Publications

A11102 32<n31

NAT'L INST OF STANDARDS & TECH R.I.C.

A1 11 02329939

/NBS research reports QC100 .U57 SP 680-3;1985 C.1 NBS-PUB-R JBS Research

Reports

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBS SPECIAL PUBLICATION 680-3

100

J57

580-3

.1985
Cover photo: This 300,000-

volt simulated lightning bolt was produced under controlled conditions in the NBS

high-voltage measurement

laboratory where researchers

help utilities and manufacturers determine what will happen to their equipment if it is struck by lightning. See

page 12.
CONTENTS

NATIONAL BUREJ OF STANDARDS

LIBRARY

NBS

Research

Reports

Research Update 2 NBS Research on Polymer Composites: Laying the Scientific Foundation for Industrial Advance 4

Searching for the More Vital Volt, the Apter Ampere 8

Evaluating Volts, Jolts, and Lightning Bolts:

All in a Day's Work at NBS 12 NBS Fire Research is Framework for Safer Buildings 15 The Making of the Advanced Heat Pump:

Research to Influence the Marketplace 19 Measuring the Two 'Personalities' of Ozone 21 New Ultraviolet Wavelength Standards Will Aid Astronomy 24

Calibrations for the Space Telescope 28

NBS Program Boosts Quality of Clinical Measurements 29

New Publications 30

Conference Calendar 32

U.S. DEPARTMENT OF COMMERCE

Malcolm Baldrige, Secretary

National Bureau of Standards

Ernest Ambler, Director

National Bureau of Standards

Gaithersburg, MD 20899

301/921-1000

National Bureau of Standards

Boulder, CO 80303

303/497-3000.

July 1985 NBS Special Publication 680-3 Prepared by the Public Information Division Sharon Shaffer, Editor A903 Administration Building National Bureau of Standards

Gaithersburg, MD 20899

301/921-3181

Library of Congress

Catalog Card Number:

85-600549

CODEN: XNBSAV

Any mention of commercial products

is for information only; it does not imply recommendation or endorsement

by the National Bureau of Standards

nor does it imply that the products mentioned are necessarily the best

available for the purpose

1
RESEARCH UPDATE

ORE ACCURATE MEASUREMENT OF ROBOT

PERFORMANCE STUDIED

NBS researchers are devel- oping a new, automated

laser-interferometer tracking system

which could be the basis for greatly im- proved measures of the performance of a wide variety of industrial robots. The re- search prototype makes continuous position measurements while the robot is moving at its normal working pace. The

position measurements include not only the three spatial dimensions, but also the

pitch and roll of the robot wrist. Right now, says NBS researcher Kam

Lau, the industry suffers because there is no real agreement on how the per- formance of such machines should be

measured. "Each company has its own

terms and standards for robot per- formance, and they are very loosely defined," explains Lau. "We are trying to come up with a series of terms, based on

our experience with machine-tool measurements, that will be well-defined and

include all the relevant factors in robot performance."

The finished full system device should

be able to measure the position of an in- dustrial robot arm, in motion, to an accuracy of 1 part in 100,000. Such a device, Lau says, will be about 100 times more

accurate than the best device now avail- able and easier to use. Other applications for the measurement technology in- clude assessing the accuracy of milling

machines, lathes, and coordinate

measuring machines.

ECURITY OF ELECTRONIC

FUNDS TRANSFERS TO BE

IMPROVED

The more than $500 billion in federal government collections and payments and $2.5 trillion in federal

securities that are transferred electronically each year will be better protected as the result of an agreement signed by

NBS, the Department of the Treasury,

and the National Security Agency (NSA).

The agreement outlines each agency's

2

responsibilities for putting security methods in place by June 1, 1988, as specified in a recent Treasury Department di- rective. The directive states that federal electronic funds transfers be sealed using the NBS Data Encryption Standard.

Treasury also plans to use an auto- mated system for managing the cryptographic key used to seal the data. One

NBS-developed feature of this system

notarizes the key with the names of the sender and intended receiver. Based on

technical guidance from NSA and NBS,

Treasury will certify that electronic funds

transfer devices are designed properly

and that security features called for in the directive have been incorporated.

NBS will develop test methods to vali- date that the devices comply with the standards in the directive.

BS OPENS NEW HIGHINTENSITY GAMMA-RAY

FACILITY

A new high-intensity 60 Co

gamma-ray irradiation facility for high-dose dosimeter calibration work

has been set up at NBS. The sample

chamber of the new source is 6 inches in diameter and 8 inches high. The ab- sorbed dose rate at the center of the chamber is about 14 kilograys, or 1.4 megarads, per hour. Irradiation times can be preset and terminated automatically.

NBS will use the facility to speed highdose calibration services, but the facility

will also be made available to outside us- ers for research programs in dosimetry,

radiation chemistry, radiation processing,

and the like. For information on scheduling, write or call Dr. James Humphreys,

C216 Radiation Physics Building, National Bureau of Standards, Gaithersburg,

MD 20899, 301/921-2201.

BS FILM AVAILABLE

A 13j-minute color film is now

available that describes how

the National Bureau of Standards uses its measurement expertise to work cooperatively with industry, universities, and

other government agencies to help im- prove U.S. productivity and increase in- dustrial competitiveness. The film, "Measurement: The Vital Link," can be rented

from Modern Talking Picture Service,

Inc., 5000 Park Street North, St. Petersburg, FL 33709, 813/541-5763, for $15

in 16-mm film, 1-in u-matic videotape,

^-in VHS videotape, or i-in BETA II videotape.

EGRADATION OF DENTAL

COMPOSITES INVESTIGATED

In work for the National Insti- tute of Dental Research, NBS

researchers are investigating

various polymer matrices and inorganic

fillers to improve the performance of dental composites. They are looking at surface treatments of filler materials to better the corrosion resistance and overall wear. To date, NBS polymer scientists have discovered evidence that inorganic

reinforcing fillers used in dental composites corrode. Previously it was

thought that the problem with polymer

composite restorations was due primarily

to degradation of the polymer matrix. Recent NBS investigations on commercial

dental composites, conditioned in a simulated oral environment, show signs of dramatic decreases in mechanical wear

resistance. This is attributed to corrosion

of the inorganic filler material, particularly

radiopaque fillers.

ECHNIQUE FOR STABILIZING

DYE LASERS IMPROVED

Scientists at NBS and Stanford

University have developed an

improved laboratory technique

for stabilizing the frequency of tunable dye lasers. The technique makes use of a novel frequency transducer which combines an electro-optic phase modulator

and an acousto-optic frequency shifter outside the laser cavity. In initial experiments, the researchers have reduced the

linewidth of a commercial continuous wave dye laser from about 3 MHz to about 120 kHz with a frequency servo system based on sending the laser out- put through the transducer. This tech- nique eliminates the disadvantages of other methods, which can be too slow to compensate for the frequency fluctu- ations in a typical dye laser, inconvenient, or the cause of power loss.
A recent report terms the new trans- ducer "a versatile device which can

greatly facilitate the generation of ex- tremely monochromatic light." The device can be used with different lasers without modifying them to include lossy

elements inside the laser cavity. With mi- nor additions, the system can also pro- vide intensity stabilization or amplitude/

frequency modulation.

AMPLES TO HELP OIL INDUSTRY DETECT REFINERY

"POISONS"

Two of the chemical elements

that can impair the petroleum

refining process—vanadium and nickel

should be easier to measure reliably with a new Standard Reference Material (SRM) now available from NBS. Designed as a tool for checking the accuracy of a wide range of analytical chemistry instruments, the SRM contains

certified concentrations of the two ele- ments at the concentration levels that can cause problems for refiners if present in crude oils and other refinery

products. At these levels, heavy metals

like vanadium and nickel can "poi- son"—and possibly cancel—the refining process by reacting with catalysts. With a

reliable analysis of content, refiners can

adjust the vanadium and nickel in re- finery fuels to tolerable levels. The SRM

can also be used to analyze such materials as coal-derived oils, kerosene, eth- anol mixtures, or jet fuel. SRM 1618,

Vanadium and Nickel in Residual Fuel

Oil, is available for $103 from the Office

of Standard Reference Materials, B311

Chemistry Building, National Bureau of Standards, Gaithersburg, MD 20899,

301/921-2045.

CONOMIC IMPACT OF

AUTOMATION RESEARCH

ANALYZED

The contribution of the NBS

Automated Manufacturing

Research Facility (AMRF) to the in- creased use of numerical-control machine tools in U.S. industry will produce a

savings to the metalworking industry of between $72 and $219 million per year

by 1988, according to a report prepared

by the Management Collaborative Group

of Chapel Hill, N.C. The study of the ex- pected technical and economic impact of the Bureau's automation research pro- gram also predicts that this increased use of numerical-control machine tools

will save the metalworking industry up to $250 to $760 million each year by 1990. The AMRF, according to the report, "ap- pears to be playing a key role in laying the groundwork for incremental implementation of computer-integrated auto- mated manufacturing by supporting the establishment of standard interfaces be- tween pieces of equipment, and between

integrated equipment and a central control system, and by providing the means

and methods of in-processing

measurement."

The facility includes vertical and hori- zontal machining workstations, a turning

workstation, an automated inspection

workstation, and the robotic equipment

for a cleaning and deburring workstation. Equipment for the last workstation is ex- pected to be in place by this fall. Over

$2.75 millon worth of the equipment in the AMRF was loaned or donated to NBS by companies sponsoring research

at the facility.

ATENT AWARDED FOR NEW

DISPOSABLE RADIATION

DOSIMETER

A trio of researchers from NBS,

the Federal Emergency

Management Agency, and the U.S. Army

have been awarded a patent

(#4,489,240) on a new design for a

unique, disposable radiation dosimeter

that is expected to be particularly useful

in radiation therapy. The dosimeter is a

thin plastic tube (as thin as 0.8-mm outer diameter) containing a radiochromic dye

which takes on a color in proportion to the amount of radiation received. Be- cause this dosimeter has the same re- sponse to radiation as body tissue, it accurately measures the dose received by

the patient. A transparent plug at one

end of the tube and a mirror at the other make it possible to measure the degree

of color change by reflecting a light beam through the dosimeter. The dye

dosimeter at the end of a fiber optic cable can be placed in specific regions of the body through a conventional catheter. According to the inventors, the do- simeter can be used to make remote measurements of radiation dose to an accuracy of 5 percent—as the dose is being delivered. Improvements are ex- pected to push the accuracy to 2 or 3 percent.

CIENTISTS REPORT FIRST

TRAPPING OF NEUTRAL

ATOMS

NBS researchers Alan Migdall,

John Prodan, and William

Phillips, working with Thomas Bergeman

and Harold Metcalf of the State University of New York at Stony Brook, have

completed what is believed to be the first successful experiment in "trapping" neutral atoms. The experiment, in which neutral atoms were confined in a magneticfield trap, is an important advance in the technology of atomic physics. The re- searchers built on their success in using

laser beams to decelerate and actually

stop neutral sodium atoms to confine a sample of the atoms in a magnetic trap

for at least a second.

"Traps," which use arrangements of electromagnetic fields to hold atomic particles in an observation region for signifi- cant lengths of time, are an important

tool in atomic physics. Accurate measurements of the properties and behavior

of atoms and atomic particles through

techniques such as spectroscopy are lim- ited by the speed of the particle. This de- velopment opens the possibility of a new

generation of experiments in atomic

physics. Among the new opportunities are measurements of previously un- measurably long atomic lifetimes or studies of collisions with very small rates.
hey are light of weight, ounce for ounce up to five times stronger

than steel, and immune to rust. They are easily molded or shaped

during processing, an advantage

to product designers as well as

manufacturers. In final form, they can be rigid and tough enough to serve as a bridge strut, a building

support, an auto part, or an

airplane wing.

They are a relatively new class

of materials called synthetic poly- mer composites, and yes, indeed,

they are very versatile. But their commercial development is being

retarded by the absence of basic

knowledge—such as a funda- mental understanding of how the

variables of the manufacturing process affect the properties of the finished materials. "These are very complex materials," says Dr. Donald Hunston, a polymers physical chemist with the National Bureau of Standards.

"And, they are, in many ways,

poorly understood, sometimes to the point that manufacturers can't get reproducible results from the

fabrication process. "The difficulties are sur- mountable," Hunston says. In fact the NBS polymer composites

group, which he heads, is making

considerable progress in some of the measurement-related aspects

of the problem.

The group consists of a core of

six NBS researchers, augmented

by scientists and engineers from

other organizations. They are studying the component materials

of composites before processing,

exploring what happens during

processing and how that affects material performance, and in- vestigating how the finished materials behave and fail.

The Market Picture

Today in the United States, poly- mer composites are a $1.3 billion industry, accounting for 5 percent

of the entire polymer market. The

annual growth rate of the polymer

market overall is 5 percent, but polymer composites are growing

at double that rate. "Advanced"

composites—those used in place

of traditional engineering materials such as steel—are growing at a rate of 16 percent a year. In the

April 22, 1985, issue of Chemical

Dr. Donald Hunston, polymers

physical chemist, uses a mechanical testing instrument to study crack growth in advanced polymer matrix

composites to improve the

strength of resin materials.

and Engineering News, Anthony

J. Cardinal, vice president of Du Pont's Textiles and Fibers Department, says advanced composites could grow at the rate of 30 percent a year, to $10 billion
by the year 2000, in the air- craft, aerospace, automotive, in- dustrial, and orthopedic markets. With such robust market per- formance, what could possibly be

ailing this industry? Hunston explains, "In many areas it operates

almost on a custom production,

rather than a mass production,

basis. The current high rate of growth cannot continue unless

manufacturers can increase the speed and reduce the cost of production and improve the reliability of the finished materials. To accomplish these things, they

have to acquire the theoretical and data bases needed to im- prove processing and to predict a

material's performance and life expectancy." Not uncommonly, manufacturers of advanced polymer

composites have to reject from

10 to 20 percent of the materials they produce. They simply cannot

get predictable, reproducible results, especially when they try to accelerate processing. One major

American corporation reports that 80 percent of one of the aero- space parts it produces is re- jected by the company's production line quality-control system.

