A111D2 a^DElS

NBS

PUBLICATIONS

I nstitute for Materials Science and Engineering

REACTOR

RADIATION

Technical Activities

1987

Institute for Materials Science and Engineering

REACTOR

RADIATION

Dr. Robert S. Carter, Chief

Mr. Tawfik M. Raby, Deputy Chief

RESEARCH INFORMATION CENTER

Nat i onal Institute of

Standards and Technology

Ga i thersburg s HD 208^9

a’ ch

NAS-NRC

Assessment Panel

November 1987

NBSIR 87-3616

U.S. Department of Commerce

National Bureau of Standards
ABSTRACT

This report summarizes all those programs which depend on the NBS

reactor. It covers the period from October 1, 1986 through September 30,

1987. The programs include the application of neutron methods to the

characterization of materials, neutron standards, trace analysis by neutron

activation analysis, neutron depth profiling, nondestructive evaluation, and

the production of radioisotopes.

Key words: Activation analysis; crystal structure; diffraction; isotopes;

molecular dynamics; neutron; neutron radiography; nondestructive

evaluation; nuclear reactor; radiation.

DISCLAIMER

Certain trade names and company products are identified in order to

adequately specify the experimental procedure. In no case does such

identification imply recommendation or endorsement by the National Bureau of

Standards, nor does it imply that the products are necessarily the best

available for the purpose.

11
TABLE OF CONTENTS

Abstract ............................... ii

Introduction and Overview ...... ........... 1

Organization Charts ......................... 7

Research Staff . ..................... 15

Description of Technical Activities ................ . 17

Reactor Operations and Services .............. 19

Neutron Scattering Characterization of Materials

for Advanced Technologies ............... 22

Cold Neutron Project .................... 33

Independent Programs .................... 36

Outputs/Interactions ......... . . . . .......... 43

Publications ........................ 45

Technical and Professional Committee Participation

and Leadership .................... 52

Industrial and Academic Interactions ............ 54

Associated Activities ........................ 55

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INTRODUCTION AND OVERVIEW

REACTOR RADIATION DIVISION (460^)

Robert S. Carter, Chief

Tawfik M. Raby, Deputy Chief

S. E. Tassey, Secretary

The National Bureau of Standards reactor (NBSR) is a national center for the

application of reactor radiation to a variety of problems of national

concern. The major areas of activity are:

Materials Characterization

Nondestructive Evaluation

Trace Analysis

Radiation Standards and Measurement

The Reactor Radiation Division (RRD) , in collaboration with other scientists

within the Institute for Materials Science and Engineering (IMSE), other NBS

Centers, and outside organizations uses neutron scattering methods to

determine the properties and behavior of materials at the submicroscopic

level. These methods are used to study a wide variety of problems in such areas as hydrogen in metals, the microstructure of ceramics and metals,

microscopic properties of advanced crystalline and amorphous magnetic

materials and polymers, molecular species, interactions and pore structures

in catalysts and microporous materials, and the structure of biological

molecules. These measurements contribute to an understanding of hydrogen

effects on metal properties, properties of new and improved alloys and

magnetic materials, ceramics and fast- ion conductors, high- temperature

superconductors, polymer blends, chemical catalysis, and biological

processes. NBS is in an excellent position to carry out such a multidisciplinary program because of its strong materials programs located

in IMSE and other centers and its 25 state-of-the-art reactor facilities

that are not available in private-sector laboratories.

Major Activities:

The major research activities of the Reactor Radiation Division involve

developing state-of-the-art neutron diffraction, inelastic scattering and

radiographic methods and associated experimental facilities, and fostering

their application by other NBS divisions and offices and other U.S.

industrial, university and government groups to meet critical research needs

in physics, chemistry, materials science, and biology. The scientific core group maintains essential research capabilities in condensed-matter science

and engages in cooperative research with more than 200 scientists from NBS

and outside groups, including studies of new high technology magnetic and

amorphous materials, modern electronic and structural ceramics, hightemperature superconductors, chemical catalysts and advanced metals and

alloys being developed for new products and technological applications.

In the area of nondestructive evaluation (NDE) , RRD uses neutron radiography

and both large and small-angle neutron diffraction to examine objects for

defects or hidden components that must be examined nondestructively . The

major effort is in the development of new or improved neutron NDE methods.

Methods are being developed for such diverse applications as the use of

1
autoradiography to study rare paintings and the use of neutron scattering to

investigate voids and other defects causing failure in structural materials.

Neutron activation analysis is a very sensitive technique for measuring*

trace elements at very low concentrations. RRD provides the sample

irradiations, but the program and sample analysis is carried out by the

Center for Analytical Chemistry (CAC) . It is used extensively for

characterizing Standard Reference Materials (SRM) and a variety of other

measurements such as the determination of Iodine -129 concentrations and

environmental studies. A large number of outside organizations also use

this technique for measuring trace elements or pollutants in foods and

drugs, environmental samples, criminal artifacts, etc. This is one of the

largest neutron activation analysis activities in the country with thousands

of samples irradiated each year. Although the primary effort in this

activity is centered around neutron activation analysis, other neutron

analytical methods are also being developed. A facility has been built to

analyze for trace elements by measuring the prompt gamma ray spectrum

induced by neutron capture in the sample, and a facility has been developed

(depth profiling) to measure concentrations of light elements (e.g., B, Li) as a function of depth with - 100 A depth resolution, which is the best in

the United States.

A program in radiation standards and measurements is carried out by the

Center for Radiation Research (CRR) . Through the use of double fission

chambers and a series of accurately calibrated fission foils, they provide

the basis for reactor neutron flux and power density measurements needed in

the U.S. fast-flux development program. The calibration and intercomparison

of the series of fission foils makes use of standard reference neutron

fields established in the thermal column of the NBSR. CRR also maintains

well characterized, filtered neutron beams in the reactor of 2 keV, 25 keV,

and 144 keV energy for the calibration and development of personnel neutron

dosimeters

.

A number of other groups both within and outside NBS utilize the long-term

irradiation facilities at the NBSR for activities ranging from y-ray and

x-ray physics and standards to application of isotopes in medical diagnosis.

Items of Special Interest:

The installation of a large-volume cold neutron source in the NBSR in order

to increase the flux of long wavelength (cold) neutrons is a high priority

of NBS and the Department of Commerce. The cold source cryostat was received in November of 1986 and has successfully undergone an extensive

series of tests outside the reactor. Its installation in the reactor was completed during the summer, and it is now (as of September 1987) awaiting

reactor startup to complete its own startup tests.

Funding was approved by Congress in November 1986 to allow us to go forward

with our program to develop a Cold Neutron Research Facility for the United

States at the NBSR. Detailed design of the large guide-hall complex has

been completed and a solicitation for fixed price bids was issued in August.

Bid opening to grant the construction will occur in October. At the same

time, the hiring or transfer of key scientific and engineering staff to

carryout the planning, design, and development of the fifteen experimental

stations in the guide hall is occurring. The contract for the seven guide

2
tubes is also close to being ^et. The large volume cold source will allow

the provision of over 700 cm of cold neutron beams (seven guide tubes, one beam hole) for cold neutron research. Ten of the major new instrtiments to

be built in the guide hall have been identified and active design and

analysis is underway for several classes of instruments. Already under

detailed design and construction is the high-resolution 30 m SANS facility

being jointly developed with the EXXON Research and Engineering Company.

There have been a ntimber of accomplishments in our neutron scattering

research programs during the past year, including some of the first and most

accurate results (with AT&T and NRL) on ’the structure, oxygen arrangements,

and phonon density of states in new high T superconductors; discovery (with

U. of IL) of the existence of two distinct, magnetic propagation vectors in

new, artificially produced thin-layer magnetic superlattices, along with

propagation of magnetic phase information across magnetically "dead" layers;

and the first direct determination (with Center for Analytical Chemistry) of

the thickness and uniformity of adsorbate layers chemically bonded to the

surface of microporous silica particles. In our research on hydrogen in

metals and catalysts. Division scientists have revealed that the highly

unusual pairing of hydrogen around metal atoms in the (hep) rare -earths is

associated with dynamic coupling modulated by one -dimensional concentration

and temperature -dependent occupation correlations and have provided evidence

(with the Center for Chemical Physics) for the coexistence and nature of

surface and near-surface adsorbed H in a Pd black catalyst. In our theoretical efforts, we have achieved a significant advance in the theory of

small angle scattering by extending the simulation technique proposed by

Cahn to the treatment of scattering from bicontinuous interfaces in

microdispersed and microporous media and have developed a new mathematical

approach for extending the phases of diffraction data from biomolecules. In

another area, the Neutron Group's Crystal Data Center has recently released

for worldwide distribution (with Scientific Numeric Database of Canada) a greatly expanded crystal database with a state-of-the-art search system.

Over 110 institutions, including many major industrial companies have signed

up to use the system. Finally, in our new instrumentation development

efforts, we have done the first experiments on the new NBS/U. of MD

polarized beam spectrometer, and have made extensive use of the recently

commissioned subthermal time-of-flight neutron spectrometer in studies of

the dynamics of catalysts, hydrogen in metals, protonic conductors, and

magnetic materials. In addition, some major components have been assembled

for a modernization of the Biological Crystallography station of the NBS

Biotechnology program (Center of Chemical Physics)

Reactor Utilization:

As is indicated above, RRD has a dual function. It conducts research

programs in the areas of materials characterization and NDE and serves as a focal point of neutron scattering expertise for many other programs both

within and outside of NBS. The second function includes not only the

operation of the reactor, but also providing sample irradiation services for

a large number of users.

An important part of the overall Reactor Division contribution to the NBS

mission and to the scientific and technical community is in fostering the

utilization of the reactor by other NBS groups and outside organizations.

Interactions with other scientists and organizations take the form of both

3
collaborative efforts and independent programs which rely on utilization of

the reactor and facilities provided by the NBSR staff. The extent of such

interactions for FY 87 are indicated in the tables below. The number of

personnel shown in Tables 1 and 2 include many short-term collaborators as well as permanent other agency and university guest workers. These numbers

are constantly changing and so may not be exact.

Collaborative interactions are those in which workers from outside the RRD

collaborate scientifically with RRD scientists on problems of mutual interest. These interactions are summarized in Table 1.

Many of the other agency, university, and industrial collaborators have

worked with us regularly for many years. Others come from all over the

world to spend a few days, weeks, or months to carry out specific

experiments using the facilities available at the NBSR. Collaborative

programs include measurements on new magnetic materials and superconductors,

fast- ion conductors, polymers, catalytic materials, hydrogen embrittlement,

voids and precipitates in alloys, and ceramics, etc.

Table 1. Collaborative Interactions

No. of Personnel

FY 87

RRD Permanent Scientists 17

Non-RRD Participants

Other NBS 31

Other Agency 27

University 66

Industrial 36

International 32

Total Non-RRD 192

Independent programs are those programs carried out independently of the

Reactor Radiation Division scientific staff by other NBS Divisions and

outside organizations. Table 2 summarizes these interactions.

Table 2. Independent Programs

No. of Personnel

FY 87

Other NBS 30

Other Agencies 30

Universities 40

Industrial 23

International 7 Total 130

These tables demonstrate the extensive utilization of the NBS reactor by

scientists and engineers from outside the Division. They come from 17 NBS

4
Divisions and offices, 16 other Federal organizations, 37 U.S. universities,

23 U.S. industrial laboratories, and 18 foreign laboratories.

Organization of Technical Activities:

The technical activities of the Division are organized into major tasks.

These are summarized below and described in more detail in the "Description

of Technical Activities" section. Because the reactor serves not only the

Reactor Radiation Division and IMSE, but many other NBS Centers and outside

organizations, a description of the major outside activities (Independent

Programs) will also be included.

REACTOR OPERATIONS AND SERVICES

This task operates and maintains the NBSR, handles all licensing

interactions, reactor security, and provides sample irradiation services to

a large variety of users. Services range from pneumatic tube irradiations

for neutron activation analysis to the production of radioisotopes for

medical research.

NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR ADVANCED TECHNOLOGIES

This task develops and applies neutron scattering methods and related

theoretical analysis for research on the fundamental properties of materials

which affect their use in technological applications. Current areas of

emphasis include new magnetic and superconducting materials, hydrogen in

metals, catalytic materials, and graphite intercalation compounds. Task

scientists also utilized the special role of neutrons in the structural

analysis and nondestructive testing of materials, including concentrated

efforts in neutron diffraction, small angle scattering, profile refinement,

and state-of-the-art computer methods for: (1) precise structure and

microstructure analysis for effective use of materials (e.g., in

electronics, advanced transportation systems, and chemical catalysis), (2)

development and transfer of an evaluated materials structure database . (3)

nondestructive reference me thods for texture, and strains affecting

materials product processing and performance. The members of this task (and

the following task) are also responsible for establishing and maintaining a national center of excellence for neutron scattering, including a computercontrolled network of nine spectrometers at the reactor.

COLD NEUTRON PROJECT

The goal of this program is to develop, install and operate a national

facility for cold neutron research at the NBS reactor. This includes the

operation of a large volume cold neutron source, as well as the design and

construction of an extensive neutron guide tube network and a neutron guide

hall with fifteen major experimental stations for research in the condensed

matter and material science, biology, and fundamental physics and metrology.

INDEPENDENT PROGRAMS

Although a great deal of research by non-Division scientists is carried out

in collaboration with Division scientists, there are many research projects

that utilize the reactor and its services, but which are designed and

carried out without any scientific collaboration with the Reactor Radiation

5
Division. These Independent programs typically include, trace analysis,

depth profiling, radiation standards, neutron dosimetry, environmental

studies, and medical research.

6
ORGANIZATION CHARTS

AND

RESEARCH STAFF

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Research and Engineering Staff

N. F. Berk

R, S. Carter

R. C. Casella

R. W. Erwin

C. J. Glinka

J. Gotaas

P. A. Kopetka

J . LaRock

C. F, Majkrzak

B. Mozer

D . Neumann

J. H. Nicklas

o Condensed matter theory

o SANS theory for microstructure analysis

o Computer software for graphics and data

analysis

o Reactor physics and nuclear engineering

o Cold Source development

o Theory of neutron scattering from light-atom

defects in metals

o Group theory analyses of neutron scattering

from condensed matter

o Elementary particle theory, especially as related to reactor generated experiments

o Magnetic materials

o Phase transformations

o Spin echo techniques

o Cryogenics

o SANS microstructure of metals and porous media

o Magnetic materials

o Cold neutron Instrument development

o Low temperature phase transformation

o SANS microstructure studies

o Magnetism

o Mechanical engineering

o Cold Source design

o Electro -mechanical systems

o Mechanical engineering

o Neutron instrumentation design

o Condensed matter physics

o Polarized neutron scattering

o Polarizing and monochromating devices

o Structure and microstructure of metallic

glasses

o Dynamics of liquids

o NDE of alloys

o Two-dimensional materials

o Solid state physics

o Neutron and x-ray scattering Instrumentation

o Mechanical engineering

o Reactor fuel design

o Reactor engineering support

15
E. Prince o Structural properties of alloys, catalysts and

minerals

o Advanced crystallographic refinement methods

o Software for materials structure analyses

T. M. Raby o Reactor operations

o Sample irradiations

o Reactor standards

J . J . Rhyne o Properties and transformations of high

technology magnetic materials

o Structure of amorphous solids

o Data acquisition and analysis system

J . M . Rowe o Orientationally disordered solids

o Hydrogen in metals

o Cold neutron research and instrumentation

J . J . Rush o Hydrogen in metals

o Catalysts and molecular materials

o Two dimensional system

A. Santoro o Structure of electronic and structured

ceramics

o Theory of crystal lattices

o Powder diffraction methods

I. G. Schroder o Cold neutron instrumentation development

o Nuclear and engineering physics

o Optical devices for neutron transport

S. Satija o Low- dimensional molecular systems

o Fractal aspects of microporous media

o Neutron reflectometry

J. F. Torrence o Reactor supervision

o Reactor maintenance

T. J. Udovic o Neutron time-of- flight instrumentation

o Properties of catalysts

o Spectroscopy of surfaces

16
DESCRIPTION OF TECHNICAL ACTIVITIES

The technical activities of the Division are suiiunarized in this section. A more detailed description of each project can be found in the NBS Technical

Note "NBS Reactor, Summary of Activities July 1986 through June 1987."

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REACTOR OPERATIONS AND SERVICES

The NBSR is a national center for the application of neutron methods and

standards to problems of national importance. The reactor provides intense

neutron beams and sample Irradiation facilities for more than 300

participants from many NBS divisions and outside organizations.

FY 87 Representative Accomplishments

o Nine shipments of spent fuel were made for the first time in nine years.

o The reactor control rods were replaced after more than seven years of

operation.

Reactor Operations

T. M. Raby and J. F. Torrence

Reactor operations continued at the higher power level of 20 MW for most of

the year. The reactor was shut down in May 1987 for installation of the

Cold Neutron Source. The shutdown was used for major maintenance that will

considerably reduce the length and frequency of future shutdowns. Included

among these are the replacement of the shim control rods and the overhaul of

the fuel transfer, both of which are complex and difficult operations.

Considerable problems were encountered in the older of the two main heat

exchangers. Leaks in 16 tubes suddenly developed shortly after the heat

exchanger was checked and found to be free of new leaks . The heat exchanger

will be monitored over the next few months to assure reliable performance.

Replacement heat exchangers are being ordered, however, it will be several

years before they are installed.

For the first time in several years, spent fuel was shipped for

reprocessing. It took all this time to obtain an appropriate spent fuel

cask and have it licensed by the Nuclear Regulatory Commission. Nine

shipments were made over a period of nine weeks. This was timely because

the storage pool capacity reached its limit. Again, this effort will

considerably reduce future shutdowns.

During this period, the reactor was on-line almost two- thirds of the time, even with the extended shutdowns. Fuel utilization continues to be

outstanding, reaching an average burnup high of 66%, by far the best in the

country. Two new senior operators were licensed and a third was hired.

This brings the operating staff to an acceptable level.

Irradiation Services

N. A. Bickford and J. H. Ring

Extensive irradiation services were provided to many users from within and

outside NBS. In all, more than 1,500 irradiations involving thousands of

samples were performed in many areas of research and application. Included

among these are developments of standard reference materials, preservation

and analysis of living tissue, and analysis of food and drugs and physical

evidence in criminal investigations among others.

19
Engineering Services

J. H. Nicklas and R. S. Conway

In addition to normal engineering and design services provided to reactor

operations, experimenters and users, the engineering staff is involved in a continuing effort to upgrade the reactor instrumentation, in addition to

normal surveillance calibrations.

Thirty fuel assemblies have been inspected and accepted from the DOE

contractor by the NBSR staff. An additional 34 fuel assemblies have been

fabricated and are awaiting acceptance. Fuel compacts now being made

contain 350 gms per element, a change from 300 gm elements. The first 200

plates of the 350 gm elements were radiographed and determined that the

process is under control.

The fuel element handling tool heads have been modified slightly by adding

another spring pin to the mounting block with bars on the lifting shaft to

increase its resistance to rotation. This resistance will assure locking of

the element to the upper grid and provide operators with a more positive

feel when transferring fuel. A new tool for the transfer of fuel from the

reactor core to the storage pool was made and tested.

The method developed to plug heat exchanger tubes with rubber plugs has been

successful in reducing radiation exposures. The previous method of pounding

metal plugs into the tubes required entry into the bonnet with subsequent

high radiation exposure to personnel and was limited to personnel that could

enter a 12 -inch manhole.

A new tool for pulling the fuel transfer arm bearings which will facilitate

fuel transfer has been designed and fabricated, but has not been tested to

date

.

The shim arm yokes were fabricated and assembled with shim arms, bearings,

and splines into a complete assembly for installation into the reactor. The

lost replacement of shim arm assemblies required reuse of the old yokes in a tedius underwater assembly method.

The telescopic cylinder for transferring fuel into and out of the reactor

was completely rebuilt with new bearings, seals, and end caps. It was not

necessary to rebuild the erecting hydraulic cylinder nor replace the

connecting stainless steel lines because they were in excellent condition.

A fuel element separator was designed for installation in the licensed fuel

shipping cask.

The regulation control rod was upgraded by installing a mechanical stop,

replacing the multipoint plug and bearing. Special selsjrn motors for the

regulation rod were ordered and a new relay in the chassis of the regulation

rod position indicator was installed.

A new and more reliable (personnel safety) spring compressor for the shim arm was designed and built.

20
The design of the auto- radiographic facility for the Smithsonian Institution

was completed.

Methods were studied for plugging leaks in the thermal shield piping system.

Methods were also studied for redesigning the main heat exchangers to

increase their reliability.

Negotiations are proceeding with a supplier to fabricate new shaft seals for

the shim arm splined shafts. The previous vendor has sold that division and

no longer makes shaft seals.

The installation of a 133 KUA uninterruptible power supply for the

experimental computer and associated instrximentation was completed and

placed in service.

The modernization of reactor conductivity and tritium measuring

instrumentation, including the installation of a new multipoint recorder in

the tritium monitoring system, was completed. Six conductivity amplifiers

were replaced with new units, and eleven conductivity cells and wiring were

replaced.

New transmitters and venturis at the experimental level for the cryogenic

facility were prepared and installed. For the bismuth-tip shield, readout

meters, lights, push-buttons, and alarms, both locally on the cryogenic

refrigerator and on the console of the reactor control room, were installed.

21
NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR ADVANCED TECHNOLOGIES

This task develops and applies neutron scattering techniques for precise

measurement and research on the structure and microscopic properties of

industrial and high technology materials which underlie their processing and use in technological applications. It establishes and maintains a national

center and state-of-the-art research facilities using neutron techniques.

It also fosters the application of neutron methods to NBS programs and to serve the diverse needs of the U.S. scientific and industrial communities.

Neutron beams are a powerful probe of the critical microscopic properties of

materials used in the design, development and production of industrial

products, in particular new materials for advanced technologies. The

neutron scattering expertise and state-of-the-art, ten- spectrometer network

at the NBS reactor are a central resource for 13 NBS divisions and offices

and for over 50 U.S. industries and universities (over 200 participants)

which need neutron techniques to address an increasing number of problems

and opportunities in materials science, physics, and chemistry. Neutron

scattering provides critical information on all classes of materials, which

cannot be obtained by other techniques. Neutron diffraction and

radiographic methods and a materials structure database are developed and

maintained to meet NBS and U.S. needs for more precise structural analysis

of materials. Improved capabilities will also be developed to

nondestructively measure stresses and defects which affect the performance

and failure of modern structural materials. Inelastic, quasielastic, and

magnetic scattering methods are tailored as key probes of the submicroscopic

properties of high-technology magnetic materials, industrial catalysts, and

superconductors. To serve the crucial U.S. need for cold neutron

measurement technology, a large cold-neutron source is being developed to be

used for neutron spectroscopy and small angle scattering.

NBS scientists are currently engaged in cooperative research with industrial

labs and universities on new or improved materials for semiconductor

circuits, power transformers, automobiles and aircraft, sonar and microwave

devices, microbatteries and fuel cells, high-strength polymers and ceramics,

chemical catalysts, and microporous materials. Neutron methods are essential to many high priority NBS program areas, including surface

science, biotechnology, ceramics processing, and nondestructive evaluation.

Outside interactions and cooperative materials research underway includes

industrial labs (e.g. Exxon, Allied, E-Kodak, IBM, AT&T, W. R. Grace, GE,

GTE, DuPont, Mobil), government (NIH, Army and Navy Labs, Sandia,

Smithsonian), universities (e.g. U. MD. , U. Illinois, U. Calif., Carnegie

Mellon, Auburn, Iowa State, Purdue, MIT). Joint research agreements or collaboration also in place with international centers: Institute LaueLangevin, Saclay research centre, and CNRS (France), Max Planck Institute

and KFA, Julich (W. Germany), U. Antwerp (Belgium), Chalmers Institute

(Sweden) . The materials structure database serves a nationwide user group

from industry, universities and government, and has joint agreements with

data centers around the world.

