*z (0 NBS SPECIAL PUBLICATION 260-49

U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards

Standard Reference Materials:

Calibrated Glass Standards

for Fission Track Use
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

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Standard Reference Materials:

Calibrated Glass Standards

for Fission Track Use

B. Stephen Carpenter and

G. Michael Reimer

Analytical Chemistry Division

Institute for Materials Research

t^<S« National Bureau of Standards

* • Washington, D.C. 20234

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, D/recfor

Issued November 1974
Library of Congress Cataloging in Publication Data

Carpenter, B Stephen.

Calibrated glass standards for fission track use.

(Standard reference materials) (National Bureau of Standards

Special Publication; 260-49)

Supt. of Docs. No.: C13.10:260-49

1. Neutron flux standards. 2. Glass—Standards. 3. Thermal

neutrons—Measurement. I. Reimer, G. Michael, joint author. II. Title. III. Series: United States. National Bureau of Standards. Standard reference materials. IV. Series: United States. National Bureau of Standards. Special Publication; 260-49. OC100.U57 No. 260-49 [QC793.5.N4626 ] 389'.08s 74-20566

[539.7'62]

National Bureau of Standards Special Publication 260-49

Nat. Bur. Stand. (U.S.), Spec. Publ. 260-49, 27 pages (Nov. 1974) CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1974

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.10:260-49). Price .75 cents.
PREFACE

Standard Reference Materials (SRM's) as defined by the

National Bureau of Standards are "well-characterized materials, produced in quantity, that calibrate a measurement

system to assure compatibility of measurement in the nation."

SRM's are widely used as primary standards in many diverse

fields in science, industry, and technology, both within the

United States and throughout the world. In many industries

traceability of their quality control process to the national

measurement system is carried out through the mechanism and

use of SRM's. For many of the nation's scientists and technologists it is therefore of more than passing interest to

know the details of the measurements made at NBS in arriving

at the certified values of the SRM's produced. An NBS series

of papers, of which this publication is a member, called the

NBS Special Publication - 260 Series is reserved for this

purpose

This 260 Series is dedicated to the dissemination of

information on all phases of the preparation, measurement,

and certification of NBS-SRM's. In general, much more detail will be found in these papers than is generally allowed,

or desirable, in scientific journal articles. This enables

»the user to assess the validity and accuracy of the measurement processes employed, to judge the statistical analysis,

and to learn details of techniques and methods utilized for

work entailing the greatest care and accuracy. It is also

hoped that these papers will provide sufficient additional

information not found on the certificate so that new applications in diverse fields not foreseen at the time the SRJl

was originally issued will be sought and found.

Inquiries concerning the technical content of this

paper should be directed to the author(s). Other questions

concerned with the availability, delivery, price, and so

forth will receive prompt attention from:

Office of Standard Reference Materials

National Bureau of Standards

Washington, D.C. 20234

J. Paul Cali, Chief

Office of Standard Reference Materials

iii
i
CONTENTS

PAGE

I. INTRODUCTION 1

II. CHARACTERIZATION OF THE GLASS STANDARDS . . 2

III. CERTIFICATION AND PACKAGE DESCRIPTION ... 3

IV. PREPARATION AND IRRADIATION PROCEDURES. . . 3

V. FLUX DETERMINATION . 4

VI. RECOMMENDED USE OF STANDARD REFERENCE

MATERIALS 6

VII. ACKNOWLEDGEMENT 8

LIST OF TABLES

Table No.

I. The Uranium Concentration ^^^U Isotopic Abundance

g

II. Concentration of Elements That May Cause

Track Interferences 9

III. Activation Energies for Track Fading in

the NBS Standard Glasses 10

IV. SRM 961 Fission Track Glass Standard .... 10

V. SRM 962 Fission Track Glass Standard .... 11

VI. SRM 963 Fission Track Glass Standard .... 12

VII. SRM 964 Fission Track Glass Standard .... 13

V
LIST OF FIGURES

PAGE

Figure I. Annealing studies of uranium fission

tracks in the 50 ppm SRM 962. Extrapolation of the data on this Arrhenius

plot indicates that glasses used as

track references should be stored in

a cool place in order to prevent

partial annealing of tracks 14

Figure II. Position of RT-3 and RT-4 irradiated

glasses and the four unirradiated

glasses (UG) within SRM package 15

Figure III. Arrangement of the glass, metal

foils and detectors during neutron

irradiation 16

vi
OTHER NBS PUBLICATIONS IN THIS SERIES

NBS Spec. Publ. 260, Standard Reference Mate- NBS Misc. Publ. 260-12, Standard Reference

rials: 1973 Catalog, April 1973, $1.25.* Materials: Homogeneity Characterization of