Each rejected part must be re- viewed individually, by an expert,

to determine whether it is acceptable.

To a large extent, at present, the market for advanced polymer

composites is the U.S. government. The Defense Department

and the National Aeronautics and

Space Administration (NASA) in particular require the advantages,

especially the one-third to onehalf reduction in weight, that poly- mer composites offer over tradi- tional materials. To no surprise, the Department of Defense and

NASA operate large polymer

composites laboratories, and col- lectively they fund a large fraction

of NBS' work. Hunston foresees,

however, that the commercial

market could soon overshadow

government demand, particularly

if improvements in processing

and performance can be

achieved.

More on Polymers

Whether organic or inorganic, natural or synthetic, a polymer is a polymer because of the size and

internal structure of its molecules. Smaller molecules join chemically

in one or more chains of repeating units to form a larger polymer

molecule. The spiraling double

chain of DNA represents one of an infinite variety of possible

structural arrangements.

The overall size of a polymer

molecule and its internal arrangement—both the sequence

of the components and their spatial relationship—impart certain properties to the material. They

account for the brittleness of glass, the gooiness of protoplasm, the resilience of seat

cushions, the elasticity of rubber

tires, and the toughness of bowling balls. The synthetic polymer industry

began with the development of Bakelite in 1909. Synthetic poly- mer composites started to appear

in the 1940's but the advanced,

high-performance composites

used today are a more recent de- velopment. Essentially, they consist of a polymer matrix, such as an epoxy resin, reinforced with

particles or fibers of a different material. The reinforcing agent

contributes certain mechanical

properties to the finished material,

such as improved tensile strength—the extent to which a

material withstands a load without

tearing apart.

Military planes are now up to 27 percent by weight, 38 percent

by volume polymer composites.

Some commercial aircraft are al- ready polymer composites in the

following proportions: 3 percent

by weight and 5 percent by vol- ume. The potential in these air- craft may be 65 percent by

weight, 76 percent by volume, but only if composites become pre- dictable enough for use in critical load-bearing applications.

While aerospace applications

have been the biggest engine

driving innovation and growth in the advanced polymer composites industry, Earth-bound

applications—from car bodies to dental fillings—also abound. And

here, on Earth, lies the greatest

potential for commercial advance. Hunston says NBS wants to help

industry to exploit this potential

fully.

The Central NBS Program

"On a selective basis, and on a

laboratory scale, we are coming

at the problem from both ends

processing and performance," Hunston says. "We look at the chemical and physical properties

of the constituent materials—the

matrix resin and the particles or

fibers—before processing. We

monitor the curing processes as- sociated with fabrication of composites at the molecular level and

higher levels to find out exactly

what's happening. Finally, we

measure the performance of fin- ished composites, all the way to

failure. In all aspects of this work, we watch what happens to the

material's microstructure."

In the NBS Boulder, Colo., lab- oratories, several researchers are

looking independently at certain aspects of the polymer composites: how they are affected by

exposure to radiation or ex- tremely low temperatures and

how the progress of internal
Hardener 1—

Curing Process

Deuterium

Labeled Epoxy

Network Formation

Giving Matrix Material

of Polymeric Composites

Disordered Network

Disordered Network

l l

I 1_ .00 .075 .15 .23 .30 .37 .45 .52 .60 .67 .75 .80 Q (A- 1

) Function of scattering angle

NBS researchers are developing methods for predicting how and to what extent the molecular net- works of a thermoset polymer will be ordered,

depending on its constituents and the processing variables. The graph above shows how

closely data on network structure from an NBS

neutron-scattering experiment follow the pre- dicted curve. To acquire such data, researchers

first label an epoxy monomer with deuterium

atoms (top). Neutrons scattered off deuterium

reveal the spatial position of the atoms of an average network. Ordered networks produce a scattering pattern with distinctive peaks;

disordered networks produce a featureless

background.

cracking, which researchers monitor by nondestructive means, re- lates to the material's ultimate

failure. These efforts complement

the studies being carried out by

Hunston's group in the Polymers

Division at NBS' Gaithersburg,

Md., site. His group is looking at both types of polymer composites: the high-performance thermosets in

which the matrix material polymerizes during fabrication and the thermoplastics which are made

from a matrix polymerized prior to fabrication. The reinforcing materials that become embedded in the matrix during the curing

process—materials such as glass

or graphite—may come in particle or fiber form, and the fibers can

be long or short. In general, the longer the fiber, the stronger and

stiffer the composite.

The researchers at NBS are monitoring the curing processes

that take place in composites during fabrication to find out what

changes occur in chemical, physical, and mechanical properties;

how these changes relate to the performance of the finished product; and how the curing process can be controlled. They use six laboratory techniques to monitor

changes during processing:

Fourier-transform infrared spectroscopy for studying chemical re- actions; dielectric spectroscopy,

optical-wavegude fluorescence,

and small-angle neutron scattering for studying molecular mobility; and dynamical-mechanical

testing (shaking the material and

using the internal movements to determine the relationship be- tween applied stress and the re- sulting strain) and ultrasound for studying mechanical properties.

Several of these techniques may

be applicable, after further devel- opment, to commercial quality control or automation of manufacture.

The polymer composites group

also wants to elucidate the behavior of polymer composites in use, relate that behavior to the

properties of the constituent materials and the variables of the

curing process, and develop

mathematical models for predicting (and thus controlling) per- formance. Basic studies are being

carried out in five general areas:

1) characterizing the constituent

materials of a composite in terms

of physical and mechanical properties and structure—both molecular structure and gross structure (voids and other defects); 2) re- lating the characteristics of the

constituents to the curing pro- cess; 3) studying the interface be- tween the matrix and the reinforc- ing material; 4) characterizing the

properties of the finished composite; and 5) synthesizing experimental data into a predictive theoretical model.

Cooperative Research

As part of its research program, NBS is carrying out several cooperative projects. In one such ef- fort with the Air Force, researchers at NBS are measuring the molecular properties of innovative new polymers that contain rodlike polymer molecules instead of

'...they have to acquire

the theoretical and data

bases needed to improve

processing and to predict

a material's performance

and life expectancy."

long fibers. The Air Force wants

to achieve the advantage of a

short-fiber composite

specifically its ease of processing—without sacrificing the high performance of the long

fibers. The main challenge is to get a homogeneous distribution of the rod-like molecules throughout

the matrix material during pro- cessing, but the first hurdle is to develop a definitive technique for measuring their distribution. At the moment, nuclear magnetic resonance is the primary tech- nique under consideration. NBS is studying delamination at the behest of several other federal agencies. Delamination is the

failure of a polymer composite by

the separation of its constituent

layers, for one of two reasons:
cracks growing in the matrix that holds the layers together or cracks growing along a boundary

of the matrix and the fiber material.

In one study for NASA, the Bureau is developing test methods to characterize resistance to delamination in composites. In a

project for both NASA and the Navy, NBS researchers are looking for ways to prevent delamination by using thermoplastic resins or by toughening the matrix materials through the use of polymer additives such as rubber

particles.

Several projects with the American Dental Association are aimed at developing and testing

filled-polymer composites (resins reinforced with particles rather than fibers) as dental restorative materials.

Ideally, Hunston says, manufacturers might one day predict—

and therefore control—the per- formance of a finished composite on the basis of the known properties of the "raw" materials and

the control of variables in pro- cessing, such as temperature,

pressure, humidity, and cure time.

"It will never be quite that simple," Hunston admits, "but this technology can be brought under

control. "We are just scratching the sur- face in some of these areas," Hunston allows. "But we are making progress. We're on the way."

by Julianne Chappell

NBS Writer-Editor

Wanted: Industry Researchers

to Join NBS Polymer Composites Program

Reply to: Dr. Leslie Smith

A305 Polymer Building

National Bureau of Standards

Gaithersburg, MD 20899

301/921-3734.

The time is ripe for manufacturers to join the NBS poly- mer composites program by

sending their researchers to work with NBS scientists and

engineers, says Dr. Leslie Smith, chief of the Polymers

Division. "Firms stand to gain a good

deal by joining us at this time,"

he says. "They can get a head

start in both basic knowledge

and technical know-how."

Private companies can avail themselves of this opportunity

through the NBS Research Associate Program. Under this program, researchers from in- dustry, who are paid by their parent companies, have free access to NBS facilities and

the benefit of collaborating

with Bureau staff. Likewise,

NBS programs are enriched by

the expertise of outside re- searchers, and research

results are made public.

The Bureau is actually taking the initiative in polymer composites research supporting

commercial applications on

behalf of industry. NBS is the

only federal laboratory ex- pressly empowered by Congress to use public resources

for such a purpose. And it has

done so in many areas over

the last 85 years, with particularly notable success in materials research. Some U.S. industries—like optical glassgot their start in NBS laboratories. For many others, NBS

has developed a solid foundation of data, measurement

technology, and standards. That foundation is what the young polymer composites in- dustry lacks, according to Dr. Donald Hunston, head of the NBS polymer composites

group. Providing this missing

base involves long-term basic

research and the development

of test methods and Standard

Reference Materials.* "The

work is too far removed from

product development for in- dustry," he explains. Hence

the need for NBS to take the

initiative. But, as Hunston emphasizes, companies and uni- versities are encouraged to

take an active part in the NBS

program and to help determine

its direction. "We have several researchers from universities working

with us now," Hunston says. "We also have direct inter- actions with more than 30

companies and many universities through visits, seminars,

and other forums, plus we ex- change written information. NBS, NASA, and Hercules,

Inc., have a formal cooperative

arrangement for sharing materials and information and publishing together. Other companies, including Martin Marietta,

B.F. Goodrich, and Texaco,

participate in this arrangement

on an informal basis."

* Standard Reference Materials are

materials samples characterized and

certified by NBS as to certain physical

or chemical properties or composition. They are sold by the NBS Office of Standard Reference Materials to cus- tomers in science and industry for use

in calibrating measurement systems.

For more information, write or call the

Office of Standard Reference Materials, B311 Chemistry Building, National Bureau of Standards, Gaithersburg. MD

20899, 301/921-2045.
3

he more honest ohm.... They're the units used to measure electricity: the volt of potential, the ampere of current, the ohm of resistance, the farad of capacitance. You probably

thought that somewhere there was someone who knew exactly

how much each of those

amounted to. After all, you get

billed for the stuff (in kilowatt- hours, which involves volts, amps,

and time.) Not exactly. But there are people who have a very good idea how much. And they'd like to have an even better idea. They work for the National Bu- reau of Standards. Many people

think of measurement standards as something to be put in neat

glass display cases, tended by

employees in white lab coats carrying feather dusters. That's not

the way it works at NBS, where

"maintaining" measurement stan- dards means keeping up with

and frequently creating—new ad- vances in science and

technology.

Standards of measurement are

rather transient. The official meter

this year, the basis for all length

measurements in the United

States, is not what it was 2 years

ago, thanks in large part to research at NBS.

The Bureau goes to a great deal of time and trouble to im- prove the way we measure

things. Nowhere is this more true than in the field of electrical measurements, where the most accurate standards possible are needed for applications ranging

from basic physics research to the construction of sophisticated

navigation and defense systems.

Electrical engineer Bruce Field (sitting) and physicist Marvin

Cage use an automated system developed at NBS to monitor

the quantum Hall resistance phenomenon against the electri- cal resistance standard maintained by NBS. The quantum Hall effect may become the basis for a new standard of electrical

resistance based on fundamental neutral constants.

There are official definitions for these things, but they are not the

sort that you can use every day.

Take the ampere. By international agreement, its definition is in terms of the constant current

flowing through two infinitely long,

infinitely thin, parallel wires (in a vacuum) that would produce a

certain amount of force per unit

...at NBS, ..."maintaining"

measurement standards

means keeping up with—

and frequently creating

new advances in science

and technology.

length between them. Practical problems make such a definition cumbersome to use every day.

Instead, national standards lab- oratories like NBS develop ways

to approximate the legal defini- tions of these units. The result is an "as-maintained" unit, which

differs somewhat from the official definition. Just how much of a dif- ference can be a difficult thing to measure. The typical (estimated)

difference between an "as maintained" electricity unit at NBS and

the international definition is in the neighborhood of a few parts per million (ppm). To put that in perspective, a ppm is about the

difference 1 inch makes over the course of 16 miles.

" 'As-maintained units are a convenience," explains Dr. Bruce

Field, an electrical engineer with the NBS Center for Basic Standards. "They are picked because

they are stable—they don't change much with time—and they are easier to achieve than more

basic measures.

"For example, at NBS the 'as- maintained' volt hasn't changed

by as much as 0.1 ppm over the

last 13 years. During that time, we've tried to measure that volt against the international definition
to determine how far off it is. We

think the difference may be about

9 ppm, but because of uncertainties in the values used in the

definition, we only really know that

it's somewhere between 7 and

1 1 ppm. We would say that the

precision of the 'as- maintained'

volt is about 100 times better than the accuracy with which we

can implement the official definition."

Do It Yourself Standards

For the past few years, according

to Field, the trend at NBS has

been toward intrinsic standards

for electricity. There are a lot of opinions about what constitutes an intrinsic standard. In general, says Field, it's a standard that relies on nothing but some very fun- damental properties like the basic constants of nature (such as the speed of light). A device that can measure some quantity directly in terms of its internationally agreed- on definition is also considered an intrinsic standard.

In any event, an intrinsic stan- dard definitely does not depend

on some particular, unique object.

