1. NAME AND TITLE

CERPI-CEREL: Code Systems for Automatic Analysis of Gamma-Ray Spectra Obtained with Ge(Li) Detectors.

2. CONTRIBUTORS

Institute of Physics, University of Rome, Rome, Italy.

Comitato Nazionale per l'Energia Nucleare, Centro di Studi Nucleari della Casaccia, Roma, Italia.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370.

4. NATURE OF PROBLEM SOLVED

CERPI and CEREL are automatic analyzers of gamma-ray spectra obtained with Ge(Li) detectors. CERPI analyzes experimental gamma-ray spectra in order to find the photopeak positions and areas. CEREL looks for those elements or nuclides which are potential emitters of the gamma-lines. It is possible to search by elements or nuclides, depending on the input parameter.

CERPI-CEREL contains features such as determination of peak energies and intensities, nuclide identification, and mass computation.

5. METHOD OF SOLUTION

CERPI detects the significant peaks in the spectrum by observing the behavior of the second derivative function after random variations in counts per channel have been minimized by the application of a smoothing filter function. Once the peaks have been identified, CERPI determines their mass centers, areas and corresponding errors with a least-squares fit. Each significant peak is fitted with a Gaussian function superimposed on a linear or quadratic background. The determination of the minimum of the X² function is accomplished by a variant of the gradient method.

CEREL does automatic isotope identification on the basis of gamma-ray energy comparison. It contains features such as determination of peak energies and intensities, nuclide identification, and mass computation. The energy calibration curve is determined starting from some known energy lines and by means of a fitting procedure with orthogonal polynomials using the F test for the automatic determination of the polynomial order. The single and double escape peaks are used for a more careful determination of the photopeak intensities and then removed from the observed spectrum. Pagden's isotope catalog is used for both nuclide identification and mass calculation.

6. RESTRICTIONS OR LIMITATIONS

The high precision and sensitivity of CERPI-CEREL make it very suitable to very complex spectrum analyses where many peaks overlap each other. This high sensitivity may imply the introduction of some spurious peaks. The higher the number of peaks identified, especially the number of spurious ones, the higher is the probability of introducing fictitious elements and the more complicated is the resolution of the mass matrix.

Particular care must also be taken in the choice of the input parameters because the fitting procedure is affected by this choice.

7. TYPICAL RUNNING TIME

The running times of CERPI-CEREL depend strongly on the complexity of the spectrum and the number of channels in a typical peak. On an IBM 360/75 system, the analysis of a 4096-channel spectrum requires approximately 4 min of CPU processor time if about 250 peaks are printed on the final table.

8. COMPUTER HARDWARE REQUIREMENTS

CERPI-CEREL is operable on the IBM 360/370 computers.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

M. Giannini, P. R. Oliva, and C. Ramorino, "CERPI and CEREL, Two Computer Codes for the Automatic Identification and Determination of Gamma Emitters in Thermal Neutron Activated Samples," RT/FI(78)5 (May 1978).

M. Giannini, P. R. Oliva, and M. C. Ramorino, "Automatic Element Analysis in Thermal Neutron Activated Samples," RT/FI(78)15 (October 1978).

M. Giannini, P. R. Oliva, and M. C. Ramorino, "Automatic Peak Identification in the Analysis of Gamma-Ray Spectra Obtained with Ge(Li) Detectors," RT/FI(72)14 (April 1972).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source code and sample problem input and output, the isotope catalogue and the array listings.

12. DATE OF ABSTRACT

March 1984.