NBS

PUBLICATIONS IMSIi

NATL INST. OF STAND & TECH R.I.C.

A 1 1 1 4 5 5 A 3 7

Institute for Materials Science and Engineering

REACTOR

RADIATION

NBSIR 86-3439

U.S. Department of Commerce

National Bureau of Standards

—QC

ion

. 1)56

86-3439

1986

Technical Activities

1986

NAS-NRC

Assessment Panel

January 20-21, 1987
Layout of the NBS reactor experimental facilities and the

experimental instruments located on the first floor of the reactor

building.
RESEARCH

INFORMATION CENTER

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IMSE

Institute for Materials Science and Engineering

REACTOR

RADIATION

R.S. Carter, Chief

T.M. Raby, Deputy

NAS-NRC

Assessment Panel

January 20-21, 1987

NBSIR 86-3439

U.S. Department of Commerce

National Bureau of Standards
I
ABSTRACT

This report summarizes all those programs which depend on the NBS

reactor. It covers the period from October 1 , 1985 through September 30,

1986. 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.

ii
III1IIiiiiiIiiiiiji
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

Advanced Neutron Methods 34

Independent Programs 37

Outputs/Interactions M3

Publications 45

Technical and Professional Committee Participation

and Leadership 51

Industrial and Academic Interactions 53

Associated Activities 54

iii

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, 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-ofthe-art reactor facilities (10 IMSE 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 200 scientists from NBS and outside

groups, including studies of new high technology magnetic and amorphous

materials, modern electronic and structural ceramics, 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 nondes true t i vel y . 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.

This program is partially funded through the Office of Nondestructive

Evaluation and is part of the Bureau-wide effort to improve productivity

through better quality assurance and increased component lifetime.

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 - 1 00 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 NBS Reactor has operated very successfully at 20 MW since April 3» 1985.

The total operating time since then was 10248 hours, which reflects a 75 %

availability, a figure comparable to the best achieved at 10 MW. All

experiments at the reactor have realized the expected increase in intensity,

and experimenter radiation exposures have not increased significantly from

those observed at 10 MW operating power.

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 first cold source cryostat was

received and extensively tested (outside the reactor) in the past year. As

a result of these tests, the design was modified in order to increase the

flow of He cooling gas through the heavy ice chamber, and the cryostats were

2
returned to the contractor for modification. The first modified cryostat is

scheduled for delivery to NBS in November (as of September 25, 1986, the

contractor was on schedule), at which time it will again be tested

extensively outside the reactor. Assuming that no problems arise during

these tests, the cryostat and cold source will be installed in the reactor

this winter.

The two prototype instruments being developed with the funding provided by

Congress are proceeding well. The new neutron time-of-fl ight spectrometer

has been installed at the CTW beam port (which will be served by the cold

source), and the operating parameters are being verified at this time. The

first measurements of intensity and resolution are in reasonable agreement

with predictions, and the instrument is in the final stages of tuning for

operation. This facility will be used at this beam port until the cold

source is installed, at which time the intensity will be substantially

increased by the enhanced flux of long wavelength neutrons provided by the

source. It will be the best instrument in the U. S. A. for studies of

quasielastic scattering, allowing entirely new types of research to be

carried out, e .g

.

in the study of the motion of molecules on catalyst

surfaces. A spare detector for the Small Angle Neutron Scattering (SANS)

instrument has been ordered, and is scheduled for delivery in the coming

year. A new data acquisition system capable of handling the increased data

rates that will be available with the installation of the cold source is

under development. The design is based on the operational system developed

for the TOF spectrometer, which in turn is based on the use of a 32 bit

minicomputer and a CAMAC interface with histogramming. This system provides

a large memory for the storage of data accumulated in real time

measurements, and provides a much larger capacity for on-line data

reduction. In addition, both instruments are on an Ethernet Local Area

Network that connects all instruments in the reactor, and allows remote

operation and monitoring of experiments. A high resolution graphics station

dedicated to these two instruments is also on this network, as is access to

the existing color graphics system.

There have been a number of notable accomplishments in our neutron

scattering research programs over the past year, including the collaboration

of Purdue and NBS scientists to achieve the first direct observation of

charge density waves in a simple metal, using high resolution, high

sensitivity crystal spectrometry ; and the first neutron scattering study of

a new class of multilayer materials composed of magnetic and non-magnetic

layers, which has revealed that helical magnetic order in the magnetic

layers is propagated through the "dead" layers without loss of phase

coherence. In our research on hydrogen in metals, neutron group scientists

have achieved the first measurements ever of the phonon spectra of a tritiated material, superconducting PdT

Q ^

. These results show that the

theory of superconductivity must be reexamined, as it applies to such

materials with large mean-square displacements. Another notable

accomplishment, in collaboration with Metallurgy Division and U. Illinois

scientists, is the first measurement of the neutron diffraction patterns and

phonon density of states spectra of a '’quasicrystal." These results provide

critical information for tests of models of the structure and interatomic

forces of this new kind of material discovered at NBS. In the area of

instrumentation development group scientists have successfully tested a new

3
graphite/beryllium filter analyzer for neutron spectroscopy, which greatly

increases the resolution for studies of the dynamics of catalysts, hydrogen

in metals, polymers and other materials, while maintaining very high

sensitivity. We have also begun assembly and testing of a new state-of-theart polarized neutron beam spectrometer , jointly funded by NSF, U.of Md.,

and NBS.

Finally during FY 86, joint neutron research efforts with industry continued

to increase, including e.g.; new or expanded efforts with Exxon, Mobil, and

GTE on research ranging from wetting phenomena in microporous media, to

molecular processes and arrangements in catalysts, to studies of residual

stresses and interatomic structures in new ceramics for automobile and

electronic applications.

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

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 86 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 and university 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 fast-ion conductors, polymers, catalytic materials, hydrogen

embrittlement, voids and precipitates in alloys, and ceramics, etc.

4
Table 1 . Collaborative Interactions

No. of Personnel

FY 86

RRD Permanent Scientists 14

Non-RRD Participants

Other NBS 35

Other Agency 23

University 68

Industrial 35

International 25

Total Non-RRD 186

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 86

Other NBS 31

Other Agencies 32

Universities 36

Industrial 25

International 6

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

Divisions and offices, 14 other agency organizations, 34 universities, 24

industrial laboratories, and 15 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 . 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. All the many steps

necessary to upgrade the NBSR to 20 MW were accomplished under this task.

5
NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR ADVANCED TECHNOLOGIES.

This task develops and applies neutron inelastic 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 glassy 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. Task members have

competences at the forefront of measurement and analysis of materials

structure, including concentrated efforts in neutron diffraction, profile

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

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

chemical catalysis), (2) development and transfer of an evaluated materials

structure database , (3) nondestructive reference methods 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 computer-controlled network of nine spectrometers at the

reactor

.

ADVANCED NEUTRON METHODS .

The objective of this competence building task is to develop and maintain

new state-of-the-art facilities and technologies for neutron scattering and

to further their application in solid-state-physics, chemistry, materials

science, and biology. Under this initiative the NBS small angle neutron

scattering (SANS) facility, and an improved high resolution crystal

spectrometer have been developed and are being widely used for research on

the microstructure and dynamics of materials by many NBS divisions,

industrial labs and universities. Currently under development is a new

world-class ultra-high resolution powder diffractometer for materials

structure analysis.

COLD NEUTRON PROGRAM .

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

source in the NBS reactor, to develop two prototype instruments to utilize

the two existing beams from the cold source facility, to conduct scientific

research using these two instruments, and to perform preliminary R & D on a large cold neutron research facility that would fully utilize the cold

source

.

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 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

«c«»«ni««iin«n««c«i 9

Approval

pending
a

m
REACTOR RADIATION DIVISION

460

R. S. Carter, Chief

T. M. Raby, Deputy Chief

*E. C. Maxwell, Admin. Officer

*S. E. Tassey, Secretary

S. C. Shatzer, Clerk-Typist

Neutron Radiography

M. Ganoczy

#T. Cheng

Division Staff

R. Casella

B. Mozer

F. Shorten

Cold Neutron Program

J. M. Rowe (3/4)

// I. Anderson

C. Glinka (3/4)

+M. Kahn

P. Kopetka

I . Schroder

T. Udovic

R. Williams

*G. Greene

W. Knill (1/2)

#H. Stanley

REACTOR OPERATIONS

T. M. Raby, Chief

J. F. Torrence, Deputy Chief

C. Harrison, Secretary

ENGINEERING SERVICES

J. H. Nicklas, Chief

C. Harrison, Secretary

NEUTRON CONDENSED MATTER SCIENCE

J. J. Rush, Chief

M. Clark, Secretary

+L. Clutter, Secretary

Reactor Operators Mechanical Design

Magnetic and

Crystallography Amorphous Materials

R. Beasley E. Guglielmo

M. Bell

N. Bickford

J. Sturrock

J. Clark

F. Clark

Electronics

H. Dilks R. Conway

L. Lindstrom R. Hayes

M. McDonald

W. Mueller

T. Myers

J. Ring

R. Sprow

R. Stiber

A. Toth

D. Wilkison

L. Shuman

Part-time

+WAE, Coop, Intermittent

//Guest Scientist, research assoc. (Full Time)