The great thing about intrinsic standards is that there can be so many of them, and all the same. Between 1910 and 1972, the volt, as far as the United States was

concerned, was measured in terms of a set of wet electro- chemical cells kept at NBS. If you

wanted to calibrate something in terms of the U.S. volt, your device

(and sometimes you) travelled to NBS.

In 1972, NBS converted to an

intrinsic standard for the volt—the Josephson junction, based on the Josephson effect. The Josephson

effect is an elegant physical phe- nomenon. You start with a comparatively simple superconductor

device, made much the same way

integrated circuits are. You put in

an electrical current at a very ac- curately known frequency, and

the device produces a constant

voltage which you can calculate very accurately from the fre- quency and the ratio between two

constants of nature (the charge on an electron [e] and Planck's constant [h]). You can get the same standard

wherever you have access to ac- curate frequencies, which is al- most anywhere in the world. This

makes the volt standard a lot more portable, and the new

standard is more stable as well. "Anytime you find a new stan- dard with improved stability," says Field, "you can improve the accuracy of your measurements, even with the old standard. Before we had the Josephson ef- fect, we had to maintain the volt with a collection of electro- chemical cells—at one time, as many as 44. The only way to test

their stability was to measure them against each other and try to make corrections. After we

started making measurements

against the more stable Josephson effect, we discovered

that the set as a whole had been

drifting down in value ever so

slightly."

The discovery of intrinsic stan- dards like the Josephson junction

is nice, but rare and difficult to

predict. The Josephson effect ap- peared on the physics scene

quite unexpectedly in the 1960's, the work of a very talented British graduate student.

In 1980, something similar happened to the standard for electrical resistance, the ohm. A Ger- man researcher, von Klitzing, showed that a particular re- sistance, called the "Hall re- sistance," generated by a current

flowing in a semiconductor, could be calculated under special cir- cumstances in terms of our old friends h and e, or equivalently, in terms of another string of basic

Current in Current out

Voltmeter

Shown is the a.c. Josephson effect, as used in maintaining the constancy of the U.S. legal volt. Microwaves of fixed, accurately known frequency

irradiate the junction of two superconductors

(the temperature is near absolute zero) separated

by a thin nonconducting film. If the current is increased steadily from zero, voltage remains

zero until a critical current, when the voltage

jumps to Av, a small value determined by the

microwave frequency. At a somewhat greater current, the voltage rises suddenly to 2* Av, and so on—rising in a series of equal steps. At any point,

the voltage is some whole number times Av. By setting the current so that it is in the range

where the voltage is some specified multiple,

n*Av, we always obtain the same voltage, to a high degree of precision. This voltage is then

compared with the voltages of NBS standard cells.

constants: the speed of light, the electromagnetic permeability of a vacuum, and the "fine structure constant," which has to do with the energy levels of electrons in an atom. Since 1930, the NBS standard

for resistance has depended on a

set of 10 standard resistors. NBS

researchers, in common with measurement specialists around

the world, seized on von Klitzing's

phenomenon—now called the "quantized Hall effect" —as a new opportunity for an intrinsic standard and by 1983 had devel- oped it to a sufficient degree that

9
Above is the advanced cur- mm feialacTic® used! iiini MKS

experiments to determine the

v®hm ©fi She ampere,

Researcher Pi Thomas Onsen

adjusts the balance wheel ©if tih© mstrumeeitt, which 5s housed! "m a feiWafmedl host to reduce external influences.

The coils carrying the electrical current during the eapero-

-n i r Ih 1 i immediately below the bal- ance mechanism.

it could be used to check the stability of the NBS ohm and elimi- nate a drift in the standard of about 5 parts in 100 million per

year.

What's in Store?

Today, NBS researchers are at work on a variety of fronts to keep the nation's electrical stan- dards at "the state of the art."

The Josephson junction is an

excellent standard, but it pro- duces extremely low levels of voltage (around 5 thousandths of a volt at best), at least for practical purposes. National standards

laboratories use collections of Josephson junctions, from a couple up to about 20, each with its own source of current and each

individually "biased" (sort of like tuning). They are hooked up in series to raise the total voltage of the standard. But even that leaves you far below the 1 -volt level where most calibrations have to be performed.

Researchers at the NBS

Boulder, Colo., laboratories, working with colleagues from the West

German national standards laboratory, have developed ways to produce up to 1,500 Josephson

junctions linked on a single

integrated-circuit chip that can

"Intrinsic standards offer

the possibility that anyone who wants one can have a standard for voltage or resistance or whatever that is equivalent to the national standard right there in their

plant."

produce reliable 1 -volt voltage standards. They now are running

tests on the stability and accuracy

of their handiwork, with hopes of having it become the U.S. standard for voltage in about a

year. The quantized Hall effect is still so new that, according to Field, "we don't yet completely under- stand why the effect works." NBS

research has shown that as long as the Hall effect device is kept
What's a Microvolt

Here or There?

Electrical standards at 1 part

in 10 million. Who needs that sort of ac- curacy? One of the major con- sumers of electrical measurements at the ultimate

levels reached by the National Bureau of Standards are re- search physicists, particularly

those interested in such ar- cana as the theory of quantum

electrodynamics (QED).

QED, one of the basic theories of modern physics, describes the fundamental behavior of electromagnetism on

an atomic scale. It is perhaps

the most successful scientific theory in history, since experi- ments to verify the predictions

of QED have found no discrepancies even when pushed to

limits of modern technology.

Interestingly, it turns out that both our ability to make predictions based on QED theory

and our ability to test those

predictions depend to a surprising extent on extremely ac- curate values for the basic

electrical units. Thus experi- ments on the quantized Hall

effect, for example, serve not

only to refine our standard for electrical resistance but also

to refine our understanding of

the basic mechanisms of the

universe. Improvements to the electrical standards maintained by

NBS also have an ultimate ef- fect on more prosaic customers. The best available accuracy for instruments used "in the field" depends on the best

available accuracy at the laboratory that sets the standards, even if the field instruments

generally operate at a level far below that of a standards lab. The best digital multimeters

of today, basic tools for elec- tronics engineers, operate at levels of precision and accuracy that would have been im- possible to test without im- provements in the NBS

standards over the last few

years.

Intrinsic electrical standards

are even more important be- cause they offer users the

possibility of on-the-spot electrical standards at the same

level of accuracy as those at NBS.

Military systems designers,

for example, could conceivably use on-board Josephson junctions to keep inertial navigation

systems at the necessary lev- els of accuracy.

cold enough—it functions within a degree of absolute 0—the effect

is independent of the actual device being used, but there are still some unknowns in the process. NBS researchers are studying

the behavior of quantized Hall devices made from different materials to learn if there are any un- expected differences in the

devices' behavior and to deter- mine how stable the devices are over time. They also are doing an experiment to measure the official value

of the farad, the unit of electrical capacitance. This can be done to about 0.05 ppm, and given a value for the farad and a stan- dard frequency, you can get a

value for the international ohm

that can be compared with the

Hall resistance standard. The pro- cess takes a couple of years to complete, which helps to explain

why such experiments are run only about once in a decade.

As a practical, day-to-day

matter, with a working standard

for the volt and one for the ohm,

you can calculate the value of the ampere. However, NBS scientists are working on two different methods for measuring the inter- national ampere. At the moment

that value is known to little better than 10 ppm, but the Bureau hopes to push that to 0.1 ppm.

In a way, NBS is hard at work

putting itself out of the electrical standards business. As Dr. Barry

Taylor, who supervises the re- search in this area at the NBS

labs in Gaithersburg, Md., explains,

"Right now our measurement

system is a hierarchy. NBS cali- brates standards for primary laboratories, they calibrate standards

for secondary labs, and so on down the chain. Each step costs you something in accuracy. But as some industries, particularly in electronics, require better and

better accuracy in their measurements, you may have to im- prove the system by eliminating some or all of the middlemen.

"Intrinsic standards offer the

possibility that anyone who wants one can have a standard for volt- age or resistance or whatever

that is equivalent to the national standard right there in their plant.

You could do away with the old concept of calibration chains. Conceivably you could remove

the need for a National Bureau of Standards, at least for

electrical calibrations."

by Michael Baum

NBS Public Affairs Specialist
e are all familiar with the annoy- ance of electrical power blackouts. Lights flicker and die. The

TV quits. And the family makes a mad dash for candles and flashlights. More importantly, vital ser- vices such as traffic control and

residential heating are disrupted.

Often, lightning is the culprit. For most of us, lightning is a dangerous and frightening phenomenon, as well as the cause of occasional inconveniences. But researchers at the National Bu- reau of Standards are using

lightning-like pulses as a high- tech tool to help utilities and manufacturers define how well their equipment will hold up if struck by

lightning.

Such predictions require an ex- tremely accurate and reliable sys- tem of measurement, something

that is an NBS specialty. Here, re- searchers are working for and

with industry, universities, and

other government agencies in a newly expanded high-voltage

measurement facility. They tackle problems ranging from lightning bolts to fluctuating currents in machines used to weld metal

shipping containers. In each case, NBS performs a special measurement service unlike that of other electrical measurement

laboratories around the country.

Take lightning for example. To

evaluate the response of power

equipment when it is hit by light- ning, private laboratories routinely create simulated versions of light- ning bolts—pulses that last only a few millionths of a second (microseconds). But since the instru- ments needed to measure these

"bolts" would be destroyed by

such high voltages, the laboratories use a voltage divider to re- duce the simulated lightning to a few hundred volts. NBS gets into the act because utility test operators need to know how the di- viders will respond to high

voltages before they can be used.

12

Because NBS is one of the few

places in the world where voltage

dividers can be specially cali- brated, utilities, manufacturers,

and other laboratories turn to the Bureau for these very accurate measurements. With an accurate measurement base traced to NBS, the effect of lightning on

utility equipment could possibly

be predicted before a disastrous blackout occurs. The Bureau facility also is being

put to use for examining the pheDr. Robert Hebner adjusts a unique NBS device that optically measures electrical fields

and space charges in highvoltage insulating systems. nomenon known as "break- down." While that word may

prompt the image of a car stalled helplessly by the side of the road,

NBS researchers know "break- down" as another curse they are
helping the electric utility busi- ness to investigate: the sudden

failure of an insulator to insulate. Such a failure could cause damage at a power plant or substation, which would require ex- pensive repairs and leave per- haps hundreds of thousands of customers without electricity. Thus utility companies, and agencies that regulate them, are inter- ested in reliable measurements of

just how well an insulator can do

its job. At NBS, amid a bank of controls, monitors, and test devices,

researchers work out highly specialized measurement standards

that permit utilities and other lab- oratories to test with confidence

insulators, electrical outlets, light- ning arresters, and even citizens- band antennas. Since NBS is not a regulatory agency, Bureau re- searchers develop the test methods, then turn the results over to others, who often adopt these

test methods as voluntary, private sector standards. To study insulating materials,

which may be solids (paper, for example), liquids (oil), gases (air), or combinations of these (oil and

paper are used in many trans- formers), NBS researchers con- nected them to a huge machine

with rows of softball-sized electrodes. Called a standard light- ning generator, this machine can

energize an insulating material with as much as one-half million

volts. The idea is to create a tran- sient voltage, which simulates

what might happen to the insulator if the substation were subjected to rapid increases in volt- age or struck by a bolt of

lightning. With specialized instru- ments, NBS researchers measure

the effectiveness of the insulator and evaluate the accuracy of test equipment used by the utility companies.

Utilities have become especially interested in the per- formance of gas insulators in re- cent years because of the many

gas-insulated substations that have been built nationwide.

These facilities use a gas, such

as sulfur hexafluoride, to insulate transformers, high-voltage cables,

and switches. Though the substations are compact and fairly in- expensive to build, breakdown is of particular concern because

ideal conditions are present for the transient voltages that prompt

failure. To study these gas insulators,

NBS uses a nanosecond (billionth of a second) transmission line—

a

long, tubular device that allows

transient voltage signals and their effects to be observed in a controlled situation. NBS researchers

and utility representatives expect

this research to lead to more ef- fective insulators as well as to a

This dramatic series of highspeed motion picture images

shows how an insulating oil can break down in a trans- former at a power substation.

Each frame represents 10 bil- lionths of a second. In frame

1, an anchor-shaped lightning

bolt begins at the upper (negative) electrode. Frame 2

shows the beginning of

another bolt from the lower

(positive) electrode. By frame

3, the bolt has made contact

from positive to negative, and

in the remaining frames, the

characteristic lightning is formed. The dark cylinder

surrounding the bolt is the

shock wave or thunder.

better understanding of the conditions under which existing insulators will perform more

reliably. Though utilities and other in- dustries often use the NBS facility, the Bureau has many of its

In each case, NBS performs a special measurement service unlike

that of any other electrical measurement

laboratories around the

country.

own projects which aim to im- prove the science of voltage and

current measurements. In one

such study, NBS researchers are comparing voltage and current measurements made with conventional equipment to those pro- duced with newer electro-optical

and magneto-optical devices. They also are investigating how

well standard voltage and current measurements can be simulated on a computer. Such computer

13
modeling could save both time

and money.

A laboratory like the Bureau's,

with its variety of equipment and

experienced staff, is a boon to many industries, universities, and

other federal agencies. "We have

a lot of demand from industry to accept guest workers because

they need a facility of this kind to do their work," says Dr. Robert E. Hebner, who manages the facility

in the NBS Center for Electronics and Electrical Engineering.

