 3, 1981.

221
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

Chemical Physics Seminars (continued)

Name/Aff i 1 i ati on/T i tl e/Date

D. Spence (JILA Visiting Fellow) - Elucidation of Molecular Dynamics

from Electron Scattering Experiments, April 10, 1981.

P. L. Jones (Fachbereich Physik der Univ. Kaiserslautern) - Somewhere

Over the Rainbow: Supernumerary Structure in Na

2 ~Ne Rotationally Inelastic Scattering Cross Sections, April 24, 1981.

S. V. ONeil (JILA) - Computation in Chemistry: A Pedagogical Potpourri

,

May 1, 1981.

K. Evenson (NBS, Boulder) - Laser Magnetic Resonance of Free Radicals

Important in Radio Astronomy, May 8, 1981.

222
SEMINARS AND COLLOQUIA

Quantum Physics Division (525)

JILA Colloquium Speakers

Name/Aff i 1 i ati on/T i tl e/Date

G. Leuchs (Univ. of Munich) - Quantum Interference Effects in Time

Resolved Spectroscopy, October 15, 1980.

B. Kayser (Stanford Linear Accelerator) - Particle Physics--What is the

Excitement About?, October 22, 1980.

K. Thorne, (Cal. Tech.) - Quantum Non-demolition Measurements: Circumventing the Heisenberg Uncertainty Principle in the Search for Gravity

Waves, November 19, 1980.

H. Robinson (JILA Visiting Fellow) - Experiments Yielding Precise Ratios

of Electron Magnetic Moments in Simple Atoms, November 25, 1980.

R. P. Bauman (JILA Visiting Fellow) - Why Johnny Can't Do Physics--Underlying Causes of Student Difficulties in Reasoning, February 11, 1981.

D. Abbott (JILA) - The Consequences of Mass Loss from Early-Type Stars,

February 17, 1981.

P. Drummond (Univ. of Rochester) - Transverse Effects in Laser Pulse

Propagation, February 24, 1981.

J. A. Eddy (NCAR) - Is the Sun Shrinking?, March 3, 1981.

D. Levy (Univ. of Chicago) - The Spectroscopy of Weakly Bound Organic

Dimers, March 10, 1981.

W. Fairbank (Stanford Univ.) - Experimental Gravitational Wave Astronomy

at Stanford, March 17, 1981.

K. A. McAfee (Bell Labs) - Energy Transfer and Charge Exchange Oscillations During Ar

+ and N + Collisions with Various Molecules, March 31, 1981.

F. M. Pipkin (JILA Visiting Fellow) - Fast Beam Measurements of the Lamb

Shift in Hydrogen, April 15, 1981.

C. Wheeler (Univ. of Texas) - Black Holes in Active Galactic Nuclei,

April 21, 1981.

B. Woodgate (Goddard Space Flight Center) - SMM Flare Observations and

Plasma Diagnostics, May 12, 1981.

Y. M. Chan (JILA) - Telephones, Terminals, RS232, Modems and All That

Jazz: Data Communications for the Pedestrian, May 28, 1981.

223
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name University and Departmental Committees Served On

Bender, P. L. Internal University of Colorado Review Panel for

the Astro-Geophysics Department

Dunn, G. H. Graduate Committee, Department of Physics,

JILA Executive Committee

JILA Shops Committee

JILA Data Center Advisory Committee

Member, several thesis and examinations committees

NML EEO Coordinator

Faller, J. E. Chairman, JILA Shops Committee

Gallagher, A. C. JILA Space Committee

Thesis Committee for H. Gunn (University of Otago,

Dunedin, New Zealand)

Thesis Committee for S. Buckman (Flinders

University, Adelaide, Australia)

Gebbie, K. B. Thesis Committee for Michael Francis (Department

of Astro-Geophysics, University of Colorado)

Examinations Committee, Department of AstroGeophysics, University of Colorado

The Billings Award Committee, Department of AstroGeophysics, University of Colorado

Geltman, S. Secretary for JILA Visiting Scientists Program

Leone, S. R. Chemical Physics Committee, University of Colorado

JILA Colloquium Committee

JILA Safety Committee

JILA Executive Committee

JILA Data Center Committee

NBS Research Advisory Committee

Linsky, J. L. Thesis Committee, Mark Giampapa (Astronomy

Department, University of Arizona)

224
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name University and Departmental Committees Served On

Phelps, A. V. Chairperson, J I LA (to December 31, 1980)

CU Institute Directors Committee

JILA Data Center Advisory Committee

Smith, S. J

.

