NAT L INST. OF STAND & TECH

NBSIR 84-2857-2

CEKTER run ELECTRONICS hmd

Electrical Ehcxkeerxhc

Techkxcrl Prdcreee Bulletin

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Electronics and Electrical Engineering

Gaithersburg, Maryland 20899

Covering Center Programs, April - June 1983

April 1984

Issued June 1 984

QC I S. DEPARTMENT OF COMMERCE

100 IATIONAL BUREAU OF STANDARDS

U56

04 - 2857-2

1004
INTRODUCTION TO APRIL 1984 ISSUE OF THE CEEE TECHNICAL PROGRESS BULLETIN

This is the third issue of a quarterly abstract journal covering the work of the

National Bureau of Standards Center for Electronics and Electrical Engineering. This

issue of the CEEE Technical Progress Bulletin covers the second quarter of calendar

year 1983.

ORGANIZATION : Abstracts and citations are arranged by technical topic as identified

in the table of contents and alphabetically by first author under each subheading

within each topic. Each abstract ends with a telephone number of the individual to

contact for more information on the topic; unless otherwise noted, this individual is

the first author. Each citation ends with identification of the issue of the

Technical Progress Bulletin in which the associated abstract appeared. This issue

also includes a calendar of Center conferences and workshops for the remainder of

calendar year 1984, an announcement of newly released standard reference materials,

and a list of sponsors of the work. SPECIAL NOTE : Because the four issues covering

calendar year 1983 are later than intended, the contents of these issues will differ

from the original plan of providing abstracts for all papers approved by NBS in a quarter as follows: Each issue will contain (1) abstracts of papers approved for

publication by NBS for the appropriate quarter and not subsequently published until

calendar year 1984, (2) abstracts of papers approved and published during the

quarter, and (3) citations for papers published during the quarter, but for which

abstracts have appeared in an earlier issue of the Technical Progress Bulletin . Items in category (1) appear under the subheading "Approved for Publication"; items

in categories (2) and (3) appear under the subheading "Recently Published."

Center for Electronics and Electrical Engineering : Center programs provide national

reference standards , measurement methods , supporting theory and data, and

traceability to national standards.

The metrological products of these programs aid economic growth by promoting equity

and efficiency in the marketplace, by removing metrological barriers to improved

productivity and innovation, by increasing U. S. competitiveness in international

markets through facilitation of compliance with international agreements, and by

providing technical bases for the development of voluntary standards for domestic and

international trade. These metrological products also aid in the development of

rational regulatory policy and promote efficient functioning of technical programs of

the Government.

The work of the Center is divided into two major programs: the Semiconductor

Technology Program, carried out by the Semiconductor Materials and Processes and

Semiconductor Devices and Circuits Divisions in Gaithersburg, MD, and the Signals and

Systems Metrology Program, carried out by the Electrosystems Division in Gaithersburg

and the Electromagnetic Fields and Electromagnetic Technology Divisions in Boulder,

CO. Key contacts in the Center are given on the back cover; readers are encouraged

to contact any of these individuals for further information.

Previous special issues : Two special issues of the Technical Progress Bulletin have

been published with abstracts for the Signals and Systems Program only, NBSIR 83-

2719-1, covering October 1981 through March 1982 and NBSIR 83-2719-2, covering April

1982 through September 1982. NBSIR 82-2636, a special issue of the Semiconductor

Technology Program Progress Briefs published in January 1983, listed abstracts of

publications from that Program for Federal fiscal year 1982 (October 1981 through

September 1982, fifty-third through fifty-seventh quarters of the Program). The new CEEE Technical Progress Bulletin replaces the Progress Briefs series [single copies

of 82-2636 are available from the Center, see back cover for address!.

Center sponsors : The Center Programs are sponsored by the National Bureau of

Standards arTS a number of other organizations, in both the Federal and private

sectors; these are identified on page 14.
national bureau

OF STANDARDS

T T 5T>y

CEEE Technical Progress Bulletin - April 84 Page 1

TABLE OF CONTENTS

INTRODUCTION inside front cover

SEMICONDUCTOR TECHNOLOGY PROGRAM

Silicon Materials

Integrated Circuit Test Structures

Process & Device Modeling A Power Devices 5

Packaging 5 Other Semiconductor Metrology 5

SIGNALS AND SYSTEMS METROLOGY PROGRAM

FAST SIGNAL ACQUISITION, PROCESSING, & TRANSMISSION 6

Cryoel ectronic Metrology 6

Antenna Metrology 7 Microwave & Millimeter-Wave Metrology 7 Laser Metrology 8

Optical Fiber Metrology 8

Other Fast Signal Topics

ELECTRICAL SYSTEMS 8

Power Systems Metrology 8

Magnetic Materials and Measurements 11

Superconductors 11

Other Electrical Systems Topics 12

ELECTROMAGNETIC INTERFERENCE 12

CEEE CALENDAR 13

NEW STANDARD REFERENCE MATERIALS 14

SPONSOR LIST 14

KEY CONTACTS IN CENTER, CENTER ORGANIZATION back cover
Page 2 CEEE Technical Progress Bulletin - April 84

SEMICONDUCTOR TECHNOLOGY PROGRAM

Silicon Materials

Recently Published

Baghdadi, A., Implicit Apodization of

Interferograms in Fourier Transform

Spectroscopy, Applied Spectroscopy,

37, No. 6, pp. 520-523 (June 1983).

The removal of secondary and tertiary

interferograms from the main interferogram in Fourier transform spectroscopy

can lead to an implicit apodization of

the specimen interferogram. This effect

can result in the generation of unwanted

artifacts in the specimen's transmittance or absorption spectrum. One approach for avoiding this problem is to use an apodization function on the background and reference interferograms

which matches the function used on the

specimen interferogram.

r (301 ) 921-3625]

Lowney, J.R., Larrabee, R.D., and

Thurber, W.R., The Relationship

Between Deep-Level Measurements and

Lifetime in Devices, Proc. 1983 Custom Integrated Circuits Conf., Rochester, NY, May 23-25, pp. 152-156 (1983).

