1. NAME AND TITLE OF DATA LIBRARY

GAMTOT78: Compilation of Radioactive Decay and Capture Gamma Rays.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAM

GAMIDEN: An Aid to the Identification of Unknown Materials through Gamma-Ray Spectroscopy.

3. CONTRIBUTOR

Lawrence Livermore Laboratory, Livermore, California.

4. HISTORICAL BACKGROUND AND INFORMATION

The intent of GAMIDEN is to help identify isotopes by their gamma-ray emissions and, thus, to assist in the nondestructive assay of unknown materials from both radioactive decay and neutron captures.

5. APPLICATION OF THE DATA

GAMIDEN searches GAMTOT78, a file of gamma-ray spectra, for matches with observed photon energies. The gamma-rays emitted by an isotope undergoing radioactive decay or neutron capture have energies and intensities that are characteristic of that isotope. A useful method for the nondestructive assay of unknown materials is based on identifying the signature of the isotope.

Since there are thousands of known gamma-rays, the automated search procedure searches for isotopes that satisfy the input criteria. Each such isotope is printed out, accompanied by a list of other gamma emissions from the isotope that one might expect to see.

The data file is taken from two compilations of gamma-ray spectra. The compilation of radioactive-decay gammas includes the half-life for each isotope and the energy and probability of emission per decay for each gamma emitted by that isotope.

6. SOURCE AND SCOPE OF DATA

Included are photon energies greater than 1 MeV and probabilities greater than 0.01. A total of 43,940 entries are provided.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM

GAMIDEN lists the matching isotopes, eliminates isotopes that are likely to be the source of the observed protons, and then lists the isotopes that are left. It is designed for the Cray 1. It is written in standard Fortran (ANSI), but contains some LRLTRAN instructions to make use of the Livermore time-sharing system.

8. DATA FORMAT AND COMPUTER

Character type EBCDIC; GAMTOT78 data 120 character records, Cray 1, IBM 3033.

9. TYPICAL RUNNING TIME

For GAMIDEN, the typical problem requires less than 0.75 min. Please note that disk file GAMTOT78 must be present. No input data required.

10. REFERENCES

a. Included in the documentation:

R. J. Howerton, "GAMIDEN: A Program to Aid in the Identification of Unknown Materials by Gamma-Ray Spectroscopy," UCRL-50400, Vol. 22 Rev. 1 (June 1982).

b. Background information:

G. Erdtmann and W. Soyka, "The Gamma Rays of the Radionuclides," in Verlag Chimie (Weinheim, New York, 1979).

V. J. Orphan et al, "Line and Continuum Gamma-Ray Yields from Thermal-Neutron Capture in 75 Elements," DASA 2570 GA-10248 (1970).

11. CONTENTS OF LIBRARY

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the program to search the data file.

12. DATE OF ABSTRACT

March 1984.