NBS Misc. Publ. 260-1, Standard Reference Ma- NBS Spectrometric Standards HI: White Cast

terials: Preparation of NBS White Cast Iron Iron and Stainless Steel Powder Compact,

Spectrochemical Standards, June 1964. COM September 1966. NBS Misc. Publ. 260-12.**

74-11061.** NBS Misc. Publ. 260-13, Standard Reference

NBS Misc. Publ. 260-2, Standard Reference Ma- Materials: Mossbauer Spectroscopy Standard

terials: Preparation of NBS Copper-Base for the Chemical Shift of Iron Compounds,

Spectrochemical Standards, October 1964. July 1967. NBS Misc. Publ. 260-13.**

COM 74-11063.** NBS Misc. Publ. 260-14, Standard Reference

NBS Misc. Publ. 260-3, Standard Reference Ma- Materials: Determination of Oxygen in Ferterials: Metallographic Characterization of an rous Materials - SRM 1090, 1091, and 1092,

NBS Spectrometric Low-Alloy Steel Stand- September 1966. NBS Misc. Publ. 260-14.**

ard, October 1964. COM 74-11060.** NBS Misc. Publ. 260-15, Standard Reference

NBS Misc. Publ. 260-4, Standard Reference Ma- Materials: Recommended Method of Use of

terials: Sources of Information on Standard Standard Light-Sensitive Paper for CalibratReference Materials, February 1965. COM ing Carbon Arcs Used in Testing Textiles for

74-11059.** Colorfastness to Light, June 1967. NBS Misc.

NBS Misc. Publ. 260-5, Standard Reference Ma- Publ. 260-15.**

terials: Accuracy of Solution X-Ray Spectro- NBS Spec. Publ. 260-16, Standard Reference

metric Analysis of Copper-Base Alloys, Materials: Homogeneity Characterization of

March 1965. 25 cents. (Out of print). NBS Spectrometric Standards IV: PreparaNBS Misc. Publ. 260-6, Standard Reference Ma- tion and Microprobe Characterization of

terials: Methods for the Chemical Analysis of W-20% Mo Alloy Fabricated by Powder

White Cast Iron Standards, July 1965. COM Metallurgical Methods, January 1969. COM

74-11068.** 74-11062.**

NBS Misc. Publ. 260-7, Standard Reference Ma- NBS Spec. PubL 260-17, Standard Reference

terials: Methods for the Chemical Analysis of Materials: Boric Acid; Isotopic and Assay

NBS Copper-Base Spectrochemical Stand- Standard Reference Materials, February

ards, October 1965. COM 74-11067.** 1970. 65 cents.*

NBS Misc. Publ. 260-8, Standard Reference Ma- NBS Spec. Publ. 260-18, Standard Reference

terials: Analysis of Uranium Concentrates at Materials: Calibration of NBS Secondary

the National Bureau of Standards, December Standard Magnetic Tape (Computer Ampli1965. COM 74-11066.** tude Reference) Using the Reference Tape

NBS Misc. Publ. 260-9, Standard Reference Ma- Amplitude Measurement "Process A",

terials: Half Lives of Materials Used in the November 1969. NBS Spec. Publ. 260-18.**

Preparation of Standard Reference Materials NBS Spec. Publ. 260-19, Standard Reference

of Nineteen Radioactive Nuclides Issued by Materials: Analysis of Interlaboratory Measthe National Bureau of Standards, November urements on the Vapor Pressure of Gold

1965. COM 74-11065.** (Certification of Standard Reference Material

NBS Misc. Publ. 260-10, Standard Reference 745), January 1970. PB 190071.**

Materials: Homogeneity Characterization on NBS Spec. Publ. 260-21, Standard Reference

NBS Spectrometric Standards II: Cartridge Materials: Analysis of Interlaboratory MeasBrass and Low-Alloy Steel, December 1965. urements on the Vapor Pressures of CadCOM 74-11064.** mium and Silver, January 1971. COM

NBS Misc. Publ. 260-11, Standard Reference 74-11359.**

Materials: Viscosity of a Standard Lead-Silica NBS Spec. Publ. 260-22, Standard Reference