FY 87 Representative Accomplishments

o Scientists in the Reactor Radiation Division, in collaboration with AT&T

Bell Laboratories, NRL, and the Ceramics Division, have provided some of

the first and most accurate results on the atomic scale structure, oxygen

22
arrangements, and phonon density of states in new high

superconductors. Key information has also been obtained on the oxygen

chains whose removal is associated with the loss of superconductivity.

o A significant advance in the theory of small -angle scattering has been

achieved by the mathematical treatment of scattering from bicontinuous

interfaces in microdlspersed and microporous media. Based on a simulation technique proposed by J . W. Cahn in the context of spinodal

decomposition, these methods provide the first topologically well-defined

description of scattering from diverse physical systems united by having

random morphologies with a definite length scale. The theory should

provide new insights into the microstructure of technologically important

materials as diverse as oil and water microemulsions and controlled-pore

glasses

o Scientists from the Reactor Radiation Division and the University of

Illinois have discovered the existence of two distinct magnetic

propagation vectors in artificial superlattices of erblxom and yttrium

produced by molecular beam epitaxy. These results also reveal the

propagation of magnetic phase information across the magnetically "dead"

layer of Y and showed the strong influence of "lattice clamping" on the

magneto-strictively driven phase transitions occurring in this new class

of tailored magnetic materials.

o High- resolution neutron vibration spectra over a wide range of H

concentration for H dissolved in hep yttrium have revealed that the

highly unusual pairing of hydrogen around metal atoms in the rare -earths

is associated with dynamic coupling which is modulated by concentration

and temperature dependent occupation correlations along the c-axis,

o A new mathematical approach, making use of the principle of maximum

entropy, has been developed for extending the phases of diffraction data

from biological macromolecules from a low-resolution starting set to

higher resolution. This procedure has broad potential for facilitating

the determination of the structures of larger macromolecules.

o The Neutron Group's Crystal Data Center has collaborated with the

Scientific Numeric Database of Canada to make the recently released,

greatly expanded NBS Crystallographic Database (1.7 million records)

available worldwide through CRYSDAT, an on-line, state-of-the-art

database search system. Currently, over 110 institutions, including many

major U.S. industrial companies, have signed up to use CRYSDAT.

o Contrast variation small angle neutron scattering (SANS) measurements

have provided the first direct determination of the average thickness and

degree of uniformity of adsorbate layers chemically bonded to the

internal pore surfaces of microporous silica particles. The SANS results

are being used to relate the morphology of the bonded phases to trends

observed when such bonded phase particles are used in high-performance

reverse-phase liquid chromatography.

o New insight has been gained into the origin of harmonic spin waves propagating in dilute magnetic semiconductors by workers from the Reactor

Radiation Division and the University of Notre Dame. These materials are protypical examples of new perfect exchange "frustrated" coupled systems.

23
The work has also given the first direct determination of the isolated

pair exchange energy in a series of Zn-Mn Chalcogenide magnetic

semiconductors

.

o In an extensive neutron- scattering study of hydrogen adsorption on the

surface of Pd particles, in collaboration with the Center of Chemical

Physics, neutron group scientists have found direct spectroscopic

evidence for the existence and nature of subsurface hydrogen which has

been predicted by theory and other experiments to be present along with

surface species in a number of metals.

1 . Microscopic Properties of Molecular Materials and Metallic Systems

R. C. Casella, D. Neumann, J. J. Rush, W. Rymes, S. F. Trevino^, J, Nicol^

,

T. Udovic

^Guest Scientist, Army Armament Munitions and Chemical Command

^Guest Scientist, University of Maryland

Catalysts and Hydrogen in Metals

In our joint research on catalysts with the Surface Science Division, we have completed an extensive study of the interaction of hydrogen and oxygen

with the surface of Pd particles ("cleaned” Pd black) by neutron vibrational

spectroscopy. An analysis of the energies and intensities of the observed

vibrational peaks, along with isotope dilation spectra, indicate that the

hydrogens are adsorbed on regular triangular sites on (111) surface planes

and that very strong H-H dynamic interactions are present on the surface.

In addition, a careful study of a lower energy feature in the measured

spectra suggests that it is due to the presence of hydrogen bound in

subsurface layers at sites which are octahedrally coordinated. The

existence of such subsurface species has been predicted by theory and also

invoked to explain the results of macroscopic surface experiments under high

vacuum on palladium and other metals. In collaboration with scientists from

DuPont and University of California (S.B.), we have also completed the

analysis of an extensive study by neutron inelastic and quasielastic

scattering, and neutron diffraction of the deammoniation process in the

catalyst zeolite-rho. There is considerable interest in the nature of the

bonding and dynamics of protons and molecular species in this zeolite and

their relationship to subtle changes vs. temperature in the framework

geometry. Our neutron studies have provided information on the details of

reorientation of NH^ ions bound in the cages, and on significant changes in

the framework breathing modes and NH^ rotational modes which occur as a function of temperature and ammonia concentration. Recent neutron studies

involving re-ammoniation of the zeolite suggest a significant difference in

the dependence of framework breathing modes on ammoniation when compared to

the deammoniation experiments.

Other neutron scattering research underway on catalytic systems include

studies with Auburn University of hydrogen chemisorption on RuS^ catalysts

used in de - sulfurization processes and low-energy spectroscopic studies of

the dynamics of adsorbed molecular hydrogen in Co-Na-A zeolite.

Our research this past year on hydrogen in metals has concentrated on the

study of unusual bonding states of dilute hydrogen in rare earth metals and

24
in ^-phase vanadium hydride. The BT-4 spectrometer continues to be the most

sensitive in the world for studies of vibrational dynamics of dilute metal

hydrogen systems and for isotope -dependent spectroscopy. We have extended

our previous study of the novel pairing of protons around metal atoms along

the c-axis in hep yttrium to a careful measurement of vibrational energies

and lineshapes as a function of hydrogen concentration. These results,

along with an investigation of dynamic interactions between protons by

isotope dilution spectroscopy, clearly demonstrate that these unusual

pairing interactions are dynamically coupled across the metal atoms and are modulated by longer-range concentration and temperature -dependent

occupations along the c-axis.

In our study of the metal -hydrogen potential of /3-phase vanadium hydride

(whose vibrational dynamics exhibits both the lowest, 55 meV, and highest,

220 meV, optical phonon modes ever observed in a hydride), we have

demonstrated by measuring spectra on V^H, V^D and V^T that recent

theoretical models to account for the highly unusual anharmonic H potential

in the ab plane of the pseudo tetragonal structure are inadequate. Our

results show that there are highly complex interactions between the low

energy optic modes and the acoustic vibrations (band modes) , which make the

potential both isotope and temperature dependent. Other systems which have

been investigated recently include the study of H influenced by

substitutional or interstitial defects in Pd Sc and Pd^Si glass.

Two-Dimensional Systems and Disordered Alloys

During the past year, we have also continued our work on the structure and

dynamics of two-dimensional potassium- ammonia solutions intercalated in

graphite being done in collaboration with scientists from the University of

Illinois, Michigan State University, and the Institute Laue-Langevin. These

studies have revealed that above the intercalate melting transition the

ammonia molecules form four- fold complexes with the K ions which reorient

about the graphite c-axis and that the ammonia molecules display essentially

"free" rotations about the three-fold molecular axis. Below about 185 K the

intercalate undergoes a transition to a modulated, solid phase, the exact

nature of which is still under investigation. Quasielastic scattering

studies of this phase have shown that while reorientations of the complexes

are not present in the solid intercalate phase, the rotations of ammonia

molecules persists to about 50 K, where rotational tunneling develops. In

addition, inelastic scattering measurements on both phases have revealed a strong interaction between a rotational modes of the ammonia molecules and

the out-of-plane phonons.

In the past year, analysis was completed on measurements reported last year

of the vibrational density of states of both the crystalline and the

icosahedral phases of Al^Mn in collaboration with scientists from the

University of Illinois, and the results were published. The principal

conclusions of this work were: at low ^nergies the density of states of

both phases display nearly identical g(E)cxE dependences indicating that the

two phases are elastically similar contrary to some predictions; in the

intermediate energy regime (20-35 meV) the density of states of the

crystalline phase shows some weak structure, while that of the icosahedral

phase remains smooth; and above 40 meV there is an excess g(E) for the

icosahedral phase compared to the crystalline phase. These results provide

a direct test for models of the interatomic forces and dynamics of the

25
icosahedral phase. In another study of glassy GeSe and SiTe alloys, we have, in collaboration with Ames Laboratory and Ohio University, obtained

evidence for very low energy "floppy" modes predicted for "under

constrained" glass systems.

It has recently become possible to synthesize pillared clays with a wide

variety of gallery heights using in situ oxidation of metal cluster cations.

These systems then exhibit zeolite pore sizes and adsorption properties,

thus holding out the promise of fabricating pillared clays which have

catalytic properties tailored to a given chemical reaction. To date,

however, little is known about the nature of the pillaring species and their

interaction with the silicate layers. We have thus begun collaborative

efforts with scientists from Michigan State University, SUNY at Binghamton

and Schlumberger-Doll research aimed at elucidating the details of the

interactions between the pillars and the host and how these interactions are modified in the presence of adsorbed species.

2 . Microscopic Properties of Magnetic. Superconducting. and Amorphous

Materials

J. J. Rhyne, R. W. Erwin, T. Giebultowicz^ , J. Lynn^ , M. Spano^ , J.

Fernandez - Baca^ , S. C. Yu^ , and W. H. Li^

^University of Notre Dame

^Consultant, University of Maryland

^Guest Scientists

This continuing effort provides a focus for the development and application

of neutron elastic and inelastic scattering techniques for fundamental

studies of the microscopic magnetic properties of new classes of materials

(including layered magnetic systems, rare earth compounds, magnetic

semiconductors, magnetic superconductors, amorphous magnetic alloys, and

spin glasses), many of which exhibit novel properties of potential use in

device applications and high technology products. The effort this year was expanded to include studies of the statics and dynamics of the new high T

superconductors. This research is carried out in collaboration with many

industrial labs and universities, and the research leader was an invited

speaker at the Federal Conference on Commercial Applications of

Superconductivity.

During the year a number of research areas have been stressed including:

(1) the determination of magnetic and magnetostrictive effects influencing

the ordering of metallic superlattices produced by molecular beam epitaxy,

(2) the determination of the vibrational density of states in the new high

T^superconductor YBa-Cu^O^ and the role of the "chain" oxygen in these

excitations, (3) the determination of the effects of exchange and crystal

field interaction effects in dilute alloys of rare earths and yttrium, (4)

the demonstration of spin-wave like modes in dilute magnetic semiconductors

in the absence of long range order, (5) the discovery of two-dimensional

magnetic order in the high T superconductor ErBa2Cu20^. The following

summarizes some key achievements of this research:

o Established the phase coherence of magnetic order in artificial metallic

superlattices (multilayers) of dysprosium and yttrium via the formation

of a spin density wave. The magnetic coupling is carried from the

26
magnetic Dy layers through the "dead" yttrium layers with a length scale

found to be inversely proportional to the thickness of the intervening

yttrixam layers.

o Determined quantitatively the effect of the "lattice clamping" effect on

the helical- ferromagnetic phase transition in dysprosium-yttrium

multilayers and in thin films of dysprosium metal. This was the first

controlled experimental test of a theory of the magnetostrictive origin

of the spontaneous helical to ferromagnetic moment collapse observed in rare earths

o Established the validity of the existence of "quasi-harmonic" magnons in

dilute semi -magnetic semiconductor materials which exist in these

materials in the absence of long range order. Inelastic scattering data

were shown to be in agreement with a calculational model involving

nearest neighbor and next-nearest neighbor antiferromagnetic couplings in

a ratio of 1:10 demonstrating the protypical frustration in these

systems

o Developed a procedure for determining magnetic states utilizing the

change in phase of a polarized neutron beam in transmission and have

applied the technique to several re-entrant spin glass systems and

coexistent magnetic superconductors. These measurements were carried out

using a new polarized beam instrument jointly developed with NBS and NSF

funding through the University of Maryland.

o Discovered the existence of a time -dependent relaxation effect in the

magnetization of single crystal alloys of the rare earths dysprosium and

yttrium not previously seen in analogous alloys not possessing crystal

field anisotropy. The existence of long range order in a very dilute

Y_ Q.^Dy_ __ was established and the temperature of the order parameter

determined with a zero temperature value nearly equal to the free ion

value of Dy.

o Discovered the antiferromagnetic ordering of erbium in the high T

superconductor ErBa2Cu20^ at 0.6 K. The ordering is dipolar-coupling

induced and of two-dimensional character, reflecting the highly

dissimilar c-axis and basal plane lattice parameter of the Pmmm

orthorhombic cell.

o Determined the one-phonon vibrational density of states in the new high

T superconductor YBa^Cu^O^ and demonstrated that little change occurs in

tfiese energies with temperature. A complimentary measurement of the

semiconducting analog compound YBa-Cu^O^ was made to determine the

energies associated with the Cu-6 breathing modes of the b-axis chain

sites. It is the occupation of 0 in these chains which is closely tied

to the occurrence of super conductivity and the high value of T^

o Established that superconductivity, induced at elevated pressure, is

suppressed by antiferromagnetic correlations in the compound Tm

2 Fe^Si^.

A careful search for ferromagnetic order using polarized beam techniques

showed that no such orderings occur and that the antiferromagnetic order

which sets in at 1.1 K is indeed responsible for the destruction of the

superconductivity in contrast to current theoretical predictions.