One such client, the Exxon Research and Engineering Company

(ER&E), is studying electrical breakdown in the oils used as in- sulators in transformers. With an

elaborate high-speed photography system that runs at a speed

equivalent to 20 million frames

per second, researchers are making accurate measurements of precisely when breakdown occurs

after a voltage is applied to the

oils under study. "NBS has the

specialized equipment we need

for our work," says Eric Forster, a

scientific adviser for ER&E who

has collaborated with NBS for 5

years. Forster adds that by joining

forces, NBS and ER&E have pro- duced research results that have

put both organizations in the forefront of technology in solving

complex problems encountered in the electrical industry. In what he

terms "an ideal marriage," Forster says the NBS/ER&E pro- gram helps both parties because

it pairs the Bureau's interest in measurement science with ER&E's interests in understanding the properties of hydrocarbon liquids. While much of the Bureau's work at the facility is in deter- mining voltage, there is also a need for reliable measurements

of current. For example, Sandia

NBS researchers and util- ity representatives ex- pect this research to lead

to more effective insulators as well as to a better understanding of the

conditions under which

existing insulators will

perform more reliably.

National Laboratories in Albu- querque, N.M., has turned to NBS

for help in improving quality control for large industrial welding

machines, which typically draw

100,000 amperes of high-pulsed

current. (At its peak, this current

level is equivalent to that drawn

by 1,000 homes.) But in order for welds to be consistent, current must also be constant. Sandia

needs to know if its test equipment is giving accurate current measurements so the welding

machines can produce the re- peatable welds needed for sealing metal container plates.

The New Mexico laboratory has

asked the Bureau to evaluate measurements made by its test equipment under simulated conditions in the NBS lab, as well as to suggest how to make the current more consistent. The accuracy of test equipment

also has been a problem for electric utilities that make measurements of various aspects of

direct current power lines. There

has been interest in such measurements in recent years be- cause of concern about the possible health effects of dc

transmission lines. But, as Hebner

says, utilities "have bought test equipment that sometimes

gives inaccurate measurement

readings." To evaluate the accuracy of such equipment, NBS has

set up a scaled-down version of a

typical dc power line. Instruments under study are electric field meters, Wilson plates (for measuring

current), and ion counters. The

latter instruments, which measure

the ion density in air, have be- come important for their role in studying the biological effects of ions, as well as for industries,

such as semiconductor manufacturers, which are interested in manipulating ion density in clean rooms to control static electricity. Recently, the NBS facility also has been used to help the Con- sumer Product Safety Commission determine what might happen if a home-based citizens- band antenna were to fall on a power line. And the Rural Electrification Administration has used

the facility to measure how much

current a telephone cable can

take before melting and causing a

fire hazard. More companies, universities, and federal agencies have lined up to use the NBS facility in be- tween the Bureau's own projects. That's because while there are other electrical testing facilities in the United States, the NBS laboratory is the only one exploring the fundamentals of electrical measurements—fundamentals

that other labs ultimately use as

standards. As Hebner says: "We're the ones who are in the business of worrying about how

well the measurements can be

made."

To discuss the possibility of co- operative work or the availability of the high-voltage facility, write or call Dr. Robert E. Hebner,

B344 Metrology Building, National Bureau of Standards,

Gaithersburg, MD 20899,

301/921-3121.

by John Henkel

NBS Public Affairs Specialist
J

or years, architects, engineers,

and code officials have been in somewhat of a dilemma. How do

they ensure that buildings that are

functional and attractive are also safe from the threat of fire? Traditionally, architects and engineers

have used their expert judgment,

within the bounds established by

local officials who set and enforce strict codes that often dic- tate choice of materials, building

design, and safety features. Like- wise, these officials' decisions are made on the basis of their experi- ence and judgment.

Researchers at the National Bureau of Standards' Center for Fire Research, however, are helping to resolve that dilemma. In re- cent years, their studies have re- sulted in new knowledge of how

fire grows and spreads, new tests

to determine the safety of fur- niture and furnishings, and new

methods to evaluate the fire safety of a room or building. Little

by little, these achievements have

added flexibility to building design

and retrofit. In particular, the Bureau's sci- entists and engineers have

brought fire research into the computer age. New mathematical

models have been developed that enable NBS researchers to predict how furniture will behave in a

fire, to estimate how long it takes people to get out of a burning

building, and to assess alternative ways to achieve different levels of safety. In turn, architects and en- gineers can use these models to produce fire-safe computerized

designs. For researchers, computer

modeling has at least one distinct advantage: Once developed, it is cheap. A computer test often costs $100 or less. A full-scale room burn, by comparison, can

cost up to $20,000 and averages

$10,000. Even a laboratory-scale

test can cost $5,000 and take a

Researcher Walter Jones is developing sophisticated computer models designed to predict smoke and toxic gas move- ment throughout a building.

week to set up. Further, each test reproduces only one fire situation.

In the laboratory, it is impossible

to test every size and shape—let alone all potential contents—of a room or building.

Mathematical models allow re- searchers and designers to use what is known about fires to predict what would happen if a particular fire were to break out in different-sized rooms or buildings

or under different conditions. A

fast, reliable computer model just

completed by Bureau researchers can predict the spread of fire, smoke, and toxic gases throughout a structure. Smoke and toxic gases that are produced when

materials burn are of particular concern since 80 percent of the people who die in fires succumb

to smoke and gas rather than to flames or heat. Called "FAST," the model predicts the buildup of fire in a room

or other compartment, such as on

a ship. It also shows how the smoke and toxic gases will move

from one room to another, how

quickly they move, and their concentrations in different areas. "The model incorporates the same chemistry and physics as

other models do, but it is considerably faster and much more

'robust,' " says Dr. Walter Jones, a Bureau scientist. "In other words, it can complete calculations where some programs

would run and run and not come

up with an answer." FAST is designed to be used

by building and product managers, fire safety experts, and regulatory officials in state and local governments. Written in ANSI

Fortran, FAST can run on mainframe and minicomputers, and

15
Here physical scientist

Randall Lawson adjusts

instrumentation on the

Bureau's furniture calorimeter,

part of an NBS-developed

method to measure the rate at which heat is released by

burning furnishings. The

heat release rate in large part

determines how a material

will contribute to a room fire.

16

the NBS researchers are experimenting with it on a microcomputer.

Says Jones, "Anyone who is moderately knowledgeable about

computer modeling can use FAST. Initially it will probably be

used by some of the bigger fire protection engineering firms and

architectural firms which now use modeling to solve problems. But it will catch on as others, including

firefighters and code officials, be- come familiar with the technology."

To help broaden the use of FAST and other fire models, NBS

is setting up a fire simulation lab- oratory to demonstrate the fire and smoke models in a variety of applications. Workshops are ex- pected to begin this fall. In research aimed at improving

the fire safety of existing build- ings, the Bureau has devised a system that allows architects, engineers, researchers, and code

officials to assess alternatives for reaching the level of safety re- quired for and provided by some

specific types of public buildings

according to the National Fire Protection Association's (NFPA)

Life Safety Code. The Life Safety

Code is used by many state and

local jurisdictions in their building

and fire codes. NBS' system,

known as the Fire Safety Evaluation System (FSES), awards

points for a building's fire safety features and subtracts them for missing features or unsafe conditions. Through the use of the FSES, a building can meet the code by having combinations of

fire safety features other than the

fixed requirements in the code as

long as equivalent safety is provided.

The Fire Safety Evaluation System was designed originally to up- grade fire safety and reduce fire protection costs in hospitals and

other health care facilities. For new hospitals, the solution is relatively easy: Safety features are

simply incorporated into the build- ing's design. But for older hospitals, adding stairways to eliminate dead-end corridors, for example,

could cost millions of dollars.

In one case the FSES was

used to evaluate a major hospital

complex, an older facility facing

massive renovations to meet fire safety codes. The FSES ap- proach allowed the hospital to choose a fire safety system in- volving judicious use of smoke

detectors, smoke barriers, and some sprinklers, among other im- provements, to give code equivalency. The estimated cost of the FSES changes was $4-6 million compared with previous estimates

that ranged from $8-40 million, and the hospital was able to choose an approach that did not

interrupt medical services. Published in 1978 and included as an appendix to the 1981 NFPA

Life Safety Code, the Fire Safety

Evaluation System has recently

been modified for use with board

and care homes. In the United

States, these dwellings house an

estimated 2 million residents who

are elderly, physically handicapped, or developmentally

disabled. NBS researchers developed a

set of requirements that categorizes homes as either large or

small, depending on the number

of residents, and ranks them by ease of escape from a fire. The

more people in a home and the more time needed to evacuate it, the more safety features would

be required.

Says Harold Nelson, head of

fire safety performance at NBS,

"The goal is to upgrade fire safety, decrease building or retrofit costs, and at the same time

permit quarters that are as

homelike as possible."

The Veterans Administration is now using the system, while the

state of Colorado has been using

it for over a year to evaluate the
safety of small board and care homes housing mentally retarded and developmental^ disabled

residents. And the city of Topeka,

Kan., is using part of the system

in connection with its own housing codes. Published in March

1983, the FSES for board and

care homes has been incorporated in an appendix to the 1 985

revision of NFPA's Life Safety

Code.

At the request of the National

Institute of Justice, a third FSES

has been developed for prisons

"Our job is to develop

and bring together the

various fire research

techniques to ensure that

everybody involved in fire safety is using the

best available technical

framework for making

decisions."

and jails. It acknowledges cell doors that can be opened automatically by at least two different methods and the use of fire doors

to divide corridors and prevent

fire spread. The FSES for prisons

and jails was evaluated at 30 in- stitutions and was subsequently

published as an appendix to NFPA's 1985 Life Safety Code.

But not all research at the National Bureau of Standards is done on computers. Fire re- searchers also use laboratory

studies to investigate how smoke

spreads, how different materials

burn, and how effectively

sprinklers control fires. "Our job is to develop and

bring together the various fire re- search techniques to ensure that everybody involved in fire safety

is using the best available technical framework for making deci- sions," says Dr. Jack Snell, director of the NBS Center for Fire

Research. (As the nation's central

fire research laboratory, NBS

conducts research for a number

of federal agencies and sponsors most of the academic research on fire done in this country.)

"To do that, we all have to operate from the same set of fig- ures," Snell adds. "The figures

could result from a standard test, a computer model, or anything in- between. But they had better be

accurate, available, and applicable. That is the goal of good,

broad-based research." Toward that end, as a nonregulatory research laboratory,

NBS has developed new tech- niques and tools for measuring

how much heat is emitted when

materials, or even whole pieces

of furniture, burn. Such measurements are vital in determining

how a fire might grow and spread,

and thus what safety requirements should be considered for furniture and materials and what

additional safety is provided by

smoke control fans or sprinklers.

In one Bureau lab, a small piece of rayon-and-polyestercovered foam sits atop a metal stand ready to be burned. Once

ignited, a fan above the stand

pulls hot gases and soot from the

flaming material into ducts con- nected to a machine. The machine contains sensitive instru- ments that measure how much

oxygen the hot gases contain and

compare that with the amount

normally in air. Scientists use data from the as- sembly, called a cone cal- orimeter, to calculate the rate of heat release, which increases

with the amount of oxygen used. The rate of heat release tells whether a material will burn

slowly, or so quickly that it will ig- nite other furniture, carpeting, or bedding in the same room. The

latter scenario could lead to flash- over, that point when fire sud- denly spreads from the initial burning object to an entire room,

engulfing it in flames. "Rate of heat release is the

single most important factor in a

building fire," says Vytenis

Babrauskas, an NBS fire re- searcher. "That is what is meant

when someone asks, 'How big is the fire?' " Under development at the Bu- reau since 1978, the cone cal- orimeter is now being considered

by ASTM as a standard test method.

In an extension of the same

concept, Babrauskas and his NBS colleagues have developed

a furniture calorimeter. Like the cone calorimeter, it measures how much oxygen is used when

furniture burns as a way of knowing the rate of heat release. In this case, however, whole sofas,

chairs, desks, and other furniture items can be tested rather than

just small samples of materials. Babrauskas has recently devel- oped a set of rules with which re- searchers can predict the peak

rate-of-heat-release values of the

furniture calorimeter from cone

calorimeter data. So now these

small-scale, inexpensive cone

calorimeter measurements can be

used to estimate what will happen

to individual pieces of furniture in a fire. From this work, NBS re- searchers are developing broader

predictions of the rate of heat re- lease, and they also plan to de- termine the rates at which soot and toxic gas are produced. They

are now cataloging the fire properties of different materials and

furniture items using the cone and

furniture calorimeters. Somewhat earlier the Bureau developed a special test to deter- mine the extent to which carpeting and other floor materials will spread a fire. Previously, sci- entists and code officials had to

rely on the Steiner tunnel test, which was designed for wall and

ceiling materials, but not for carpets. Some carpets, rugs, and
Barbara Levin, research biol- ogist, prepares an experiment

aimed at establishing in a measurable way the relative

contrilijiyttflfffiin! ©fi smoke toxicity to the overall hazards of

Urnpads rated well on the Steiner tunnel test for flammability, only

to propagate fire rapidly when in a corridor near a burning room. The reason: Flames and hot gases passing down the corridor radiate energy, often raising the temperature of the flooring materials enough to allow flames to

travel rapidly.

This test apparatus, called the

flooring radiant energy panel test,

is used to judge how much radi- ant energy is needed to cause a hazard with different flooring materials. It offers a way to select materials to prevent a room fire from spreading to a hall or corridor. Originally developed for

hospitals and other health care

facilities, it was adopted by the Department of Health, Education

and Welfare (now the Department

of Health and Human Services) in 1977. The National Fire Protection Association added the test to

its Life Safety Code in 1981. It is now used to test attic insulation products, too.

