**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.

**KEYWORD: ** NUCLEAR MODELS