RSICC CODE PACKAGE PSR-498

1. NAME AND TITLE

STAPREF: Code System to Calculate Nuclear Reactions Cross Sections by the Evaporation Model.

2. CONTRIBUTORS

Radiation Physics and Chemistry Problems Institute, Minsk-Sosny, Belarus and the Institut fur Radiumforschung und Kerphysik der Osterreichischen, Akademie der Wissenchaften, Vienna, Austria, through the OECD NEA Data Bank, Issy-les-Moulineaux, France.

3. CODING LANGUAGE AND COMPUTER

STAPRE: Fortran IV; CDC 7600, VAX 6000

STAPREF: Fortran 90; IBM PC (P00498/PC586/00).

4. NATURE OF PROBLEM SOLVED

Both STAPRE and STAPREF are included in this package. STAPRE calculates energy-averaged cross sections for nuclear reactions with emission of particles and gamma rays and fission. The models employed are the evaporation model with inclusion of pre-equilibrium decay and a gamma-ray cascade model. Angular momentum and parity conservation are accounted for.

Major improvement in the 1976 STAPRE program relates to level density approach, implemented in subroutine ZSTDE. Generalized superfluid model is incorporated, boltzman-gas modeling of intrinsic state density and semi-empirical modeling of a few-quasiparticle effects in total level density at equilibrium and saddle deformations of actinide nuclei.

In addition to the activation cross sections, particle and gamma-ray production spectra are calculated. Isomeric state populations and production cross sections for gamma rays from low excited levels are obtained, too. For fission a single or a double humped barrier may be chosen.

5. METHOD OF SOLUTION

Integrations in connection with the evaporation formulas are approximated by summation over energy bins. For the gamma-ray cascades a recursion formula is employed. The width-fluctuation correction factor is calculated by use of Simpson's rule. Since transmission coefficients are needed as input data for the code STAPRE, it is advantageous to have an optical model code at one's disposal to generate these quantities.

6. RESTRICTIONS OR LIMITATIONS

Only particle induced reactions can be treated. The number of sequentially emitted particles is limited to 6, while the number of gamma rays is arbitrary. Angular distributions of emitted particles and photons are not calculated. For STAPREF, the number of sequentially emitted particles could be easily extended up to, say, 30 by increasing the array dimensions to cover incident particle energy range up to 150 MeV.

7. TYPICAL RUNNING TIME

The STAPREF calculation of cross sections at 77 energy points in the neutron energy range from 1 MeV up to 20 MeV for actinide nucleus requires 50 sec. on an IBM PC Pentium 200Pro.

8. COMPUTER HARDWARE REQUIREMENTS

STAPRE ran on either a VAX running VMS or a CDC running NOS/BE. STAPREF runs on IBM PC and compatibles and requires about 1.4 Mbytes of storage.

9. COMPUTER SOFTWARE REQUIREMENTS

STAPRE is written in Fortran IV. The STAPREF code is written in Fortran 90. Executables produced by the Lahey Fortran 95 version 5.5 compiler are provided in the package.

10. REFERENCES

a) Included in documentation:

V. Maslov, "Manual on STAPRE Code (Definition of Input and Output Files for Code STAPREF)."

M. Uhl and B. Strohmaier, "STAPRE - A Computer Code for Particle Induced Activation Cross Sections and Related Quantities," IRK 76/01 (1976).

b) Background information:

V. M. Maslov, "Fission Level Density and Barrier Parameters for Actinide Neutron-Induced Cross Section Calculations," INDC(BLR)-13 (1998).

V. M. Maslov, Y. V. Porodzinskij, A. Hasegawa, et al, "Neutron Data Evaluation of 238-U," JAERI-Research 98-040 (1998).

11. CONTENTS OF CODE PACKAGE

Included in the package are the reference documents in (10.a) and one DS/HD diskette with a self-extracting compressed DOS file that includes a STAPREF PC executable, STAPREF and STAPRE source code, documentation and sample problems.

12. DATE OF ABSTRACT

November 2000.

KEYWORDS: GAMMA-RAY CROSS SECTION PROCESSING; MICROCOMPUTER; NUCLEAR MODELS; PARAMETRIC MODELS