The mi nority-carrier lifetime in silicon

devices affects performance by influencing such lifetime-related quantities as switching times, storage times, and

reverse-1 eakage currents. A computer

program has been developed to model the

behavior of deep-level recombination

centers that control the minority-carrier lifetime. The input parameters

that characterize the deep levels can be

measured by capacitive-transient techniques coupled with a measurement of the

low-injection level lifetime. These

parameters can be used for deep-level

identification and diagnostic purposes

and, as input to the program, for predicting lifetime under different

injection-level conditions. This technique of deep-level characterization is

illustrated for n+p and £

+n_ diodes con- taining deep levels from intentionally

added platinum.

[(301) 921-3786]

Phillips, W.E. and Lowney, J.R.,

Analysis of Nonexponential Transient

Capacitance in Silicon Diodes Heavily

Doped with Platinum, J. Applied

Physics 54, pp. 2786-2791 (May 1983).

An analysis having improved rigor has

been made of the capacitance transient

in a space charge layer due to thermal

emission from charged defect centers in

a semiconductor depletion region. This

analysis extends the range of applicability of capacitance-transient defect

characterization techniques to nonexponential transient conditions such as found in heavily doped diodes or when

defect centers are charged in only a part of the depletion region. An example of the improvement is shown for

three silicon diodes heavily doped with

platinum.

[Contact: Lowney, (301) 921-3786]

Integrated Circuit Test Structures

Approved for Publication

Cassard, J.M., A Sensitivity Analysis

of SPICE parameters Using an ElevenStage Ring Oscillator, to be

published in special joint issue of

IEEE Trans. Electron Devices and the

IEEE J. Solid State Circuits [companion

paper describing first phase of work

given at 1983 Custom Integrated

Circuits Conference, Rochester, NY, May

23-25, 1983 and published in the

proceedings of that conference, under

the title The Sensitivity of SPICE

Simulations to Input Parameter Variations, pp. 224-228 (May 1983)].

SPICE is a circuit simulator which predicts node voltages and currents as a function of time from device model parameters. Model parameters are affected

by the manufacturing process. Process-
CEEE Technical Progress Bulletin - April 84 Page 3

Integrated Circuit Test Struc ., cont'd.

induced variations in these parameters

occur within a chip or from chip to chip

and cause corresponding variations in

circuit performance. Values for the

model parameters used in simulators are usually obtained from test structures

which are found along the periphery of

the circuit or in test chips located at

several sites on the product wafer.

Because of the spatial separation

between test structures and the circuits

of interest, differences between measured and simulated performance can occur. This paper presents examples of

how well input parameters extracted from

a test chip can predict the ac response

of a dynamic circuit element on the same

wafer. Simulation results show which

model parameters are critical to performance. A comparison of measurement and

simulation results is given and the

importance of intra-chip and intra-wafer

parameter variations is discussed. For

the samples tested, the polysilicon gate

linewidth variation was determined to be

the primary cause of the ring oscillator

frequency variation.

[(301) 921-36211

Recently Published

Mazer, J.A., Linholm, L.W., Pramanik,

D., Tsai, S., and Saxena, A.N., Effects of Phosphorus Contact Doping and

Sheet Resistance Variations on A1/S1

Interfacial Contact Resistance, Proc.

Custom Integrated Circuits Conf.,

Rochester, NY, May 23-25, pp. 291-294

(1983).

A microelectronic test structure and

electrical measurement method for the

determination of interfacial contact

resistance Rq and interfacial contact

layer uniformity are described. This

test structure and method are used to

investigate the effects of phosphoruscontact doping and sheet resistance

variations on Rq and on interfacial

layer uniformity. Measurement results

indicate that phosphorus-contact doping

lowers the value of Rq by as much as a

factor of two without sacrificing the

uniformity of the interfacial layer.

The specific contact resistance pc is

shown to be approximately directly proportional to the sheet resistance of the

silicon in the contact window.

[(301 ) 921-3621]

Russell, T.J., Description of a CMOS

Test Chip, NBS-39, NBSIR 83-2683

(April 1983).

Test chip NBS-39 was designed to analyze

the scaling properties of short-channel

metal oxide-semiconductor field effect

transistors (MOSFETs). This report is a guide for identifying and locating each

test structure included on the test

chip. There is a table with each test

structure identified by name, number,

parameter measured, and a reference of

how to perform the measurement when

appropriate. The test chip can be fabricated by a junction-isolated (JI)

silicon complementary metal oxide semiconductor (CMOS) p-well process and by a local oxidation o? silicon (LOCOS) CMOS

p-well process. The modifications re- quired to go from a JI-CMOS fabrication

process to a L0C0S-CM0S are discussed.

[(301) 921-3621]

Suehle, J.S., Linholm, L.W., and

Kafadar, K. , A Method for Selecting a Minimum Test Chip Sample Size to Characterize Microelectronic Process Parameters, Proc. Custom Integrated

Circuits Conference, Rochester, NY, May

23-25, pp. 308-312 (1983).

A method for determining a test chip

sample size to estimate effectively the

electrical parameter distributions on an integrated circuit wafer is presented.

This method gives relations among sample

size and the figure of merit for four

statistical techniques (trimmed mean,

biweighted mean, median, and arithmetic

mean) by which estimates are calculated.

To demonstrate the use of this method,

it has been applied to the evaluation of

a CMOS fabrication process. Measurements on wafers completely patterned

with identical test chips were used to
Page 4 CEEE Technical Progress Bulletin - April 84

Integrated Circuit Test Struc ., cont'd.

determine actual parameter distributions

for an entire wafer (true parameter

values) Estimates of true parameters

were determined using a site selection

plan which is representative of sampling

plans employed in industry. The above

four statistical techniques were used to

compute estimates for electrical parameters and their respective figures of

merit. These estimates were compared

with the true parameter values determined from testing all test chips on the

wafer. When this method is used in

conjunction with the cost criteria for

test chip sample size, it enables judgments to be made on the effectiveness of

sampling strategies for various pro- cesses and process technologies. The

results reported in this paper for CMOS

processes are interpreted for the case when no sample size cost criteria are

given. [(301) 921-3621]

Process and Device Modeling

Released for Publication

Brodfuehrer, B.P., Galloway, K.F., and

Wilson, C.L., Comparison of Simple

Approximations and Numerical Solutions

for the Threshold Voltage of IonImplanted Long-Channel MOSFETs,

submitted to IEEE Trans. Education.