°Post-doc

E. Prince J. Rhyne

A. Santoro //J. Fernandez-Baca

#C. Choi °R. Erwin

//V. Himes #T. Giebultowicz

J. LaRock (1/2) *J. Lynn

A. Mighell #P. Mangin

W. Rymes (1/2) #M. Spano

# J. Soubeyroux W. Knill (1/2)

J. Stalick //Y. Yu

# F. Beech

Advanced

Neutron Methods

Metal Hydrides and

Molecular Materials N. Berk

D. Fravel (1/2)

D. Fravel (1/2) C. Glinka 0/4)

#H. Prask J. Gotaas

J. Rowe (1/4) #S. Krueger

W. Rymes (1/2) J. LaRock (1/2)

//H. Savage

#S. Trevino

//J. Nicol

13

Research Staff

N. F. Berk o Condensed matter theory

o SANS theory for microstructure analysis

o Computer software for graphics and data

analysis

R. S. Carter o Cold Source development

o Reactor physics and nuclear engineering

R. C. Casella 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

C. J. Glinka o Magnetic materials

o SANS microstructure of metals and porous media

o Cold neutron instrument development

J. Gotaas o Low temperature phase transformation

o SANS microstructure studies

o Magnetism

P. A. Kopetka o Mechanical engineering

o Cold Source design

o Electro-mechanical systems

J. LaRock o Mechanical engineering

o Neutron instrumentation design

B. Mozer o Structure and microstructure of metallic

glasses

o Dynamics of liquids

o NDE of alloys

J. H. Nicklas o Mechanical engineering

o Reactor fuel design

o Reactor engineering support

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 transf ormat i ons of high

technology magnetic materials

o Structure of amorphous solids

o Data acquisition and analysis system

15
J. M. Rowe o Orientationally disordered solids

0 Hydrogen in metals

0 Cold neutron research and instrumentation

J. J. Rush o Hydrogen in metals

o Catalysts and molecular materials

0 Two dimensional system

A. Santoro 0 Structure of electronic and struct

ceramics

0 Theory of crystal lattices

0 Powder diffraction methods

I. G. Schroder 0 Cold neutron instrumentation development

0 Nuclear and engineering physics

0 Optical devices for neutron transport

J. F. Torrence 0 Reactor supervision

0 Reactor maintenance

T. J. Udovic 0 Neutron time-of-fl ight instrumentation

o Properties of catalysts

0 Spectroscopy of surfaces
DESCRIPTION OF TECHNICAL ACTIVITIES

The technical activities of

more detailed description

Note "NBS Reactor, Summary

the Division are summarized in this section. A

of each project can be found in the NBS Technical

of Activities July 1985 through June 1986."

17

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 users from

many NBS divisions and outside organizations.

FY 86 Representative Accomplishments

o More than 1 35,000 MWH of reactor operation, the best in the history of

the facility, were made available to researchers and other users.

o Development of heavier loaded fuel element that will significantly

increase core life and hold down overall fuel costs.

Reactor Operations

T. M. Raby and J. F. Torrence

The past year was the first full year of operation at the higher power level

of 20 MW. The new power level proved very successful. Reactor operation

was continuous except for periods of refueling and maintenance. During this

period, new and refined operating parameters were established that will

assure smooth and reliable operation at the higher power level.

Management and shipping of spent fuel is a high priority activity of this

task. In the past year, the capacity of the spent fuel storage pool was enlarged to accomodate the increase in spent fuel- that has resulted from

20 MW operation. In addition, extensive planning for spent fuel shipment

has taken place. In particular, a shipping cask suitable for NBS fuel is

under review by the Nuclear Regulatory Commission, and licensing approval is

expected later this year. Quality assurance, operating and handling

procedures for the use of this cask have been prepared and approved.

A new rule issued by the Nuclear Regulatory Commission requires all research

reactors to convert from high enriched uranium fuel to low enriched uranium

fuel unless exempted by the Commission. This would have a significant

impact on most of the programs at the NBSR because of the resultant

reduction in the thermal flux and the decrease in the signal-to-noise ratio.

NBS will apply for an exemption from the rule on the basis that important

research programs would be compromised by the conversion to low enriched

uranium

.

A new on-line thermal shield monitoring system along with additional

controls have been developed and installed, which resulted in significantly

improved performance.

Attracting and keeping qualified operations personnel is becoming exceeding

difficult. One experienced reactor supervisor retired, and another

experienced senior operator resigned to accept a position in nuclear power.

After much effort, two replacements were found. They will require one year

of comprehensive training before they become eligible for their licensing

examination

.

19
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 2,000 irradiations involving thousands of

samples were performed.

The Food and Drug Administration continued work at the NBS reactor on

improving methodology for determining trace elements in foods and biological

materials. Multielement analytical procedures developed at the reactor

during the past ten years have been applied to many food types. Work is

also being performed on methodology for determining aluminum in biological

materials at the 1 ug/g level. The high neutron flux at the NBS reactor

makes the facility ideally suited for this program.

A wide range of neutron activation analysis (NAA) procedures have been

applied to the determination of trace elements in foods. They include

instrumental NAA, pre-irradiation separations, pos t- i r r ad i at i on

radiochemistry and epithermal NAA. During the past year, detection

capabilities were improved for more than ten elements, thus maintaining the

role of FDA's NAA facility as a state-of-the-art NAA laboratory. This

laboratory facility has been involved in many regulatory investigations,

many of which are of major national concern. Included among these was the

recent tampering with over-the-counter drugs and packaged foods.

The use of the reactor by the Federal Bureau of Investigation was the

heaviest ever, with almost daily activation of physical evidence specimens.

The work involved analysis of materials such as gun shot residue and trace

elements in hair and metals important in the prosecution of criminal

activity. The National Institutes of Health continues to receive fluorine18 and other radioisotopes produced at the reactor for important medical

research

.

The University of Maryland continued to make extensive use of instrumental

neutron activation analysis (INAA) and neutron-capture prompt gamma-ray

activation analysis (PGAA) for advanced development and testing of the

methods themselves and to determine concentrations of about 40 elements in

particles, gases, rain and fog from the atmosphere, in related source

materials such as crystal dust and coal fly ash, and in standards

appropriate for use in this field. By measuring concentrations of such a large number of species, it is possible to identify contributions from

certain types of air-pollution sources to the atmospheric burden at ambient

sampling sites, a technique now known as "receptor modeling." These wide

ranging programs involved analyses and studies of samples from natural and

man-made sources worldwide, and represent a major step in determining the

origin and distribution of pollutants in the environment.

Characterization of irradiation facilities including all the pneumatic tubes

and the long-term vertical thimbles was completed. Measurements of flux

levels, flux gradients, and thermal to fast flux ratios were made.

Similarly, a variety of temperature and pressure measurements for typical

samples were also determined. These measurements will provide experimenters

with characteristic values for each facility for neutron activation

20
analysis, as well as provide optimum safe operating conditions for use of

these facilities.

A variety of other programs used the irradiation services provided by the

reactor on a smaller scale.

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.

The shim arm test assembly used for testing shim arm mechanisms and clutch

release assemblies is about finished and is also available for spare parts

for reactor shim arms. Fifty fuel assemblies have been inspected and accepted from the DOE

contractor by the NBSR staff. An additional 25 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 will be radiographed to determine that the

process is working well.

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.

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

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.

The second tritium monitor has been installed, tested and completed. Two

more modern design differential transmitters have been installed in the

process demineralized water system.

The instrument group has also provided assistance to the experimental

researchers with electronics repair, modification and interface designing.

An uninterruptible power supply system was planned, purchased and

installation is underway at this time. The UPS system will provide

continuous clean power to the experimental computer and associated

instrumentation during brief power interruptions.

An instrumentation panel for monitoring the Cryogenics Bismuth Tip

experiment facility is in the assembly and testing stage.

21
NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR ADVANCED TECHNOLOGIES

This task develops and applies neutron scattering techniques, unavailable in

the private sector, 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.

industrial and scientific 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, not available in the private

sector, for 13 NBS divisions and for over 50 U.S. industries and

universities (200 participants) which need neutron techniques to address an increasing number of problems and opportunities in materials science,

physics, and chemistry. Also under development is a large cold-neutron

source and related experimental facilities, which are essential to make

mater ial s-based U.S. science and industry competitive with other industrial

nations (Western Europe and Japan) in the crucial area of cold-neutron

research. 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 must

be 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 microscopic 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,

and chemical catalysts. 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 Laue-Langevin, 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 agreement with data centers around the world.

22
FY 86 Representative Accomplishments

o Reactor Radiation Division and U. Illinois scientists have completed the

first neutron scattering study of the magnetic order in an epitaxial

multilayer of magnetic and non-magnetic rare-earth metals. The neutron

results have revealed that the helical magnetic order in the magnetic

(Dy) layers is propagated through the intervening yttrium layer and into

the next Dy layer without loss of phase coherence, a remarkable result

which will significantly influence the tailoring of this novel new class

of layered materials for specific magnetic applications.

o Very high resolution diffraction experiments performed over the past

several years at the NBS research reactor by scientists from Purdue, U.

Missouri, and NBS have produced the first direct evidence for the

existence of charge density waves in a simple metal, potassium. Weak

satellite diffraction peaks observed in these experiments agree with

theoretical prediction that electron density varies sinusoidally with a characteristic wavelength in even the simplest solids. These results

provide fundamental new insights into the complicated ways in which

electrons behave in materials.

o NBS and Exxon Research and Engineering Company of Annandale, NJ, have

signed an agreement that establishes a Participating Research Team (PRT)

to develop and operate an improved Small Angle Neutron Scattering (SANS)

spectrometer using the cold source at the NBS reactor. The new state-ofthe-art instrument, which will be designed and developed jointly by

scientists and engineers from the Reactor Radiation Division (IMSE) and

Exxon, is expected to be the best in the country, and will be widely used

by U.S. industrial and university scientists for a broad range of

research in materials science, physics, chemistry, and biology.

o Recent NBS measurements of phonon dispersion curves in PdT

Q ^ (the first

ever achieved for a tritiated material) have clearly demonstrated that

anharmoni ci ty cannot explain the origin of the novel reverse isotope

effect in superconducting PdH. These results show that the theory of

superconductivity must be reexamined as it applies to such materials with

large mean-square atomic displacements.

o NBS scientists, in collaboration with researchers from the University of

Illinois, have performed the first measurement of the vibrational density

of states in a " quasi crystal ." These neutron scattering results provide

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

quasicrystalline materials, which were discovered at NBS three years ago.

o A Memorandum of Agreement has been signed with the Smithsonian

Institution to perform neutron autoradiography studies of works of art.

The collaborative project will involve the construction of a large

shielded enclosure that will make it possible to autoradiograph large

paintings at the reactor thermal column. The autoradiograph produces an x-ray like image of the painting revealing any paintings that may be

under the surface. The information obtained from these measurements are

of great interest to art historians, conservators , art collectors, and

galleries, and can often provide important clues relating to the

authenticity of the painting.

