1. NAME AND TITLE

ESTIMA: A Code System for Calculating Average Parameters from Sets of Resolved Resonance Parameters.

2. CONTRIBUTOR

OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette, France.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 3033.

4. NATURE OF PROBLEM SOLVED

ESTIMA calculates level spacing and neutron strength function of a mixed sequence of s- and p-wave resonances given a set of neutron widths as input parameters. Three algorithms are used, two of which calculate s-wave average parameters and assume that the reduced widths obey a Porter-Thomas distribution truncated by a minimum detection threshold. The third performs a maximum likelihood fit to a truncated chi-squared distribution of any specified number of degrees of freedom, i.e., it can be used for calculating s-wave or p-wave average parameters. Resonances of undeclared angular orbital momentum are divided into groups of probable s-wave and probable p-wave by a simple application of Bayes' Theorem.

5. METHOD OF SOLUTION

Three algorithms are used: 1) GAMN method, based on simple moments properties of a Porter-Thomas distribution; 2) Missing Level Estimator, a simplified version of the algorithm used by the program BAYESZ; 3) ESTIMA, a maximum likelihood fit.

6. RESTRICTIONS OR LIMITATIONS

A maximum of 400 resonances is allowed. However, this restriction can be relaxed by increasing array dimensions.

ESTIMA requires a certain amount of user judgement to select the best average parameters from the set of calculated estimates.

7. TYPICAL RUNNING TIME

12 seconds of IBM 3033-11 CP time were required for three analyses, using each of the above three methods, on 275 resonances.

8. COMPUTER HARDWARE REQUIREMENTS

ESTIMA is operable on the IBM 3033 computer. It used 190 Kbytes on an IBM 3033-11 computer, excluding graphics routines.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required. ESTIMA uses a standard Operating System.

10. REFERENCE

E. Fort and J. P. Doat, "ESTIMA, A Code to Calculate Average Parameters from Sets of Resolved Resonance Parameters," NEANDC-162-U (Draft).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document plus one (1.2MB) DOS diskette which contains the source code and sample problem input and output.

12. DATE OF ABSTRACT

December 1983.