Co-Chairman, JILA Colloquium Committee

JILA Executive Committee

JILA Shops Committee

225
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Graduate Students

Supervi sed

Postdoctoral Research

Associates

Supervi sed

Beaty, E. C. L. C. Pitchford

Bender, P. L. D. R. Larden

Dunn, G. H. J. Luine

S. Barlow

K. Timmer

R. Swanson

M. Blaser

A. Falk

D. Bel id

Faller, J . E

.

B. Rinker

M. Zumberge

P. Keyser

K. McLagen

Gallagher, A. C. J. Huennekens

H. Chatham

B. Robertson

W. Kamke

R. Dang

Gebbie, K. B. W. B. Kint

J. G. Porter

L. J. November

(with J. Toomre)

Geltman, S. S. Haan

Hall, J. L. L. Hollberg

M. Rayman

D. Meschede

T. Baer

(NRC)-P. Nachman

M. Hohenstatt

Hummer, D. G. D. Carroll

Birte ChristensenDal sgaard

D. C. Abbott

A. A. Kutepov (Exchange

Visitor, Univ of

Leni ngrad

226
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Name

Graduate Students

Supervi sed

Postdoctoral Research

Associates

Supervi sed

Leone, S. R. D. Nesbitt H. Hermann (DFG Fellow

W. Pence ship)

D. Guyer (NRC)-S. Baughcum

T. Zwier (NRC)-F. Magnotta

L. Kovalenko B. Koffend

M. Hale J. Weisshaar (Nobel

(NSF Fel lowship) C. Hamilton Laureate Signature

J. Smedley Award Winner)

V. Bierbaum (25%)

(NRC)-M. Duncan

L. Huwel (Max Planck

Fel 1 owship)

Li nsky , J . L

P. Bornmann F. Walter

N. Marstad R. Stencel

M. Schindler T. Simon

M. Giampapa (Univ. of K. Eriksson

Ari zona) R. Hammer

D. Zarro (Australian

National Observatory

Norcross, D. W. N. Padial

A. Pradhan

R. Christensen

Phelps, A. V. S. Yoshida (Kieo M. A. Islam

Univ., Yokohama, C. Yamabe

Japan) P. A. Vicharelli

S. Buckman

Smi th , S . J . D. Meschede D. Elliott

R . Roy

227
OTHER ITEMS OF INTEREST TO THE PANEL

Name

Quantum Physics Division (525)

Courses Taught at the University of Colorado

Bender, P. L. Physics 451 - Modem Optics (Fall 1981)

Faller, J. Experimental Physics (2 weeks)—with Bartlett and

Ri sti nen)

Geltman, S. Physics 203 (Recitation) (Fall 1980)

Hall, J. L. Topics in Modern Optics (Fall 1980)

Leone, S. R. 550 Chemical Dynamics (Fall 1980)

Linsky, J. L. AG 650 - Stellar Winds and Coronae (Spring 1981)

Smi th , S . J . Physics 331 (Spring 1982)

Course Taught Elsewhere

Leone, S. R, Modern Optics (short course at the University

of Utah, Fall 1981)

Item of Interest to the Panel

S. R. Leone was promoted to full Professor Adjoint, Department of

Chemistry, University of Colorado.

228
OTHER ITEMS OF INTEREST TO THE PANEL

Name

Quantum Physics Division (525)

Scientists Working at JILA on Sabbatical or Other Leave (other than visiting Fellows)

Beaty, E. W. Allis (MIT - Cambridge, Massachusetts)

J. A. Rees (The University of Liverpool, England)

Conti, P. & Li nsky , J . G. Wallerstein (University of Washington - Seattle, Washington)

Conti, P. L. Wilson (University College London, England)

Cooper, J

.