The very simple approximations used for

calculating the threshold voltage shifts

for ion-implanted long-channel MOSFETs

in classroom discussions are compared

with the results of a more exact

numerical simulation. Limited

experimental measurements are compared

with the calculated threshold voltage

shifts.

Recently Published

Albers, J., Wilson, C.L., and Blue,

J.L., Effect of Surface Beveling on Carrier Profiles, Extended Abstracts

of the Electrochemical Society, Vol

.

83-1, pp. 641-642 (1983) [paper given

at Society meeting at San Francisco,

CA, May 8-13, 1983].

The two-dimensional potential distribution is calculated for a beveled structure by means of finite-element techniques. The calculations are presented

for several forms of the dopant distribution as well as a number of choices of

the surface recombination velocity. The

effects of both of these variables on the location of the electrical junction

are presented with particular attention

to the implications of electrical profile measurements. The principal result

of this calculation is that the total

depletion width goes to zero where the

junction intersects the beveled surface.

[(301) 921-3621]

Berkowitz, H.L. and Albers, J., The

Relation Between Two-Probe and FourProbe Resistances on Nonuniform Structures, Extended Abstracts of the

Electrochemical Society, Vol. 83-1,

pp. 622-623 (1983) [paper given at

Society meeting at San Francisco, CA,

May 8-13, 1983].

A general relation between the two-probe

resistance and the four-probe resistance

on nonuniform structures is derived.

Numerical techniques are presented and

discussed for the evaluation of the

equations for nonuniform structures.

The relation between the four-probe

resistance and the incremental sheet

resistance is shown to arise in the

limit as the probe spacing becomes large

compared to the distance to an insulating boundary. Also presented is a method for the self-consistent calibration of spreading resistance profiles.

[(301 ) 921-3621]

Kahn, A.H. and Lowney, J.R., Multiple

Scattering Theory of the Density of

States In Semiconductors, Solid State

Communications, 46, No. 3, pp. 229-233

(May 1983).

A method for calculating the electronic

density of states of a semiconductor in

the presence of impurity scattering is

given. The approach is based on a low
C EE E Technical Progress Bulletin - April 84 Page 5

Process and Device Modeling , cont'd.

density multiple scattering expansion.

The calculation treats the density of

states of the conduction band, shifts of

the band edge, and the profiles of the

impurity bands. It is performed for a simple model, using a spherical well

potential for the individual impurity

centers, but could be extended to any

scattering potential. The first impurity band forms when the potential is

sufficiently strong that one center can bind an electron. The impurity bands

are of finite width, have a flat upper

edge, and an asymmetrically broadened

tail on the low energy side.

[(301 ) 921 -3786]

Power Devices

Recently Published

Chen, D.Y., Lee, F.C., Blackburn, D.L.,

and Berning, D.W., Reverse-Bias

Second Breakdown of High Power Darlington Transistors, Proc. 1983 Power

Conversion International Conf., Orlando

FL, April 19-21, pp. 15-25 (1983) [also

submitted to IEEE Trans. Aerospace and

Electronic Systems].

The reverse-bias second breakdown, RBSB,

characteristics of high power Darlington

transistors are discussed. The Darlingtons investigated are rated at 400 V

maximum voltage and 100 A maximum current. Devices both with and without

speed-up diodes (connected between the

bases of the input and output transistor) were studied. A nondestructive

system for characterizing the RBSB behavior of these devices is described.

The RBSB behavior was found to vary in an unpredictable manner with varying reverse base current magnitude. It was also found that the RBSB behavior of the

Darlingtons was a function of the forward base current magnitude. This is in

marked contrast to what has been found

for discrete devices. The presence of a speed-up diode also influenced the RBSB

behavior of these devices.

[(301) 921 -3541]

Packaging

Recently Published

Zimmerman, D.D. and Schafft, H.A.,

VLSI Package Reliability Workshop Report, 21st Annual Proc., Reliability

Physics 1983, pp. 310-232 [Reliability

Physics Symposium, Phoenix, AZ, April

5-7, 1983].

This report summarizes remarks made by

six panelists in an evening workshop

meeting held as part of the 1983 International Reliability Physics Symposium.

The panelists provided an overview of

package design and measurement considerations that arise because of special

requirements of packaging VLSI semiconductor chips. Considerations in the

following areas were discussed: package

materials, design, and construction;

thermal management and characterization

and moisture and hermeticity measurements.

[Contact: Schafft, (301) 921-3621]

Other Semiconductor Metrology

Approved for Publication

Dodge, M.J., Refractive Properties of

Magnesium Fluoride, submitted to

Applied Optics.

The refractive indexes of a commercially

available specimen of single-crystal

MGF^ were determined for both the

ordinary and extraordinary rays at

selected wavelengths from 0.2026 to

7.04 yin. Measurements were made by

means of the minimum-deviation method on

a precision spectrometer near 19°C.

The experimentally determined index

values for each polarization were

fitted to a three-term Sel lmei er-type

dispersion equation of the form:

n 2

- 1 = z Aj

X

2

/ (

X

2

- Xj 2

),

relating the refractive index n to the

wavelength of interest X, the calculated
Page 6 CEEE Technical Progress Bulletin - April 84

Other Semiconductor Metrology , cont'd.

wavelength Aj . The birefringence was computed as a function of wavelength

from the calculated index values

obtained for the two polarizations. The

dispersion coefficients were also

determined for the 0-ray and for the

birefringence. The results of this

study are compared with previously

reported work on the refractive properties of MgF2«

[(301) 921-3625]

Recently Published

Baylies, W.A., Scace, R.I., and ViewegGutberlet, F., International Standards for Semiconductor Materials,

ASTM Standardization News, 11, No. 5.

pp. 21-23 (May 1983).

Semiconductor silicon is an internationally traded commodity which requires

sophisticated characterization procedures for producer's quality control and

purchaser's incoming inspection tests.

International coordination at the technical committee level, being pursued by

ASTM Committee F-l on Electronics, to

create a technically consistent set of

test methods throughout the world is

described. Some further topics for

international collaboration in test

method development are also mentioned.