Glass, November 1966. NBS Misc. Publ. Materials: Homogeneity Characterization of

260-10.** Fe-3Si Alloy, February 1971. COM

74-11357**

Vll
NBS Spec. Fubl. 260-23, Standard Reference NBS Spec. Publ. 260-35, Standard Reference

Materials: Viscosity of a Standard Borosili- Materials: Thermal Conductivity of Austencate Glass, December 1970. 25 cents.* itic Stainless Steel, SRM 735 from 5 to NBS Spec. Publ. 260-24, Standard Reference 280 K, April 1972. 35 cents.*

Materials: Comparison of Redox Standards, NBS Spec. Publ. 260-36, Standard Reference

January 1972. $1.* Materials: A Referee Method for the Deter- NBS Spec. Publ. 260-25, Standard Reference mination of Calcium in Serum. SRM 915,

Materials: A standard Reference Material May 1972. COM 72-50527.**

Containing Nominally Four Percent Austen- NBS Spec. Publ. 260-37, Standard Reference

ite, February 1971. COM 74-11356** Materials: Methods of Analysis of NBS Clay

NBS Spec. Publ. 260-26, Standard Reference Standards, June 1972. COM 72-50692.**

Materials: National Bureau of Standards-U.S. NBS Spec. Publ. 260-38, Standard Reference

Steel Corporation Joint Program for Deter- Materials: Preparation and Calibration of

mining Oxygen and Nitrogen in Steel, Feb- Standards of Spectral Specular Reflectance,

ruary 1971. 50 cents.* May 1972. 60 cents.*

NBS Spec. Publ. 260-27, Standard Reference NBS Spec. Publ. 260-39, Standard Reference

Materials: Uranium Isotopic Standard Refer- Materials: The Eddy Current Decay Method

ence Materials, April 1971. COM 74-11358** for Resistivity Characterization of HighNBS Spec. Publ. 260-28, Standard Reference Purity Metals, May 1972. 55 cents.*

Materials: Preparation and Evaluation of NBS Spec. Publ. 260-40, Standard Reference

SRM's 481 and 482 Gold-Silver and Gold- Materials: Selection of Thermal Analysis

Copper Alloys for Microanalysis, August Temperature Standards Through a Coopera1971. COM 71-50365.** tive Study (SRM 758, 759, 760), August

NBS Spec. Publ. 260-29, Standard Reference 1972. 65 cents.*

Materials: Calibration of NBS Secondary NBS Spec. Publ. 260-41, Standard Reference

Standard Magnetic Tape (Computer Amph- Materials: Use of Standard Light-Sensitive

tude Reference) Using the Reference Tape Paper for Calibrating Carbon Arcs used in

Amplitude Measurement "Process A-Model Testing Textiles for Colorfastness to Light,

2", June 1971. COM 71-50282.** August 1972. COM 72-50775.**

NBS Spec. Publ. 260-30, Standard Reference NBS Spec. Publ. 260-42, Standard Reference

Materials: Standard Samples Issued in the Materials: The Characterization of Linear

USSR (A Translation from the Russian), Polyethylene, SRM 1475, September 1972.

June 1971. COM 71-50283.** 45 cents.*

NBS Spec. Publ. 260-31, Standard Reference NBS Spec. Publ. 260-43, Standard Reference

Materials: Thermal Conductivity of Electro- Materials: Preparation and Homogeneity

lytic Iron SRM 734 from 4 to 300 K, Novem- Characterization of an Austenitic Iron- ber 1971. COM 71-50563.** Chromium-Nickel Alloy, November 1972.

NBS Spec. Publ. 260-32, Standard Reference 45 cents.*

Materials: Standard Quartz Cuvettes For NBS Spec. Publ. 260-44, Standard Reference

High Accuracy Spectrophotometry. Decem- Materials: Preparation and Use of Superber 1973. 55 cents.* conductive Fixed Point Devices, SRM 767,

NBS Spec. Publ. 260-33, Standard Reference December 1972. 75 cents.*

Materials: Comparison of Original and Sup- NBS Spec. Publ. 260-45, Standard Reference

plemental SRM 705, Narrow Molecular Materials: Powdered Lead-Based Paint, SRM

Weight Distribution Polystyrene, H. L. 1579, March 1973. COM 73-50226.**

Wagner, May 1972. COM 72-50526.** NBS Spec. Publ. 260-46, Standard Reference

NBS Spec. Publ. 260-34, Standard Reference Materials: The Role of SRM's in MeasureMaterials: Thermoelectric Voltage, April