J. Dufty (University of Florida - Gainesville,

FI ori da)

Gallagher, A. C. B. Stumpf (Universit&t des Saarlandes, West

Germany)

B. Kamke (University of Marburg, West Germany)

N. Bras (University of Paris)

Geltman, S. M. J. Conneely (University College - Galway,

Ireland)

Hummer, D. G. & Norcross, D. W.

B. Chri stensen-Dal sgaard (University of Aarhus,

Denmark)

Leone, S. H. Hermann (University of Kaisers! autern, West

Germany)

L. Huwel (Max-Planck-Institut fdr

StrflmungsforschungMFellowship and Award Winner)

Lineberger, C. J. B. Peel (LaTrobe University, Australia)

Norcross, D. N. Padial (Inst. Fisica, Campinas, Brazil)

Toomre, J. D. Gough (Inst, of Theoretical Astronomy,

Cambridge, England)

J. P. Zahn (Obesrvatoi re de Nice, France)

229
OTHER ITEMS OF INTEREST TO THE PANEL

Quantum Physics Division (525)

Research Fellowship for Teachers

Over the years JILA scientists have sought means to make a scientific career attractive to talented individuals who are women or of

minority origin. There have been 1 audible individual efforts including

lecturing at schools and teaching summer classes of minority students.

Two years ago, it was decided that JILA should do something on an institutional basis, and a separate Research Fellowship for Teachers was es- tablished. The JILA Research Fellowship for Teachers is supported by

the National Bureau of Standards through a grant to the University of

Colorado. It is available for teachers who, in their home colleges or universities are in a position to influence minority and women students

towards careers in the physical sciences. There are no set duties or assignments associated with the Fellowship, similar to the Visiting

Fellowship. Selection is based on scholarly achievement or promise,

experience and interest in a field of science that will allow fruitful

interaction with JILA scientists, and demonstrated ability to motivate

their students toward careers in the physical sciences. The program

provides facilities to recipients on sabbatical salaries and may provide

full stipends for recipients without support from their home institution

or other sources. Roundtrip transportation costs are paid for the re- cipients and their immediate families.

Funding for the program was obtained by taking $15 K from the

Visiting Fellows Program, and an additional $15 K has been guaranteed,

if needed, by the Personnel Management Board of NBS. The latter is to

be used only in cases where backup is needed.

The first year (1980-81) Dr. Robert Bauman, Professor of Physics at

the University of Alabama was chosen for the fellowship. His visit was very successful. His research with Alan Gallagher on silane discharges

will be continued at Alabama. He gave lectures on overcoming learning

barriers for underprivileged persons.

This year Dr. Ronald Mickens, Professor of Physics, Fisk University, Nashville, Tennessee. A theoretical physicist with broad interests,

he has in the few weeks he's been in JILA already been very active.

Though the competition level for this fellowship has not been nearly as high as for the Visiting Fellowships, the quality of appointees

has been very high, and all indicators point to success for the program.

230
NBS-1UA irev. 2-80

U.S. DEPT. OF C O MM. BIBLIOGRAPHIC DATA

SHEET (See in struction s)

1. PUBLICATION OR

REPORT NO.

NBSIR 81-2391

2. Performing Organ. Report No, 3. Publication Date

November 1981

4. TITLE AND SUBTITLE

Technical Activities 1981

Center for Absolute Physical Quantities

5. AUTHOR(S)

Prepared bv: Karl G. Kessler

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struction s)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

10.

SUPPLEMENTARY NOTES

j Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (

A

200- word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes research projects, measurement method development, calibration

and data evaluation activities carried during Fiscal Year 1981 in the NBS Center for

Absolute Physical Quantities. These activities fall in the areas of: quantum metrolog/

measurements and standards for the electrical units, temperature and pressure, length

and mass, time and frequency; and quantum physics.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Electrical measurements and standards; length and mass measurements and standards,

temperature and pressure measurements and standards; time and frequency, quantum

mpfrnlnnw niiantnm r, hue ire

13. availabTLity

| | Unlimited

|X j For Official Distribution. Do Not Release to NTIS

T Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

!

1 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

15. Price

USCOMM-OC 6043-P90


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