[Contact: Scace, (301) 921-3786]

FAST SIGNAL ACQUISITION, PROCESSING, AND

TRANSMISSION

Cryoelectronic Metrology

Recently Published

Hamilton, C.A., 100 GHz Binary Counter

Using SQUID Flip Flops, Proc. Applied

Superconductivity Conf., November 30 - December 3, 1982, IEEE Trans. Magnetics, MAG-19, No. 3, pp. 1291-1292 (May

1983) [abstract appeared on page 11 of

July 1983 TPB ( NBSIR 83-2719-3)].

Hamilton, C.A. and Lloyd, F.L., 8-Bit

Superconducting A/D Converter, Proc.

Applied Superconductivity Conf.,

November 30 - December 3, 1982, IEEE

Trans. Magnetics, MAG-19, No. 3, pp.

1259-1261 (May 1983) [abstract appeared

on page 12 of July 1983 TPB (NBSIR 83-

2719-3)].

Harris, R.E. et al.. Microwave Mixing

and Direct Detection Using SIS and SIS1 Quasiparticle Tunnel Junctions, Proc.

Applied Superconductivity Conf.,

November 30 - December 3, 1982, IEEE

Trans. Magnetics, MAG-19, No. 3, pp.

490-493 (May 1983).

Quasiparticle mixers have shown strong

quantum effects, conversion gain and

noise levels approaching the quantum

limit, but only in tunnel junctions with

very low sub-gap "leakage" conductance.

It has been suggested that SIS' tunnel

junctions, made from two different con- ductors with unequal gaps, will function

as high-gain mixers since the dynamic

conductance below the gap is negative.

We report results of the first SIS'

mixing and direct detection experiments.

At 36 GHz, a conversion efficiency of

-4 dB with a noise temperature of 33 K (SSB) has been obtained. A novel gain

mechanism for SIS' direct detectors is

predicted. A direct detector responsivity of 250 A/W was measured. We

compare our results to quantum theory

models. In addition, we demonstrate

quasiparticle harmonic mixing of a 36-GHz signal with an 18-GHz local os- cillator in tin SIS junctions. Harmonic

mixers offer significant advantages at

high micro-wave frequencies at which

sufficient local oscillator power may

not be available.

[(303) 497-3776]

Kautz, R.L., Chaos In Josephson

Circuits, Proc. Applied Superconductivity Conf., November 30 - December 3,

1982, IEEE Trans. Magnetics, MAG-19,

No. 3, pp. 465-473 (May 1983) [abstract

appeared on page 12 of July 1983 TPB

(NBSIR 83-2719-3)].
CEEE Technical Progress Bulletin - April 84 Page 7

Cryoel ectronic Metrology , cont'd.

Kautz, R.L., Operation of a Superconducting Analog -to-digl tal

Converter at Short Conversion Times,

Proc. Applied Superconductivity Conf.,

November 30 - December 3, 1982, IEEE

Trans. Magnetics, MAG-19, No. 3, pp.

1186-1189 (May 1983) [abstract appeared

on page 12 of July 1983 TPB (NBSIR 83-

2719-3)1.

VanZeghbroeck , B.J., Superconducting

Current Injection Transistor, App.

Phys. Lett. 42(8), pp. 736-738 (April

1983) [abstract appeared on page 12 of

July 1983 TPB (NBSIR 83-2719-3)].

Antenna Metrology

Recently Published

Hill, D.A., Book Review - Leaky

Feeders and Subsurface Radio Communications, IEEE Antennas and Propagation Society Newsletter, Vol . 25, No.

3, pp. 23-24 (June 1983) [abstract

appeared on page 13 of July 1983 TPB

(NBSIR 83-2719-3)].

Yaghjian, A.D., Approximate Formulas

for the Far Fields and Gain of OpenEnded Rectangular Waveguide, NBSIR

83-1689, May 1983.

Approximate formulas are derived for the

far field and gain of standard, openended, unflanged, rectangular waveguide

probes operating within their recom- mended usable bandwidth of frequencies.

(Such probes are commonly used in making

probe-corrected near-field antenna mea- surements. )

The formulas, which yield forward farfield power patterns and on-axis gains

of X-band and larger waveguide probes to

within about 2 dB and 0.2 dB accuracy,

respectively, assume (sin<j> - cos<}>)

azimuthal angular dependence and an Eplane pattern given by the traditional

aperture integration of the TE

mode E-and H-fields in the Stratton-Ch8

equations. The H-plane pattern is

estimated by two different methods. The

first, and less accurate, method uses a purely E-field aperture integration to

estimate the H-plane pattern. The

second, more accurate, method uses an electric field integral equation (EFIE)

to show that fringe currents near the

shorter edges of the guide can be wellapproximated by isotropic line sources.

The amplitude of these line sources is

then determined more simply by equating

the total power radiated into free space

to the net input power to the

waveguide.

[(303) 497-5484]

Microwave & Millimeter-Wave Metrology

Recently Published

Engen, G.F., Redundance: A Monitor of

Six-Port Performance, U.K. Institute

of Electrical Engineers 1983 Colloquium

on Advances in S-Parameter Measurement

at Microwave Lengths, May 23, 1983,

Savoy Place, London WC2B0BL, pp. 4/1-

4/2 (1983).

By almost any standard of comparison,

today's automated network analyzers

represent a highly complex and sophisticated measuring instrument, with its own

set of maintenance problems and potential failure modes. While certain types

of malfunctions are immediately evident

to the operator, there may be others

whose effect is less obvious.

One of the more interesting features of

the six-port network analyzer is that

its response is "overdetermined" in the sense that four (scalar) detectors are employed to obtain three pieces of

information — namely the emergent wave amplitude and the complex reflection

coefficient as they exist at the mea- surement port. With proper interpretation, this additional piece of information can be used, not only to improve

the overall accuracy, but also as a continuous monitor of the system performance, and to flag a very large fraction

of potential malfunctions. (While some reference to this feature has been made
Page 8 CEEE Technical Progress Bulletin - April 84

Microwave & Millimeter-Wave , cont'd.

in earlier papers, it apparently is

still not fully appreciated by the microwave community).

[(303) 497-3511]

Laser Met r ology

Recently Published

Sanders, A. A., Laser Measurements,

Proc. 1983 Measurement Science Conf.,

Palo Alto, CA, January 20-21 (June

1983) .

This talk will review some of the

national standards and measurement ser- vices for lasers available at NBS, highlight some of the current research, and

indicate some of the future needs and

direction of NBS laser metrology

research.

