RSIC COMPUTER CODE PSR-010

1. NAME AND TITLE

EVAP: Calculation of Particle Evaporation from Excited Compound Nuclei.

An early version of EVAP is also packaged with CCC-7/NTC and with CCC-47/LEP. This version, EVAP-4, represents the latest modification and extension of the original program. It is identical to EVAP-3 in all respects except that an "improved-termination" procedure has been added.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360.

A random number generator is in machine language.

4. NATURE OF PROBLEM SOLVED

EVAP calculates the types, multiplicities, and energy distributions of particles evaporated from excited compound nuclei. The version in this package calculates the excitation energy of the compound nucleus from the data furnished for the target nucleus and incident particle; other versions are packaged with Bertini's intranuclear cascade code (CCC-47/LEP) which accept instead the output from a cascade calculation to determine the initial conditions for the evaporation. Other than the determination of these initial conditions, both versions are identical.

5. METHOD OF SOLUTION

The evaporation process is started with the collision of an incident particle with a target nucleus. An excited compound nucleus is formed from which particles are emitted until evaporation is no longer energetically possible.

The calculation is based on a theory originally proposed by Weisskopf [Phys. Rev. 52, (1937) 295], and on a Monte Carlo code written by Dostrovsky [Phys. Rev. 116 (1959) 683; Phys. Rev. 118 (1960) 781, 791].

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

No study has been made by RSIC of typical running times for EVAP.

8. COMPUTER HARDWARE REQUIREMENTS

EVAP was designed for and is operable on the IBM 360 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

a. Included in the documentation:

P. A. Seeger, "Changes to Subroutine DRES," Informal Note (June 1974).

M. P. Guthrie, "Another Modification of a Code to Calculate Particle Evaporation from Excited Compound Nuclei," ORNL-TM-3119 (September 1970).

M. P. Guthrie, "EVAP-2 and EVAP-3: Modifications of a Code to Calculate Particle Evaporation from Excited Compound Nuclei," ORNL-4379 (March 1969).

Corrections in the DRES Subroutine of the EVAP Codes (April 1971).

b. Background information:

L. Dresner, "EVAP - A Fortran Program for Calculating the Evaporation of Various Particles from Excited Nuclei," ORNL-TM-196 (1961).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents (10.a) and one 3.5-in. DOS diskette which contains the source code and sample problem input and output.

12. DATE OF ABSTRACT

September 1972, updated January 1992.