1. NAME AND TITLE

GRPANL: Code System for Analyzing Ge and Alpha-Particle Detector Spectra.

2. CONTRIBUTORS

Lawrence Livermore National Laboratory, Livermore, California through the Energy Science & Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER/OPERATING SYSTEM

Fortran 77; VMS 4.7

4. NATURE OF PROBLEM SOLVED

GRPANL (GRouP ANaLysis) is a suite of programs which analyzes and interprets regions of germanium and alpha-particle detector pulse-height spectra. GRPANL is the main peak-fitting program; the other programs included are used in conjunction with GRPANL. GRPANL is particularly useful for accurately deconvoluting and interpreting complex clusters of peaks in a spectrum. GRPANL fits peaks in specified regions of a gamma-ray, x-ray, or alpha-particle spectrum, calculates their energies and intensities, and optionally calculates the photon emission rates for the sample from which they were emitted. It can also identify and measure isotopes in a sample. GRPANL output can be immediately analyzed for quantitative isotopic assays or stored in an intermediate data file. The other programs are EDIGRP, LIBRY, and GEVAL. EDISRP (EDIt GRouP) creates and edits an analysis control file that contains input parameters and analysis options for spectral regions analyzed by GRPANL; users can repeat or modify an analysis without retyping input. LIBRY (LIBRarY) assembles and cross references selected nuclear decay scheme data and stores it in decay scheme data files for use by GRPANL and GEVAL. GEVAL (Gamma ray EVALuation) uses these data files along with GRPANL intermediate results to identify isotopes, calculate their abundance in a sample, and print the corresponding disintegration rates and abundances at counting and zero times.

5. METHOD OF SOLUTION

The peaks in any x-ray or gamma-ray spectrum are always superimposed on a background distribution resulting from the Compton scattering process. GRPANL first removes the background continuum before starting the fitting process thus reducing the number of fitting parameters. GRPANL then estimates the initial peak heights and positions. The Gauss-Seidel, or Newton-Raphson, iterative least- squares technique is applied to fit the data because the equations describing the peak-shape are nonlinear in form. Convergence is determined by comparing the magnitude of the last change in each variable with a specified convergence criterion. Once convergence is attained, fuel calculations are made for peak energies, intensities, and their respective uncertainties. The intensity uncertainties are based on counting statistics and on the goodness-of-fit.

6. RESTRICTIONS OR LIMITATIONS

Maxima of 1024 channels per peak, 40 degrees of freedom, and 40 peaks. GEVAL can evaluate a maximum of 200 peaks. The auxiliary programs CALDET, XDIST, LLFIT, and PKSHAP described in the reference reports are not included in the package. CALDET is used as an aid in calibrating a new detector. LLFIT fits an nth order polynomial to the data and reports the coefficients of the fit. These coefficients may then be stored in the detector coefficients file for subsequent analysis using this newly calibrated detector.

7. TYPICAL RUNNING TIME

The programs are interactive.

8. COMPUTER HARDWARE REQUIREMENTS

The codes run on the VAX family of computers.

9. COMPUTER SOFTWARE REQUIREMENTS

GRPANL uses the LLNL DIGRAPH and DIGLIB codes to produce graphical output. These programs are supplied in object form only. The VMS Fortran compiler was used on the VMS operating system.

10. REFERENCES

a: included in document:

R. Gunnink, W. D. Ruhter, and J. B. Niday, "GRPANL: A Suite of Computer Programs for Analyzing Complex Ge and Alpha-Particle Detector Spectra, Volume 1," UCRL-53861, Vol. 1, May 1988.

R. Gunnink, W. D. Ruhter, and J. B. Niday, "Operations Guide for GRPANL: A Suite of Computer Programs for Analyzing Complex Ge and Alpha-Particle Detector Spectra, Volume 2," UCRL-53861, Vol. 2, May 1988.

GRPANL Sample Output, September 1988.

b: background information:

R. Gunnink and W. D. Ruhter, "GRPANL: A Program for Fitting Complex Peak Groupings for Gamma and X-ray Energies and Intensities," UCRL-52917, January 1980.

11. CONTENTS OF CODE PACKAGE

Included in the package are the referenced documents and 1 DS/HD disk which includes the source files, test case input data and output.

12. DATE OF ABSTRACT

October 1992.