23
o Using neutron diffraction, the existence of a long range magnetic

ordering has been discovered in bulk dilute rare-earth alloys in a matrix

of the non-magnetic metal yttrium. This magnetic behavior has been

confirmed in alloys with magnetic concentrations under two percent and

has the form of a helix in which the magnetic spins rotate within the

material. These results have significant implications for the occurrence

of magnetic ordering in new classes of dilute alloys based on spin

density waves.

o Joint research efforts with industry in the development and application

of neutron scattering methods in catalytic materials have been expanded

to include the study of submicroscopic behavior of aromatic molecules in

production catalysts with Mobil Research Labs. The Reactor Radiation

Divison and the Center for Chemical Physics will cooperate with Mobil

scientists in high resolution neutron diffraction and spectroscopic

studies of the details of temperature-dependent molecular arrangements

and dynamical processes in these materials.

Microscopic Properties of Hydrogen in Metals and Molecular Materials

1 2

R. C. Casella, J. M. Rowe, J. J. Rush, W. Rymes, S. F. Trevino, J. Nichol

1 Guest Scientist,

2

Guest Scientist,

Army Armament Munitions and Chemical Command

University of Maryland

Hydrogen i-n Metals

The NBS neutron scattering facilities continue to be the most sensitive in

the world for studying the submicroscopic behavior of hydrogen in metals.

Research accomplishments range from the first measurements of phonons in

metal tritide crystal to the discovery of an highly unusual potential

associated with hydrogen pairing in a-phase yttrium hydride, to the first

application of neutron spectroscopy to study clustering of hydrogen around

dislocations in a metal.

A primary accomplishment of the past year was the successful measurement of

the phonon dispersion curves of palladium tritide (PdT

Q y

) • Palladium

hydride has been a system of intense interest for many years, most recently

since the discovery of high temperature superconductivity (T

c ~10K) with a strong inverse isotope effect (T

c (H,D,T)~ 8, 10, 12° respectively). It is

also the first known superconductor for which the optical vibration modes

provide the dominant election-phonon interaction. These measurements

represent one of the most difficult neutron scattering experiments ever performed (because of the small 0.4 cc sample due to radiation safety

requirements, and the small tritium cross section). The results demonstrate

conclusively that anharmoni ci ty alone cannot , as previously suggested,

explain the reverse isotope effect, and that the theory of superconductivity

must be reexamined as it applies to materials with the large mean-square

displacements characteristic of PdH, PdD and PdT.

Group scientists have also completed a high resolution inelastic scattering

study of hydrogen isotopes in hexagonal yttrium metal, which has revealed a

24
highly unusual bonding potential considerably softer and anharmonic along

the c-direction than in the basal plane. Low temperature spectra also show

a splitting of the c-axis vibrational modes which confirms the pairing of

hydrogen on either side of the Y atoms. As another example the first

measurements in a study of hydrogen clustering around dislocations in a metal (cold-worked Pd) by neutron vibrational spectroscopy and SANS have

been completed. This is the first application of neutron spectroscopy to

such a problem. The results thus far have ruled out the models involving

" pr eci pi tated" hydrogen at the dislocations in favor of a more subtle

segregation of H atoms without appreciable metal atom displacements.

Preliminary SANS measurements indicate the presence of H "clusters" (density

fluctuations) 1 00 A in dimension. These results demonstrate the potential

use of neutron spectroscopy and SANS in a variety of similar applications

correlating hydrogen impurities with other microstructure features affecting

the mechanical properties and stability of metals.

Disordered and Catalytic Materials

In our research on catalysts with the Surface Science Division, we have made

significant progress in applying neutron spectroscopy to several important

catalyst systems. For example, in collaboration with the University of

Maryland, we have completed a systematic study of the adsorption and

absorption of hydrogen on palladium black, including surface coverage

effects. Species associated with surface sites and bulk sites have been

clearly identified by differential inelastic scattering spectroscopy, and a vibration mode associated with subsurface H has also been suggested. The

character of the surface species has also been studied by a controlled

chemical titration experiment, allowing oxygen to attack the surface

hydrogen. In another study with Auburn University scientists, we have

probed the hydrogen bonding states associated with hydrodesuf urization

selectivity over RuS^ catalysts. The vibration spectra show that the

surface species are qualitatively independent of adsorption temperature and

pretreatment conditions and are primarily sulfhydryl (SH) type groups. Work

has also continued on the characterization of molecular species in zeolites

by high sensitivity neutron spectroscopy.

As another example of research on disordered materials, group scientists, in

collaboration with U. of ILL, have completed the first measurement of the

vibrational density of states of a quasicrystal (icosahedral phase) Al^Mn

.

Contrary to some predictions, the density of states do not show the

existence of localized states and demonstrate that the quasicrystal and

crystalline materials are elastically similar, but that the quasicrystal

shows a relative excess of phonon density at high vibrational energies.

These neutron scattering results provide a direct test for models of the

interatomic forces and dynamics of the icosahedral phase. In another area

of research with Illinois and Michigan State scientists, we have studied by

neutron diffraction and inelastic scattering the structure and phase

transf ormations of new metal-ammonia complexes formed between the layers of

graphite. The results thus far indicate that the NH^ and alkali metals (K)

are arranged in closely packed five-member clusters, which undergo at least

one ordering transition as the temperature is lowered. Preliminary

inelastic scattering measurements have revealed a strong interaction between

25
rotational motions and the two-dimensional translational phonon modes and

have also probed the reorientations of both the entire metal-ammonium

complex and individual NH^ molecules.

Microscopic Properties of Magnetic and Amorphous Materials

J. J. Rhyne, R. Erwin 1

, P. Mangin 2

, J. Lynn 3, T. Giebultowicz 4

, M. Spano 4, J. Fernandez-Baca 4

‘NRC Postdoctoral Associate

2 International Visitor Program

Consultant, Univ. of Maryland

4 Guest Scientists

This subtask 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 metal 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. This research is carried out in

collaboration with many industrial labs and universities.

During the year a number of areas have received intense effort including:

(1) the characterization of long-range ordered magnetism in rare earth

artificial superlattices, (2) the effects of random exchange on the magnetic

states in highly concentrated amorphous iron alloys, (3) the temperature

and wave-vector dependence of the spin wave linewidth in amorphous INVAR

systems of FeB and FeNiZr, (4) the occurrence of field- induced linear spin

density wave states in dilute alloys of Y and Gd, (5) the initial

development of a state-of-the-art polarized beam inelastic spectrometer, (6)

the damping of magnetic excitations in amorphous FeCr alloys, and (7) the

low temperature spin dynamics and pair interaction energies in dilute

magnetic semiconductors.

Highlights during the year included:

o Established the existence and character of long range magnetic order in

artificial metallic superlattices (multilayers) of magnetically

concentrated rare earth elements interleaved with magnetically "dead"

yttrium metal layers. These result have significant impact on the theory

of magnetic interactions via the formation of spin-density waves in

magnetic systems.

o Established the character of the reentrant ferromagnetic to spin glass

magnetic state in amorphous alloys of (FeCr) PC using a combination

of inelastic scattering and SANS techniques. The spin wave stiffness

parameters were observe to soften at low temperatures in contrast to the

normal behavior for a ferromagnet, and the lifetimes of the excitations

became anomalously short. Concurrent with these effects an elastic

scattering component appeared and increased strongly as the temperature

decreased

.

26
o Examined the effect of competing exchange interactions present in highlyconcentrated Fe alloys of FeB and FeZrNi via a study of the temperature

dependence of the excitation linewidths. These results conclusively

established a fourth power dependence of the linewidth on the wave vector

transfer in contrast to the previous reported second power dependence

using less accurate methods.

o Demonstrated that neutron scattering can be used to obtain the isolated

pair exchange constant in very dilute magnetic semiconductors and thus

provided the first reliable data on the magnitude of the nearest neighbor

exchange constant in a series of ZnMnS, ZnMnSe, and ZnMnTe magnetic

semiconducting systems.

o Studied the inelastic scattering spectra in a unique isotopic sample of

CdMnTe which is a magnetic semiconductor. The spectra were found to be

in remarkably good agreement with new first-principal calculations of the

magnetic excitations in dilute magnetic semiconductors with predominantly

nearest neighbor exchange.

o Established the existence of a transition from a helical spin density

wave to a linear spin density wave magnetic order on application of an external magnetic field above a critical value in alloys of Gd and Y.

The alloys studied were in the dilute limit (1.5 to of the magnetic

constituent Gd) and had been previously shown by our neutron studies to

have long range magnetic order. The discovery of the field induced

transition and its character provides important input to the

interpretation of heat capacity and magnetic data and to theoretical

model calculations which could not be obtained by normal bulk techniques.

o Examined the nature of the spin excitations in alloys of the rare earth

terbium and scandium. These alloys have been shown to be unique in that

a ’’percolation threshold” exists for the occurrence of long-range

magnetic order in contrast to other rare earth systems (e.g. Gd-Y, see above) Initial results on the excitation spectra also showed unusual

anomalies in the spin wave energies and linewidths as a function of

temperature and wave vector transfer.

o Confirmed the lack of a f erromagnetic component to the magnetic order in

the reentrant superconductor Tm^Fe-Si as a function of pressure to 5.8

Kbar . Ant i f err omagnet i c interactions or dynamical fluctuations thus

appear to be the mechanism for the destruction of superconductivity in

this compound.

o Initiated development of a new polarized beam inelastic scattering

spectrometer jointly funded by NBS and the NSF through the University of

Maryland. This will be a si te-of- the-art machine with many features not

present in previous polarized beam spectrometers in this country. It

will provide a unique measurement capability for the study of new

magnetic materials and hydrogenous solids.

27
Neutron Diffraction Methods and Application

1 1 2

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

J. Soubeyroux"5

^Guest Scientist, Armament Munitions and Chemical Compound

Guest Scientist, University of London

^Guest Scientist, Institut Laue Langevin, France

Scientists in this group continue to carry out a wide range of

crystallographic research, including method development and applications in

materials science. This work involves strong collaborative interactions

with the Metallurgy, Ceramics, and Fracture and Deformation divisions and

with the Center for Chemical Physics in areas as diverse as studies of

advanced ceramics for electronic or structural applications, tailored

inorganic catalysts, aerospace alloys and quasicrystals, and for NDE studies

of residual stress and texture in metals and ceramics. These research

efforts often involve joint projects with industries and universities.

