1. NAME AND TITLE

SAMPO-LRC: Gamma-Ray Spectrum Analysis Code.

SAMPO, originally called SISYPHUS, was developed on the CDC 6600 computer at the Lawrence Berkeley Laboratory at the University of California in 1969 in support of the author's doctoral dissertation. The IDENT subroutine included in this version carries out radioisotope identifications and elemental mass determinations after simple or cyclic thermal-neutron activation analysis. A minicomputer version of the code, PSR-204/SAMPO-80, was developed at the Helsinki University of Technology, Nuclear Engineering Laboratory, Finland.

2. CONTRIBUTOR

University of London Reactor Centre, Berkshire, England.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; CDC 6600.

4. NATURE OF PROBLEM SOLVED

SAMPO is a versatile gamma-ray spectrum analysis program used for the analysis of the complex spectra encountered in neutron-activation analysis. In particular, it is intended for photo-peak analysis of gamma-ray spectra obtained with semiconductor detectors. It includes routines for peak-finding, peak-fitting and peak intensity and energy determinations. It also makes complete statistical and calibration-error estimates. Different options are available to make the code applicable to accurate nuclear spectroscopic work as well as routine data reduction.

5. METHOD OF SOLUTION

SAMPO contains a mathematical formalism for the representation of photopeaks and the continua in their vicinity which is applicable to analysis of spectra measured under widely varying conditions. With this formalism, the line shape is defined for each peak in the spectrum. The region of data about a single peak is then fitted with the shape functions and a function representing the background continuum. The line-shape calculations and the fitting are performed by using a least-squares procedure with an iterative gradient minimization method with variable metric.

IDENT, a subroutine of SAMPO, carries out radioisotope identifications and elemental mass determinations after simple or cyclic thermal-neutron activation analysis by matching the peaks found with its nuclear data library.

6. RESTRICTIONS OR LIMITATIONS

IDENT is dimensioned to allow for a maximum of 15 peaks in any one interval and 50 unsuccessful identifications in each spectrum. These limits may be increased if necessary.

7. TYPICAL RUNNING TIME

No study has been made by RSIC of typical running times for SAMPO.

8. COMPUTER HARDWARE REQUIREMENTS

SAMPO was designed to run on the CDC 6600 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

a. Included in the documentation:

W. Carder, "A General Purpose Program for Semiconductor Spectral Analysis, User's Manual" (August 1977).

W. Carder, T. D. MacMahon, and A. Egan, "IDENT--A Radioisotope-Identification Subroutine for Use with the Gamma-Ray Spectrum Analysis Program SAMPO," Talanta 25, (1978) 21-40.

b. Background information:

J. T. Routti and S. G. Prussin, "Photopeak Method for the Analysis of Gamma-Ray Spectra from Semiconductor Detectors," Nuclear Instruments and Methods 72 (1969) 125-142.

Jorma T. Routti, "SAMPO, a Fortran IV Program for Computer Analysis of Gamma Spectra from Ge(Li) Detectors, and for Other Spectra with Peaks," UCRL-19452 (October 1969).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source codes, sample problem input and output, and JCL for the CDC 6600.

12. DATE OF ABSTRACT

June 1982; October 1983; January 1984; April 1984; reviewed May 1984.