"^^J*

^yst^^Jf• (I" P^^^^^^ H . R f 1972 COM 72 50371 ** Spec. Publ. 260-47, Standard Reference

Materials: Electrical Resistivity of Electrolytic Iron, SRM 797, and Austenitic Stainless

Steel, SRM 798, from 5 to 280K, February

1Q 74. 55 cents.*

viii
NBS Spec. Publ. 260-48, Standard Reference

Materials: Description and Use of Precision

Thermometers for the CUnical Laboratory,

SRM 933 and SRM 934, May 1974. 60

cents.*

NBS Spec. Publ. 260-49, Standard Reference

Materials: Calibrated Glass Standards for Fission Track Use. (In preparation)

*Send order with remittance to: Superintendent of Documents, U.S. Government Printing Office,

Washington, D.C. 20402. Remittance from foreign countries should include an additional one- fourth of the purchase price for postage.

**May be ordered from: National Technical Information Services (NTIS), Springfield, Virginia

22151.

CALIBRATED GLASS STANDARDS FOR FISSION TRACK USE

B. Stephen Carpenter and G. Michael Reimer

Analytical Chemistry Division

Institute for Materials Research

National Bureau o£ Standards

Washington, D.C. 20234

Four glasses of different uranium concentrations were

prepared and certified by the National Bureau of Standards

as standards for use as neutron monitors to aid fission

track studies. These Standard Reference Materials (SRM)

and their uranium concentrations are: SRM 941 (461 ppm)

,

SRM 962 (37.4 ppm), SRM 963 (0.823 ppm), and SRM 964

(0.0721 ppm). These glass wafers were irradiated in the

National Bureau of Standards Reactor and the neutron flux

was monitored using copper and gold foils.

Key Words: Fission tracks; flux monitors; glass standards;

Standard Reference Material; thermal neutron irradiation;

uranium

.

r. INTRODUCTION

The fission track technique has become an accepted

and widely used method for uranium analysis and radiometric

dating in many laboratories. Therefore, the need exists for

a primary standard to enable correlation of inter - laboratory

results. In order to fulfill this need, the National Bureau

of Standards (NBS) , through the Office of Standard Reference

Materials, has prepared and certified Fission Track Glass

Standards SRM's 961, 962, 963, and 964t (1). Although

these are not the first standards prepared for fission

track work (2,3), they are the first readily available

fission track standards for monitoring neutron fluxes during

irradiations and for comparing track densities. Since the

f Available from Office of Standard Reference Materials,

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

1
i

i glasses have some inadequacies which will be discussed,

they are not the "ideal" standards; they are, however, j the best standards available at this time.

|

II. CHARACTERIZATION OF THE GLASS STANDARDS i

The Fission Track Glass Standards, SRM numbers 961, 962,

963, and 964, are available at four different uranium concen- I tration levels, 461.5 ppm, 37.38 ppm , 0.823 ppm and 0.0721 ppm,

' respectively. These glass wafers, 12 mm in diameter and 3-mm i thick, with a nominal base composition of 72% SiO- , 12% CaO, j 141 Na20, and 1% ^'^'P-z^ came from the same lot of material as

the Trace Element in Glass SRM's 610 through 616 (4,5,6).

This series of SRM's has been analyzed for homogeneity and was

was certified for approximately half of the more than 60

trace elements present at the four concentration levels,

including uranium. However, in the preparation of these

glasses, the uranium used for the dopant was depleted uranium,

and each concentration has a different uranium-235 isotopic

abundance (as seen in Table I) . In determining uranium by

the fission track technique, thorium and boron are two major

elements that could cause possible interference since they

emit charged particles that may be recorded in many external

detectors. The concentrations of these two elements are

given in Table II. In the certification of these glasses,

the analytical competences employed by the Analytical Chemistry

Division were isotope dilution mass spectrometry, polarography

,

flame emission and atomic absorption spectrometry, spectrophotometry, and nuclear methods of analysis, which included

both neutron activation analysis and nuclear track technique.