27
3 . Neutron Diffraction Methods and Applications

E. Prince, A. Santoro, B. Mozer, H. Prask^ , C. Choi^, F. Beech^ , and

T. Miraglia®, D. Tranqui^, R. C. T. Slade^

^Guest Scientist, Armament Munitions and Chemical Compound

^Guest Scientist, University of London

^Guest Scientist, CNRS , Grenoble, France

^Guest Scientist, U. of Exeter

Research staff and guest scientists in this group continue to carry out a wide range of crystallographic research, including method development and

applications in materials science and an International Crystal Data Center.

Work involves strong collaboration with all other divisions in the Institute

for Materials Science and Engineering, the Center for Chemical Physics, and

with many universities and industrial laboratories, in a number of diverse

research areas, including advanced ceramics for electronic or structural

applications, catalysts, aerospace alloys, quasicrystals, and biological

structure. Development of improved methods for residual stress and texture

measurements in alloys, ceramics and composites is also a key activity.

A large component of the crystallographic effort in the winter and spring of

1987 (before shutdown in May to install the cold source) was devoted to

studies (in collaboration with AT&T Bell Labs, NRL, U. of Maryland, and the

Ceramics Division) on the new high- temperature superconductors. These

efforts provided timely and accurate information on the oxygen chains whose

occupation is associated with the onset of superconductivity, on local

disorder reflected by the large temperature factors derived for these

oxygens, and on the tetragonal-orthorhombic phase transformations in these

materials. In addition, recent studies have been directed toward an examination of the similar ceramic structures with higher oxygen content,

which also exhibit high T superconductivity, and toward a careful analysis

of subtle structural changes which occur in nonsuperconducting compounds

whose crystal chemistry is of interest for the understanding of the

superconducting phases.

Our efforts in studies of structural arrangements in ionic conductors,

catalysts, and biological macromolecules have continued. For example, a study of the ionic conductor system Li^. ^ that

there are three distinct phases: for 0 < a < U.4, the structure is of the

NASICON type, and it displays similar ionic conductivity; for 0.4 < X < 1.0,

the structure is orthorhombic; for 1.0 < X < 2.0 the structure is

monoclinic. The latter two phases have substantially poorer conductivity

than the NASICON phase. In a study of V^Mo^O^q

,

a phase in a system that is

important because of its catalytic properties, it was found that one metal

atom and one oxygen atom were disordered about a special position. In a study of lithium- exchanged zeolite X catalyst, the lithium was shown to

occupy several extra framework positions that had been postulated but not

previously observed. As part of our biological structure research in

collaboration with scientists at the Chalmers University of Technology in

Sweden, a procedure that is much more efficient than any previously proposed

was discovered for applying the principle of maximum entropy to the

determination and extension of the phases of diffraction data in biological

macromolecules

.

28
Finally, in somewhat different crystallographic applications, we have (with

the Metallurgy Division) extended our x-ray and neutron diffraction analysis

of the structure of Al-Mn-Si quasicrystals using Patterson autocorrelation

functions and six-dimensional Fourier analysis; and (in collaboration with

the Army and the Ceramics Division) we have applied energy-dispersive

neutron diffraction techniques to a measurement of internal residual stress

in both components of Al 202/SiC composite materials.

NBS Crystal Data Center

A. D. Mighell, J, K. Stalick, V. L. Himes^, M. Mrose^ , and D. R. Anderson^

^Guest Scientist, JCPDS

^Guest Scientist, U.S. Geological Survey

^Guest Scientist, Montgomery College

The NBS Crystal Data Center is concerned with the collection, evaluation,

and dissemination of structure data on solid-state materials. The Data

Center maintains a comprehensive database with chemical, physical, and

crystallographic information on all types of well-characterized substances.

These materials fall into the following categories: inorganics, organics,

organometallics , metals, intermetallics , and minerals . During the year, the

database and specially designed scientific software have been made available

to the scientific community in three distinct modes: 1) the NBS CRYSTAL

DATA Distribution Package (87); 2) International online Search System; 3)

Specialized Database for electron diffractionists

The NBS CRYSTAL DATA Distribution Package includes the database NBS CRYSTAL

DATA, a FORTRAN program (NBS*SEARCH) , and accompanying documentation. NBS

CRYSTAL DATA contains up-to-date chemical and crystallographic data on more than 120,000 materials. Each entry consists of the reduced cell and volume,

crystal system, space group symbol and number, chemical name, chemical

formula, literature reference, and other data, NBS*SEARCH software has been

designed to be used in conjunction with the database for the

characterization and identification of crystalline materials. This product

is being distributed to the scientific community by the JCPD- -International

Centre for Diffraction Data.

The data are available internationally through the online CRYSTDAT Search

System. Within CRYSTDAT, especially designed scientific, database

management and computer systems software have been integrated to form a unified analysis system. During the year, the system has been extensively

upgraded with respect to data and software. Currently, over 110

institutions, including many major U.S. industrial companies, have signed up

to use CRYSTDAT. Over the past months, the system has been used intensively

in conjunction with the development of technologically important materials.

In the design of superconductors and lasers, the database has been

systematically searched for candidate compounds with the appropriate lattice

parameters, space group, and chemical composition. This system was created

through a collaborative effort between the NBS Crystal Data Center and

CISTI's CAN/SND Scientific Numberic Database Service (Canada).

A new database, designed specifically for electron diffractionists , has been

prepared. This product allows the experimentalist to identify materials

29
using such typical electron-diffraction data as elemental information and dspacings. The central step in preparing this new database was the

calculation of d-spacings for all inorganic compounds in NBS CRYSTAL DATA^

followed by compacting this information into a streamlined Search File. The

product is being integrated with the software associated with commercial

electron microscopes. Extensive tests using observed electron diffraction

data have proved that the product provides a major new analytical tool for

electron diffractionists . The generation of the electron diffraction

database was carried out as a collaborative effort between NBS and the

Sandia National Laboratories.

Radiographic Methods and Standards

R. S. Carter, M. Ganoczy, Y. J. Cheng ^ , and J. S. Olin^

^Research Associate, Smithsonian Institution

Cooperation continues with the Smithsonian Institution in the study of works

of art by neutron autoradiography techniques. It is planned that the

collaborative project will involve the construction of a large enclosure to

make it possible to autoradiograph large paintings at the NBSR. One great

strength of neutron radiography is that it stands alone as the only

available method that allows the observation of multiple pigment

applications beneath the surface of an oil painting. It thus offers art

historians and conservators a very special opportunity to observe the

working method of an artist, quite literally from the ground up. Great

progress was made during the past year, e.g., in an ongoing systematic study

of the works of the prominent turn-of-the century American Impressionist,

Thomas Wilmer Dewing. The work so far has provided a niomber of insights

into the techniques of this artist over his career. Each of the five

paintings radiographed appear to have been initiated and constructed in a different manner, varying from a line drawing, to several stages of painting

over, to a premier coup with no preparation at all. This evidence related

to the evolution of technique, along with detailed information on pigments

and their origin, offer an increasingly powerful probe to improve

understanding of the art of master painters here and abroad, while providing

a valuable evaluation tool for judging the authenticity of works of art.

A neutron radiographic study was also conducted at the NBSR thermal column

on twenty-one Tibetan bronzes from the National Museum of Natural History

collection. These bronzes have high- lead alloying, thus rendering them

unsuitable for studying by conventional x-ray techniques. Neutron method

offers a unique nondestructive means to examine these types of objects. The

neutron radiographs revealed, in detail, the sealed contents in the hollow

bodies of these religious figures.

4 . Small Anele Neutron Scattering

J. A. Gotaas, C. J. Glinka, N. F. Berk, S. Krueger^, J. LaRock

^Guest Scientist, University of MD

Until the reactor shutdown for the installation of the cold source, the SANS

instrument was utilized by experimenters for more than 98% of the available

beam time, including visiting scientists from universities (22), industry

30
(12) , government laboratories (4) from seven NBS divisions (18) . The areas

of experiments included polymers (44%), chemistry and physics (16%),

magnetism (15%), ceramics (9%), metallurgy (7%) and biology (6%). As usual,

the demand for beam time continued to be greater than the amount available.

A brief review of some of this work follows:

As can be seen from the distribution of beam time given above, research in

pol3nners is one of the most active programs on the SANS, with scientists

from the Polymers Division playing a key role. C. Han (Polymers Division),

with a number of collaborators from university, industry and NBS, has

continued detailed studies of the conformations of a variety of polymer

blends and of the critical behavior of low density polymer materials, and

has examined the phase diagram and interaction parameters of rubber/rubber

mixtures. In collaboration with V. Soni (Shell), Han has also used SANS to

characterize the formation of micelles in block copolymers for emulsion and

oil recovery applications. W. Wu and B. Bauer (Polymers Division) have

continued their extensive studies of epoxy networks, determining the fractal

dimension of networks and the intranetwork form factor as a function of

molecular weight, as well as elucidating molecular mechanisms for the growth

and deformation of epoxy networks. B. Bauer and R. Briber (Polymers

Division) have studied the phase diagram of crosslinked polymer blends.

Finally, M. Landry (Kodak) has used SANS to characterize both bulk

polystyrene and polystyrene blends in the vicinity of the glass transition

temperature

The most active research effort from industry has been that of Exxon, which

has involved a number of Exxon scientists along with collaborators from

universities and NBS, and has formed a substantial part of the research in

chemistry and physics. S. Sinha and J. Huang (Exxon) with H. Stanley (U.

Maryland) have studied the phase separation of binary fluids, including the

effects of adsorption on surfaces, and have characterized the structure of

heavy oils. R. Overfield (Exxon) and H. Stanley have studied the thermal

dissociation of heavy oils. W. Dozier (Exxon) has used SANS to study the

structure of microemulsions. J. Gregory (Mobil) and C, Glinka (Reactor

Radiation Division) have examined the structure of hydrogen- implanted

silicon, a material useful for solar cells. H. Hanley and G. Straty (NBSBoulder) have studied concentrated latex solutions and supercooled glycerol.

C. Glinka and L. Sander (Center for Analytical Chemistry) have continued

their study of the structure of bonded phases in porous silica, R. Slade

(U. Exeter, England) used SANS as a tool to study the porosity of clay

materials

SANS has continued to prove a vital tool for probing the microscopic

structure of amorphous magnetic systems. J. Rhyne (Reactor Radiation

Division) and M. Spano (Naval Surface Weapons Center) have studied a wide

range of concentrations of various amorphous rare earth- iron systems,

examining the competition between exchange and anisotropy which leads to

the formation of an intriguing low temperature state, the correlated spin

glass. Rhyne and G. Fish (Allied Corporation) have measured the short

correlation ranges in amorphous Fe-Zr resulting from the competition between

ferromagnetic and antiferromagnetic exchange interactions. In an international collaboration, Rhyne and B. Barbara (CNRS, France) have probed

the critical behavior resulting from the presence of random exchange and

anisotropy fields in amorphous ^y^Gd^^ ^ different area, J.

Lynn, W.-H. Li and Q. Li (U. Maryland) have examined the new high

31
temperature superconductor ErBa2Cu20^ (T^ = 95K) and found evidence for the

screening of paramagnetic fluctuations by the superconducting electrons, the

first such observation in a superconducting rare earth system.

K. Hardman-Rhyne (Ceramics Division) continued to take advantage of the non- destructive interaction of neutrons with samples to evaluate the structures

of calcinated Green State alumina and alumina powder, as well as the

porosity of a variety of systems, including slipcast alumina sheets and,

with T. Coyle (Ceramics), sol-gel networks. Hardman-Rhyne also used SANS to

study the effects of stress in causing microcracks in composites and creep

cavitation in siliconized SiC.

SANS has also been of great utility in the characterization of metallurgical

samples. B. Mozer (Reactor Radiation Division) and R. Shull (Metallurgy)

have compared the microstructures of amorphous metallic alloys prepared by

different techniques. E. Case (Michigan State U.) has examined the

microstructure of boron-doped Ni^Al as part of an investigation of

embrittlement mechanisms. R. Fields (Fracture and Deformation Division) and

R. Reno (U. Maryland) have also used SANS to study the precipitation of Curich particles and austenite in aged A710 steel. Finally, R. Odette, J.