As part of our continuing efforts in the study of key structural

arrangements related to the tailoring of new or improved catalysts, we have,

e.g., completed with DuPont and U. California collaborators a study of the

effects of lithium and silver substitution for cesium in the double rings

which provide the entry and exit channels for zeol i te-rho . While lithium

insertion had relatively little effect on ring geometry, silver substitution

resulted in major distortion of the framework, which, in fact, is the most

distorted ever observed. This work provides valuable insights into the

cation exchange mechanisms which can dramatically alter the details of

molecular adsorption and release, and thus the specific activity of the

catalyst. Work has also continued with Alfred U. scientists on studies of

hydroxyl bonds and aluminum deficiencies in activated aluminas which are of

high technological importance as catalytic substrates.

As part of our extensive research with the Ceramics Division, AT&T, GTE, and

U. of Grenoble, U. of London, etc., on new kinds of ceramics with improved

dielectric, or conducting properties, we have completed a detailed study

with AT&T of the structural arrangements induce^ +by different heat

treatments in perovski te--l ike BaBi^ Bi^ 0 . These neutron

diffraction studies have produced critical information on^the distribution

of Bi ions, which is important for the understanding and tailoring of

superconductivity in this class of compounds. As another example, group

scientists are collaborating with the Ceramics Division in a systematic

study of the alkali aluminosilicates to clarify many important questions

related to the crystal chemistry and properties of these materials,

including the dependence of coordination cage geometries on alkali metal

size, the possible ordering of A1 and Si ions, and the subtle role of water

molecules in the framework structure.

There have also been a number of new results in our development and

application of neutron diffraction techniques for bulk and depth dependent

studies of residual stress and texture. For example, residual stress

measurements employing energy dispersive techniques have been completed

jointly with Army scientists on two distinct alloy types, UTi and

7075-T6 aluminum. The results show clear differences in residual stress

patterns related to different fabrication techniques, which have

28
significance for potential stress corrosion cracking problems in aluminum

components and uranium alloy fabrication processes. These methods have also

been extended with GTE scientists to initiate studies of residual stress in

ceramic engine components. In addition, group scientists have joined with

the Fracture and Deformation Division for new systematic studies of bulk

texture profiles in mechanically deformed copper and steels.

Finally, in the area of condensed matter physics, the neutron group in

collaboration with Purdue, have utilized the very high resolution, low

background capabilities of the BT-4 spectrometer to directly confirm the

existence of charge-density waves in a simple metal, potassium. This result

is of great interest and impact in the theory of electrons in metals. Other

work has included the first neutron diffraction study of the structure of

quasicrystals, with the Metallurgy Division, and cooperation with the Center

for Chemical Engineering in a new effort in the study of the structure of

organic fluids and mixtures under shear.

NBS Crystal Data Center

1 2

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

^Guest Scientist, U.S. Geological Survey

Guest Scientist, Montgomery College

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

and dissemination of data on solid-state materials. The Center maintains a database which includes chemical and crystallographic information on all

types of substances with known unit cells. The materials fall into the

following categories: inorganics, organics, organometall ics , metals,

intermetallics , and minerals. For each substance, there are a variety of

input and derived data parameters including: the conventional and reduced

cell parameters, the space group, the compound name and formula, calculated

density, literature reference, and critical comments. The data are used by

the industrial and academic communities for a variety of research and

analytical purposes including the identification and characterization of

materials. The work of the NBS Crystal Data Center is carried out in close

collaboration with allied data centers in the United States, England,

Canada, and Germany. Some recent accomplishments are summarized below.

A major effort has focused on preparing the next version of the NBS CRYSTAL

DATA Distribution Package for official release in 1987. Both the database

and software components of this package are being upgraded. The database

will be expanded seven times over the present version and will include

115,000 entries with 1.7 million records of data. Each entry will include

all data types that are input or created by the NBS*AIDS83 program. An NBS

Technical Note (in press) has been written that describes conventions and

formats for all data records in the database.

To permit scientists to use the database, we have developed software tools

that can be distributed with the database or used to search the database on- line at a central site. NBS software ( NBS*LATTICE) , which is an integral

part of the CRYSTAL DATA Distribution Package, is designed to be used on a variety of computers. With the lattice-matching program function, unknown

29
compounds can be identified by comparison with entries in the database once

any cell of the lattice has been determined using diffraction techniques

.

A very promising method for data distribution is made possible by access to

central on-line systems. Thus using the CISTI-NBS CRYSTAL DATA Search

System, the database can be accessed worldwide. All key data items can be

searched and answers to queries can be obtained using Boolean type searches.

During the year, the system has been greatly expanded with respect to the

data (~ 115,000 entries) and available software tools. The system is

routinely used by scientists to solve a variety of scientific problems in

diverse areas of chemistry, solid-state physics, and materials science.

Radiographic Materials and Standards

1 1 R. S. Carter, M. Ganoczy, Y. J. Cheng, and J. S. Olin

1 Research Associate, Smithsonian Institution

A Memorandum of Agreement was signed this year with the Smithsonian

Institution to expand studies 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 number 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.

COLD NEUTRON PROGRAM

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

cold neutron source in the NBS Reactor, to develop two prototype instruments

to utilize the two existing beams that view this source, to conduct

scientific research using these two instruments, and to develop plans for a large experimental hall with cold neutron guides that would fully exploit

the potential of the cold neutron source. (Funding of this project began in

FY1985, and six new engineering and staff members have been brought on board)

.

FY 86 Significant Accomplishments

o Testing of the first cryostat for the cold neutron source was completed.

All of the test results except for the flow of cooling gas through the

30
system were satisfactory, including the making of ice in the cryostat,

achievement of the desired temperatures, vacuum integrity, helium jacket

operation and operation of the ref rigerator-cryostat assembly. A design

modification to increase flow was mocked up and tested, and a contract to

modify the cryostats was issued.

o Fabrication of the neutron Time-of-Fl ight (TOF) spectrometer was

successfully completed, and the spectrometer was installed and aligned at

the CTW beam port (one of two which will be served by the cold neutron

source). Preliminary tests of the intensity and resolution are in

satisfactory agreement with expectations.

o A new SANS data acquisition system was purchased, and the interface was

designed, fabricated and tested. This system will be installed and

commissioned when the cold source is installed.

o The conceptual design of a large cold neutron experimental facility was completed, including a new neutron guide tube layout. The new design

allows the same capacity as the previous design, but allows a superior

floor design at a substantially reduced cost.

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

character i stic of temperatures ^ 40 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 cr y ogen i cal 1 y 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 38 cm . block of

D 2 0 ice cooled to 25 K into this volume. As was reported last year, we received the first of two cryostats for this source, and during the past

year a series of out-of reactor tests were completed and analysed. As a result of this analysis, we concluded that the cooling flow through the

moderator was too low, and re-designed the cooling coils (which are imbedded

in the D 2 0 ice). We then tested a mockup of the new arrangement (a

difficult task, since a true test requires the end product - a cryostat),

and having satisfied ourselves that the results were satisfactory,

negotiated and awarded a contract for modification of both cryostats. The

first cryostat is scheduled for delivery to NBS in November, 1986, and is on schedule at the time of writing (September, 1986). When it is delivered, it

will be subjected to another series of tests before insertion into the

reactor. The installation date will depend on the tests, but is tentatively

scheduled for early winter. However, in view of the nature of the

installation, it will not be done until we are completely satisfied with all

possible out-of-reactor tests. In the meantime, the instrumentation for the

large refrigerator is being upgraded, and a spare compressor is being

installed in order to add to redundancy of critical systems.

31
Instrumentation and Facility Design

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

and D. Fravel

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

CTW and CTE, at which are installed a Time-of-Flight (TOF) spectrometer and

a Small Angle Neutron Scattering (SANS) instrument respectively. These two

instruments are the only ones which can be served within the confines of the

current reactor confinement building, and we have proposed a new

experimental guide hall for construction adjacent to the Reactor building.

This facility has been included in the Presidential budget for Fiscal Years

1986 and 1987, but budget constraints have prevented funding of this

proposal as of this date (September, 1986). However, we have continued to

refine our plans and specifications for this proposed facility, and in the

past year we have been able to produce a modified design incorporating a new layout of neutron guides and a new floor design that has reduced the cost

significantly without compromising the final capacity of 16-18 experimental

stations. Detailed design cannot begin until approval is received from

Congress, but we continue work on conceptual design of the building and

associated instrumentation.

The TOF spectrometer has been installed at the CTW beam port, and is in the

process of final commissioning for general use. The initial tests of

intensity and resolution are in satisfactory agreement with predictions, and

the data acquisition system, which will be the prototype for both the SANS

instrument and any new spectrometers built in association with the guide

hall, is essentially complete. When the cold source is installed, this

instrument will be unrivaled in the U.S. for the study of the molecular and

atomic motions of many systems such as molecules and molecular assemblies on catalysts, hydrogen in metals, and complex molecules in the solid or liquid

state or in solution.

The SANS instrument is installed at the CTE beam port, and we continue to

upgrade this facility in order to handle the increased capability of the

cold source. Among other upgrades underway, such as procurement of a spare

area detector, a new data acquisition system, based on the operational TOF

system, is being assembled for this facility. This system will be able to

accommodate the large amount of data that will be produced by real time

studies, and will provide greatly enhanced on-line data reduction

capabilities for the users. The software will feature a user-friendly

interface based on menu driven operation, and will also allow operation from

remote terminals through an Ethernet Local Area Network, with enhanced

graphics capabilities.

