1. NAME AND TITLE

FANAC: A Shape Analysis Code Package for Resonance Parameter Extraction from Neutron Capture Data for Light- and Medium-Weight Nuclei.

2. CONTRIBUTOR

Kernforschungszentrum Karlsruhe, Institut f. Neutronenphysik und Reactortechnik, Karlsruhe, Federal Republic of Germany, through the OECD NEA Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 370/3033.

4. NATURE OF PROBLEM SOLVED

FANAC extracts resonance parameters from high-resolution capture yields measured with the time-of-flight method and calculates for structural materials neutron capture cross sections corrected for experimental effects such as self-shielding, multiple scattering, instrumental resolution and detector efficiency, using least-squares shape analysis.

5. METHOD OF SOLUTION

The Reich-Moore multi-level formalism with Doppler broadening is used for s-wave levels and a single-level description with Doppler broadening is used for p-, d- ... wave levels. Calculated capture yields are resolution broadened. Multiple-collision events are simulated by Monte Carlo techniques.

6. RESTRICTIONS OR LIMITATIONS

The plot package must be replaced.

FANAC was written for light- to medium-weight or near-magic target nuclei whose cross sections are characterized on the one hand by broad s-wave levels with negligible Doppler broadening but pronounced multi-level interference, and, on the other hand, by narrow p-, d- ... wave resonances with negligible multi-level interference but pronounced Doppler broadening.

It permits determination of up to 20 cross section parameters by simultaneously fitting calculated capture yield curves to experimental data from up to 5 time-of-flight measurements for samples containing up to 10 isotopes. The sample may differ with respect to thickness, flight path, or other experimental characteristics.

7. TYPICAL RUNNING TIME

A realistic fitting problem which illustrates most features of FANAC (3 iterations, 12 adjusted parameters, a maximum of 30 Monte Carlo multiple-collision event simulations per grid point) used 3 min 9 sec of CPU time on an IBM 370/168 computer.

8. COMPUTER HARDWARE REQUIREMENTS

FANAC is operable on the IBM 370/3033 computers. It requires 476 K of memory on an IBM 370/168.

9. COMPUTER SOFTWARE REQUIREMENTS

Fortran H and Assembler compilers are required. FANAC must be modified to use a local plotting package.

10. REFERENCE

F. H. Frohner, FANAC--A Shape Analysis Program for Resonance Parameter Extraction from Neutron Capture Data for Light and Medium-Weight Nuclei, KFK 2145 (July 1978).

Notes to ``FANAC Users,'' by F. H. Frohner.

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and a reel of magnetic tape which contains the source code, random number generator routine, and sample problem input written in EBCDIC card images, plus output from the sample problem written in list format; total records 6044.

12. DATE OF ABSTRACT

June 1982.