2

I
To further characterize these standards, the thermal

stability o£ fission tracks in the glasses was also studied

to determine the fading rate of the tracks when subjected

to heat. Reimer e_t aJ (7) found that the glasses had

relatively low thermal stability. Extrapolation of track

fading data indicates that tracks could begin to decrease at

50 °C after a time of only several months. Figure I illustrates this extrapolation for SRM 962. Table III lists

the activation energies calculated from the track fading

experiments that would produce a specific degree of track

reduction. It is recommended that these glasses be stored

below 20 °C when not being used.

III. CERTIFICATION AND PACKAGE DESCRIPTION

The glasses are certified for the neutron flux

- 2 - 1 ^ (n*cm sec ), in which they were irradiated. Copper and

gold foils were chosen to monitor the neutron flux since

many laboratories routinely use these foils.

The SRM package contains four unirradiated glass wafers

and two separately irradiated wafers. The irradiations were

performed in either of two positions of the NBS Reactor, each

position providing different neutron energy spectra (8,9).

Each package has two numbers designating the specific irradiated glasses enclosed. Figure II illustrates the configuration of the SRM package.

IV. PREPARATION AND IRRADIATION PROCEDURES

All of the glasses were ground flat and polished on

both sides, cleaned in dilute nitric acid solution (1 part

HNO^ ; 10 parts H2O) for 2 minutes, rinsed in distilled

water, ethanol, and air dried. Each cleaned wafer was then

sandwiched between two pre-cleaned numbered detectors, Lexan*

3
polycarbonate and muscovite mica. The combination was

placed in a polyethylene bag which was hermetically vacuum

sealed to ensure intimate contact between detectors and

wafers. Each package was then placed in individual irradiation rabbits.

Pre-weighed foil flux monitors of copper, 0.1270-mm

thick with average weight 0.021 g, and gold, 0.0254-mm thick

with average weight 0.031 g, were placed in every tenth

rabbit. (See Figure III for sample configuration during

irradiation.) Each glass concentration level was divided

into two groups of 125 samples, and each sample was irradiated

individually in one of two different pneumatic tubes of the

NBS Reactor (NBSR) . In the radiation positions used for this

work, RT-3 has a cadmium ratio of 10.2 for gold foils

and 65 for copper foils, while RT-4 has a cadmium ratio

of 87 for gold and 536 for copper foils (9) . The irradiation

time used depended on the uranium concentration and

uranium-235 isotopic abundance (see Table II). Due to the

high uranium content of the 961 series of glasses, the

irradiations were not performed at the usual 10 MW Reactor

power but at a reduced power of 1 MW.

V. FLUX DETERMINATION

After irradiation, the gross radioactivity was allowed

to decay, and the foil flux monitors were removed from the

irradiation containers while external detectors and glasses

64

were separated. The activity of the 0.511 MeV, Cu positron

^as counted with a 60cc Ge(Li) solid state detector; the

same procedure was followed for counting the activity of the

198 0.412-MeV gamma-ray of Au . Each foil was counted 2 cm

from the detector. The detectors had been previously calibrated with NBS SRlvI's chosen from the NBS radio-activity

4
series; therefore, absolute peak efficiencies were determined

for the various Y"ra-y energies of copper and gold. The

copper foils were placed between aluminum discs 0.32-mm thick

in order to ensure annihilation of all ^'^Cu, 0.511-MeV positrons close to the foil. After counting all the foils that

had been irradiated in the two reactor positions, the neutron

flux for each foil was determined using nuclear and physical

constants. The following equations were used to calculate

the thermal neutron flux:

Activity A = (1)

A= activity in nuclear transformations per second at T (Time

of zero decay, i.e., end of irradiation) °

C= counts per second at T^

H= absolute counter efficiency for the appropriate energy

gamma -ray

a=Gamma ray intensity; " Cu(0.511 MeV) = 0.38; AuCO.412 MeV)

= 0.95 (10)

_A

(j) = ;;7^ Tit. (2)

^th^^ ) Thermal neutron flux (n*cm ^•sec'-'-)

a^j^ = Thermal neutron cross section; ^^Cu = 4.5x10 ^"^cm^

^^^Au=98.8xl(7"^^cm^

N = Total number of target nuclei

Dis

198

64

A = Disintegration constant of radionuclide ( Au or

Au) material

t = Time duration of exposure to neutron flux

The external detectors, previously separated from

the glass wafers, were chemically etched to optically reveal

the fission tracks. The polycarbonate detectors were etched

in a 6 . 5N NaOH solution for 45 minutes at a constant temperature of 50 °C, then rinsed in distilled water and air dried.