It is important to know how materials burn, but we also need to understand more about the smoke and gases produced when

they burn. The vast majority of

fire deaths are due to the in- halation of smoke or hot gases. Although carbon monoxide, a combustion product of most burning materials, has been widely

considered as the primary cause

of these deaths, laboratory tests and analyses of some fire victims have suggested that other tox- icants or factors may contribute

to some deaths. Product manufacturers, building officials, and

others who want to know more

about the toxicity of the combustion products of various materials have been handicapped by

the lack of an agreed upon

laboratory test. NBS fire researchers devel- oped and published a measurement method that product

manufacturers and materials re- searchers can use to assess the acute inhalation toxicity of materials when they burn. The test, pri- marily intended for research and

preliminary product screening pur- poses, was developed in cooperation with representatives from in- dustry, universities, and other government agencies. According

to Dr. Richard Gann, chief of the

Fire Measurement and Research

Division, the test involves heating a sample of a material in a special furnace and exposing test an- imals (rats) to the combustion

products. The materials are

tested under both flaming and

smoldering conditions to reflect two major modes of material decomposition in fires. "We are now learning the extent to which the data from this device can also be used in fire hazard models," says Gann. "To

this end, we are comparing the data with those from another re- search apparatus in which the same materials are burned under

a wider range of fire conditions. If successful, the values from the

toxicity measurement method can

be combined with other materials,

fire, and building data to evaluate

the materials' total contribution to

fire hazard." "What we are trying to do in all of our research," declares Snell,

"is to make buildings truly safe

for people and at the same time

reduce fire protection costs. By

combining our laboratory results with computer analyses, we

should be able to reduce the di- lemmas faced by architects and

building officials in the past."
early 30 percent of all new houses come equipped with heat pumps

for heating and cooling. Before

the year 2000, heat pump sales may reach 2 million units per year

in the United States alone. At that

time, the American home is expected to consume 33 percent

of the electric power sold by

utilities. The Electric Power Research

Institute (EPRI), the electric power industry's research organization, wants the power demand

of those 2 million heat pumps to dovetail as efficiently as possible

with the power supply, thus saving

the utilities and their customers

money. To that end, EPRI is funding a number of heat pump

research and development proj- ects with manufacturers, research

organizations, universities, utili- ties, and others. These include a $4.7-million

cost-shared project with the Carrier Corporation to develop an advanced heat pump for homes

and small businesses.

EPRI has contracted with the

National Bureau of Standards for research related to the EPRI/Carrier program. NBS is analyzing the economic effects of alternative advanced designs on both the util- ities and the homeowner.

How heat pumps affect a partic- ular utility company depends on many factors, as James M. Calm

of EPRI points out. Calm is EPRI's

project manager for heat pump

development. "It is important to remember that the electrical industry is not homogeneous," he

says. "Utility companies differ in the kinds of generating equipment

and fuels they use, the amount of reserve capacity they can control, and the way the power demand

[load] is distributed on a daily or seasonal basis. Such variables

greatly influence the costs of providing electricity now and in the

future." Virtually all utilities have sum- mer and winter "peaks"—periods

when electrical demand increases

sharply to meet air-conditioning

and heating requirements. More

than 70 percent of utilities have

higher summer than winter peaks,

however, and the trend is in this direction. In general, most utilities resort to expensive alternatives to meet these peaks. They buy

power from another source, for example, or run "peaking" generators to supplement the power

supply. No one combination of heat pump design features would

be optimal for every single utility company, but EPRI has identified general heat pump development

goals that would best benefit cus- tomers and the industry as a

whole. "EPRI's goals are very clear," says Stephen Petersen, an economist in the NBS Center for Applied Mathematics. Petersen is conducting an economic analysis

of advanced heat pumps for EPRI. "When Jim Calm first approached me about this research, he said they were after dramatic improvements in performance but wanted

to avoid developing an unmarketable product." The initial goals set

in 1981, subject to revision if nec- essary to insure commercial success, were these: a 30-percent

improvement in seasonal heating

performance over the best avail- able equipment, a 2-kilowatt reduction in peak power demand

per residence during the heating season, and summertime energy

efficiency equal to the best per- forming air-conditioning unit then on the market.

"But there's a rub," Petersen

says, and it explains why manufacturers are not already producing advanced heat pumps. "The

performance goals can be met

with known technology, but the

cost of doing so will raise the pur- chase price of a heat pump

significantly."

Petersen, with advice from

Glendon Raymond, head of the advanced heat pump project at Carrier, went in search of the right

mix of design goals that would

make a heat pump "advanced," by

EPRI's standards, and economical

as well. Petersen developed computer models based on an earlier NBS/Department of Energy model

of heat pump performance. He

factored in data and projections

from EPRI and Carrier, and drew

on expertise developed at NBS

over the past 10 years in engineering economics and energy

use in buildings.

He then calculated the effects

of alternative advanced heat

NBS is analyzing the eco- nomic effects of alternative advanced designs

[of heat pumps] on both

the utilities and the

homeowner.

pump designs—on an hour-byhour basis over an entire year

on representative utilities typical

of those in various regions in the United States. He weighed that information with data on the eco- nomic consequences to consumers who would pay to own,

operate, and maintain the advanced heat pump over its lifetime. His findings spell good news for

utility companies and consumers

alike. It is possible, says Petersen,

19
By using computer modeling,

economist Stephen Petersen

is helping EPRI find the

right mix of design goals

that will make a heat pump

"advanced" and economical.

to achieve most of the perform- ance improvements important to EPRI and still have a commercially competitive product.

One important approach is to integrate heating and cooling with water heating and by doing so reduce the total amount of electricity required for these operations. Waste heat from air conditioning can heat water—and

thus save energy—in summer. A

heat pump's excess capacity can do likewise in the winter. (The full heating capacity of a heat pump is seldom needed to keep a building warm, except during severe cold.) Petersen also emphasizes four ways of increasing the overall effi- ciency of a heat pump: 1) improve

steady-state efficiency; 2) make

output vary with load; 3) increase

low-temperature heating capacity;

and 4) use fossil fuel rather than an electric furnace for auxiliary

heating.

Improvements in steady-state

efficiency, which can be achieved

with more efficient motors and

compressors and enlarged heattransfer surfaces, provide signifi- cant improvement in cooling

performance. However, in the

heating mode, the feature with the

greatest potential for energy savings is an adjustable-speed compressor.

Today's heat pumps are generally driven by single-speed compressors: Output (capacity,

expressed in Btu/hr) is fixed, and

these compressors cycle on and

off to meet changing loads, which

reduces efficiency.

An adjustable-speed compressor would match the heat pump's

output to the heating or cooling

load. Output would vary in tandem

with changes in load, avoiding

inefficient on/off cycling. An

advanced heat pump would consume maximum power only if conditions warranted maximum

output. And there is one further advantage: An adjustable compressor can boost the heating

capacity of a heat pump at low

temperatures significantly above

that of an otherwise identical single-speed system.

Because it permits heat pump

capacity to increase without wasting power, the adjustable capacity

compressor would also decrease

the use of the auxiliary heat

source, usually an electric fur- nace, thus reducing heating peak

demands.

Raymond, of Carrier Corporation, says his company hopes to have a prototype advanced heat pump ready for production by

1988. EPRI, meanwhile, is already

pursuing advanced heat pump

concepts for applications other than homes and small busi- nesses. In addition, the institute is planning projects to "advance"

heat pumps even further in the

future. EPRI's Calm expects to use the NBS model in setting and

justifying heat pump performance

goals on which these projects will be based.

Petersen, at NBS, is looking at what electric utilities might do to get buyers interested in the EPRI/

Carrier advanced heat pump. "If you consider the costs of buying,

operating, and maintaining an advanced heat pump over its life- time, with water heating included,

it is competitive with today's heat

pumps," Petersen says, "even though its price tag is going to be

higher."

However, he thinks many buyers, confronted with that higher

initial cost, will need some additional incentive before they buy.

As part of the EPRI/NBS agreement, Petersen is preparing documentation on the computer

program he developed for analyzing heat pump performance. With

this program, a utility company

will be able to calculate the impact

of a specific advanced heat pump

on its operation. The company

can then determine what basis it might have for transferring

resulting savings to consumers

in the form of rebates or other

incentives that would make the advanced heat pump an especially good buy.

Calm sees broader uses for Petersen's research. "Steve's work will allow EPRI and heat pump manufacturers to calculate the benefits—direct and indirect

associated with all the possible

design features. Manufacturers can then set more rational goals

for product development."

Also, this research may one day

become the basis for choosing the

"right" advanced heat pump for a

particular area, Calm suggests. A

utility company or even an individ- ual buyer could determine which

combination of features, of all the options available on the market,

would yield the biggest savings.

Obviously EPRI has confidence

in its efforts to influence the marketplace. The advanced heat pump should make its market

debut before the end of this decade. If it is a success, it will be a boon to everybody who pays an

electric bill. J.C.
zone is the Jekyll and Hyde of the environment: It's both a boon and

a bane to humanity.

Consider its "split personality."

Ten miles or so into the Earth's atmosphere, ozone is a lifesaver.

It acts as a screen for keeping

humans—and every other living thing —from being scorched by

the Sun's ultraviolet rays. But on

the Earth's surface, ozone is a

noxious gas—a byproduct of auto exhaust that federal and local governments go to much trouble

to regulate. At the heart of ozone's odd nature is its behavior as gas. Unlike most others, it is impossible to contain and difficult to measure.

While scientists labor over just

how much this gas is harming or helping the environment, they

need another party to help deter- mine if the sophisticated instru- ments used to measure ozone

concentration on the ground or in the upper atmosphere are providing accurate numbers. The place

they turn to is the National Bureau of Standards, where making

such acute measurements is a

specialty.

The Elusive Gas

Scientists in the NBS Center for Analytical Chemistry routinely pro- vide very accurately measured

reference materials that are used

to check how well gas analysis

equipment performs. But ensuring

such accuracy for ozone is tricky. Regulatory agencies responsible

for measuring ground-level ozone

must periodically calibrate the in- struments that gauge ozone concentration. Such calibrations are

fairly easy to do on the equipment that measures many of ozone's pollutant gas cousins

such as sulfur dioxide or nitrogen

dioxide. This is because bottled, pre-measured standards of these

gases can be bought from NBS

to ascertain equipment

performance.

But ozone is different.

"If you have a steel cylinder

and you put pure oxygen in it, you can come back in 100 years and

the oxygen will still be there," says Dr. Arnold Bass, who manages the NBS ozone calibration laboratory. "But put ozone in there and by the time you finish putting it in and closing the valve,

most of it will be gone." What

Scientists in the NBS

Center for Analytical

Chemistry routinely provide very accurately measured reference materials

that are used to check

how well gas analysis

equipment performs.

happens, he explains, is that ozone reacts quickly with the container material and is destroyed

almost instantly.

With containment out of the

question, scientists look to other ways of measuring the elusive gas. Though there are several techniques for determining ozone

concentration, the current method

of choice is photometry, devel- oped commercially in the 1970's as an alternative to the messier,

less reliable "wet chemical"

methods used for years. (Environmental ozone is regulated by the

U.S. Environmental Protection Agency [EPA], but controls are administered by local govern- ments which can use EPA photometry standards to ensure ac- curate readings. EPA turns to NBS, which has no regulatory authority, for technical assurance

that the standards are accurate.)

NBS uses a device, appropriately dubbed an ozone reference

photometer, to calibrate the EPA

standards. First developed at the Bureau in 1976 at the request of EPA, this standard began as a

bulky, 10-foot-long device. With

the help of Dr. Richard Pauer of EPA, it has since been reinvented

and shrunk to about one-third its original size. Now it's portable

and 50 times more sensitive than

the earlier device. The changes

can be attributed, Bass says, to "improved technology and

streamlined design."

Shedding Light on a Sample

Photometers—whether they are used in the field for environmental

measurements or in the laboratory as standards—work on the

principle that ozone absorbs light

in the ultraviolet (UV) portion of the spectrum proportionate to the concentration of the gas. By shining UV light through an air sample, scientists can calculate the ozone concentration in that sample by determining the difference

in light intensity between the en- trance and exit points of the air sample container. At NBS, re- searchers have worked out methods where a known quantity of ozone can be produced by the NBS reference photometer, then

fed into another monitoring instru- ment, such as a photometer

maintained by EPA, to check its accuracy. If the monitoring instru- ment comes up with the same

readings as the NBS standard, it

is working properly. Otherwise,

the instrument will have to be

recalibrated. EPA requires local agencies to use photometry for ozone measurement and depends on NBS

to assure the accuracy of ozone

instruments. NBS initially accomplished this by having agencies come to the Bureau to calibrate

their instruments against the NBS

21
NBS technician Jim Norris

adjusts the Bureau's ozone

reference photometer which

is used as a "definitive" stan- dard for calibrating the refer- ence photometers in EPA

regional laboratories.

standard. But now NBS is in the process of building photometer

standards that can be placed in EPA regional laboratories across

the country so local governments

can take their photometers to those labs for calibration. The

EPA labs will then periodically

check their instruments against

the NBS reference photometer. EPA's central laboratory near Raleigh, N.C., is equipped with a photometer standard supplied by

NBS, as are EPA labs in Califor- nia and New Jersey. Four more of

the devices will be delivered by

the end of this year. "Without a photometer standard, all the user in the field can do is check his instrument's re- sults against those of a neighboring locality, and in that situ- ation, both instruments may be

wrong," says Larry J. Purdue, acting director of the quality assur- ance division of EPA. "What [the NBS reference photometer] will do is find photometers in the field that are not working properly. Users then will have to do mainte- nance on their defective equipment."

Concern about ozone measurements has also prompted in- dustrial firms to consult NBS. For example, one manufacturer of of- fice machines has requested NBS

assistance in determining the lev- els of ozone that might be pro- duced by photocopiers. And a

large aircraft company has asked

for measurement help from NBS

in its study of the effects of breathing ozone from the stratosphere on people aboard a

plane.

The bad name ozone gets as a

pollutant underscores its highly reactive nature—that is, the gas

reacts chemically with just about

everything it comes in contact

with. If inhaled, ozone can act as

a strong oxidant, reacting with lung tissue and irritating the respi- ratory tract. And it can cause wear on car tires by reacting with rubber. "Just how much an effect

it has on tires we don't know,"

says Bass. "We do know that if you leave a box of rubber bands
in an ozone environment in the

laboratory for a month, they'll just

fall apart."

