1. NAME AND TITLE
ESTIMA: A Code System for Calculating Average Parameters from Sets of Resolved
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.
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
KEYWORD: NUCLEAR MODELS