Research Program

1 1 1 J. M. Rowe, T. Udovic, J. W. Lynn , H. Stanley , J. Nicol , S. Krueger,

C. J. Glinka, and J. J. Rush

1 Guest Scientist, University of Maryland - NBS Cooperative Agreement

The most important aspect of this entire project is to ensure that the cold

source and associated instrumentation are properly utilized to produce the

best possible science. We have therefore initiated research efforts both

32
within and outside NBS. First results with the Center for Chemical Physics,

Dupont and the University of Maryland on the bonding states and

reorientational dynamics of ammonium species in zeolites have been completed

and new experiments are being planned with Mobil researchers on the

molecular arrangements, dynamics and interactions of aromatic hydrocarbons

in an industrial catalyst, using high resolution cold neutron spectroscopy

and diffraction. A co-operative research arrangement is also underway with

Exxon Research and Engineering, with a joint post-doctoral associate for the use of SANS to study a number of materials problems, including melting in

micro-porous media. During the coming year, our cold neutron TOF

spectrometer will also be critical to joint research on bonding and

diffusion mechanisms in hydrogenous ionic conductors, and to the study of

low lying excitations in high technology magnetic materials.

33
ADVANCED NEUTRON METHODS

N. F. Berk, D. Fravel , C. J. Glinka, J. Gotaas, J. LaRock, and E. Prince

This is one of the NBS competence building initiatives whose objective is to

develop and maintain state of-the-art facilities for advanced neutron

scattering techniques and to further the application of these techniques in

solid-state physics, chemistry and materials science. Under this initiative

the small angle neutron scattering (SANS) facility for microstructure

studies in the 10-2000 A range has been built and continues to be improved.

An improved high resolution crystal spectrometer has also been developed for

dynamic studies. An important part of this initiative has been the

fostering of collaborative programs with a number of NBS divisions,

universities, and industrial and government laboratories to develop new

science and diverse applications of these advanced neutron techniques .The new project now underway in this task is the development of an advanced

instrument for ultra high-resolution powder diffraction which will provide

the best measurement capability of its kind in the United States. This

facility will be widely used in NBS programs and by U.S. scientists from

industries and universities.

FY 86 Representative Accomplishments

o Staff scientists have successfully demonstrated the use of a berylliumgraphite band-pass filter analyzer to greatly increase (by a factor of

3) the resolution available for "incoherent" neutron spectroscopy

between 25 and 100 meV, while maintaining high sensitivity for studies of

the dynamics of catalysts, hydrogen in metals, polymers, and other

molecular materials.

o As part of a collaborative effort with the University of California, the

first SANS study of precipitate coarsening in reactor pressure vessel

steels involving in-situ specimen annealing has been carried out. A vacuum furnace which mounts between the pole pieces of a high field

electromagnet was developed for this purpose. The SANS results and

associated microhardness tests are being used to develop relationships

between the total fluence and temperature, and the precipitate population

and hardness of the steels.

Facilities

1 . Small Angle Neutron Scattering (SANS)

While the SANS instrument operated virtually without interruption during the

past year, improvements in the areas of sample environmental apparatus and

data acquisition proceeded in parallel. For example, a programmable

temperature controller and power supply were implemented which can monitor

and control the temperature of a variety of vacuum furnaces, as well as the

instrument’s multi-specimen sample changer. One such furnace, designed and

built by the Nuclear and Chemical Engineering Dept, of the University of

California at Santa Barbara, fits between the pole pieces of a high field

electromagnet to enable samples to be annealed in-situ at temperatures up to

600C in an applied field of up to 18 kilogauss.

34
An advanced data acquisition system for the SANS instrument based on a Microvax II computer is now under development an will replace the existing

system during the reactor shutdown for installation of the cold source. The

new system will utilize CAMAC-based hi stogramming memory to offload the

basic data acquisition tasks from the CPU which will then be available for

online display and analysis. This system will allow rapid switching among

several data storage arrays to enable the response of samples to cyclic

perturbations (e.g. stress, shear, fatigue, etc.) to be studied. In

addition, the instrument computer has sufficient speed and memory to enable

all routine types of data analysis to be carried out while an experiment is

in progress. With these improvements the SANS instrument will be optimized

to utilize the increased neutron flux produced by the cold source.

2. Crystal Spectrometer

The development of new higher-resolution capabilities for the BT-4

spectrometer has been extended to the development and testing of a new

beryllium-graphite band-pass filter-analyzer for neutron spectroscopy. The

new analyzer provides an energy window ~

3 times narrower than a conventional beryllium filter and makes possible for the first time, high

sensi ti vi ty neutron spectra between 30 and 100 meV with resolutions between

1.7 and 2.5 meV. This new capability has already been used with great

success in studies of the anomalous potential experienced by H isotopes in

yttrium and in measuring the density of states of quasicrystalline Al^Mn.

This analyzer will have a great impact on neutron studies of the vibrational

spectra of catalysts, molecular solids, and many other materials.

3. Ultra High-Resolution Powder Diffraction

Progress this year toward the development at NBS of the world-class ultrahigh resolution neutron powder diffractometer included (1) the design and

fabrication of a prototype of the 6 minute collimators which are a key to

the performance of the instrument; (2) completion of procurement of the 35

neutron detectors and associated electronics for the new multidetector

instrument and; (3) successful testing of the first set of copper

monochromators which will be used at one of the diffractometer takeoff

angles

Research and Measurement

In FY 86, a record number of scientists (60) from government, university,

and industrial laboratories and eight NBS divisions carried out measurements

on the SANS instrument. The bulk of this work can be broadly classified

under three areas: microstructural studies of metallic, ceramic or catalytic

materials, measurements of molecular conformation of polymers and

biomaterials, or studies of magnetic correlations and phase transitions in

novel magnetic materials. Inelastic scattering with the high-resolution

crystal spectrometer involves measurements of wave vector dependent

excitations and diffusive processes in materials.

SANS measurements in collaboration with the Center for Analytical Chemistry

have proven successful in determining the effective thickness of monomeric

and polymeric hydrocarbon chains grafted to the pore surfaces of silica

m i cr opar t i cl es . The SANS measurements have provided the first direct

evidence of the effect of various solvents entrained in the pores on the

35
effective thickness of the adsorbate layers. These results have a direct

bearing, for example, on understanding (and tailoring) the performance of

chemically modified microparticles in reverse phase liquid chromatography.

The tendency of low concentrations of hydrogen in a-palladium to cluster

under the influence of large internal stresses and dislocations, has been

convincingly demonstrated in a collaborative effort with the Max Planck

Institute involving both SANS and inelastic scattering measurements.

Characteristic cluster sizes of about 1 00A were observed in mechanically

deformed Pd foils while no evidence for clustering was seen in strainrelieved foils, a result with significant implications for studies of

hydrogen embrittlement.

A joint NBS-NIH-Uni ver si ty of Maryland collaboration in using SANS to

characterize the structure and interactions in concentrated protein

solutions has been extended to the examination of proteins in red blood

cells and neurosecretory vesicles. From measurements at appropriately

chosen conditions of scattering contrast, information on the internal

organization of a particular type of protein can be obtained under

conditions of greatest physiological relevance.

As part of an ongoing collaboration with the University of California at

Santa Barbara in using SANS to study microstruc tural changes related to

embrittlement in reactor pressure vessel steels, the first in-situ annealing

studies have been carried out of the growth of precipitates rising from

impurities in the steels. The presence of radiation damage is known to

accelerate the precipitate growth which is now being quantified by SANS and

associated microhardness tests. Additional measurements on model alloys

prepared from separated isotopes (to control the scattering contrast) are

providing new information on the composition of the precipitates.

Through the use of deuterium labeling to highlight the network structure in

epoxies, scientists in the Polymer Division have obtained significant

results with SANS regarding the molecular modes of deformation in strained

epoxies. They have observed in epoxies with short crosslink spacings

typical of commercial materials that there is essentially no change in the

average crosslink distance in samples strained up to 30%. This remarkable

result suggests that the macroscopic deformation is controlled by some type

of defect motion analogous to the way dislocations determine strain in

metals

.

The first proprietary measurements using the SANS facility have been carried

out, under recently established NBS guidelines, by polymer scientists at the

Eastman Kodak Company and the IBM Almaden Research Laboratories.
INDEPENDENT PROGRAMS

The two major independent (non-collaborat i ve ) 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 summarized

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

irradiation services provided by Reactor Operations.

FY 86 Representative Accomplishments

o A novel analytical procedure has been developed for the measurement of

baseline levels of lithium and boron in biological materials with the

combination of neutron activation followed by helium gas mass

spectrometry. The determination of these elements at their normal levels

in body fluids has been a challenge, due in part to the likelihood of

contamination for any method requiring dissolution. The nondestructive

nature of the new method means that concentrations at the ng/g normal

levels can be measured reliably. The quantification of the lithium is

based on the helium-3 decay product of the tritium from the Li-6 (n,a)Li7 reaction. To avoid helium production by fast neutron reactions, all

irradiations were done in the thermal column of the NBSR. The mass

spectrometry has been carried out at the Physics Department of McMaster

University. Extension of the method to metals, ceramics and geological

materials is underway.

235

o The NBS U Cavity Fission Source at the NBS Reactor was u^gd th^.s past

year to expose U-238 to a certified neutron fluence of 2x10 n/cm , which

is sufficient to produce a measurable 30-year Cs-137 fission-product

activity. This is the first time such a standard, which is used, e.g.,

to verify commercial neutron fluence measurements for reactor pressure

vessel surveillance, has ever been produced.

NUCLEAR METHODS

R. Fleming

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 (INAA and RNAA ) , and in LINAC-based

activation analysis using photons (PAA). In addition, the group has a unique activation analysis capability in neutron beam analysis with both

prompt gamma activation analysis ( PGA A) 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 our involvement in

the 7th International Conference on Modern Trends in Activation Analysis,

new measurements carried out at other research facilities, and by a major

renovation of our laboratory space in the Reactor Building. The MTAA-7

37
meeting, which was held in Copenhagen in June, commemorated the fiftieth

anniversary of the discovery of activation analysis by Hevesy and Levi, NBS

scientists were authors of ten of the papers presented at this conference.

The opportunity was also provided for visits to the laboratories of several

of our European colleagues.