There's a Good Side Too

Ozone is not all bad. In fact, if the

layer of ozone that surrounds the

Earth 10 to 30 miles up—which

screens the harmful UV rays of the sun—were to be seriously di- minished, scientists predict that crops would dry up, the Earth's oxygen cycle would be inter- rupted, and skin cancer would be- come epidemic. That's why re- searchers worldwide have studied

the ozone layer extensively to de- termine if it is being depleted, and

if so, how to head off disaster.

"Whether the ozone is on

the ground or in the upper atmosphere, someone needs to be responsible for the accuracy of

ozone measurements.

And that's what

our job is."

Many suspected causes of ozone depletion have been studied in the last decade, the most

celebrated probably being the chlorofluorocarbons formerly

found in nearly all refrigeration

equipment, hairsprays, and spray

deodorants. These compounds

have since been removed from

many products, but the effects of when they were used as pro- pellants in spray cans remain.

"The problem with chloro- fluorocarbons is that they are sta- ble and inert, so when they are released they just drift up into the atmosphere and there's nothing

to remove them on the way up.

They just keep going," says Bass. "When they get high enough the

action of the Sun can release

chlorine atoms and start a chain

reaction that reacts very quickly with ozone, destroying many

ozone molecules. It could take as

long as 100 years to decompose

the fluorocarbons that are already

in the atmosphere." There are

other suspected ozone destroyers, such as methane gas

produced by rice paddies and

grazing animals, and even

airplane exhaust.

Resetting the Table

Before any conclusions can be

made about the state of the

Earth's ozone layer, scientists must find out just how much

ozone is in the atmosphere compared to how much was once

there. This is done by sophisticated instruments that measure

the ozone layer from the Earth and from the sky through bal- loons, high-altitude planes, rockets, satellites, and in the future, the space shuttle. Many of these

instruments work on the same

principle of UV absorption as

photometers. However, in order

to reliably monitor the ozone

composition of the high atmo- sphere as contrasted with that determined at ground level—two measurements that ideally should

agree—scientists need an accurate system of measuring the transmission of UV radiation through the atmosphere.

NBS has contributed to these

measurements by developing—in cooperation with the National Aeronautics and Space Administration Upper Atmosphere Research Office—a table of 1 ,200

measurement points that indi- cates how much UV radiation will be absorbed at various temperatures and at different wavelengths of ultraviolet light. This

table of values, or cross sections,

refines a French study done in 1953 under which ground-based

and airborne instrument results varied as much as 8 percent. The

NBS research has cut these dif- ferences to no more than

2 percent.

"What we've done is to reduce

greatly the discrepancy between

the two methods of observing at- mospheric ozone so the differ- ences that remain may reflect dif- ferences in other aspects of the

monitoring," Bass says. "Now

someone who is making these

measurements, and needs to in- terpret what the distribution of ozone is in the atmosphere, can

use these cross sections for that

interpretation. The measurement

system is much more accurate now." The Bureau's work in this area has been recognized inter- nationally. For example, in September 1984, at the Quadrennial

Ozone Symposium in Halkidiki, Greece, the International Ozone

Commission recommended that the NBS ozone cross-section ta- ble be accepted as the inter- national standard for determining ozone concentration from satellite instruments. Ozone's strange nature will no

doubt continue to prompt debate

over whether the ozone layer is depleting, as well as concern

over the gas as a pollutant. The

environment's Jekyll and Hyde

isn't about to go away anytime

soon. But, as NBS' Bass says: "Whether the ozone is on the ground or in the upper atmosphere, someone needs to be re- sponsible for the accuracy of ozone measurements. And that's what our job is." J.H.
elestial matters are of no direct concern to Dr. Joseph Reader, a

physicist with the National Bureau

of Standards. He spends much of

his time in a laboratory buried un- der earth and otherwise shielded

from the outside world. Nevertheless, Reader is abetting astronomy in this under- ground spectrographic facility with the aid of Nicolo Acquista, an- other NBS physicist. Reader and

Acquista are measuring—to an

accuracy of 1 part in a million

some 3,000 wavelengths of ultra- violet radiation emitted by plat- inum gas in the range of 1 10 to 380 billionths of a meter. The National Aeronautics and

Space Administration's (NASA's)

Edwin Hubble Space Telescope

will use these wavelength measurements as the basis for automatically converting high- resolution observations made with a spectrograph into accurate

data. From such data, astrono- mers expect to derive much im- portant new information on the nature and dynamics of the local universe and develop a scale for measuring cosmic distances (see

box).

The Space Telescope is the most ambitious project in the his- tory of astronomy. It is a new un- manned astronomical observatory

scheduled for launch into Earth

orbit late in 1986. Its unmatched

visual powers should look on our

galactic neighborhood with 10

times better clarity than ever before and also probe seven times

deeper into the recesses of the cosmos, perhaps to the very edge of the known universe. The Space Telescope's inher- ent capability for high spectral

resolution, or clarity, is resident in

its ultraviolet High Resolution

Spectrograph. This spectrograph was specially designed and built for the new observatory, as were

its four other state-of-the-art sci- entific instruments: a spectrograph for looking at faint dis- tant objects, two cameras, and a photometer—a high-technology

counterpart of a photographer's

light meter.

24

Shown in the NBS atomic spectroscopy laboratory are Dr. Joseph Reader (left) and Nicolo

Acquista. Acquista is holding a platinum lamp similar to the one that will fly in the Space

Telescope.
What a Spectrograph

Does

A spectrograph is an observing

and recording instrument that pro- duces pictures with diffracted

light. The pictures are rows of threadlike parallel lines. Each

highly resolved line represents a

particular wavelength of electro- magnetic radiation produced by a

particular type of atom or molecule. Furthermore, each line is part of a unique pattern, or spectrum, of lines. Thus, astronomers

can determine what an object in space is made of chemically by

identifying spectral patterns.

They can also glean other types of information with a spectrograph. From the intensity of

light (number of photons per sec- ond) associated with a spectral

pattern, they can infer how much

of a particular element or type of molecule is present in a celestial object and distinguish physical, as

well as chemical, composition.

Deuterium and hydrogen are chemically indistinguishable, for example, but deuterium—

sometimes called heavy

hydrogen—is an isotope with twice the mass of hydrogen. The

From such data, astronomers expect to derive

much important new in- formation on the nature

and dynamics of the local

universe and develop a

scale for measuring

cosmic distances.

ability to distinguish isotopes and

determine the relative proportions

of constituents is key to understanding the dynamics of the uni- verse, present, past, and future, including the processes going on

inside our Sun.

Last, but far from least, astron- omers can figure how fast and in which direction—toward or away

from the Earth—an object is moving by comparing spectral lines from space with a reference

spectrum of lines from a cali- bration lamp in a "rest state" rel- ative to the spectrograph. (See

box for the importance of deter- mining the velocity of celestial objects.)

Calibrating the Picture

A spectrographs picture is really a wavelength "ruler" with the

shortest wavelength on the scale represented by the spectral line at the beginning of the row, and

the longest wavelength by the

line at the end of the row. The

wavelength associated with any

line in between can be calculated on the basis of its position rela- tive to known reference lines.

In the High Resolution Spectrograph, the reference lines will be produced by the platinum

lamp, and they will be

characterized—each of the lines

will be designated according to wavelength—by computer, with Reader's wavelength standards. The computer will derive the wavelengths represented by the unknown lines in the same "pic- ture" from their spatial re- lationship to the known lines of platinum.

Reader's standards—which will be completed by January

1986—are the only component of the High Resolution Spectrograph's calibration system that must be specially developed. The

platinum lamp was invented in the

late 1970's by Johns Hopkins

University and the Westinghouse

Electric Corporation for another

NASA satellite observatory, the

International Ultraviolet Explorer.

The lamp is now available commercially. But the only wavelength stan- dards as yet available for characterizing the lamp's emissions are 10 times too poorly determined

for the High Resolution Spectrograph. If used, they would

215.277 215.422

1 215.424

I 215.492

nanometers

These two strip-chart recordings are spectrograms in diagram-form that show by comparison

the extent to which Reader's new determinations

will improve platinum wavelength standards for the far ultraviolet. Existing platinum standards were resolved at 30,000, as represented by the

top tracing, and measured with an accuracy of 1 part in 100,000. The new standards (bottom) are being resolved at 150,000 and are accurate to about 1 part in 1 million. Note that one broad

peak in the top tracing becomes twin peaks

separate wavelengths—at the higher resolution.

convert high-resolution

observations—the instrument has

a resolving power of up to 100,000*—to low-resolution data, says Dr. William Martin, head of the NBS atomic spectroscopy group to which Reader belongs.

Martin keeps abreast of devel- opments in astronomy because

his group traditionally supplies a measurement base for that area. Two years ago he read about the Space Telescope's platinum-lamp

calibration standard, and he sus- pected that new platinum wavelength standards would be

needed. Reader made some

high-resolution measurements on

platinum and confirmed Martin's suspicions.

Together, they drew up a pro- posal that NBS develop the stan- dards and submitted it to NASA

* Resolving power—or resolution—as the term applies to a spectrograph, is the in- strument's ability to distinguish one wavelength of radiation from another. The extent

of this ability is determined by dividing the average wavelength of the two closest dis- cernible spectral lines by the difference in wavelength between those lines. 25
Above are two spectrograms recorded on a single photographic plate by the 35-foot NBS

vacuum-ultraviolet spectrograph. The top spectrum contains spectral lines of both platinum

and copper over the wavelength range 148 to 154 nanometers. The bottom spectrum consists

off ipSatiiinwjfnra Bines only, 'm the same wavelength range.

and the Space Telescope Sci- ence Institute in Baltimore. The

institute is operated by a consortium of some 17 American uni- versities for NASA and the European Space Agency.

"New standards are absolutely

necessary," Martin explains. "And

I don't know anybody but NBS

that could develop them to the

required accuracy. Most wavelength measurements of the high- est accuracy in the far ultraviolet are made here. We have the most extensive vacuum-ultraviolet

facility in the world, and we can make better measurements [in that region] than anybody else. We have the expertise and the

capability built in." The High Resolution Spectrograph's design team and offi- cials at NASA and the Space

Telescope Science Institute re- viewed the NBS proposal. They

quickly concurred: NASA would

fund the development by NBS of the required standards. One of the members of the design team is Dr. Jeffrey Linsky, an astronomer with the Joint Institute for Laboratory Astrophysics oper- ated by NBS and the University of Colorado. Linsky says, "Frankly, we knew from the design stage

that we would have a problem

with the existing wavelength

standards—they were developed more than 50 years ago. But before we could even think of doing

something about it, the spectrograph had to be built and

tested." When tested, the instrument,

built by Ball Aerospace, Inc., ex- ceeded the expectations of the

Linsky says Reader's

platinum wavelength

measurements "should

satisfy astronomy's need

for far-ultraviolet standards for at least a decade."

design team. This increased the accuracy required of the wavelength standards. "We were certainly relieved when Martin and

Reader came forward and said they could solve the problem,"

Linsky says.

Underground at NBS

It takes an instrument with a long

focal length to measure short wavelengths to an accuracy of 1 part in a million. So, in relative

size, the vacuum-ultraviolet spectrograph at NBS is the whale of the NBS spectrographic laboratory. It is a bulky, 35-foot-long, self-contained assembly consisting mainly of a large hollow pipe.

A vacuum pump evacuates air from this pipe to create a vacuum

between the emission source at one end of the pipe and the opti- cal equipment and photographic

plate at the opposite end. This is necessary because the Earth's atmosphere absorbs wavelengths

below 200 nanometers (200 bil- lionths of a meter)—hence this region is referred to as the "vac- uum ultraviolet." If we could see

in this region, the air would literally be as clear as mud. For this reason, ultraviolet astronomy must be carried out in space, above the atmosphere.

Reader is using the vacuum

spectrograph for comparative

analyses of the spectra of copper

and platinum. Ionized copper

emissions in the ultraviolet are

the well-characterized—in large part by Reader—but diff icult-to- produce reference spectrum used

by laboratory spectroscopists in- terested in making vacuumultraviolet wavelength measurements.

Astronomer Linsky predicts this

will change. A commercially avail- able platinum lamp and new

platinum-wavelength standards,

he says, will make platinum emissions the ultraviolet laboratory standard.

In the meantime, Reader, as

well as every other spectroscopist, has to build his own cop-
per lamp to produce vacuumultraviolet reference lines. He has

also built a special platinumcopper emission source for the comparative studies on platinum

and copper.

His work on platinum does not

require measurements below 100

nanometers. In other experiments, however, Reader has de- termined wavelengths as short as

1 nanometer. That is, he says, the lower limit of optical spectros- copy. Below 1 nanometer, waves

cannot be reflected by optical means and other technologies

are required for spectral analysis.

Linsky says Reader's platinum

wavelength measurements

"should satisfy astronomy's need

for far-ultraviolet standards for at least a decade."

Reader is pleased to hear this assessment, and amused at an

irony. "Here I am doing something for astronomy, and I hardly ever get out of the basement," he

says, referring to the time he

spends in the NBS spec- trograph^ laboratory. That makes

his association with the stars an underground connection. J.C.

Redshift, Blueshift: Why Astronomers Need

to Make Accurate Wavelength Measurements

"Velocity is very important in astronomy," says NBS astron- omer Jeffrey Linsky. "Many im- portant questions can only be

answered by precise velocity measurements.

"For instance," he explains,

"if a star has a planet going

around it, you won't be able to see the planet directly, but you

can infer its presence because

its gravitational attraction will make the star wobble."