[(303) 497-5341]

Optical Fiber Metrology

Recently Published

Gallawa, R.L., Chamberlain, G.E., Day,

G.W., Franzen, D.L., and Young, M.,

Measurement of Multimode Optical Fiber

Attenuation: An NBS Special Test

Service, NBS Technical Note 1060,

(June 1983) [abstract appeared on page

15 of July 1983 TPB ( NBSIR 83-2719-3)].

Gallawa, R. and Franzen, O.L., EIA

Fiber Performance Measurement

Standards, Photonics Spectra, pp.

55-68 (April 1983).

This paper reviews optical waveguide

test procedures and techniques that are approved by, or in review for, the Electronics Industries Association (EIA).

We concentrate on those procedures and

documents to which we have been a party,

either directly or indirectly. In particular, we discuss a glossary of terms,

fiber attenuation, fiber bandwidth, and

refractive index profile, the last of

which leads to a determination of core diameter. [(303) 497-3761]

Kim, E.M. and Franzen, D.L., TwoDimensional Near-Field Contouring of

Optical Fiber Cores, Proc. SPIE -- The International Society of Optical

Engineering (June 1983) [abstract

appeared on page 8 of May 1983 TPB

(NBSIR 83-2719-2)].

Other Fast Signal Topics

Recently Published

Danielson, B.L., Optical Time-Domain

Reflectometer Performance and Calibration Studies, NBS Technical Note

1065 (June 1983).

The measurement accuracy of the optical

time-domain reflectometer (OTDR) is

restricted in some applications by a limited operational dynamic range and by

a lack of standardized test procedures.

In an effort to better understand these

restrictions, we have measured the range

of linearity of some avalanche photodiodes used as backscatter detectors.

Also, the effect of input launch conditions is examined and a possible standardized OTDR test procedure is proposed. Using these suggestions, we have

made comparisons between attenuation

values determined by cutback and backscatter methods and found that good

agreement is possible. Finally, some methods are described for checking the

response linearity of OTDR systems.

[(303) 497-5620]

ELECTRICAL SYSTEMS

Power Systems Metrology

Released for Publication

Hillhouse, D.L., NBS Experience, Field

Calibration of CCVTs, Proc. Workshop

on Metering Accuracy CCVTs, June 2-3.,

1983, to be published by Electric

Power Research Institute.

Since its completion in 1976, the EPRINBS field calibration system for

coupling capacitor voltage transformers
CEEE Technical Progress Bulletin - April 84 Page 9

Power Systems Metrology , cont'd.

(CCVTs) has been in NBS custody and has

been used in field calibrations at six

utilities. Measurements have been

performed on 61 CCVTs, including 51 of

metering class (12 of which were not

using the X1X3 metering tap) and on nine

metering VTs. This paper discusses the

measurements at the six utilities, and

summarizes all zero burden and connected

burden results on metering windings. A

large proportion of these CCVTs were

found to be out of metering tolerance at

both zero and connected burdens.

However, the data base is not large

enough to allow extension of these

results to metering CCVTs in general.

[(301) 921-3121]

Hi 1 1 house , D.L., The EPRI-NBS CCVT

Calibration Systems, Proc. Workshop

on Metering Accuracy CCVTs, June 2-3,

1983, submitted to Electric Power

Research Institute (EPRI). *

This paper describes briefly a prototype

system for field calibration of CCVTs

developed by NBS in EPRI project RP-134-

1, and in more detail, a simplified,

less costly system developed later with

partial support from the Pennsylvania

Power and Light Co. The latter system

was breadboarded as part of the above

EPRI project.

The prototype system contains five major

dedicated components: (1) a currentcomparator bridge, (2) a modular capacitive transfer standard divider, (3) a compressed-gas standard capacitor, (4) a resonant power supply and (5) a calibration truck. Its field accuracy is estimated to be 0.1% and 0.3 mrad, but it

would be very expensive to reproduce.

The simplified system contains only

three major components: (1) the transfer standard divider mentioned above,

(2) a voltage comparator, and (3) a combined standard-power transformer

module. The latter two items represent

much lower cost and weight than those of

items (2), (3), and (4) in the prototype

system, which they replace. The dedicated truck could then be eliminated as well, and the entire system transported

to the field in a non-dedicated truck

and a van. The accuracy of the simplified system is comparable to that of

the prototype.

[(301) 921-3121]

McKnight, R.H., Measurements of DC

Electric Fields and Ion Related Quantities, submitted to Proc. Conference

on Environmental Ions and Related

Biological Effects.

Measurement techniques developed by

atmospheric scientists for characterizing the earth's electrical environment

are useful for measuring various electrical parameters near high voltage dc

(HVDC) transmission lines. Parameters

of primary interest are the electric

field, vertical current density, and

polar space charge density. Other quantities which have been measured include

conductivity, net space charge density,

and the mobility spectrum of ions making

up the space charge.

Errors associated with the various mea- surements are discussed, including those

which result from the high electric

fields and space charge densities existing near the lines. In addition, these

measurement techniques are being used to

characterize the operation of biological

exposure systems.

[(301) 921-3121]

McKnight, R.H. and Fulcomer, P.M.,

Operation of Ion Counters Near High

Voltage DC Transmission Lines, submitted to Proc. Fourth International

Symposium on High Voltage Engineering.

Measurements of electrical quantities

such as electric field, vertical current

density, and space charge density are necessary to characterize the electrical

environment around high voltage dc

transmission lines. Ion counters are used to measure space charge densities.

A monopolar line has been used in the

laboratory to study the effects of
Page 10 CEEE Technical Progress Bulletin - April 84

Power Systems Metrology , cont'd.

external electric fields on the

operation of ion counters located above

ground. Space charge densities were determined as functions of counter air

flow, electrical potential, and inlet

geometry. The effects of counter

potential were not large until the

potential was approximately equal to

that of the space potential near the

counter, when the indicated ion density

dropped significantly. A dependence of

flow rate was observed, which appears to

be due to the large external electric

fields existing at the inlet to the ion

counter causing a loss of ions to the

counter walls at lower flow rates.

[(301) 921-3121]

Misakian, M. and Ful comer, P.M.,

Measurement of Nonuniform Power

Frequency Electric Fields, submitted

to IEEE Trans. Electrical Insulation.

