**1. NAME AND TITLE**

GELI2-SPAN2: Calculation of Nuclide Abundances from Multichannel Gamma-Ray Spectra.

GELIZ-SPAN2 was written by modifying and supplementing GEL1 and by replacing the SPAN first derivative peak search with SPANZ, a much more sensitive and quicker second difference peak search.

**2. CONTRIBUTOR**

Savannah River Laboratory, Aiken, South Carolina.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

GELI2-SPAN2 does routine analytical calculations of 4096-channel gamma-ray spectra. It incorporates a second difference peak search to calculate nuclide abundances from gamma-ray spectra on magnetic tape without applying iterative fitting techniques.

**5. METHOD OF SOLUTION**

Nuclide abundances are determined by summing counts above a statistically justified cubic or linear equation background in a region of the spectrum defined for each peak by empirical equations relating energy and full width at half maximum to channel numbers. Backgrounds are approximated using either a linear or cubic equation, depending on statistical justification. Confidence limits are reported for all analysis results including "less than" estimates for non-detected nuclides. Peak search data are reviewed and peaks which may interfere are listed for each nuclide.

The peak search applies five tests in its evaluation of the second difference curve to locate significant peaks and accurately determines the peak energy from a linear channel-energy relation by fitting a Gaussian curve to the spectral data. Areas of sufficiently separated single peaks are calculated by summing counts above background, and an error analysis is provided. Five edit options control the amount of printed detail obtained from the peak search routine. These options vary from no printout at all to the extremely detailed output which includes a graph of the spectrum. Comment codes generated during the search cross reference overlapping peaks and identify all test failures.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for GELIZ-SPAN2.

**8. COMPUTER HARDWARE REQUIREMENTS**

GELI2/SPAN2 is operable on the IBM 360/370 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required.

**10. REFERENCE**

R. V. Slates, "GEL12 and SPAN2 FORTRAN Programs to Calculate Nuclide Abundances from Multichannel Gamma Ray Spectra," DP-1275 (October 1971).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.44MB) DOS diskette which contains the source code and sample problem input.

**12. DATE OF ABSTRACT**

March 1984.

**KEYWORDS:** DATA PROCESSING; SPECTRA