Fint and D. Klingensmith (U. California- Santa Barbara) made strenuous

efforts to push the background of the SANS instrument to record- low levels

in their attempt to observe small structural changes related to

embrittlement in irradiated pressure vessel steels.

Several research groups have taken advantage of SANS to study the structure

of biological systems. D. Engelman and J. Flanagan (Yale U.) examined the

unfolded states of proteins with altered amino acid sequences in order to

understand how one -dimensional amino acid chains fold to produce threedimensional proteins. As part of a continuing program, S. Krueger (U,

Maryland) and R. Nossal (National Institutes of Health) have studied

neurosecretory vesicle systems in an effort to understand the role of

proteins and protein interactions in their function.

Finally, as part of our theoretical effort in this area, a significant

advance has been made in the treatment of small angle scattering from

bicontinuous morphologies that bear on an understanding of microdispersed

materials, such as porous glasses and microemulsions. The new approach

develops a rigorous mathematical analysis of a computer simulation

technique, thus accurately predicting the scattering from topologically

realistic three-dimensional multi-phase interfaces.

32
COLD NEUTRON PROJECT

The goal of this program is to develop a Cold Neutron Research Facility at

the NBS reactor. This facility will consist of a large volume D^O ice cold

neutron source in the reactor, which will be viewed by seven

2neutron guides

and one beam port. The neutron guides, each of 15 X 6 cm cross-section,

will transport low energy (cold) neutrons into a new experimental hall of

dimensions 200 feet by 100 feet, providing sgace for 15 new experimental

stations. Additional support space of 15,000 ft will also be provided.

Funding for this program began in FY 87, and five new staff members have

been brought oh board. The total construction cost is estimated at $25 M

over five years.

FY 87 Significant Accomplishments

o Testing of the cold neutron cryostat outside of the reactor was completed. The cryostat was installed in the reactor, and the first

startup tests have been completed.

o A detailed design of the new building was completed, and a solicitation

of bids was issued. Bid opening is scheduled for October 5, 1987.

o The preliminary design of the cold neutron guide tube network was completed, and a request for proposals was issued. The proposals have

been evaluated, and a contract will be signed early in FY 88.

o The conceptual design of the first four new experimental stations was initiated, and some detailed design was begun.

o A study of advanced neutron optical devices was begun, and results have

been obtained for various focusing devices (e.g., elliptical and toroidal

mirrors, supermirrors). A request for proposals for advanced R&D on special thin film coatings was issued.

o A project to develop better neutron monochromators was begun in

cooperation with the Institut Laue Langevln in Grenoble, France.

1 . Cold Neutron Source

R. S. Carter, J. M. Rowe, P, A. Kopetka and R. S. Williams

The use of cold neutrons ( i . e

neutrons with wavelengths and energies

characteristic of temperatures < 60 K) is important to many areas of

materials science, including the study of microstructure in alloys, polymers

and polymer blends, and biologically significant molecules; the study of the

motions of large molecules and molecular assemblies; the use of depth

profiling to study sub-surface impurities and dopants; and the study of the

structure and dynamics of novel materials. The normal reactor moderator

produces a spectrum in which the cold neutrons are only 1 % of the total

number. However, by replacing a portion of the normal moderator with a cryogenically cooled moderator, this fraction can be increased

substantially. The NBSR was designed with a large volume suitable for the

insertion of a cold neutron source, and we are installing a 36 cm diameter

block of D

2 O ice cooled to 30 K into this volume. The first of the two

cryostats, modified to increase the cooling flow through the moderator was

33
received in November 1986. Before installation in the reactor, it was extensively tested for leak tightness, structural Integrity, and cooling

flow rate. Ice was made in it a total of five times. The final timeincluded a complete test with the cryostat connected to the refrigerator.

The cryostat, with ice in it, was successfully cooled to 25 K. Since it was not in the reactor, it had no significant heat load, so the heat load was simulated using auxiliary heaters built into the refrigerator. The system

was run for several days with a simulated heat load of 1100 W and the

cryostat at 25 K. The expected heat load in the ice from gamma- ray heating

is about 800 W, so the system appears to have adequate cooling capacity.

The cryostat and its bismuth/lead gamma- ray shield was installed in the

reactor during the summer. Once again, ice was made in the cryostat, but

D

2 O was used for the first time. The ice making proceeded smoothly and the

ice was cooled to 25 K and maintained there for several days with the

reactor shutdown. This was the last of the "dry runs," and we are now (September 1987) awaiting reactor start up to begin the final cold source startup tests. These will measure the release of radiolytic gas as the ice warms up after various periods of reactor operation. Measurements will also

be made of the cold neutron intensity and spectrum during these tests. The

first tests were satisfactorily completed on September 14, 1987, at 5 MW

reactor power.

2 . Instrumentation and Facility Desien

J. M. Rowe, T. Udovic , I. G. Schroder, C. J. Glinka, G. Greene, J. Larock,

and D. Travel

When the cold source is operational, it will be viewed by two beam tubes at

which a Small Angle Neutron Scattering (SANS) spectrometer and a Time-ofFlight (TOF) spectrometer are installed. At

2 the same time, we are constructing a new research facility of 20,000 ft (200' X 100') adjacent to

the north face of

2 the existing reactor confinement building, and an additional 16,000 ft of support space (laboratories, mechanical equipment

and offices) adjacent to the north end (A wing) of the existing office/lab

building. The detailed design of this work has been completed, and a solicitation package for bids has been issued. Bids are due by October 5,

1987, and construction will begin within 60 days of that date. The new facility will provide space for at least 15 new experimental stations, of

which one-third will be built and operated with non-NBS funds. An agreement

has been started with Exxon Research and Engineering for development of one station, and active negotiations for development of another four are actively underway.

In order to make use of the cold neutrons from the cold source, a series of

seven "neutron guides" will be installed to conduct neutrons from the source

to the new experimental hall. These guides consist of thin layers of nickel

deposited on optically polished glass, and provide beams of large cross- section (15 X 6 cm ) in the new hall. These beams can then be used for the

fifteen new experimental stations. In order to increase intensities, the

guides will be coated with a special nickel isotope, or possibly with the

special "supermirror" coatings discussed below. The conceptual design of

the guide network is complete, and detailed design and construction will

begin in the fall of 1987.

34
We have begun the conceptual design of the first four stations to be

installed in the new facility- -one SANS, one TOF, one triple-axis

spectrometer, and one back- scattering spectrometer. In addition, an extensive research and development project on advanced neutron optical

devices has been initiated. This project is based upon two major areas-

first, neutron focusing devices (mirrors, converging guides, etc.) and

second, improved neutron guide materials. In the first area, we have

developed Monte Carlo computer codes to simulate various geometries,

including realistic manufacturing problems (surface roughness, precision of

machining). In the second area, we are cooperating with Oak Ridge National

Laboratory and Brookhaven National Laboratory on the development of

"supermirrors," which are essentially neutron guides with four to nine times

the total intensity of the normal nickel guides referred to above. These

devices can be used to enhance total intensity, to focus beams, and to

select neutrons of a given spin state (polarized beams) . We are also

developing a new test station at BT-7 to allow testing of devices as they

are made. If this project is successful, at least some of the seven neutron

guides will be coated in this way, providing the better cold neutron

intensities than have been produced thus far worldwide.

35
INDEPENDENT PROGRAMS

The two major independent (non- collaborative) Bureau programs using the

reactor are nuclear methods group in the Center for Analytical Chemistry and

standard neutron fields for neutron flux calibration and materials dosimetry

in the Center for Radiation Research. These programs will be sximmarized

here. The major non-NBS Independent programs were summarized under the

irradiation services provided by Reactor Operations

.

FY 87 Representative Accomplishments

o As part of the joint NBS/FDA/USDA/IAEA study of trace elements in the

human diet, a total of 30 biologically important minor and trace elements

have been measured on a total diet material. A second diet material is

now in preparation, which will be developed as an NBS Standard Reference

Material

.

o In many applications, solid state track recorders require fissionable

deposits of very low mass, as, for example, in the monitoring of 18-

month-long power reactor fuel cycles. A cooperation has begun with

Westinghouse Corp. to provide mass assay of deposits of three fissionable

isotopes in the picogram and sub-picogram range. The accuracy goal is a few percent! The quantity measured is the total number of fissions which

take place in the SSTR deposit during a high fluence thermal or fission

spectrum irradiation. The final mass is established relative to FIMS

,

the NBS set of Fissionable Isotope Mass Standards.

Nuclear Methods

R. Fleming, Leader

The development and application of nuclear analytical techniques for greater

accuracy, higher sensitivity and better selectivity are the goals of the

Nuclear Methods Group. A high level of competence has been developed in

reactor-based activation analysis, which includes instrtomental and radiochemical neutron activation analysis (INAA and RNAA) , and in LINAC -based

activation analysis using photons (PAA) . In addition, the group has a unique

capability in neutron beam analysis with both prompt gamma activation

analysis (PGAA) and neutron depth profiling (NDP) . The NDP technique utilizes

prompt charged particle emission to determine elemental distributions within

the first few micrometers of a surface while the PGAA technique utilizes

prompt gamma- ray emission to measure the total amount of an element in a sample, regardless of its distribution. These techniques provide an arsenal

of tools to address a wide variety of analytical problems in science and

technology

.

The activities of the past year have been highlighted by the initiation of

the National Facility for Cold Neutron Research to be established at NBS

during FY89. The Group's involvement includes the design and construction of

second generation instruments for prompt gamma activation analysis and for

neutron depth profiling. In addition a facility is envisioned at which we will study the techniques for focusing neutron beams to increase the neutron

intensity on a point. The combination of intense focussed beams applied to

the existing analytical methods could result in greatly enhanced measurement

capability.

36
The Group's contribution to the certification of Standard Reference

Materials is illustrated by the multielement measurements done on the SRM

Filter Paper Blanks, Bovine Serum, River Sediment, and Creatinine. In

addition, individual elements have been analyzed in the SRM Cholesterol,

Monel, and the Depth Profiling Standard. The extension of the fast neutron

activation analysis developed for silicon determination is being made to

nickel determination, quantifying the cobalt- 58 activity produced by the

(n,p) reaction on nickel-58,

The Biomonitoring Specimen Bank Research Project continued its support for

other agencies' monitoring programs. These included the EPA human liver

project, the NOAA National Status and Trends program, the NCI Micronutrient

program, the lAEA/NBS/FDA/USDA Total Diet Study, and most recently, the NOAA

Alaska Marine Mammal Project. Research has centered on banking protocols and

improved analytical methodology; for example, the determination of vanadium

at sub-ppm levels in fish livers. Our participation in intercalibration

exercises with the project participants and the development of marine QA

materials helped enhance the quality of the analytical results used in the

assessment of the Nation's environmental health.

Bioanalytical research focused on the determination of metal species in

various materials. Elements at trace and ultratrace levels have been

determined in separated proteins and other macromolecules. The use of

autoradiography to determine phosphorus has been added to the INAA and RNAA

techniques. The occurrence of inorganic and organic compounds of tin in

marine tissues is also being studied.

The strong interaction with industrial scientists using neutron depth

profiling, prompt gamma activation analysis, and neutron activation analysis

has continued with a growing niomber of guest workers, research associates,

and joint publications. The longterm NDP study of the mobility of helium in

nickel has been completed. The measurement of distributions of lithium and

boron in metals, glasses, and polymers continues to produce important

results

The joint NBS/FDA/USDA study of trace elements in human diet, sponsored by

the International Atomic Energy Agency, has completed its third year. A

total of 40 minor and trace elements have been measured on the the total

diet material. The preparation of USDIETS II, III, and IV has been

completed, and analysis of these and other diets received from countries

participating in this global study is in progress. In addition, a candidate

SRM mixed diet reflecting the US dietary matrix is under preparation.

During the coming year the Group will continue to improve the accuracy and

sensitivity of nuclear methods as applied to elemental measurements.

Problems to be addressed include those inherent in sample preparation,

irradiation, radiochemical separation, counting and data reduction, with the

goal of minimizing and quantifying the various sources of random and

systematic errors in analysis by nuclear methods.