The performance of free-body electric

fieldmeters which have been calibrated

for use in nearly uniform power frequency electric fields is examined under

nonuniform field conditions. Theoretical and experimental results are presented which indicate that measurements

can be made with small error.

[(301) 921-3121]

Recently Published

Hebner, R.E., Development of Power

System Measurements — Quarterly

Report July 1, 1982 to September 30,

1982, NBSIR 83-2705 (May 1983).

This report documents the progress of

four technical investigations sponsored

by the Department of Energy. Three were performed by the Electrosystems Division, the National Bureau of Standards

and the fourth by the Department of

Electrical Engineering of the University

of Southern California. The work described covers the period from July 1,

1982 to September 30, 1982. The report

emphasizes the calibration of

instruments designed to measure the 60-

Hz electric field in biological exposure

facilities, the determination of the

role of photodetachment of SFg corona discharges, the measurement of failure

mechanisms in liquid/solid insulating

systems, and the development and behavior of active insulators.

[(301) 921-3121]

McKnight, R.H., Kotter, F.R., and

Misakian, M., Measurement of Ion

Current Density at Ground Level in the

Vicinity of High Voltage DC Transmission Lines, IEEE Trans. Power

Apparatus & Systems PAS-102, No. 4, pp.

934-941 (April 1983).

Sensors for measuring vertical current

density at ground level near high voltage dc (HVDC) transmission lines are subject to error when the sensor is not

in the ground plane. The magnitude of

this error, for guarded and unguarded

sensors, has been investigated using

both dc electric fields with space

charge and ac electric fields in a parallel plate facility. For conditions

like those expected under HVDC transmission lines, the results obtained

using ac and dc methods agreed to within

experimental uncertainty. The measured

errors are as large as 25 percent for

guarded sensors and significantly larger

for unguarded sensors. Data for various sensor elevations and guarding are presented in graphs to aid the designer.

Comparisons with results from an IEEE

Working Group field day are also presented.

[(301) 921-3121]

Van Brunt, R.J. and Misakian, M., Role

of Photodetachment In Initiation of

Electric Discharges In SFg and

02» J. Applied Physics 54, No.

6, pp. 3074-3079 (June 1983).

The role of photodetachment in the initiation of electron avalanches near a positive point electrode was investigated for a discharge gap in which the

negative ion flux was controlled by UV

irradiation of the cathode. For irradiation of the anode region with light
CEEE Technical Progress Bulletin - April 84 Page 11

Power Systems Metrology , cont'd.

beams up to 500 mW, photodetachment was found to make a negligible contribution

to avalanche initiation in SF6 and 0

2 at

pressures from 50 to 500 kPA (~0.5 to 5 atm). The conditions under which the

role of photodetachment might be observed are discussed, and it is shown

that for the conditions considered here

the expected dominant electron release

mechanism in the gap is through collisional detachment of stable negative

ions. Previously reported enhancements

in avalanche rates resulting from

irradiation of a positive point can be

explained as arising from increases in

negative ion densities due to attachment

of photoelectrons ejected by scattered

radiation,

f (301) 921-3121]

Magnetic Materials and Measurements

Recently Published

Cromar, M. and Muhlfelder, B., Double

Transformer Coupling to a Very Low

Noise SQUID, Proc. Applied Superconductivity Conf., IEEE Trans.

Magnetics, MAG-19, No. 3, pp. 303-307

(May 1983).

We demonstrate a new way to couple

efficiently to a low-inductance, lownoise SQUID. We have built and tested a planar dc SQUID with an integral

matching transformer. The measured

coupling agrees with our calculations.

We demonstrate that this configuration

can efficiently couple a 1 pH signal source to a 16 pH SQUID loop. We have

also built an uncoupled SQUID of this

design that has an energy sensitivity,

referred to the S0UID inductor, of

1.3 x 10-* 2 J/Hz = 20 h over a flux

range of about 0.15 4> 0

. [(303) 497-5375]

Fickett, F.R. and Goldfarb, R.B.,

Magnetic Properties, Chapter 6 in

book. Materials at Low Temperatures,

American Society of Metals, Metals

Park, OH 44073, pp. 203-235 (June 1983)

[abstract appeared on page 18 of July

1983 TPB ( NBSIR 83-2719-3)].

Superconductors

Recently Published

Ekin, J.W., Effect of Stainless Steel

Reinforcement on the Critical Current

Versus Strain Characteristic of Multifilamentary Nb

3 Sn Superconductors, J.

Applied Physics 54 (5), pp. 2869-2871

(May 1983) [abstract appeared on page

14 of May 1983 TPB (NBSIR 83-2719-2)].

Ekin, J.W., J-B-T-e Interaction in

A15, Bl, and C15 Crystal Structure

Superconductors, Proc. Applied

Superconductivity Conf., IEEE Trans.

Magnetics, MAG-19, No. 3, pp. 900-902

(May 1983) [abstract appeared on page

18 of July 1983 TPB (NBSIR 83-2719-

3)].

Ekin, J.W., Superconductors, Chapter

13 in book. Materials at Low

Temperatures, American Society of

Metals, Metals Park, OH 44073, pp. 465-

513 (June 1983) [abstract appeared on page 13 of May 1983 TPB (NBSIR 83-2719-

2 )].

Fickett, F.R., Oxygen-Free Copper at

4K, Proc. Applied Superconductivity

Conf., IEEE Trans. Magnetics MAG-19,

No. 3, pp. 228-231 (May 1983) [abstract

appeared on page 18 July 1983 TPB NBSIR

83-2719-3)].

Gavaler, J.R., Greggi , J., Wilmer, R.,

and Ekin, J.W., Properties of NbN

Films Crystallized from the Amorphous

State, Applied Superconductivity

Conf., IEEE Trans. Magnetics, MAG-19,

No. 3, pp. 418-421 (May 1983) [abstract

appeared on page 18 of July 1983 TPB

(NBSIR 83-2719-3)].

Goodrich, L.F., The Effect of Field

Orientation on Current Transfer in

Multifilament ary Superconductors

,

Proc. Applied Superconductivity Conf.,

IEEE Trans. Magnetics, MAG-19, No. 3,

pp. 244-247 (May 1983) [abstract
Page 12 CEEE Technical Progress Bulletin - April 84

Superconductors , cont'd.

appeared on page 18 of July 1983 TPB

( NBSIR 83-2719-3)].