5
The mica detectors were etched in 481 HF for 15 minutes

at 20 °C, rinsed in water, and heated to dry and to

volatilize any remaining HF . The irradiated glass wafers

were etched in 161 HF for 75 seconds at 20 °C, rinsed with

water for 15 minutes and allowed to air dry.

After etching, both of the external detectors were

counted with the aid of an image analyzing microscope under

the pre-established conditions of either a minimum of at

least 1,000 tracks or 50 random fields of view. The random

fields of view were of an area of 1.74xl0"^cm^ at a magnification of 480X. The same counting criteria were employed

for the glasses. Counting data was also collected for each

series of metal foils, the two external detectors and both

sides of the glasses and a statistical evaluation was performed

for trends or variations in the neutron flux.

The flux determinations for glasses SRM 961, 962, 963,

and 964 are reported in Tables IV, V, VI, and VII,

respectively. The neutron fluence is determined by

multiplying the flux by the irradiation time. There were

no obvious trends or variations outside of those imposed by

counting statistics that would require rejecting any of the

irradiated material. However, a systematic effect was

noticed for Glasses 963 and 964 which were irradiated over

several days. No such errors were indicated in Glasses 961

and 962 which were all irradiated during the same day.

VI. RECOMMENDED USE OF STANDARD REFERENCE MATERIALS

The SRM's were prepared and certified in a manner to

minimize restriction of their specific use. The selection

of a reactor facility, the etching conditions, and the

counting criteria are all the choice of the individual

laboratory

.

6
It is recommended that one of the non- irradiated wafers,

or a portion of it, be included with the samples being

irradiated. The choice of the wafer included should be

based upon the total expected neutron exposure and the

uranium concentration of the wafer so that the number of

tracks produced will be in a range convenient for counting.

After irradiation, the wafer should be polished together

with the SRM irradiated wafer to remove approximately 30

micrometers from the surface, which is greater than the

fragment range, thus providing an internal surface. Low

speed polishing should be used to keep heating to a minimum.

Both glasses should then be etched and counted together. The

unknown neutron fluence can be determined from the track

densities and the known neutron exposure of the SRM irradiated wafer. The counting accuracy would be dependent on the

number of tracks counted.

For future irradiations, it is not necessary to repolish

and re-etch the SRM irradiated standard if the etching conditions of the newly irradiated wafer are ident ical to those

of the previously etched SRM irradiated wafer. They need only

to be counted together. It is suggested, however, that all the

irradiated glasses be stored below 20 °C to reduce the chance

of track annealing.

The two SRM irradiated glasses allow an additional option.

There was a difference in the thermal to fast neutron ratio for

the irradiation of these wafers, as indicated by the cadmium

ratios for gold and copper foil. The wafer selected for the

counting comparisons should most closely approximate the neutron energy conditions of the reactor used. The specific glass

used as a standard should always be mentioned by its NBS-SRM

number in publication.

7
ACKNOWLEDGEMENT

The authors would like to thank P. D. LaFleur of the

Analytical Chemistry Division and the members of the Reactor

Operation Section for their help in the irradiation of the

glass wafers, and to L. Hernandez, J. A. Hormuth, and R. M.

Young, former members of the Activation Analysis Section,

for their help in packaging and preparation of the Standards.

Appreciation is also extended to J. Mandel, statistical consultant for the Institute for Materials Research, for his

statistical evaluation. A special note of thanks is extended

to J. Paul Call and R. E. Michaelis of the Office of Standard

Reference Materials whose encouragement and support made

these Standards a reality.

Certain commercial equipment, instruments, or materials are

identified in this paper 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 material or equipment identified is necessarily the best available for the

purpose.

8
Table I 235 The Uranium Concentration U Isotopic

Abundance

Total U Concentration 235 Reactor Location

U Atom and Irradiation

ppm (by weight) Percent Time (sec .