Ronald F. Fleming , Group Leader; Thelma A. Allen, M. James Blackman, Latane E. Brackett, Donald A. Becker, R. Gregory Downing, Kathleen A. Fitzpatrick,

Brent L. Grazman, Robert R. Greenberg, G.Venkatesh Iyengar, John K. Langland, Richard M. Lindstrom, Bruce R. Norman, Craig A. Stone, Susan F. Stone, Theresa M. Sullivan, and Rolf L. Zeisler.

37
Neutron Field Standards and Dosimetry

J , Grundl , Leader

The Neutron Dosimetry Group of the Center for Radiation Research (CRR) is

engaged in the development and the application of well-characterized neutron

fields as permanent irradiation facilities for neutron dosimetry

standardization, for neutron detector development and calibration, and for

reaction cross section measurements. Strong interactions with outside

organizations, both in the federal and private sections, are important

programmatic elements. The condensed list of technical activities given

below includes only those projects which involve facilities at the reactor.

Neutron Personnel Dosimetry

In neutron personnel dosimetry, the Neutron Dosimetry Group's activities

include the use of the NBS standard neutron fields for routine calibrations

of health physics instrumentation, for development and testing of new types

of instrumentation, and for quality control of production instruments. In

the area of dosimetry, methods research, a tissue equivalent proportional

counter system (TEPC) is under development to determine neutron dose as a function of energy deposited.

1. Purity of the filtered beams . In response to questions concerning the

purity of the NBS 2 keV filtered beam, the neutron spectrum was carefully remeasured using a He-3 spectrometer with a new low-noise

preamplifier and pile-up rejection circuitry. Newly observed lines

between 70 keV and 550 keV amount to only about 2% of the primary 2 keV

line. The pulse height spectrum shows that by far the cleanest 2 keV

beam at any reactor facility in the world is at NBS. The 144 keV beam

also has been improved recently by increasing the amount of Ti in the

filter

.

2. Quality assurance and type testing . The filtered neutron beams,

together with the beam at the thermal column, continue to be used for

testing radiation protection instrumentation. Included this year were quality control measurements on neutron area monitors for the Naval

Surface Weapons Center, dosimeter irradiations as part of the Department

of Energy Laboratory Accreditation Program (DOELAP) , and testing of a new type of neutron detector developed at the Chalk River Laboratories.

The latter testing, done in collaboration with several other

laboratories in the United States and England, forms the basis for a paper to be given at the Sixth Symposium on Neutron Dosimetry to be held

in Neuherberg, Germany, in October 1987.

Dosimetry for Materials Performance Assessment

Exposure to neutrons can cause critical performance degradation in materials

as different as a silicon wafer and an 8 -inch thick plate of steel.

Dosimetry methods for assessing the degradation of materials in highintensity neutron fields are equally diverse. The Neutron Dosimetry Group

provides some form of measurement assurance, standardization, methods

development, and/or advice for nearly all of the approaches to materials

neutron dosimetry pursued in the United States. Because of assorted

38
commercial interests, foreign involvement is also a strong component of this

activity.

1. Neptuninm neutron fluence standard . For the first time an Np fluence

l^^ndard was prepared with sufficient activation to allow the 30 -year

' Cs activity generated by the Np fission reaction to be calibrated for

dosimetry. The Np fission detector is a uniquely effective threshold

dete^^^r for establishing a neutron exposure component below 1 MeV, and

the Cs fission product activity is especially useful for monitoring

long-term exposures.

2. Pulsed reactor dosimetry . The Nuclear Effects Laboratory at the White

Sands Missile Range has requested help in developing an in-house active

fission rate measurement capability connected to NBS standard neutron

fields. Plans have been formulated for initial on-site measurements in

early FY 88. Fission rate measurements at this laboratory are used to

establish neutron dose for electronic components exposed to leakage

neutrons from the White Sands fast burst reactor.

Benchmark Neutron Field Facilities and Fission Rate Measurement Capability

The foundation of the Neutron Dosimetry Group's service to nuclear

technology are the well-specified neutron fields that are maintained as permanent irradiation facilities mainly at the reactor. Ten separate

irradiation sites at NBS provide certified fluences of thermal neutrons

(beam or isotropic) , of keV neutrons (filtered beams) , of sub-MeV

distributions (ISNF and the D

2 O Moderated Cf Fission Source), or of pure

fisslo^Qspect^um neutrons (Cf or U-235 with fluence rates of up to

4 X 10 n/cm s) . Complementing the neutron fields, but with independent

applications of its own, is the NBS fission rate measurement capability. At

the center of this capability are the set of fissionable isotope mass standard (FIMS) and the double fission chambers in which they are used.

Passive and active neutron detectors of all kinds are exposed to these

neutron fields for calibration, for measurement assurance projects, for cross section measurements, and for development of new measurement

techniques

1 . Facility Improvements

o An in-depth review and reworking of the calibration base for the U-235

cavity fission source has begun. The complicated path by which the

absolute fission neutron fluence rate is established will be set out more explicitly and calculations of irradiation fluences will be handled

with computerized spread sheets.

o A new method for monitoring ISNF irradiation fluences has been

perfected. It involves neutron fluence transfer from the Cf fission

source via fission product activation counting of U-235.

o The calibration docvunents SP250-13 covering activation foil irradiations

at the Cf fission neutron Irradiation Facility and SP250-14 for

activation foil irradiations at the U-235 Cavity Fission Source were completed and published.

39
2 . Fission Chamber Monitors.

Enlarged versions of the NBS double fission chamber were designed and.

constructed for use as the primary monitor for exposure rooms at the

AFRRI TRIGA reactor in Bethesda. This new monitoring scheme, which

replaces existing ion chambers, will provide an unambiguous response to

neutrons in the MeV range for biological specimen irradiations at high

fluence rates.

Integral Neutron Cross Section Measurements

The standard and reference neutron fields, together with the fission rate

measurement capability and the nearby facilities of the Radioactivity Group,

conspire to make NBS an excellent place to measure absolute reaction- rate cross sections. As a base program this activity has been pursued for a long

time, generating influential data in reactor physics as well as neutron

dosimetry.

1 . Nben-n^") for High-Fluence Materials Neutron Dosimetry .

The NBS cavity fission source at the reactor was the site for a DOE

sponsored, multilaboratory cross section measurement that included

substantial international participation. Nb is an up and coming

dosimetry detector with a 16 year half-life that is attractive for longterm sub-MeV neutron exposure monitoring, but not so attractive for

differential cross section measurement. Hence, for this detector, a fission- spectrvim-averaged cross section is of particular importance.

The results of this work were reported at the Sixth ASTM/EURATOM Reactor

Dosimetry Symposium in June, 1987.

2 . Photofission for Correcting Fission Detector Responses .

The problem of photofission interference in fission detectors has been

around for a long time. To check existing corrections, photofission

cross sections in four fissionable isotopes were measured in the new neutron driven gamma ray source designed and constructed by the Neutron

Dosimetry group in cooperation with the SCK/CEN laboratory in Belgium.

For these measurements, the source was operated first with a cadmium and

then with an iron converter. The data obtained will be used to validate

and/or adjust calculated correction methods, notably, those developed by

C. Eisenhauer at NBS. The measurements were carried out in a cooperation headed by Prof. T. Williamson of the University of Virginia

and were reported by him at the ASTM/EURATOM Reactor Dosimetry Symposium

in June.

3 . Capture Reactions in ISNF .

Two carefully planned irradiations of 20 activation detectors were carried out in the Intermediate -Energy Neutron Field (ISNF). The

purpose was to extend previous capture cross section measurements to

include Na, Ag, and Sc, all important reactions for reactor physics

applications. Major measurement issues were the perfection of a new method of neutron fluence transfer and corrections for resonance selfabsorption. Executing and documenting the irradiations was largely done

under contract by a retired group member.

40
special Projects

The unique irradiation facilities and measurement capabilities in the

Neutron Dosimetry Group coupled with the wide range of institutional

Involvements characteristic of neutron dosimetry in practice continues to

bring on small worthwhile projects and unavoidable responsibilities.

1 . Neutron Lifetime Experiment .

In the measurement proposed by the NBS Quantum Metrology Group, the

Neutron Dosimetry Group will determine the average linear density of

neutron beam downstream from an electromagnetic proton trap.

Preliminary^^experiments carried out this year explored the possibility

of using a B(n,a, 7 ) coincidence technique for absolute thermal neutron

counting. More than promising results were obtained and reported in a paper to be published in the Journal of Radioanalytical Chemistry. A

visiting scientist from the Unlv. of Sussex in England participated in

this work.

2 . LiF Chips for Meeaerav Gamma Dosimetry .

The new LiF Chip dosimeter (see Tech. Act. -86) has been tested for

neutron sensitivity this year by exposure in the U-235 Cavity Fission

Source. In the course of this work, a new color center was explored and

the sensitivity of the dosimeter was extended to the 10 MGy range. In a typical application, the correction for neutron response will be 15 to

20%. Special LiF-glass encapsulation for the dosimeters are being

fabricated prior to shipment to Babcock &. Wilcock, Co., who have

supported this R&D effort. The calibration work has been done in

cooperation with the X-ray Physics Group and the results were presented

at the ASTM/EURATOM Reactor Dosimetry Symposium in June, 1987.

3 . Sixth ASTM/EURATOM Reactor Dosimetry Symposium on Reactor Dosimetry .

The sixth symposium in this biennual series was held this last June in

the U.S, and two group members were strongly involved in preparing and

running what has become a rather large international gathering.

41
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43

Publications

Alberi, J.; Jeenicke, E. ; Ost, R. ; Wilson, R. ; Schroder, I. G. ; Avenier, A.;

Bagieu, G.; Benkoula, H. ; Cavaigmac, J. F. ; Adrisi, A,; Koang, D. H. ; and

Vignom, B. ; "Studies of Parity Violation Using Polarized Slow Neutron

Beams," International Conference on Parity Violation in the Nucleon-Nucleon

Interactions, Vancouver, BC. May 1987.

Anderson, I. S.; Rush, J. J.; Udovic , T. J.; and Rowe, J. M. ; "Hydrogen

Pairing and Anisotropic Potential for Hydrogen Isotopoes in Yttrium."

Phys . Rev. Lett 51_, 2822 (1986).

Anderson, I. S.; Berk, N. F. ; Rush, J. J.; and Udovic, T. J.; "Concentration

and temperature Dependence of Hydrogen Vibrations along the C-axis for

Hydrogen in Yttrium; Evidence of Dynamically- coupled Hydrogen Pairs,

"Phys. Rev. B, in press.

Beech, F. ; Miraglia, S.; Santoro, A.; and Roth, R. S.; "Neutron Study of the

Crystal Structure and Vacancy Distribution in the Superconductor Ba Y

Cu„ 0„ -." Phys. Rev. B 35, 8778-8781 (1987).

6 y - 6 Berk, N. F. ; "Scattering Properties of a Model Bicontinuous Structure with a Well Defined Length Scale." Physical Review Letters No. 25, 2718

(1987)

Boggs, P. T. ; Collins, D. M. ; Finger, L. W. ; Konnert, J. H. ; Prince, E. ; and

Spiegelman, C. H. ; "International Tables for Crystallography, Vol. C, Part 8 Refinement," in press.

Borchers , J.; Sinha, S.; Salamon, M. B.; Du, R. ; Flynn, C. P.; Rhyne, J. J.;

and Erwin, R. W. ; "Magnetic and Structural Characterization of Dy-Y

Multilayers," J. Appl. Phys. 4049 (1987).

Borchers, J.; Salamon, M. B.; Du, R. ; Flynn, C. P. ; Erwin, R. W. ; and Rhyne,

J. J.; "Characterization of Structural and Magnetic Order of Er/Y

Superlattices." Superrlattices and Microstructures (to be published in

1988.

Bouillot, J.; Rowe, J. M. ; and Rush, J. J.; "Structure of the Mixed Crystal

(KCN)_ .^(KBr)_ „ Determined by Neutron Powder Diffraction, Phys. Rev.

B. , July 1987

Cahn, J. W. ; Gratias , D.; and Mozer, B.; "Patterson Fourier Analysis of the

Icosahedral (Al, Si) - Mn Alloy," Phys. Rev. Letters, in press.

Carr, M. J.; Chambers, W. F. ; Melgaard, D.; Himes, V. L. ; Stallck, J. K.

and Mighell, A. D.; NBS/Sandia/ICDD Electron Difraction Database.

Technical Report (Sandia) , 1987 in press.