Hong, M., Hull, G.W., Jr., Holthuis,

J.T., Hazzenzahl, W.V., and Ekin, J.W.,

Multi -filamentary Nb-Nb, Composite by

Liquid Infiltration Metnod: Superconducting, Metallurgical, and Mechanical

Properties, Proc. Applied

Superconductivity Conf., IEEE Trans.

Magnetics, MAG-19, No. 3, pp. 912-916,

(May 1983) [abstract appeared on page

19 of July 1983 TPB (NBSIR 83-2719-3)].

Other Electrical Systems Topics

Recently Published

Clark, A.F., Thermal Expansion,

Chapter 3 in book. Materials at Low

Temperatures, Eds. R. Reed and A.F.

Clark, American Society for Metals,

Metals Park, OH 44073, pp. 75-132 (June

1983).

The thermal expansion behavior of materials at low temperature is reviewed.

The tutorial chapter describes the theory, experimental methods, typical data,

and sources and applications of data for

thermal expansion. Materials covered

are metals and alloys, nonmetal lie com- pounds, glasses and ceramics, polymers,

and composites.

[(303) 497-3253]

Fickett, F.R., Electrical Properties,

Chapter 5 in book. Materials at Low

Temperatures, Eds. R. Reed and A.F.

Clark, American Society for Metals,

Metals Park, OH 44073, pp. 163-201

(June 1983)

.

This chapter gives a review of the electrical properties of materials at cryogenic temperatures. Measurement techniques, the data base, and uses of the

data are presented. The emphasis is on metals and alloys of technological importance; a topic which covers a large

range of materials. The treatment of

theory and of measurement techniques is

primarily for the user interested in the

more practical aspects. In every instance, however, extensive references

are given that allow the reader to pur- sue the subject further. The text is

essentially that of NBS Technical Note

1053 with minor modifications.

[(303) 497-3785]

ELECTROMAGNETIC INTERFERENCE

Recently Published

Kanda, M., An Electric and Magnetic

Field Sensor for Simultaneous Electromagnetic Near-Field Measurements

Theory, NBS Technical Note 1062

(April 1983).

This paper describes the theory of a single sensor to perform simultaneous

electric and magnetic near-field mea- surements. The theory indicates that it

is possible to obtain the magnetic-loop

and electric-dipole currents using a loop terminated with identical loads at

diametrically opposite points. The

theory also indicates that it is possible to obtain an ideal load impedance

for achieving equal electric and magnetic field responses of the loop.

Preliminary experiments have been performed using plane waves to verify these

results.

[(303) 497-5320]

Kanda, M. and Ries, F.X., Time Domain

Sensors for Radiated Impulsive Measurements, IEEE Trans. Antennas and

Propagation, AP-31, No. 3, pp. 438-444

(May 1983) [also given as paper by

Kanda and Ries at the IEEE 1982

International EMC Symposium, Santa

Clara, CA, September 8-10, 1982, pp.

296-301; abstract appeared on page 5 of

May 1983 TPB (NBSIR 83-2719-2)].

Ma, M.T. and Koepke, G.H., Uncertainties in Extracting Radiation

Parameters for an Unknown Interference

Source Based on Power and Phase

Measurement, NBS Technical Note 1064

(June 1983)

.
CEEE Technical Progress Bulletin - April 84 Page 13

Electromagnetic Interference , cont'd.

A method for determining the radiation

characteri sties of a leaking interference source has been reported in a previous publication, in which the

unintentional, electrically small leakage source was modeled by two vectors

representing a combination of equivalent

electric and magnetic dipole moments.

An experimental setup, measurement procedures, and the necessary theoretical

basis were all described therein to

explain how the relevant source parameters can be extracted from the measurement data of output powers and phases

taken when the interference source is

placed inside a transverse electromagnetic ( TEM) cell. Simulated examples

were also given to show that the equivalent source parameters of unknown vector

dipole moments and, thus, the detailed

radiation pattern and the total power

radiated by the source in free space

could be uniquely determined by the

method if the measurement data were not

contaminated by noise. This report

presents the mathematical analysis of

the uncertainties in the final,

extracted results when the experimental

data are degraded by the background

noise and measurement inaccuracies.

[(303) 497-38001

CEEE CALENDAR

1984

April 30 - May 4 (Boulder, CO)

NBS Noise Measurement Seminar. The

course is intended for practicing noise

metrologists and technical managers

responsible for systems for which

accurate noise measurements are

important. The seminar introduces and

describes reference noise sources, noise

measuring systems, and the problems of

characterizing and measuring noise in

passive components, amplifiers, and

satellite earth terminals. Class

examples will specifically address the

measurement of noise power; amplifier

noise; and antenna system noise,

including measures such as noise

equivalent flux, the ratio of system

gain to system noise temperature G/T,

and the ratio of carrier power to noise

density C/kT.

The course will cover both theory and

practice of precision noise measurements; the practical lectures are

designed to stand alone and to be

understood by those having minimal

mathematical background.

[Contact: Sunchana Perera (303)

497-35461

June 18-21 (Gaithersburg, MD)

Power Electronics Specialists

Conference. Co-sponsored by the

National Bureau of Standards and the

Power Electronics Council of the

Institute of Electrical and Electronics

Engineers, the Conference is intended to

provide a venue where specialists in

circuits, systems, electron devices,

magnetics, control theory, instrumentation, and power engineering may

discuss new ideas, research,

development, applications, and the

latest advances in power electronics.

The Conference will incorporate six

technical sessions (on converter

circuits, converter systems, converter

control, motor drives, power components,

and modeling and analysis techniques),

a one-day tutorial on Electromagnetic

Compatibility in Power Systems, and

three special "rap sessions" (EMI, RFI,

and Noise: Fact or Fiction Emerging

Power Semiconductors: Positive and

Negative Attributes; and Future Trends

in Aircraft Power Electronics and

Electrical Actuators).

[Contact: Sandra B. Kelley (301)

921-3541]

October 2-3 (Boulder, CO)

Symposium on Optical Fiber Measurements.
CEEE Technical Progress Bulletin - April 84 Page 14

CEEE CALENDAR, cont'd.