In addition to our ongoing use of the nearby reactors at the University of

Maryland and the University of Virginia, primarily for fast and epithermal

activation analysis, Group members carried out measurements on the neutron

beam facilities at the new cold neutron source at Julich and the intense

guided thermal neutron beams at Grenoble. The Julich work, which was

reported at the MTAA~7, provided the first demonstration of the use of cold

neutron beams for prompt gamma activation analysis. At the ILL reactor,

which currently has the world’s most intense thermal neutron beams, the

neutron depth profiling facility was used to demonstrate the profiling of

oxygen with the 170(n,a)l4C reaction. This work has since been repeated on

the NBS facility, but the actual implementation of NDP for oxygen must await

the very intense beams of the proposed NBS Cold Neutron Facility to be

practical

.

The Group's contribution to the certification of Standard Reference

Materials is illustrated by the multielement measurements done on the

following SRM’s: Fly Ash, Flint Clay, Plastic Clay, Dolomitic Limestone,

Rice Flour, and Wheat Flour. At major levels, the determination of silicon

by fast neutron activation analysis has been demonstrated. Preliminary

measurements of trace levels of lithium and boron in biological materials

will be published using a thermal neutron irradiation followed by a helium

gas mass spectrometric determination for quantification.

Research into biomedical problems has again been strong this year centered

around the activities of the joint NBS/NOAA/EPA Environmental Specimen Bank.

A new stable isotope technique for the measurement of total blood volume in

humans has been reported based on the NAA determination of the Cr-51/Fe-59

ratio in samples spiked with Cr-50. The characterization of biological

macromolecules by a combination of gel electrophoresis and neutron

activation analysis is under development. A special large volume

irradiation facility has been constructed for this purpose. A systematic

effort has begun on the accurate and efficient measurement of trace elements

in human serum, focused initially on zinc and selenium. The crucial step of

valid sampling of biological materials was reviewed in a special issue of

the Bureau's Journal of Research.

The strong interaction with industrial scientists using neutron depth

profiling, prompt gamma activation analysis, and neutron activation analysis

has continued with a large number 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 second year. A

total of 30 biologically important minor and trace elements have been

measured on the total diet material, USDIET-I. A second composite diet

38
material is being prepared for study and as a candidate for an NBS Reference

Material

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

sensitivity with which nuclear methods are applied to elemental measurement.

This will address the problems of sample preparation, irradiation, and

counting with the goal of reducing and quantifying the various sources of

systematic error in analysis by nuclear methods.

Neutron Field Standards and Dosimetry

J. Grundl

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

engaged in the development and application of standard and reference neutron

fields as permanent facilities for neutron detector calibrations, and for

reaction rate cross section measurements. Strong interactions with outside

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

programmatic characteristics. A substantial component of the Group's

activities involve the use of the NBS Research Reactor thermal column and

tangential beams where facilities designed and built by the Neutron

Dosimetry Group are in operation.

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,

for non-routine testing, development, and calibrations of new types of

neutron instrumentation, and for quality control measurements of production

instruments. A tissue equivalent proportional counter (TEPC) system to

determine neutron dose as a function of energy deposited is being developed

under contract with the Armed Forces Radiobiology Research Institute

(AFRRI), and the first operational tests of the system have been

successfully conducted at the AFRRI TRIGA reactor. Also, a new type of

neutron dosimeter is under development in cooperation with Yale University

and a remmeter based on a TEPC with Battelle Pacific Northwest. New fission

chamber monitors for the AFRRI exposure rooms have been fabricated and

tested. These monitors will provide a direct measure of neutron exposure

over the full range of the TRIGA reactor dose rates, without sensitivity to

gamma ray background. Based on a double ionization chamber arrangement,

these monitors will establish exposures with a precision of one percent for

power levels as low as one kW and irradiations as short as one minute, or alternatively, will monitor exposure rates at a power level of one MW with

less than one percent deadtime correction.

Dosimetry for Materials Performance Assessment

Neutron fluence standards are neutron sensors (activation foils generally)

in which a radioactive species relevant for dosimetry is induced by

irradiation in a standard neutron field. The NBS U-235 Cavity Fission

Source, at the NBS react(j>g, was

2

used to expose U-238 to a certified neutron

fluence of about 2 X 10 n/cm which is sufficient to produce a measurable

30-year Cs-137 fission-product activity. This is the first time such a standard has ever been produced. This fluence standard is used to verify

commercial neutron fluence measurements made in connection with vessel

39
surveillance. Furthermore, reactor pressure quality assurance measurements

of tantalum impurity in niobium were performed for several commercial and

government laboratories using the thermal neutron irradiation facility at

the reactor. Thes|

2 measurepen£s were made in support of the wide interest

in the use of the Nb(n,n Nb reaction for fast neutron fluence

measurements

.

Integral Neutron Cross Section Measurements

As a result of a DOE sponsored multi-laboratory, multi-^tion effort,, to

measure the f ission-spectrum-aver^ged crcjss section of tjop ^b(n,n ) Nb

reaction for high fluence (> 10 n/cm ), a 30-day (10 n/cm ) irradiation

has been completed at the NBSR D U Cavity Fission Source Facility. The 30-

day irradiation, an essential component of the measurement, was 6 times

longer than any previously performed at this facility.

The collaboration with the University of Virginia Department of Nuclear

Engineering and Engineering Physics is continuing. The photo-fission cross

sections of Np-237, U-235, U-238, and Th-232 have been measured in the NBS

neutron driven (iron and cadmium) gamma-ray fields. A paper will be

presented at the 6th ASTM-Euratom Symposium on Reactor Dosimetry. These cross sections are important for correcting the neutron response of fission

dosimeters used in all areas of materials performance assessment under

stress of radiation. Also, ap p§£t of this collaboration the analysis of

the data from the Nb(n,n ) Nb is being performed at the University of

Virginia. Integral tests of 10-100 keV-range neutron activation cross

sections for Au, In, and Cu have begun at the Intermediate Energy Standard

Neutron Field (ISNF) facility at the reactor thermal column. The ISNF is

ideally suited to cross section tests in this 10-100 keV region, and these

tests may contribute to understanding the inconsistencies in the B-10 cross

section in this energy range.

NBS Cavity Fission Neutron Irradiation Facility

Several man months of effort were spent this year in documenting the

calibration services offered in association with the NBS Fission Neutron

Irradiation Facility. Four documents entitled Activation Foil IrradiationCavity Fission Sources (44090C), now in the NBS review process, will be

published as and NBS Internal Report. This document describes the

characteristics, theory, and operation of this benchmark neutron field,

including the traceability of its calibration to NBS-I. Available neutron

fluences are given along with the uncertainty of relevant exposure

parameters

.

Neutron Life-Time Experiment

Preliminary work in support of a proposed neutron life-time experiment has

begun. The responsibility of the Neutron Dosimetry Group in the proposed

experiment would be the determination of the average liner density of

neutrons in the neutron beam, downstream from an electromagnetic proton

trap. A detachable neutron detector would be absolutely calibrated in a series of subsidiary measurements employing both cold neutron beams and

thermal neutron beams. The active neutron detector will consist of a thin

B-10 deposit, viewed by four surface barrier detectors. A study of possible

materials for the backing of the B-10 deposit has been made, and thin

40
(0.38 mm) crystalline silicon wafers have been chosen as the backing

material. These single-crystal backings will scatter thermal neutrons less

than half as much as would the thinnest possible A1 backing (0.13 mm).

Furthermore, these crystal wafers are extremely smooth, flat, and rigid, so that good solid angle reproducibility and stability can be maintained.

41
T.
OUTPUTS/INTERACTIONS

Publications

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

and anistropic potential for hydrogen isotopes in yttrium. Phys . Rev. Lett.;

in press.

Berk, N. F. ; Har dman-Rhyne, K. A. Characterization of alumina powder using

small angle scattering, I: theory. J Appl. Cryst. J_8_ 467; 1985

Berk, N. F. ; Hardman-Rhyne , K. A. The phase shift and multiple scattering in

small angle neutron scattering: application to beam broadening from

ceramics. Proc. of the 1985 Santa Fe Intern. Conf. on Neutron Scattering:

Physica; 1 36, 21 8: 1 986.

Berk, N. F. Exact properties of model for biocontinuous structures. Phys.

Rev. Lett.; 1986; in press.

Bonnet, J. E. ; Rose, D. K.; Faux, D. A.; Anderson, I. S. Long range and

short range ordering of H and D atoms in solid solution in yttrium. J. Less

Common Metals; in press.

Bordet, P. ; Mchale, A.; Santoro, A.; Roth, R. S. Powder Neutron Diffraction

Study of ZrTiO,., Zr^Ti-O^,. and FeNb-O,-. J. of Solid State Chem. 64 ; 30-46

(1986).

4 5 7 24 26 —

Bouillot, J. ; Rowe, J. M.; Rush, J. J. Structure of (KCN) (KBr) mixed

crystal by neutron powder diffraction. Phys. Rev.; in press.

' °

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

Marsh, P. ; Roth, R. S. The structure of the littium inserted metal oxide 6-

LiV o 0,_. J. Solid State Chem.; in press.

2 5

Cavanagh, R. R. ; Rush, J. J. ; Kelley, R. D. Incoherent inelastic neutron

scattering: vibrational spectroscopy of adsorbed molecules on surfaces.

Methods of Surface Characterization , T. E. Madey and J. Yates, eds . ; Plenum,

NY; 1986.

Casella, R. C. On the theory of coherent neutrino scattering from crystals.

IL Nuovo Cimento; in press.

Casella, R. C. Coherent scattering of low energy neutrinos from macroscopic

objects. American Institute of Physics Conference Proceedings; in press.

Chaillout, C.; Remeika, J. P. ; Santoro A.; Marezio M. Bismuth valence orderdisorder study in BaBiO by powder neutron diffraction. Solid State

Communications 56_, 833; 1 985.

Choi, C. S. ; George, C.; Gilardi , R. ; Alippen-Anderson, J. L. ; Marchand, A. P.; R ed cly

, ^ D~ S. Structure of 6,6, 10,10-Tetranitropentacyclo

[5.30.0 .0 ’]decane, C 1A H Q 0 Q

. Acta Cryst. C4l 788-791; 1985.

I (J o o —

Choi, C. S. ; Prask, H. J. Texture of extruded uranium alloy by neutron

diffraction. J. Appl. Cryst. 1 8 , 413-418; 1985.