Casella, R. C.; "Coherent Scattering of Low Energy Neutrinos from

Macroscopic Objects," in Intersections Between Particle and Nuclear

Physics- -1986 . ed. D. F. Geesman, AIP Conf. Proc . No. 150, p. 1040, American

Institute of Physics, New York, (1986).

45
Casella, R. C. ; "On the Theory of Coherent Neutrino Scattering from

Crystals," Nuovo Cimento 94A . 42 (1986).

Cava, R. J.; Santoro, A.; Johnson, D. W. ; and Rhodes, W. W. ; "Crystal

Structure of the High Temperature Superconductor La_ nq-Sr- Cu 0

above and below T^." Phys . Rev. B. 35, 6716-6720 (1987)!'^^ ^

Cava, R. J.; Santoro, A.; Murphy, D. W. ; Zahurak, S. M. ; Fleming, R. M,

Marsh, P.; and Roth, R. S.; "The Structure of the Lithium Inserted

Metal Oxide J-LiV^O^." J. Sol State Chem. , in press.

Cavagnat, D.; Magerl, A.; Trevino, S.; Pesquer, M. ; and Vettier, C.; in

D3mamics of Molecular Crystals, Ed, J. Lascombe, Elsevier Science

Publishers, Amsterdam, p649 (1987).

Choi, C. S.; Prask, H. J.; "Neutron Diffraction Study of Age-Hardened U - 0.75wt% Ti Alloy," J. Nucl. Mater., in press.

Didisheim, J. J.; Prince, E. ; and Wuensch, B. J.; "Neutron Rietveld Analysis

of Structural Changes in Nasicon Solid Solutions Na.. Zr^Si P_ 0- . at

Elevated Temperatures: x = 1.6 and 2.0 at 320° C," SoliS^State^Ionics 18 &

19, 944-958 (1986).

Dougherty, D. A,; Choi, C. S.; Kaupp, G. ; Buda, A. B. ; Rudzinski, J. M.

; ^nd

Osaw^, E. ; "Effects of Substituents on the Length of Central C(sp )-

C(sp ) bond in Anthracene Photodymers and Related Molecules," J. Chem. Soc.

Perkin Trans. II, 1063-1070 (1986).

Erwin, R. W. ; Rhyne, J. J.; Salamon, M. B.; Borchers, J.; Slnha, S.; Du, R.

Cunningham, J. E.; and Flynn, C. P.; "The Magnetic Structure of Dy-Y

Superlattices," Phys. Rev. B 6808 (1987).

Fan, Y. B. ; Solin, S. A.; eumann, D. A.; Zabel, H. ; and Rush, J. J.;

"Phonons in Graphite Intercalated with Potassium and Ammonia," in Graphite

Intercalation Compounds , edited by M. S. Dresselhaus, G. Dresselhaus, and S. A. Solin, Materials Research Society, Pittsburgh, 165 (1986).

Fan, Y. B.; Solin, S. A.; Neumann, D. A.; Zabel, H. ; and Rush, J. J.;

"Elastic Neutron Scattering Study of the Structure of Graphite Intercalated

with Potassium and Ammonia," Phys. Rev. B, (in press).

Fernandez -Baca, J. A.; Lynn, J. W. ; Rhyne, J. J.; Fish, G. E.; "Spin

Dynamics of Amorphous Fe^g^ ^^Ni^Zr^Q," J. Appl. Phys. 3406 (1987).

Fernandez -Baca, J. A.; Lynn, J. W. ; Rhyne, J. J.; and Fish, G. E.; "Study of

the Long Wavelength Spin-Wave Energies and Linewidths of the Amorphous Invar

Alloy Fe^QQ x^x’" * Rev. (to be published).

Fischer, R. ; Neumann, D. A.; Zabel, H. ; Morkoc, H. ; Choi, C. ; and Otsuka,

N. ; "Dislocation Reduction in Epitaxial GaAs on Si (100)," Appl. Phys. Lett.

1223 (1986).

Fischer, R. X.; Baur, W. H. ; Shannon, R. D.; Staley, R. H.; Viga, A. J.;

Abrams, L. ; and Prince, E. ; "Neutron Powder Diffraction Study and Physical

Characterization of Zeolite D-rho," J. Phys. Chem., £0, 4414-4423 (1986).

46
Fischer, R. X.; Baur, W. H. ; Shannon, R. D.; Staley, R. H. ; Vega, A. J.;

Abrams, L. ; and Prince, E. ; "Neutron Powder Diffraction Study and Physical

Characterization of Zeolite D-ZK-5 Deep-bed Calcined at 500 C and 650 C,"

Zeolites, 6, 378-387 (1986).

Giebultowicz , T. M. ; Rhyne, J. J.; and Furdyna, J. K. ; "Mn-Mn Exchange

Constants in Zinc -Manganese Chalcogenides , " J. Appl. Phys . SI (8), 3537

(1987).

Giebultowicz, T. M. ; Rhyne, J. J.; Furdyna, J, K. ; and Debska, U. ; "Neutron

Diffraction Study of the Wurtzite-Structure Dilute Magnetic Semiconductor

ZUq 45^1^0 55

^® >" Appl- Phys. ^

(8), 3540 (1987).

Giebultowicz, T. M. ; and Holden, T. M. ; "Neutron Scattering Studies of the

Magnetic Structure and Dynamics of Diluted Magnetic Semiconductors," in

Diluted Magnetic Semiconductors, series on Semimetals and Semiconductors, by

Academic Press (in press).

Glinka, C. J.; Rowe, J. M. ; and LaRock, J. G.; "The Small Angle Neutron

Scattering Spectrometer at the NBS , " J. Appl. Cryst. 1£, 427-439 (1986).

Gotaas, J. A.; Rhyne, J. J,; Wenger, L. E. ; and Mydosh, J. A.; "Magnetic

Field- induced Transition in

x^^x’

" ‘ Phys. 3415 (1987).

Gotaas, J. A.; L3mn, J. W. ; Shelton, R. N. ; Klavins, P. ; and Braun, H. F.

"Suppression of Superconductivity by Antiferromagnetism in Tm

2 Fe2 Si^," Phys.

Rev. B in press.

Hanley, H. J. M. ; Straty, G. C. ; Glinka, C. J.; and Hayter, J. B. ; "Low-Q

Neutron Diffraction from Supercooled D-Glycerol," Molecular Physics, in

press

Hempelmann, R. ; and Rush, J. J.; "Neutron Vibrational Spectroscopy of

Disordered Metal -Hydrogen Systems." Proceedings of NATO Workshop,

Rhodes, Greece; Physics B, (in press).

Himes, V. L. and Mighell, A. D. ; "A Matrix Approach to Syinmetry," Acta

Cryst. M3, 375-384 (1987).

Jin, L. ; James, W. J.; Lemaire , R. ; and Rhyne, J. J.; "Magnetic Structure of

DyFe^," Jour. Less-Common Metals, 118 . 269 (1986).

Kircheim, R. ; Huang, X. Y. ; Carstanjen, H. D. ; Rush, J. J.; and Udovic, T. J.; "Inelastic Neutron Scattering and Resistivity of Hydrogen in ColdWorked Palladium." J. Less Common Metals, (in press).

Li, Q. ; L}mn, J. W. ; and Gotaas, J. A.; "Absolute Measurement of the Ordered

Moment in Holmium-rich (Er^ ^Ho^)Rh^B^," Phys. Rev. B35, 5008 (1987).

Loidl, A.; Knorr, K. ; Rowe, J. M. ; McIntyre, G. J.; "Glass and Phase

Transitions in (KBr)l-x(KCN)^, Phys. Rev. B. , in press.

Lynn, J. W. and Rhyne, J. J.; "Spin Dynamics of Amorphous Magnets," Chapter

14 in Spin Waves and Magnetic Excitations , edited by S. K. Sinha and A. S. Borovik -Romanov, North Holland Physics Publishers, in press.

47
Maeland, A. J.; Lukacevic , E. ; Rush, J. J.; and Santoro, A.; "Neutron Powder

Diffraction and Inelastic Scattering Study of the Structures of Zr^Pd,

J. Less Comm. Metals 121, 77 (1987).

^ Zr^PdD^ and zraPdOi^geMangin, P. ; Bomazouza, D.; Tete, C.; Rh}me , J

"Reentrant Spin-Glass Properties of a-(Fe Cr

61, 3619 (1987).

X

J . ; and

l-x^75^15'"l0’

Erwin, R. W.

’ J . Appl . Phys

Miceli, P. F. ; Youngquist, S. E. ; Neumann, D. A.; Zabel, H. ; Rush, J. J.;

and Rowe, J. M. ; "Quasicrystalline and Crystalline Phonon Density of States:

Neutron Scattering Measurement on Al^Mn," in Phonon Scattering in Condensed

Matter V . Springer Series in Solid-State Sciences vol, 68, edited by A. C.

Anderson and J. P. Wolfe, (Springer-Verlag, Berlin, 1986) p.344.

Miceli, P. F. ; Youngquist, S. E. ; Neumann, D. A.; Zabel, H.; Rush, J. J.;

and Rowe, J. M. ; "Neutron Scattering Study of the Vibrational Density of

States in Icosahedral and Crystalline Al_ Phys. Rev. B 34 8977

(1986).

Mighell, A. D.; Stalick, J. K. ; and Himes, V. L. ; "NBS CRYSTAL DATA: A

Comprehensive Database with Chemical, Physical and Crystallographic Data on Solid-State Materials," Crystallographic Databases . edited by G. Bergerhoff,

Int. Union of Crystallography, in press.

Neiomann, D. A.; Zabel, H. ; Rush, J. J.; Fan, Y. B. ; and Solin, S. A.;

"Quasielastic Neutron Scattering Study of Rotations and Diffusion in

^," (in press).

Nicol, J. M. ; Udovic , T. J.; Kelley, R. D. ; and Rush, J. J.; "Isotope

Dilution Neutron Spectroscopy: A Vibrational Probe of Hydrogen/Deuterium

Interactions on Palladium Black, Langmuir, in press.

Nossal, R. ; Glinka, C. J.; and Chen, S.-H.; "SANS Studies of Concentrated

Protein Solutions. I. Bovine Serum Albumin," Biopolymers , 25, 1157-1175

(1986) .

Prask, H. J.; and Choi, C. S.; "Residual Stress Measurements in ArmamentSystem Components by Means of Neutron Diffraction." ASM 1987

Conference on Residual Stress, Cincinnati, OH, in press.

Prince, E. ; "Diffraction Patterns from Tilings with Five-fold Symmetry,"

Acta. Cryst. A43, 393-400 (1987).

Prince, E. ; "Applications of Fixed Wavelength Neutron Powder Diffraction,"

Transactions ACA, 22 , in press.

Prince, E. ; "Phase Extension by Combined Entropy Maximization and Solvent

Flattening," Acta Cryst. A, in press.

Rhyne, J. J.; Erwin, R. W. ; Salamon, M. B. ; Sinha, S.; Cunningham, J. E.

Borchers, J.; and Flynn, C. P. ; "Long-Range Incommensurate Magnetic Order in

Dy-Y Multilayers," Invited Paper, Seventeenth Rare Earth Research

Conference, Hamilton, Canada, Jour. Less-Common Metis. 126 . 53 (1986).

48
Rhyne, J. J.; Erwin, R. W. ; Salamon, M. B. ; Sinha, S.; Cunningham, J. E.

Borchers , J.; Du, R. ; and Flynn, C. P. ; "Occurrence of Long-Range Helical

Spin Ordering in Dy-Y Multilayers," Invited Paper, Thirty-first Annual

Conference on Magnetism and Magnetic Materials, J, Appl. Phys . 4043

(1987) .

Rhyne, J. J.; "Highlights from the Exotic Phenomena of Lanthanide

Magnetism," Chapter 76, Handbook on the Physics and Chemistry of Rare

Earths, Vol. 11, edited by K. A. Gschneidner and LeRoy Eyring, North Holland

Publishing (to be published in 1988)

Rhyne, J. J.; Neumann, D. A,; Gotaas, J. A.; Beech, F. ; Toth, L, ; Lawrence,

S.; Wolf, S.; Osofsky, M. ; and Gubser, D, U. ; "Phonon Density of States of

r>or vRa Tii o Jind the Non- Supetconduc t ing Analog YBa^Cu^O^ , "

Rhyne, J. J.; Erwin, R. W. ; Borchers, J.; Salamon, M, B, ; Du, R. ; and Flynn,

C. P. ; "Magnetic Ordering in Rare Earth Multilayers Studied by Neutron

Diffraction," Invited Paper, 1987 Metallurgical Society Annual Meeting,

Trans. Metallurgical Soc., in press.