That wobble may amount to no more than 1 kilometer per second, Linsky says, but it will be detectable, by the High

Resolution Spectrograph, as displacements from the rest position of spectral lines associated with the star. When a prominent line, such

as the Lyman alpha line of hydrogen at 122 nanometers,

shifts toward the red, or longer

wavelength, region of the elec- tromagnetic spectrum, the matter responsible for the fea- ture is moving away from the

Earth. A blueshift—toward

shorter wavelengths—means

the object is moving toward

the Earth. In either event, the

extent of displacement is the measure of velocity.

In the case of the hypothetical wobbly star, Linsky says,

"The velocity of the hydrogen

line indicates the velocity of the star relative to the Earth. Over time, as the planet re- volves around the star, the velocity of the star shifts from

blue to red and back again as

the planet pulls the star first toward the Earth—when it is between the star and the Earth—and then away from

the Earth when the planet is behind the star. This wobble

may only be 1 kilometer per second, but it is enough to re- veal the presence of the unseen planet."

This example of how

velocity—and therefore wavelength measurement—is used

in astronomy could be aug- mented by countless others. One application is of particular interest in relation to the Space Telescope, however. Astronomers expect the High Resolution Spectrograph

to produce measurements pre- cise enough for "calibrating" a

celestial yardstick. If so, they

will be able to make reasonably accurate determinations,

for the first time in history, of distances outside our solar system and shed more light, perhaps, on the age and

extent of the observable

universe.

This "calibration" in part consists of determining precisely the extent to which certain Cepheids, or variable

stars, seem to expand and

contract—in other words, to change their velocity as they seem to move toward the Earth and away. These pulsations, astronomers think, vary strictly according to the

intrinsic brightness of the star. Since apparent brightness de- pends on both intrinsic bright- ness and distance, astrono- mers could calculate the distance to any Cepheid of known intrinsic brightness by

employing a very simple law: the law of inverse squares. According to this law, familiar to every serious photographer,

apparent brightness diminishes

by a factor of four every time

distance doubles. Of course, calculations of distance based on brightness

will have to take into account many factors, including the amount of light being absorbed

by the dark matter that evi- dently pervades the universe. But the dark matter is yet an- other subject the Space Tele- scope will be looking into. And

quite another story.
he space shuttle will carry a pre- cious astronomical cargo indeed

when it ferries the Edwin P. Hubble Space Telescope into orbit next year. Precious in terms of hard currency—the telescope will probably end up costing some

$1.5 billion —and high scientific hopes for a better view of the universe than ever before

achieved.

These hopes are pinned on the

reliable performance of specially

designed, state-of-the-art sci- entific instruments, including two

spectrographs. The National Bu- reau of Standards, through the

Dr. Jules Klose holds a krypi Ian ip ! imilar to the one he

and several of his industrial

colleagues calibrated for the

Space Telescope.

Atomic and Plasma Radiation Di- vision, is carrying out several cali- bration projects to help assure

that this equipment goes into space ready and able to perform as expected.

Dr. Wolfgang Wiese, chief of the division, says these projects involve the development of plat- inum ultraviolet wavelength stan- dards for the High Resolution

Spectrograph and a variety of

light-intensity calibrations.* He

says the light-intensity projects

relate to the independent cali- bration of both spectrographs and

to the retesting of equipment in the assembled telescope.

Dr. Jules Klose is the principal

NBS researcher responsible for the intensity calibrations. "Measuring light intensity means, in some form or other, measuring

photons—light particles," he explains. For Klose and his associates, working in the NBS vacuum

ultraviolet radiometry laboratory, the challenge in regard to the Space Telescope calibrations has

been manifold. They have had to: Measure and characterizein terms of total output, stability of output, and shape of beam—an

argon lamp, a krypton lamp, and

a hydrogen lamp produced by

Quantatec, Inc., and two different platinum-chromium-neon lamps

produced by Westinghouse Electric Corporation, all developed for Martin Marietta Aerospace. Two

of the lamps were redesigned

and constructed according to NBS recommendations. These

* NASA's Goddard Space Flight Center

contracted with NBS for the development

of the platinum wavelength standards. (See page 24 for a discussion of these stan- dards.) Ball Aerospace and Martin Marietta Aerospace, both under contract to NASAGoddard, subcontracted to NBS for the re- maining work. The Space Telescope Science Institute, which administers the Space Telescope operations, has provided guidance.

five light sources are used in a "Space Telescope optical simulator." This is an instrument de- veloped by Martin Marietta Aero- space "to simulate conditions of

light coming from weak stars," Klose says. "Together, the lamps

produce a continuous band of radiation from the vacuum ultra- violet through the visible." This is the range of the electromagnetic

spectrum in which the Space

Telescope's Faint Object

Spectrograph will operate.

Calibrate the Space Tele- scope optical simulator before and after Martin Marietta used it to calibrate the Space Tele- scope's Faint Object Spectrograph. The company shipped

the simulator to NBS along with a

6-foot vacuum chamber in which

it has to be encased during operation. NBS researchers measured

the absolute spectral intensities emitted by the five lamps in this device by comparison with the known intensities of argon arc emission sources specially de- signed and calibrated by NBS.

This calibration established an

absolute ultraviolet intensity scale for the Faint Object

Spectrograph.

Develop for Ball Aerospace,

Inc., builders of the High Resolution Spectrograph, an argon arc

ultraviolet emission standard

for use in calibrating that spectrograph.

Klose is now calibrating several platinum-chromium-neon lamps

for Martin Marietta to use in re- testing the equipment in the as- sembled Space Telescope. As- sembly of the telescope is under

way at Lockheed Missiles and

Space Company in California. J.C.

28
hen Dr. John Taylor talks, analytical chemists listen. They listen to what the NBS

chemist tells them about how to improve what they do—that is, make analytical measurements.

With Taylor's advice, the 40 or 50

attendees at each of his frequent

"quality assurance seminars" re- turn to their laboratories better equipped to arrive at reliable fig- ures for nanograms, milliliters, or any other units within the critical measuring realm of analytical

chemistry.

Taylor has been preaching the gospel of good measurement

through his seminars on behalf of the National Bureau of Standards.

He readily admits that chemistry

industry professionals sometimes

need help in getting on the right track for their measurement pro- grams, and that's why he started the seminars. "We try to emphasize quality control and quality as- surance while giving tips on more

precise and accurate measurements," Taylor says. He has taken the seminars on

the road to China, Canada, and

cities across the United States. About a dozen of the 70 he has

held have been conducted at the main NBS site in Gaithersburg,

Md.

Though his 2-day workshops

are designed to help a variety of researchers within the analytical

chemistry field, they are ideal for

clinical chemists who need to know the best tricks of the trade

to make measurements accurately at the parts per million level or lower. The seminars fit well into the mission of the Bureau's clinical chemistry program, which is, simply, to help industries and govern- ment agencies make the best

possible analytical measurements. Taylor's seminars

help NBS reach this goal, as does the Bureau's production of Standard Reference Materials (SRM's) for calibrating equipment

and assessing analytical

methods.

The current catalog of SRM's

lists 900 different items, of which

annual sales total about 40,000

units. More than 60 of the SRM's now offered are clinical chemistry

standards. And while many are

"old favorites" that are consistently in demand, new clinical SRM's are being developed to help solve old problems.

One such example is a Stan- dard Reference Material NBS re- searchers recently completed for measuring the concentration of lead in blood. Wide-ranging re- sults had been obtained in nu- merous studies when samples

with known lead concentrations were sent to a variety of laboratories. This prompted the National

Institute for Occupational Safety

and Health to request that NBS

develop a standard sample to im- prove the measurement reliability of lead in blood. The resulting

SRM is expected to help improve

the accuracy of lead-in-blood measurements.

"We try to emphasize

quality control and quality assurance while giving

tips on more precise and

accurate measurements."

While NBS seminars and Stan- dard Reference Materials are, in a sense, a "reaching out" to in- dustrial, professional, or trade or- ganizations, there are times when

a longer-term, more personalized

NBS/industry relationship is desirable. The Bureau offers just

such an environment through its Research Associate Program. In existence since 1921, the pro- gram allows non-NBS scientists and engineers to work closely

with NBS staffers and to use the

extensive Bureau facilities. Sal- aries of associates are paid by

the sponsoring company or or- ganization. Currently there are 168 research associates at the Bureau, representing 63

companies and organizations.

Though participation in the pro- gram can be of great benefit to an industry, NBS also is helped in the process, says Dr. Howard

Sorrows, director of the Bureau's

Office of Research and Technology Applications. "We learn firsthand the views and needs of the industrial community," he

says. "The information we receive from the associates helps us

structure our research programs

so they are of maximum benefit

to industry."

The program has an allure for

clinical chemists in that virtually

all available analytical techniques

are practiced at NBS, and the ar- ray of instruments is one of the best in the world. The College of American Pathologists (CAP) has

taken advantage of the program

by sponsoring research associ- ates in clinical chemistry for 6

years. Most recently a CAP

researcher performed work in gas chromatography/mass spectrometry to certify the amount of creatinine in an NBS human

serum SRM and in samples used

in a CAP laboratory testing pro- gram. Measurement of creatinine

is an important factor in the

analysis of kidney function. But whether a clinical chemist comes to work at NBS as a re- search associate, attends an NBS

quality assurance seminar, or uses Bureau SRM's, the goal re- mains the same: better chemical measurements.

For more information about the Bureau's quality assurance seminars, write or call Dr. John K. Taylor, A309 Chemistry Building, National Bureau of Standards,

Gaithersburg, MD 20899,

301/921-3497. J.H.

29
NEW PUBLICATIONS

WEIGHTS AND MEASURES TRAINING

TEXT

Introduction to Electronic Weighing

and Measuring Systems, Natl. Conf. on

Weights and Measures, inspector's manual, 86 pages (January 1985), instructor's manual, 62 pages (January 1985). Order

both from the National Conference on

Weights and Measures, P.O. Box 3137,

Gaithersburg, MD 20878, $25 prepaid (or inspector's manual, $10 prepaid; in- structor's manual, $15 prepaid).

A recent training text has been published

by the National Conference on Weights

and Measures (NCWM) under a grant

from NBS. The text is the first of 36 to be written and published during the next 6 years. Technological advances in the

application of electronics and micro- processing to commercial devices have

created a need for special training of weights and measures officials nation- wide. These texts are designed to pro- vide the states with the material they

need to conduct their training programs. Each text, called a training module, is composed of two volumes—an in- spector's manual and an instructor's manual. Provided with the instructor's manual are instructional aids, including

35-mm slides designed for classroom

presentation of the training material.

TEST CHIP DESIGN PROCEDURES

Carver, G.P. and Wachnik, R.A., TERRY- 2: A Test Chip for Characterization of

the Performance of Buried-Channel

Charge-Coupled Device (CCD) Imagers, Natl. Bur. Stand. (U.S.), NBSIR

84-2894, 135 pages (December 1984). Order from NTIS by stock no. PB

85- 13770 1,$14. 50 prepaid.

This NBS report will aid electronics firms that design test chips and methods for automated measuring of material and

process properties in integrated circuit fabrication. The product of a detailed study performed by the Bureau's Center

for Electronics and Electrical Engineering, the report is a recounting of how NBS scientists designed the 5-mmsquare TERRY-2 chip for testing chargecoupled device (CCD) imagers. Included

are descriptions of chip componentsresistors, capacitors, transistors, and

other test structures. There are also hints

for developing and implementing a test program for drop-in test chips, which in- terested companies can adapt for their own use.

INTRODUCTION TO DATAPLOT

Filliben, J.J., DATAPLOT—Introduction

and Overview, Natl. Bur. Stand. (U.S.), NBS Spec. Pub. 667, 112 pages (June

1984). Order from NTIS by stock no. PB

84-2 1 4055, $ 13 prepaid (paperback),

$4.50 prepaid (microfiche).

NBS has published a reference manual

for DATAPLOT, a high-level, interactive programming language developed at NBS for analyzing scientific data, plotting

data on continuous or discrete graphs,

and performing linear or non-linear curvefitting. The text includes a general intro- duction to DATAPLOT and a guide, with examples, to the various commands and

features of the language. DATAPLOT is written in ANSI FORTRAN and is easily

transported to a variety of systems.

Known implementations exist on Univac,

Vax, Honeywell, IBM, Data General,

Perkin Elmer, and Prime computers.

OPTICAL FIBER MEASUREMENTS

Day, G.W. and Franzen, D.L., editors,

Technical Digest—Symposium on Optical Fiber Measurements, 1984, Natl. Bur. Stand. (U.S.), NBS Spec. Pub. 683,

148 pages (October 1984). Order from

GPO by stock no. 003-003-02604-2, $5

prepaid.

Summaries of 31 papers presented at an October 1984 symposium on optical fiber measurements in Boulder, Colo., are now

available. The papers deal with measurements on single and multimode

fibers, the characterization of fiber for sensors, instrumentation and field measurements, and standards.

PROGRAMMING LANGUAGE

SELECTION

Cugini, J.V., Selection and Use of

General-Purpose Programming

Languages—Overview (Vol. 1) and

Program Examples (Vol. 2), Natl. Bur

Stand. (U.S.), NBS Spec. Pub. 500-117

(Vol. 1 and Vol. 2), 81 and 178 pages, re- spectively (October 1984). Order from

GPO: Vol. 1 by stock no. 003-003-02612-3, $3 prepaid; Vol. 2 by

stock no. 003-003-02613-1,

$5.50 prepaid.

A two-volume set of publications issued

by the NBS Institute for Computer Sci- ences and Technology should help data

processing managers and users select the right language for their special re- quirements. Volume 1 explains the fea- tures of seven popular programming

languages—Ada, BASIC, COBOL, C, FORTRAN, Pascal, and PL/1—and

points out special advantages and disad- vantages for each. Selection criteria dis- cussed are the language and how it is to be used, the application to be pro- grammed, and the user's existing facili- ties and software. Volume 2 contains

program examples to help illustrate the features of the various languages.