45
Didisheim, J. J. ; Prince, E. ; Wuensch, B. J. Neutron rietveld analysis of

structural changes in nasicon solid solutions Na Zr Si P P 0 at

elevated temperatures: x = 1.6 and 2.0 at 320°C. SolidX State

X loni cs o — 1 9

,

944-958; 1986.

Eick, H. ; Prince, E. A neutron diffraction and electron microscopy

examination of SBaBrSBaCl^ . Acta. Cryst. C42 , 915-917; 1986.

Erwin, R. W. ; Lynn, J. W.; Rhyne, J. J. ; H. S. Chen. Spin stiffness anomaly

in the reentrant spin-glass (Fe. ot-Ni_ )_ „ c Pn 1 <; Bn n .Aln ... J. Appi

.

Phys. 57 3473; 1985.

°' 25 0-750.750.160.06 0.03

Erwin, R. W.; Lynn, J. W.; Magerl , A. The reentrant spin-glass order

parameter in (Fe

Q 7 JyrP, /-B^Al- . Proc. of the International Conference

on Magnetism 1 985, Nor tn-Hol land, Amsterdam; 101; 1985.

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

neutron scattering studies of the structure of graphite interacalated with

potassium and ammonia. Phys. Rev. B; in press.

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

of amorphous Fe

Q 35

B

0 Physica 1 36 B; 53; 1 986.

Fernandex-Baca , J. A. ; Rhyne, J. J. ; Fish, G. E. Neutron scattering study of

the spin dynamics of amorphous Fe

? Nip Zr . J. Magnetism and Magnetic Matls.

54-57 ; 289; 1986. '

Fischer, R. X.; Baur, W. H. ; Shannon, R. D.; Staley, R. H. ; Vega, A. J. ; Abrams, L. ; Prince, E. Neutron patterns from tilings with five-fold

symmetry. J. Phys. Chem.; in press.

Fisher, R. X.; Baur, W. H. ; Shannon, R. D.; Staley, R. H. ; Vega, A. J. ; Abrams, L. ; Prince. E. Neutron powder diffraction study and physical

characterization of zeolite D-rho. J. Phys. Chem.; in press.

Giebultowicz, T. M. Monte carlo simulation of dilute magnetic semiconductors

for high concentrations of the magnetic component. J. Magnetism and Magnetic

Materials 54-57 , 1287-1288; 1986.

Giebultowicz, T. M.; Overhauser, A. W.; Werner, S. A. Direct observation of

the charge-density wave in potassium by neutron diffraction. Phys. Rev.

Letters 56, No. 14; 1485-1488; 1986.

Giebultowicz, T. M.; Rhyne, J. J. , Ching, W. Y., Huber, D. L. ; Galazka, R.

R.. Static and dynamic spin correlations and exchange interactions in

Cd^ Mn Te. J. Magnetism and Magnetic Matls. 54-57 ; 1149; 1 986.

Gignoux, D.; Rhyne, J. J. Spin excitations in TbNi by inelastic neutron

scattering. J. Magnetism and Magnetic Matls. 54-57 ; 1179; 1986.

Glinka, C. J. ; Rowe, J. M.; LaRock, J. G. The small angle neutron scattering

spectrometer at the National Bureau of Standards; in press.

Gotaas, J. A.; Rhyne, J. J. ; Wenger, L. E. ; Mydosh, J. A. Long-range

incommensurate spin state in dilute YGd alloys. J. Magnetism and Magnetic

Matls. 54-57, 93; 1 986.

46
Hardcastle, S. E. ; Neumann, D. A.; Zabel, H. ; Rush, J. J. Critical behavior

of the interlayer shear constant in stage 2 K and Rb graphite intercalation

compounds. Synthetic Metals; in press.

Hardman-Rhyne , K. A.; Berk, N. F. Characterization of alumina powder using

small angle scattering, II: experiment. J. Appl . Cryst. _1_8» 473; 1 985.

Hardman-Rhyne, K. A.; Frase, K. G.; Berk, N. F. Applications of multiple

small angle scattering to studies of ceramic processing. Pro. of the 1985

Santa Fe Clntern. Conf. on Neutron Scattering ; Physica B 1 36 B; 223; 1986.

Hardman-Rhyne, K. A.; Berk, N. F. Ceramics material characterization using

small angle neutron scattering techniques. Materials Characterization for

Systems Performance and Reliability, eds. James W. McCauley and Volker

Weiss; Plenum Press, New York; 257—269 ; 1986.

Hardman-Rhyne, K. A.; Berk, N. F. Small angle neutron scattering form

porosity in sintered alumina; Communication of the American Ceramic Society;

1 986 ; in press

Hemplemann, R. ; Rush, J. J. Neutron vibrational spectroscopy of disordered

metal-hydrogen systems; Proceedings of NATO Workshop, Rhodes, Greece;

Physica B; in press.

Himes, V. L. ; Mighell , A. D. NBS lattice - a program to analyze lattice

relationships. NBS Tech. Note 1214; U. S. Dept, of Commerce NBS; 1985.

Jin, L. ; James, W. J. ; Lemaire, R. ; Rhyne, J. Magnetic Structure of DyCo^.

J. Less-Common Metals.; in press.

Jin, L. ; James, W. J. ; Lemaire, R. ; Rhyne, J. J. Magnetic structure of DyFe.

J. Less-Common Metals 118 , 269; 1986.

Kircheim, R. ; Huang, H. Y.; Carstanjen, H. D.; Rush, J. J. ; Udovic, T. J.

Inelastic neutron scattering and resistivity of hydrogen in cold-worked

palladium. J. Less Common Metals; in press.

Lukacevic, E. ; Rush, J. J. ; Santoro, A. Neutron powder diffraction and

inelastic scattering study of the structures of Zr^Pd, Zr^PdD^

Q

and

Zr^PdD^

gg

. Acta Cryst.; in press.

Lukacevic, E. ; Santoro,

the structure of the

19; 922-928; 1986.

A. ; Roth, R. S.

compound Li„ „ u . o

do

Neutron powder diffraction study

La

Q 5625Mo0 i4

* Solid State Ionics

of

18 -

Lynn, J. W. Helium condensation observed in small angle neutron scattering.

Physica 1 36B ; 117-119’ 1986.

Lynn, J. W.; Rhyne, J. J. Spin dynamics of amorphous magnets. Chapter in

Spin Waves and Magnetic Excitations ; edited by S. K. Sinha and A. S.

Borovik-Romanov, North Holland Physics Publishers; in press.

Magerl , A.; Rush, J. J. ; Rowe, J. M. Local modes in dilute metal-hydrogen

alloys. Phys. Rev. B33.; 4; 2093-2097; 1 986.

47
Miceli, P. F. ; Youngquist, S. E. ; Neumann, D. A., Zable, H. ; Rush, J. J. ; Rowe, J. M. Neutron scattering study of the vibrational density of states in

icoshedral and crystalline A1

Q g Q

Mn

0

. Phys . Rev. Lett.; in press.

Michel, K. H. ; Rowe, J. M. Molecular symmetry and translation-rotation

coupling in orientationally disordered crystals. Phys. Rev. B32 ; 9; 5 8 1 8 — 5832; 1985.

Michel, K. H. ; Rowe, J. M. KCN, a model system of translation rotation

coupling in orientationally disordered crystals. J. Chimie Phys.. _82; 2-3;

199-204; 1985.

Mighell, A. D.; Himes, V. L. Compound identification and characterization

using lattice-formula matching technqiues. Acta Crysta. A; 101-105; 1986.

Mozer, B; Gratias, D.; Shechtman, D. Neutron diffraction studies of the

icosahedral phase of Al-Mn alloys. J. de Physique Collogue; No. 3; in press.

Murphy, D. W.; Cava, R. J. ; Rhyne, K.; Roth, R. S. ; Santoro, A.; Zahurak, S.

M.; Dye, J. L. Structural aspects of insertion reactions of the pyrochlore

KNbW0

&

. Solid State Ionics 18-19 ; 799-801; 1986.

Nossal, R. ; Glinka, C. J. ; Chen, S. H. SANS studies of concentrated protein

solutions. I. bovine serum albumin. Biopolymers 25_; 1 157-1 175; 1 986.

Prask. H. J. ; Choi, C. S. Neutron diffraction characterization of tungstenNickel-iron alloys. Technical Report AREAE-TR 8501 5, AD-E401 ; 461; ARC,

Dover, NJ ; 1 986.

Prask, H. J; Choi, C. S. Encyclopedia of materials science and engineering,

]_; 4095-97; edited by M. B. Bever, Pergamon Press, NY; 1 986.

Prask, H. J.’; Choi, C. S. Sub-surface residual stress measurements by means

of neutron diffraction: aluminum, steel, and depleted uranium, materials

character i zat i on for systems performance and reliability; edited by J. W.

McCauley and W. Weiss; Plenum Press; NY and London; 1986.

Prince, E. ; Nicholson, W. The influence of individual reflections on the

precision of parameter estimates in least squares refinement. Structure and

Statistics in Crystallography, Ed. A. J. C. Wilson, Adenine Press;

Guilderland, NY; 183-195; 1985.

Prince, E. Precision and accuracy in structure refinement by the rietveld

method. Structure and Statistics in Crystallography, Ed. by A. J. C. Wilson,

Adenine Press, Guilderland, NY; 93“ 1 03 ; 1985.

Rhyne, J. J. Magnetic properties of amorphous metals. Invited paper,

Research Opportunities in Amorphous Solids with Pulsed Neutron Sources

Workshop, Argonne Natl. Lab.; J. of Non-Crystalline Solids 76_, 129; 1 985.

Rhyne, J. J. Effects of random field interactions in amorphous rare earth

alloys. Invited paper, INTERMAG Conf., St. Paul, MN ; IEEE Trans. Mag. 21 ; 1990; 1985.

48
Rhyne, J. J. Quenching of long-range magnetic order by random interactions

in amorphous alloys. Invited paper. International Conference on Neutron

Scattering, Santa Fe, NM; Physica 1 36B, 30; 1986.

Rhyne, J. J. ; Cooper, B. R. ; Huber, D. A.; Koon, N. C.; O'Handley, R. C.

editors; Proceedings of the International Conference on Magnetism ICM-85 ; J.