)

SRM 961 461.5 ± 1.1 0.2376 RT-3 8

RT-4 12

bRM 9dZ 37. 38 ± U.U8 0 . Z39z Rl -

3

o8

RT-4 12

SRM 963 0.823 ± 0.002 0.2792 RT-3 80

RT-4 120

SRM 964 0.0721 ± 0.0013 0.616 RT-3 360

RT-4 540

Table II

Concentration of Elements

That May Cause Track Interferences

SRM 961

SRM 962

SRM 963

SRM 964

Boron (ppm by weight) Thorium (ppm by weight)

351 457.2 ± 1.2

32 37.79 ± 0.08

1.3 0.748 ± 0.006

0.20 ± 0.002 0.0252 ± 0.0007

9
Table III

Activation Energies for Track Fading

in the NBS Standard Glasses

Density

Reduc t ion

P/Pq

oKM oKM

964 963

C "DAT oRM

962

oRM

961

u . y 5 0 . o eV U . 7 eV 1 . Z eV 0.8 eV

U . 9 U in1.0 no0.5 1 . 3 1 .

n ft n u . o u IX± . o HQu . y 1 . D 0.70 1.5 1.1 1.7 1.4

0.60 1.7 1.2 1.8 1.6

0.50 1.8 1.5 2.0 1.7

Table IV

SRM 961 Fission Track Glass Standard

NBS Reactor

PoL \J 1JL 1 1-1_ onW J. J.

Neutron Flux Mean Valug

and Standard Deviation

fxlO ^ A • cm" ^• sec

Tolerance

(95%)

Intervals^

(99%)

Cu Foil

Rl - 4 1.31 0.0/8 0.06 0.09

RT-3 4.56 0.086

Au Foil

0.20 0 . 28

RT-4 1.46 0.042 0.09 0 .13

RT-3 5.43 0.17 0.39 0.55

Standard deviations refer to individual metal foils.

Irradiation was performed at a power of 10 megawatts;

A 95 percent tolerance interval is estimated to include the

measurement of approximately 95 percent of all individual

wafers of the population of wafers. Thus, the probability

is approximately 95 percent that any individual wafer measurement will lie inside the 95 percent tolerance interval. A

similar definition holds for 99 percent tolerance interval.

10
Table V

SRM 962 Fission Track Glass Standard

Neutron Flux Mean Valug Tolerance Intervals

NBS Reactor and Standard Deviation

Position (xlO^ ^n • cm" ^ - sec " M ^ X^SJJ (991)

Cu Foil

RT-4 1.29 ± 0.072 ±0.16 ±0.23

RT-3 5.29 ± 0.21 ±0.49 ±0.69

Au Foil

RT-4 1.43 ± 0.012 ±0.03 ±0.04

RT-3 5.93 ± 0.17 ±0.40 ±0.57

Standard deviations refer to individual metal foils

Irradiation was performed at a power of 10 megawatts;

8 seconds in RT-3, or 12 seconds in RT-4.

95 percent tolerance interval is estimated to include

the measurement of approximately 95 percent of all

individual wafers of the population of wafers. Thus,

the probability is approximately 95 percent that any

individual wafer measurement will lie inside the 95 percent

tolerance interval. A similar definition holds for 99

percent tolerance interval.

11
Table VI

Wafer Number

Identification

614001-614040

614041-614090

614091-614125

SRM 963 Fission Track Glass Standard

Tolerance Intervals'

sec (951) [991]

NBS Reactor

Position

RT-4

RT-4

RT-4

Neutron Flux Mean Valu§

and Standard Deviation'

(XIO^^ -2 -l^b n*cm

Cu Foil

1.26 ± 0.026

1.24 ± 0.026

1.26 ± 0.026

±0.06

±0.06

±0,06

±0.09

±0.09

±0.09

614126-614165 RT-3

614166-614215 RT-3

614216-614251 RT-3

5.38 ± 0.17

5.10 ± 0.17

5.14 ± 0.17

±0.42

±0.42

±0.42

±0.60

±0.59

±0.60

Au Foil

614001-614040 RT-4 1 41 +

0 024 ±0 06 ±0 09

614041-614090 RT-4 1 36 + 0 024 ±0 06 ±0 08

614091-614125 RT-4 1 44 + 0 024 ±0 06 ±0 09

614126-614165 RT-3 6 03 + 0 059 ±0 15 ±0 21

614166-614215 RT-3 5 97 + 0 059 ±0 15 ±0 21

614216-614251 RT-3 6 13 + 0 059 ±0 15 ±0 21

^Standard deviations refer to individual metal foils

Irradiation was performed at a power of 10 megawatts;

80 seconds in RT-3, or 120 seconds in RT-4.

A 95 percent tolerance interval is estimated to include the

measurement of approximately 95 percent of all individual

wafers of the population of wafers. Thus, the probability is

approximately 95 percent that any individual wafer measurement

will lie inside the 95 percent tolerance interval. A similar

definition holds for 99 percent tolerance interval.