SIMPLIFIED SCALE INSPECTIONS

Warnlof, O.K., editor, Specifications,

Tolerances and Other Technical Requirements for Weighing and Measuring Devices, Natl. Bur. Stand. (U.S.), NBS Hdbk. 44—1985, 294 pages

(November 1984). Order from GPO by

stock no. 003-003-02625-5, $9 prepaid.

The jobs of hundreds of state inspectors

who regulate weighing and measuring

scales will be simplified due to major re- visions by the National Conference on

Weights and Measures (NCWM) in this handbook. NCWM's Specification and

Tolerance Committee has worked with the Scale Manufacturers Association in developing new tolerance procedures

whereby the allowable error increases

with the size of the load up to the max- imum capacity of the scale. The new

code in Section 2.20 of the handbook,

30
Scales, which becomes effective January

1, 1986, eliminates complicated calculations for each type of scale and en- ables manufacturers to produce products

that are compatible with foreign codes.

PERSONAL COMPUTER SECURITY

Steinauer, D.D., Security of Personal

Computer Systems: A Management

Guide, Natl. Bur. Stand. (U.S.), NBS

Spec. Pub. 500- 120, 66 pages (January

1985). Order from GPO by stock no. 003-003-02627-1, $3 prepaid.

Security risks are increasing as personal

computers become as common in the of- fice as electric typewriters. No "cookbook" approach can solve security problems for every organization. But in this booklet the experts in the NBS Institute for Computer Sciences and Technology

recommend several basic steps that will help. They suggest a prompt inventory of personal computer equipment, noting

where it is located and who uses it. A

risk analysis will help determine how vul- nerable your information is. Then costeffective controls can be put in place,

ranging from an inexpensive lock to specially designed software or hardware.

LASER-INITIATED COMBUSTION OF

ALLOYS

Bransford, J.W., Laser-Initiated Combustion Studies on Metallic Alloys in Pressurized Oxygen, Natl. Bur. Stand.

(U.S.), NBSIR 84-3013, 76 pages (August

1984). Order from NTIS by stock no. PB

85-28114, $10 prepaid.

In 1981, NBS provided qualitative data on the combustion of several aluminum,

stainless steel, and copper alloys (NBSIR

81-1647). Since then, quantitative data

have been acquired on aluminum-,

cobalt-, iron-, and nickel-based alloys.

These data include measurements for ig- nition and combustion temperatures and

other combustion parameters at highoxygen pressures. It was found that alu- minum could be ignited below the melting point of the alloy oxides produced.

Cobalt-, iron-, and nickel-based alloys

generally ignited slightly below to slightly

above the melting range of the respective alloy. Unsupported combustion was

not achieved until the alloys and oxides were melted. These experiments and

results are described in this publication.

INSTALLATION OF WOOD-BURNING

APPLIANCES

Loftus, J.J. and Peacock, R.D., Clear- ances and Methods of Protection for Wall and Ceiling Surfaces Exposed to Radiant Heating Appliances, Natl. Bur. Stand. (U.S.), NBS Tech. Note 1205, 112

pages (December 1984). Order from

GPO by stock no. 003-003-02630- 1, $4.50 prepaid.

Accompanying the increasing use of wood-burning appliances over the past 10 years has been a dramatic increase in house fires. Mainly, say NBS fire re- searchers, because homeowners im- properly install, operate, and maintain

these appliances. In recent studies for the Consumer Product Safety Commission and the Department of Energy, the NBS researchers have investigated the

fire safety of wood-burning appliances.

The report gives the results of these

studies and recommendations for build- ing and fire code officials to use in pre- paring fire safety codes and regulations.

Many of these guidelines have been

adopted by the National Fire Protection Association (NFPA) as changes to NFPA's code on heat-producing

appliances.

THERMODYNAMIC DATA FOR AQUEOUS AND BIOCHEMICAL SYSTEMS

Goldberg, R.N., Compiled Thermodynamic Data Sources for Aqueous

and Biochemical Systems: An Annotated Bibliography (1930- 1983), Natl. Bur. Stand. (U.S.), NBS Spec. Pub. 685,

106 pages (December 1984). Order from

GPO by stock no. 003-003-02606-9,

$4.50 prepaid.

NBS has compiled an annotated bibli- ography of sources of data on the ther- modynamic properties of aqueous and

biochemical systems. The bibliography

lists 162 different sources of compiled

and evaluated chemical thermodynamic

data such as Gibbs energy and equilibrium data, enthalpies of formation and

reaction, heat capacities and entropies,

and the corresponding partial molar and

excess properties. Derived quantities

used to calculate data and some trans- port and mechanical data are also in- cluded. The bibliography covers publications released between 1930 and 1983,

and includes brief descriptions of the types of properties tabulated in each

source, the classes of materials dealt

with, and the degree of completeness of the compilation. It is indexed by author and subject.

SHIELDING EFFECTIVENESS OF

BUILDINGS

Wyss, J.C., Anson, W.J., and Orr, R.D., Building Penetration Project, Natl. Bur. Stand. (U.S.), NBSIR 84-3009, 310 pages

(September 1984). Order from NTIS by

stock no. PB 85- 126001, $25 prepaid.

Electrical engineers and others con- cerned with the effectiveness of buildings

in shielding their interiors from electro- magnetic (EM) radiation will be interested

in this publication from NBS. It documents a computer program which calculates building attenuation of EM radiation over the frequency range 10 kHz to 10

GHz. Attenuation is computed from build- ing shape, dimensions, room layout, and

the electrical properties of the construction materials; no electromagnetic measurements are required. Although per- formed for the U.S. Army, the work is applicable to almost any situation where it

is desirable to estimate the extent of penetration of EM radiation into a multi- room, one-story building.

ORDERING INFORMATION

To order publications from NTIS, send

request with payment to: National Technical Information Service, Springfield, VA

22161. Publications can be ordered from

GPO by mailing order with payment to: Superintendent of Documents, U.S. Government Printing Office, Washington, DC

20402.

31
CONFERENCE CALENDAR

11th international Conference on

Atomic Collisions in Solids, Georgetown University, Washington, DC

August 4-9, 1985

The subject atomic collisions in solids deals with the fundamental aspects of particle interactions with matter in a con- densed state. It crosslinks not only the basic fields of elementary particle, nuclear, atomic, molecular, and solid state physics but also topical areas such as

surface chemistry, physics, and radiation effects on matter. The International Conference on Atomic Collisions in Solids, held every 2 years since 1965, is one of the few conferences that truly bridges

these disciplines. The conference ad- dresses the scientific underpinnings of such important technologies as sub- micron devices and new materials used

in a variety of applications. Sponsored by

NBS, Georgetown University, and the In- ternational Union of Vacuum Science,

Techniques, and Applications. Contact: Kathy C. Stang, A353 Physics Building,

NBS, Gaithersburg, MD 20899,

301/921-2255.

EMI Metrology Short Course, University of Colorado, Boulder, CO

August 6-8, 1985

This course will bring together engineers,

scientists, technicians, and managers

from industry, government, and academia

for the most up-to-date information on in- struments and techniques for measuring

electromagnetic interference. Topics to be covered include: open-site measurement as related to FCC require- ments; TEM cells; shielding effec- tiveness; anechoic chambers; probes;

reverberating chambers; and measurement services. Sponsored by NBS, it will be held at the University of Colorado

Boulder campus with demonstrations at the NBS Boulder laboratories. Contact: Kent Zimmerman, Office of Conference

Services, Campus Box 153, University of Colorado, Boulder, CO 80309,

303/492-5151.

Time and Frequency Seminar, NBS,

Boulder, CO

August 13-15, 1985

This seminar is intended for those who

want a comprehensive introduction to the generation and dissemination of time and

frequency. It will include demonstrations

of practical means for making time and

frequency measurements as well as

tours of NBS time and frequency facili- ties. Topics will include: types of fre- quency standards and their operational

principles; mathematical characterization

of clocks and frequency standards; measurement of clock stability in both time

and frequency domains; pitfalls in data

collection and analysis; the process of timekeeping; NBS dissemination ser- vices; and NBS frequency calibration ser- vices. Sponsored by NBS. Registration fee is $575. Contact: Judy Rapozo or James L. Jespersen, Division 524, National Bureau of Standards, Boulder, CO

80303, 303/497-3294 or 303/497-3849.

VLSI Chip Packaging Workshop, Gaithersburg Marriott, Gaithersburg, MD

September 9-11, 1985

This workshop has become a premier fo- rum for technical professionals in the

field of package development and analysis for VLSI integrated circuits. The topics covered will include large chips, high- lead-count packages, conventional and

pin-grid-array chip carriers, TAB and wire bonding, and electrical and thermal per- formance packages. Sponsored by the

Institute of Electrical and Electronics Engineers, the Component Hybrids and

Manufacturing Technology Society, and

NBS. Contact: for technical information,

Courtland Robinson, AT&T Bell Labs,

Allentown, PA 18105, 215/439-5166; for registration information, Sandy Kelley,

B344 Technology Building, NBS, Gai- thersburg, MD 20899, 301/921-3541.

2nd International Symposium of Roofing Technology, NBS, Gaithersburg, MD

September 18-20, 1985

The theme of this symposium will be

"Roofing Materials and Practices—A De- cade of Change and Future Trends." The

speakers will focus on such topics as: fu- ture technologies in roofing; advances in roofing membranes; the impact of computers on roofing design; roofing condition assessment; quality assurance; practical experiences in design, application,

and field performance; metal roofing,

flashings, and accessories; and steep

roofing. Sponsored by NBS, the U.S. National Roofing Contractors Association,

and the International Union of Testing

and Research Laboratories for Materials and Structures (RILEM). Contact: Robert

G. Mathey, B348 Building Research,

NBS, Gaithersburg, MD 20899,

301/921-2629.

First International Symposium on Fire Safety Science, NBS, Gaithersburg, MD

October 7-11, 1985

Approximately 114 papers will be

presented at the First International Symposium on Fire Safety Science by speakers representing 13 countries. The symposium's ten sessions will cover such

topics as fire physics; fire chemistry;

smoke toxicity and toxic hazard; statistics, risk, and system analysis; people-fire

interactions; detection; suppression;

structural behavior; specialized fire prob- lems; and translation of research into practice. The meeting has been or- ganized by an ad hoc committee with a view to initiating an International Association for Fire Safety Science. The pur- pose is to provide a continual forum dedicated to all aspects of fire science and

their application to solving problems

presented by destructive fire. Sponsored

by NBS. Contact: Sonya Cherry, B260

Polymer Building, NBS, Gaithersburg,

MD 20899, 301 /921 -3245.

32
The National Bureau of Standards was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the nation's science and technology and facilitate their effective application for public benefit. To this end,

the Bureau conducts research and provides: (1) a basis for the nation's physical measurement system, (2) scientific and

technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote

public safety. The Bureau's technical work is performed by the National Measurement Laboratory, the National Engineering

Laboratory, the Institute for Computer Sciences and Technology, and the Center for Materials Science.

THE NATIONAL MEASUREMENT

LABORATORY

Provides the national system of physical

and chemical measurement; coordinates

the system with measurement systems of other nations and furnishes essential ser- vices leading to accurate and uniform

physical and chemical measurement

throughout the nation's scientific community, industry, and commerce; provides

advisory and research services to other government agencies; conducts physical

and chemical research; develops, pro- duces, and distributes Standard Refer- ence Materials; and provides calibration services. The laboratory consists of the

following areas:

• Standard Reference Data

• Measurement Services

• Basic Standards

• Radiation Research

• Chemical Physics

• Analytical Chemistry

THE NATIONAL ENGINEERING

LABORATORY

Provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support

of these efforts; builds and maintains

competence in the necessary disciplines

required to carry out this research and

technical service; develops engineering

data and measurement capabilities; pro- vides engineering measurement traceability services; develops test methods

and proposes engineering standards and

code changes; develops and proposes new engineering practices; and develops

and improves mechanisms to transfer re- sults of its research to the ultimate user. The laboratory consists of the following centers: Applied Mathematics

• Electronics and Electrical Engineering

• Manufacturing Engineering

• Building Technology

• Fire Research

• Chemical Engineering

THE INSTITUTE FOR COMPUTER

SCIENCES AND TECHNOLOGY

Conducts research and provides scientific and technical services to aid federal agencies in the selection, acquisition, application, and use of computer

technology to improve effectiveness and

economy in government operations in ac- cordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders,

and other directives; carries out this mission by managing the Federal Information Processing Standards Program, de- veloping federal ADP standards

guidelines, and managing federal participation in ADP voluntary standardization activities; provides scientific and

technological advisory services and as- sistance to federal agencies; and provides the technical foundation for computer-related policies of the federal government. The institute consists of the

following centers:

• Programming Science and Technology

• Computer Systems Engineering

THE CENTER FOR MATERIALS

SCIENCE

Conducts research and provides measurements, data, standards, reference

materials, quantitative understanding,

and other technical information funda- mental to the processing, structure, properties, and performance of materials; ad- dresses the scientific basis for new

advanced materials technologies; plans research around cross-country scientific themes such as nondestructive evaluation and phase diagram development; oversees Bureau-wide technical pro- grams in nuclear reactor radiation re- search and nondestructive evaluation; and broadly disseminates generic technical information resulting from its pro- grams. The center consists of the following divisions:

• Nondestructive Evaluation

• Inorganic Materials

• Fracture and Deformation

• Polymers

• Metallurgy

• Reactor Radiation

J
iic nFPARTMENT OF COMMERCE BULK RATE

National Bureau of Standards POSTAGE & FEES PAID

Gaithersburg, MD 20899 NBS

OFFICIAL BUSINESS PERMIT No. G1 95

Penalty for Private Use, $300