Magnetism and Magnetic Materials North Holland 54-57 ; 1 986.

Rhyne, J. J. ; Erwin, R. W. ; Salamon, M. B. ; Sinha, S. ; Cunningham, J. E. ; Borchers, J. ; Flynn, C. P. Long-range incommensurate magnetic order in Dy-Y

multilayers. Invited paper; Seventeenth Rare Earth Research Conference,

Hamilton, Canada, J. Less-Common Metis.; in press.

Richter, D.; Hempelmann, R. ; Rush, J. J.; Rowe, J. M.; Eckert, J.;

Goldstone, J. A.; Tonks, D. Localized vibrations of hydrogen in metals.

Physica B; in press.

Rowe, J. M.; Bouillot, J. ; Rush, J. J. ; Luty, F. Structural phase diagram of

mixed (ICN) (KA), crystals by means of neutron powder diffraction. Physica

B 136; 498-^02; 19&6.

Rowe, J. M.; Rush, J. J. ; Schirber, J. E. ; Mintz, J. M. Isotope effects in

the PdH system - lattice dynamics of PdT

Q y

Phys. Rev. Lett.; in press.

Rush, J. J. ; Rowe, J. M. Chemical physics with emphasis on low energy

excitations. Reprinted from Physica B1 37 ; 1 — 3 ; 1 69-182; 1 986.

Rush, J. J. ; Cavanagh, R. R. ; Kelly, R. D.; Rowe, J. M. Interaction of

vibrating H atoms on the surface of platinum particles by isotope dilution

neutron spectroscopy. J. Chem. Phys. 83_; 5339-5341; 198.5.

Salamon, M. B. ; Sinha, S. ; Rhyne, J. J. ; Cunningham, J. E. ; Erwin, R. W.;

Borchers, J. ; Flynn, C. P. Long-range incommensurate magnetic order in a DyY multilayer. Phys. Rev. Lett. 56_; 259; 1 986.

Schioler, L. J. ; Wuensch, B. J. ; Prince, E. The relation between structural

change and fast ion conduction in the NASICON solid solution system. Solid

State Ionics; in press.

Smith, H. K.; Rhyne, J. J.; Hardman-Rhyne , K. A.; Wallace, W. E.

Thermodynamics of hydrides and deuterides of R.Fe^and R.Mn^^. J. Less

n b 2 3 o 2 3 Common Metals; m press.

Spano, M. L. ; Rhyne, J. J. Effects of applied fields on the magnetic order

of amorphous Tb Fe n _ alloys. J. Magnetism and Magnetic Matls. 54-57; 300;

1986.

xix

Stalick, J. K.; Mighell, A. D. Crystal data version 1.0 database

specifications; NBS Tech. Note; in press.

Torardi , C. C.; Reiff, W. M.; Lazar, K.; Prince, E. Structures and low

temperature magnetism of the new lithium and sodium insertion compounds:

LiFe ( II )ClMoO^ and NaFe( II )ClMoO^ . J. Chem. Phys. Solids; in press.
Torardi , C. C.; Prince, E. Structure of the lithium insertion compound

Li^Fe (Mo0.)3 from neutron powder diffraction data. Materials Research

Bulletin 21_; 71 9-726; 1 986.

Trevino, S. S. ; Tsai, D. H. The simulation of condensed matter chemistry and

destontion. Proceedings of the 1986 Army Science Conference; 1986; in press.

Udovic, T. J. ; Kelley, R. D. Neutron scattering studies of hydrogen in

catalysts. Hydrogen in Catalysis: Theoretical and Practical Aspects ; Z Paal

and P. G. Menon, eds . ; Marcel Dekker, Inc., NY; 1 986.

Wax, M. J. ; Cavanagh, R. R. ; Rush, J. J. ; Stucky, G. D. ; Abrams, L. ; Corbin,

D. A neutron scattering study of zeolite Rho. Phys. Chem. 90_°, 532; 1 986.

Weiss, G. H. ; Shmueli, U.; Prince, E. Discussion of Fourier representations

of Pdfs arising in crystallography . J. Res. NBS 90_; 513~515; 1 985.

Wenger, L. E. ; Hunter, G. W.; Mydosh, J. A.; Gotaas, J. A.; Rhyne, J. J.

Spin density wave transition in dilute YGd single crystal. Phys. Rev. Lett.

56; 1090; 1986.

Werner, S. A.; Rhyne, J. J. ; Gotaas, J. A. Spin density wave magnetism in

copper-manganese alloys. Solid State Commun. j56_; 457; 1 985.

Yu, H. ; Kitano, T. ; Kim, C. Y.; Amis, E. J. ; Chang, T. ; Landry, M. R. ; Wesson, J. A.; Han, C. C.; Lodge, T. P. ; Glinka, C. J. Uniaxial deformation

of rubber network chains by small angle neutron scattering. Macromolecules;

in press.

50
Technical and Professional Committee Participation and Leadership

American Crystallographic Association

Crystallographic Computing and Data Committee, A. D. Mighell, Member

American Crystallographic Association

Neutron Scattering Special Interest Group, E. Prince, Chairman

American Crystallographic Association

Small Angle Scattering Special Interest Group, C. Glinka, Secretary

American National Standards Committee

N— 1 7 : Research Reactors, Reactor Physics, and Shielding

R. S. Carter, Chairman, T. M. Raby, Secretary

Argonne National Laboratory, Pulse Neutron Sources

Program Review Committee, J. J. Rhyne, Member

American Nuclear Society

ANS-15 Standards for Research Reactors, T. M. Raby, Member

Standards Steering Committee', R. S. Carter, Voting Member

BNL Beam Facility Users Committee, J. J. Rush, Member

DOE Basic Energy Science Advisory Committee, J. M. Rowe, Member

Fe-based Multilayer Session of Magnetism and Magnetic Materials (MMM)

Conference, Baltimore, Md., R. Erwin, Chairman

Gordon Conference on Orientational Disorder in Crystals, 1986

J. M. Rowe, Chairman

International Centre for Diffraction Data

Data Base Subcommittee, J. K. Stalick, Member

International Conference on Magnetism, 1985-1986

Publications Chairman and Member Executive Committee, J. J. Rhyne

International Union of C r y s t

1 1 ogr aphy , Subcommittee on Statistical

Descriptors, E. Prince, Member

Joint Committee-Crystal Data Task Group, A. D. Mighell, Member

Journal of Applied C r y stal lography , Journalist Committee of the

International Union of Crystallography, E. Prince, Co-editor

Journal of Applied Physics, 1986 Member, Editorial Board, J. J. Rhyne

National Bureau of Standards and JCPDS—International Centre for Diffraction

Data, Crystal Data Management Board, A. D. Mighell, Member

NSF Review Team for MRS at Michigan State, J. J. Rush, Member

51
Seminar on International Research Facilities, American Physical Society

Representative on Large Matter Condensed Matter Science Facilities,

Organizing Committee, J. J. Rush, Member

Steering Committee for an Advanced Steady State Neutron Source in the United

States, R. S. Carter, Member

Steering Committee for an Advanced Steady State Neutron Source in the United

States, J. J. Rush, Chairman

Workshop on Advanced Steady State Neutron Facility, Organizing Committee,

J. J. Rush, Member

52
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 34 universities, 24 industrial and 15 foreign

laboratories. A few examples of these many interactions are:

o A new collaborative research effort has been initiated with Mobil to

apply neutron diffraction and inelastic scattering in probing of

molecular arrangements and dynamics which are a key to understanding and

improving chemical processing in prototype catalysts.

o An agreement was established 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. An interim cooperative research effort has been established at

the existing SANS instrument at the reactor in research on wetting in

microporous media and micellar systems.

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 Cooperative Research efforts with the Physics Department and Materials

Research Laboratory at the University of Illinois were greatly expanded

during the past year to include the first neutron diffraction work

worldwide on a new class of layered magnetic materials and the initiation

of research on new kinds of metal-molecular complexes created within the

layers of oriented graphite.

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,

catalysts, biological materials, and in the development of state-of-theart polarized neutron scattering instrumentation. Some of this research

is carried out jointly with scientists from industrial labs.

o The joint catalytic materials program between Auburn University and the

Reactor Radiation Division at the National Bureau of Standards is

concerned with utilizing neutron scattering techniques in conjunction

with more traditional catalysis research methods to investigate the

influence of adsorbate orientation, surface stoichiometry, and

crystallite size/morphology on metal sulfide catalyst selectivity toward

important hydrotreating applications.

o Collaborative research activities with GTE Research Laboratories have

been extended to 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

53
Associated Activities

During the past year, scientists in the Reactor Radiation Division delivered

some twenty-seven invited lectures in the U.S. and abroad. The Division

also coorganized with the Department of Energy and private sector

laboratories a workshop for planning a new advanced steady state neutron

facility in the United States. Neutron Group scientists also received

European support for cooperative research efforts abroad including a NATO

grant for research with West German scientists on hydrogen in metals and a position as visiting scientist at the Chalmers Institute in Sweden for

collaborative development of advanced crystallographic methods and

instrumentation. Finally, the Division Chief, Robert S. Carter was elected

a fellow of the American Nuclear Society this past year.
NBS-114A (rev. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

1. PUBLICATION OR

REPORT NO.

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

SHEET (See instructions) NBSIR 86-3439 NOVEMBER 1986

4. TITLE AND SUBTITLE

Institute for Materials Science and Engineering

REACTOR RADIATION DIVISION TECHNICAL ACTIVITIES 1986

5. AUTHOR(S)

R. S. Carter, NBS, 460

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

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

10. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes all those programs which depend on the NBS reactor. It covers

the period from October 1, 1985 through September 30, 1986. 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 semicolon s) Activation analysis; crystal structure; diffraction; isotopes; molecular dynamics;

neutron; neutron radiography; nondestructive evaluation; nuclear reactor; radiation.

13. AVAILABILITY

r~

] Unl imited

L X f: ° r Official Distribution. Do Not Release to NTIS

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

‘ 20402.

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

14. NO. OF

PRINTED PAGES

15. Price

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