Rhyne, J. J.; "Neutron Scattering in Interme tallies , " Invited Paper,

International S3miposium on Magnetism of Intermetallic Compounds, Kyoto,

Japan, Jour. Mag. and Mag. Matls., in press.

Richter, D. ; Hempelmann, R. ; Rush, J. J.; Rowe, J. M. ; Eckert, J.;

Goldstone, and Tonks , D.; "Localized Vibrations of Hydrogen in Metals."

Physica B, (in press).

Rowe, J. M. ; "The NBS Cold Neutron Research Facility," NBS Special

Publication 711, (1986).

Rowe, J. M. ; Rush, J. J,; Schirber, J. E. ; and Mintz , J. M. ; "Isotope

Effects in the PdH system - Lattice dynamics of PdT_ ," Physical Review

Letters, 57, (1986).

Rowe, J. M. ; Rush, J. J,; and Michel, K. H. ; "Comment on Dielectric

Susceptibility Measurements in (KCN) (KBr)- Mixed Crystals." Phys.

Rev. Lett, (in press). ^ ^

Santoro, A.; Miraglia, S.; Beech, F. ; Sunshine, S. A.; Murphy, D. W.

Scheemeyer, L. F. ; and Waszczak, J. V.; "The Structure and Properties

Ba^Y Cu^Og." Mat. Res. Bull. 22, 1007-1113, (1987).

Schroder, I.; Gilliam, D. ; Carlson, A. D. ; Bright, S. W. ; and Hutchinson, J.

M. R. ; International U-235 Fission Foil Mass Intercomparision,

Transactions American Nuclear Society 473 (1986).

Smith, H. K. ; Rhyne, J. J.; Hardman- Rhyne , K. A.; and Wallace, W. E.

"Thermodynamics of Hydrides and Deuterides of R-Fe»_ and R Mn-_," Jour.

Less-Common Metis. 130, 421 (1987).

6 23 6 23

Spano, M, L. ; Rhyne, J. J.; Pickart, S. J.; Hasanain, S. K. ; Gambino, R. J.;

and McGuire, T. R. ; "Magnetic Correlations in an Amorphous Gd-Al Spin

Glass," J. Appl. Phys. 61, 3639 (1987).

49
Spano , M. L . and Rhyne

,

J. J."Neutron Scattering Study of the Spin

Freezing in Amorphous Tb^^Fe

55

and Tb Fe " 25 75’ J. Appl. Phys

.

61, 4100

(1987) .

Stalick, J. K. and Mighell, A. D. ; "Crvstal Data Version 1.0 Database

Specifications," NBS Technical Note 1229, (1986).

Stalick, J. K. and Mighell, A. D. ; "NBS CRYSTAL DATA. A Magnetic Tape of

Chemical and Crystallographic Data Compiled and Evaluated by the NBS Crystal

Data Center," NBS Tech . Note 1229, U.S. Dept, of Commerce, NBS, (1987).

Stalick, J. K. and Mighell, A. D. ; Crystal Data Version 1.0 Database

Specifications, American Crystallographic Association Annual Meeting June

22-27, 1986, McMaster University, Hamilton, Ontario (in press).

Torardi , C. C.; Reiff, W. M. ; Lazar, K. ; and Prince, E. ; "Synthesis

Structures and Low Temperature Magnetism of the New Lithium and Sodium

Insertion Compounds: LiFe (II)ClMoO, and NaFe(II)ClMoO, , " J. Phys . Chem.

Solids, 741-750 (1986).

^ ^

Trevino, S. F. and Tsai, D. H. ; "The Simulation of Condensed Matter

Chemistry and Detonation," Proc . Army Sci. Conf . , West Point (1986), in

press

.

Trevino, S. F. ; "The Rotational Potential of Solid Nitromethane , " Quantum

Aspects of Molecular Motions in Solids , ed. by A. Heidemann, A. Magerl,

M. Prager D. Richter, and T. Springer, p. 9 Springer-Verlag, (1987).

Udovic , T. J. and Kelley, R. D.; "Neutron Scattering Studies of Hydrogen in

Catalysts," Hydrogen in Catalysis: Theoretical and Pratical Aspects, (Z.

Paal and P. G. Menon, eds . ) Marcel Dekker, Inc, New York (1987) pp 167-182.

Udovic, T. J.; Cavanagh, R. R. ; Rush, J. J.; Wax, M. J.; Stucky, G. D.^

Jones, G. A.; and Corbin, D. R. ; "Neutron Scattering Study of NH^

Dynamics During the Deammoniation of NH^-rho Zeolite," J. Phys. Chem.

in press.

Wax, M. J.; Cavanagh, R. R. ; Rush, J. J.; Stucky, G. D.; Abrams, L. ; and

Corbin, D.; "A Neutron Scattering Study of Zeolite Rho." Phys. Chem.

90, 532 (1986).

Werner, S. A.; Giebultowicz , T. M. ; and Overhauser, A. W. ; "Charge Density

Wave Satellites in Potassium?" Physica Scripta (materials of the 1987

European Physical Society Meeting, Piza, Italy), in press.

Wong-Ng, W. ; Hubbard, C. R. ; Stalick, J. K. ; and Evans, E. H.

"Computerization of the ICDD Powder Diffraction Database: Critical Review

of Sets 1 to 32," Powder Diffraction . in press.

Yu, H. : Kitano, T. ; Kim, C. Y. ; Amis, E. J.; Chang, T. ; Landry, M. R.

Wesson, J. A.; Han, C. C.; Lodge, T. P.; and Glinka, C. J.; "Uniaxial

Deformation of Rubber Network Chains by Small Angle Neutron Scattering,"

(submitted to Macroraolecules)

.

50
Yu , S . C . ; Lynn , J . W . ; and Lau , B . W . X-ray Diffraction Studies of

Amorphous (Fe^ ^Ni^) alloys.

Zabel, H. ; Hardcastle, S. E. ; Neumann, D. A.; Suzuki , M. ; and Magerl,

"Dynamics of Two-dimensional Melting on a Periodic Substrate," Phys

Lett. 57, 2041 (1986).

A. ; Rev.

51
Technical and Professional Committee Participation and Leadership

American Crystallographic Association

Small Angle Scattering Special Interest Group, C< J, Glinka, Secretary

American Crystallographic Association

A.I.P. Crystal Data Committee, A. D. Mighell, ACA Representative

American Crystallographic Association

Neutron Scattering Special Interest Group, E. Prince, Chairman

American National Standards Committee

N-17: Research Reactors, Reactor Physics, and Shielding

R. S. Carter, Chairman, T. M. Raby, Secretary

American Nuclear Society

ANS-15 Standards for Research Reactors, T. M. Raby, Member

Standards Steering Committee, R. S. Carter, Voting Member

Basic Energy Sciences Advisory Committee (DOE) (appointed by the Secretary

of Energy), User Facilities Subcommittee, J. M. Rowe, Member and

Chairman

BNL Neutron Scattering Facility Scheduling Committee, J. J. Rush, Member

Intense Pulsed Neutron Source Scientific Advisory Committee (ANL)

J. M. Rowe, Member

International Centre for Diffraction Data

Data Base Subcommittee, J. K. Stalick, Member

International Symposium on Metal -Hydrogen Systems, J J. Rush, Advisory

Committee Member

International Union of Crystallography

- Commission on Crystallographic Nomenclature, E. Prince, Member

- Commission on Journals, E. Prince, Member

JCPDS- - International Centre for Diffraction Data

- Crystal Data Management Board, A. D. Mighell, Member

- Crystal Data Task Group, A. D. Mighell, Member

- Database Subcommittee, A. D. Mighell, Member

Journal of Applied Crystallography

E. Prince, Co-Editor

Journal of Applied Physics

Editorial Board, J, J. Rhyne, Member

Los Alamos Neutron Scattering Center

Scientific Advisory Committee, J. M, Rowe, Chairman

National Steering Committee for an Advanced Neutron Source

J. J. Rush, Chairman

R. S. Carter, Member

52
Neutron Sources Subcommittee of the National Steering Committee for an Advanced Neutron Source, R. S. Carter, Chairman

Program Review Committee, Argonne and Los Alamos National Labs Pulsed

Neutron Sources , J . J . Rhyne , Member

Steering Committee for Joint DA/DOE Insensitive Munitions Technology

Development Program, H. Prask, Chairman

53
Industrial and Academic Interactions

As a national center for the development and application of neutron methods,

in condensed matter and materials science, chemical analysis and radiation

standards, the Reactor Radiation Division currently has direct interactions

and cooperative programs with 37 universities, 23 industrial and 18 foreign

laboratories. A few examples of these many interactions are:

o An agreement is in place between NBS and Exxon Research and Development

Corporation to jointly develop and operate a world-class small angle

neutron scattering spectrometer at the NBS cold neutron source. Active

work is underway in the design and construction of this facility.

Cooperative research efforts on the existing SANS instrtjment at the

reactor include work on wetting in microporous media and micellar

systems

.

o An intense cooperative research effort was organized early in 1987 with

several groups at AT&T Bell Laboratories on the systematic studies of the

structure and properties of the new class of high- temperature

superconductors

.

o The Reactor Radiation Division's Crystal Data Center is engaged in a number of interactive links including joint development and distribution

to U.S. science and industry of evaluated crystal data with the

International Center for Diffraction Data. The Data Center also has

long-term agreements in place with crystal data programs in Canada, Great

Britain, and Germany to jointly develop and share critical data on the

structure of materials.

o The Neutron Scattering Group has in place wide collaborative research

with the University of California (Santa Barbara) involving neutron

inelastic scattering, neutron diffraction, and SANS studies of catalysts,

non-linear optical materials, and radiation damage.

o Extensive cooperative research efforts with the Physics Department and

Materials Research Laboratory at the University of Illinois and with

Michigan State have continued during the past year to include the first

neutron diffraction work worldwide on a new class of layered magnetic

materials and research on new kinds of metal -molecular complexes created

within the layers of oriented graphite and in pillared clays.

o Cooperative Research Program with the Department of Physics and Astronomy

of the University of Maryland. Under the program RRD staff are engaged

with Maryland scientists in joint research on magnetic materials,

superconductors, catalysts, biological materials, and in the development

of state-of-the-art polarized neutron scattering instrumentation. Some

of this research is carried out jointly with scientists from industrial

labs

.

o Collaborative research activities continue with GTE Research Laboratories

on the application of neutron diffraction and small angle scattering

techniques to study the structure, residual stress, and microstructure in

new ceramics used for electronic and auto-engine components.

54
Associated Activities

During the past year, scientists in the Reactor Radiation Division delivered

some twenty- five invited lectures in the U.S. and abroad. The Division is

also hosting the national meeting of the U.S. Test, Research, and Training

Reactors this year. Neutron Scattering Group scientists have also received,

along with French and German colleagues, several NATO grants to stimulate

cooperative research in such areas as magnetism and hydrogen in metals

55
NBS-114A iREv. 2»ac) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2 BIBLIOGRAPHIC DATA

REPORT NO.

SHEET (See instructions) NBSIR 87-3616

2. Performing Organ. Report No. 3. Publication Date NOVEMBER 1987

4. TITLE AND SUBTITLE

Institute for Materials Science and Engineering

REACTOR RADIATION DIVISION TECHNICAL ACTIVITIES 1987

5. AUTHOR(S)

R. S. Carter. NBS. 460

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

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Contract/Grant No.

I. Type of Report & Period Covered

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

10. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bliography or literature survey, mention it here)

This report summarizes all those programs which depend on the NBS reactor. It covers

the period from October 1, 1986 through September 30, 1987. The programs range

from the use of neutron beams to study the structure and dynamics of materials

through nuclear physics and neutron standards to sample irradiation for activation

analysis, isotope production, radiation effects studies, neutron radiography and

nondestructive evaluation.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Activation analysis; crystal structure; diffraction; isotopes; molecular dynamics;

neutron; neutron radiography; nondestructive evaluation; nuclear reactor; radiation.

13. AVAILABILITY

I I Unlimited

IXXl Fo’’ Official Distribution. Do Not Release to NTIS

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

20402.

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

14. NO. OF

PRINTED PAGES

15. Price

USCOMM'OC S043-P80
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