This symposium, the third in the series

of biennial meetings, is co-sponsored by

the National Bureau of Standards, the

Optical Society of America, and the

Optical Waveguide Communications

Committee of the Institute of Electrical

and Electronics Engineers. Papers have

been solicited "for any experimental or analytical aspect of the characterization of optical fibers and fiber optics

systems, including attenuation,

bandwidth/distortion, dispersion, index

profile, cut-off wavelength, mode

diameter/core geometry, fiber device

(e.g., joint, coupler, multiplexer)

evaluation, physical measurements, link

parameters (e.g., concatenation),

polarization characteristics, system

performance, field measurements, and

standards."

[Contact: Douglas L. Franzen (303)

497-3346]

NEW STANDARD REFERENCE MATERIALS

Two new Standard Reference Materials

(SRMs) for calibrating equipment used to

make spreading resistance measurements

have been released by the Semiconductor

Materials and Processes Division to the

NBS Office of Standard Reference

Materials for sale to the public. SRM

2526 applies to (lll)-oriented p-type

silicon surfaces and SRM 2527 to Tlll)-

oriented n-type silicon surfaces. Each

SRM consists of a set of about 15

specimens (number of specimens varies

depending on availability of material of

appropriate resistivities) of silicon,

6 x 12 mm in area and mounted on beveled

metal blocks for convenient use in

calibrating commercial spreading

resistance equipment. These silicon

chips have resistivities ranging from

about 0.001 to 200 ft*cm. Slices are measured before dicing; only slices

having uniformity of resistivity within

predetermined bounds are selected. The

uncertainties in resistivity range

typically from 2 to 5 percent for p-type

specimens and from 4 to 10 percent; for

n-type. Two companion SRMs for (110)

silicon surfaces are about to be

released (2528, p-type and 2529, n- type)

.

SPONSORS OF WORK REPORTED IN THIS ISSUE

National Bureau of Standards

Department of Defense

Defense Advanced Research Project

Agency; Calibration Coordination

Group; Defense Nuclear Agency

U.S. Air Force

Bolling Air Force Base; Kirtland

AFB; Newark Air Force Station; Space

Division; Wright-Patterson AFB

U.S. Army

Aviation Research & Development

Command; Fort Huachuca; Fort Monmouth; Materials & Mechanics

Research Center; Redstone Arsenal

U.S. Navy

Aviation Logistics Center (Patuxent

River); Medical Research & Development Command; Metrology Engineering

Center (Seal Beach); Naval Air Systems Command; Naval Ship Research & Development Center; Naval Sea Systems Command; Naval Surface Weapons

Center; Naval Weapons Support Center

(Crane); Office of Naval Research

Department of Energy

Bonneville Power Administration;

Energy Systems Research; Fusion

Energy

Department of Justice

Law Enforcement Assistance

Administration

Department of Transportation

National Highway Traffic Safety

Admi ni st rat ion

Environmental Protection Agency

International Copper Research

Association

Sandia Laboratories
NBS»H4A (rev. 2 «ec> U.5. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions) ±

1. PUBLICATION OR

REPORT NO.

NBSIR 84-2857-2

2. Performing Organ. Report No. 3. Publication Date

June 1984

4 . TITLE AND SUBTITLE

Center for Electronics and Electrical Engineering Technical Progress Bulletin,

Covering Center Programs April - June 1983 and Current 1

-98 4 CEEE Calendar*

5. AUTHOR(S)

Compiler: J. Franklin Mayo-Wells

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8 . Type of Report & Period Covered

April - June 1983

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

U.S. Department of Commerce

National Bureau of Standards

National Engineering Laboratory

Center for Electronics and Electrical Engineering

10. SUPPLEMENTARY NOTES

All technical information included in this document has been approved for

publication previously.

[ 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 si gn i fi cant

bi bl iography or literature survey, mention it here)

This is the third issue of a quarterly abstract journal covering the work of the

National Bureau of Standards Center for Electronics and Electrical Engineering.

This issue of the CEEE Technical Progress Bulletin covers the second quarter of

calendar year 1983. Abstracts are provided by technical area for both published

papers and papers approved by NBS for publication.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) antennas; electrical engineering; electrical power; electromagnetic interference;

electronics; instrumentation; lasers; magnetics; microwave; optical fibers;

semiconductors; superconductors.

13. AVAILABILITY

Uni i mi ted Qj For Official Distribution. Do Not Release to NTIS

J Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[X Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

18

15. Price

$7.00

UlCOMM-DC
CENTER FOR

ELECTRONICS AND ELECTRICAL ENGINEERING

H

Applied Electrical Measurements

Electronic Instrumentation and Metrology

I Antenna Systems

I Metrology

I Fields

I Characterization

I Interference

I Characterization

HMicrowave Metrology

JOptical Electronic

I Metrology

H

Cryoelectronics

Metrology

Superconductors

and Magnetic

Materials

KEY CONTACTS

SEMICONDUCTOR

MATERIALS AND

PROCESSES

DIVISION H

H

Silicon Characterization

Process Control Measurements

i Micrometrology

H

Compound

Semiconductor HProcessing Facility

SEMICONDUCTOR

DEVICES AND

CRCUfTS

DIVISION

4

Integrated

Circuit Test

Structures

Device and

Process

Modeling

Device

Metrology

NBS/CEEE/FEB 84

Center (720)

Director

Deputy Director

Administrative Officer

Electrosystems Division (722)

Chief

Electromagnetic Fields Division (723)

Chief

Electromagnetic Technology Division (724)

Chief Dr. Robert A. Kamper (303) 497-3535

Semiconductor Materials and Processes Division (725)

Chief Mr. Robert I. Scace (301) 921-3786

Semiconductor Devices and Circuits Division (726)

Chief Dr. Kenneth F. Galloway (301) 921-3541

Mr. Judson C. French (301) 921-3357

Dr. Alvin H. Sher (301) 921-3357

Ms. Carol P. Mullis (301) 921-3357

Dr. Oskars Petersons (301) 921-2328

Mr. Charles K.S. Miller (303) 497-3131

INFORMATION:

For additional information on the Center for Electronics and Electrical

Engineering, write to or call:

Center for Electronics and Electrical Engineering

National Bureau of Standards

Metrology Building, Room B-358

Gaithersburg, Maryland 20899 Telephone (301) 921-3357

USCOMM-NBS-DC