**1. NAME AND TITLE**

POLLA: A Fortran Program to convert R-MATRIX-Type Multilevel Resonance Parameters
for Fissile Nuclei into Equivalent KAPUR-PEIERLS-Type Parameters.

**2. CONTRIBUTOR**

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; IBM 3033.

**4. NATURE OF PROBLEM SOLVED**

POLLA converts a set of R-matrix resonance parameters for fissile nuclei into an equivalent set
of Kapur-Pierls parameters. The program utilizes the multilevel formalism developed by Reich and
Moore and avoids the diagonalization of the level matrix, hence it is particularly useful where many
levels and few fission channels are involved.

**5. METHOD OF SOLUTION**

The program is designed to convert R-matrix parameters into equivalent Kapur-Peierls parameters.
The program obtains the Kapur-Peierls parameters by the direct partial fraction expansion of the Reich
and Moore expression of the collision matrix. This direct approach appears simpler and faster when
the number of fission channels is known and small. (The program is coded for a maximum of four
fission channels.) The method, like the Reich and Moore formalism, is particularly useful when a large
number of levels must be considered because it does not require the diagonalization of a large level
matrix.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

To compile and execute the sample problem using the OS/VS2 operating system on the IBM 3033
computer required 22 seconds.

**8. COMPUTER HARDWARE REQUIREMENTS**

Input/Output units are required. The storage requirement is 366 K and 200 K for execution of the
sample problems.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCE**

G. de Saussure, R. B. Perez, "POLLA, A Fortran Program to Convert R-MATRIX-TYPE,"
ORNL-TM-2599 (June 1969).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

October 1984.

**KEYWORDS: ** NUCLEAR MODELS