12
Table VII

SRM 964 Fission Track Glass Standards

Neutron Flux Mean Value Tolerance Intervals

Wafer Number NBS Reactor and Standard Deviation

Identification Position (xlO^ ^n-cm" ^ -sec" ^

)

(95^) (99%)

Cu Foil

616001-616027 RT-4 1 31 + 0 057 ±0 15 ±0 21

616028-616060 RT-4 1 26 + 0 057 ±0 15 ±0 21

616061-616090 RT-4 1 32 + 0 033 ±0 08 + 0 12

616091-616125 RT-4 1 39 + 0 033 ±0 08 ±0 12

616126-616163 RT-3 4 84 ± 0.20 ±0 52 ±0 76

616164-616185 RT-3 4 57 ± 0.20 + 0 57 ±0 84

616186-616195 RT-3 4 50 ± 0.20 ±0 66 ±0 96

616196-616215 RT-3 4 55 ± 0.20 ±0 57 ±0 84

616216-616250 RT-3 4 41 ± 0.20 ±0 52 ±0 76

Au Foil

616001-616027 RT-4 1 46 ± 0.033 ±0 08 ±0 12

616029-616060 RT-4 1 48 + 0.033 ±0 08 ±0 12

616061-616090 RT-4 1 40 ± 0.057 ±0 15 ±0 21

616091-616125 RT-4 1 41 ± 0.057 ±0 14 ±0 21

616126-616163 RT-3 4 69 + 0 10 ±0 26 ±0 37

616164-616185 RT-3 5 21 + 0 10 ±0 28 ±0 41

616186-616195 RT-3 5 45 + 0 10 ±0 32 ±0 47

616196-616215 RT-3 4 11 + 0 10 ±0 28 ±0 41

616216-616250 RT-3 4 50 + 0 10 ±0 26 ±0 37

Standard deviations refer to individual metal foils.

'irradiation was performed at a power of 10 megawatts; 360 seconds

in RT-3, or 540 seconds in RT-4.

A 95 percent tolerance interval is estimated to include the

measurement of approximately 95 percent of all individual wafers

of the population of wafers. Thus, the probability is approximately

95 percent that any individual wafer measurement will lie inside

the 95 percent tolerance interval. A similar definition holds

for 99 percent tolerance interval.

13
Figure I. Annealing studies of uranium fission tracks in the

50 ppm SRM 962.

14
Figure II. Position of RT-3 and RT-4 irradiated glasses.

STANDARD REFERENCE MATERUL

961

FISSION TRACK GLASS

STANDARD

URANIUM

500 ppm

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

WASHINGTON. D.C. 20234 0

0 0

0

15

0
a

•H

j_, -1iJow

(J

+-> 0)

T-t\J

rrHrj

,—1 •H

V)

nj I—

tJO

<U

O

XI •H

4-> +-> nJH o xt

+->

H

0)

O

+-)

(D <

CD

•H

tin

16
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUHLICATION OR REPORT NO. SP 260-49

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

STANDARD REFERENCE MATERIALS: Calibrated Glass

Standards for Fission Track Use

5. Publication Date November 1974

6. Performing Organization Code

7. AUTHOR(S)

B, S. Carpenter and G. M. Reimer

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as #9.

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 74-20566

16. ABSTRACT (A 200-word or less factual suwmary of most sigriificant information. If document includes a significant

bibliography or literature survey, mention it here.) Four glasses of different uranium concentrations were

prepared and certified by the National Bureau of Standards as standards for use as neutron monitors to aid fission track

studies. These Standard Reference Materials (SRM) and their

uranium concentrations are: SRM 941 (461 ppm) , SRM 962

(37.4 ppm), SRM 963 (0.823 ppm), and SRM 964 (0.0721 ppm).

These glass wafers were irradiated in the National Bureau

of Standards Reactor and the neutron flux was monitored using

copper and gold foils.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Fission tracks ; flux monitors ; glass Standards;

standard Reference Material; thermal neutron irradiation; uranium.

18. AVAILABILITY Unlimited

I

' For Official Di stribution. Do Not Release to NTIS

I^y' Order From Sup. of Doc, U.S. Government Erijitirig JDffitie Washington, D.C. 20402, SD Cat. No. C13» ltJ:26U-4V

I I Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

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(THIS REPORT)

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21. NO. OF PAGES

27

22. Price.75^

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