PSR-0302 COMNUC3B.

1. NAME OR DESIGNATION OF PROGRAM:  COMMUC3B (A Compound Nucleus
Analysis Program).

3. DESCRIPTION OF PROGRAM OR FUNCTION

COMMUC3B was written to analyze compound nucleus interactions. Only reactions for which the incident particle is a neutron are considered.

4. METHOD OF SOLUTION

When the outgoing particle is a neutron, two types of reactions are considered. The first occurs when the target  is left in a well-defined excited state. The other occurs when the target nucleus is left in one of many excited levels. These reaction types are known as individual channel inelastic and continuum inelastic respectively. The individual channel model is described by the known levels of the target nucleus. The continuum inelastic neutron calculation requires a model for the nuclear level density and a set of spin, parity, and energy dependent transmission coefficients. These two functions are convoluted for energies greater than the last identified target level. As with emerging neutrons, the fission component is separated into two parts: a part  due to discrete channels and a part due to fission through a continuum of states.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The maximum number of levels for the individual channel model which can be specified is twenty.

6. TYPICAL RUNNING TIME

The code was tested on a Cray XMP under the CTSS operating system. The sample problem took 9 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES:

- C.L. Dunford:
  Compound Nucleus Reaction Analyis Programs COMNUC and CASCADE
  T1-707-130-013 Atomics International (Jan. 19, 1971).
- Input Description for FTNCOMNUC
  Los Alamos Informal Notes (October 1980).
- Card Input for COMNUC8D
  Los Alamos Informal Notes (October 1980).

11. MACHINE REQUIREMENTS:  The code will run on the Cray computers.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

The code is written in FORTRAN IV. On the Cray, the compiler used was CFT under  the CTSS operating system.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

Los Alamos National Laboratory
Los Alamos
New Mexico, U.S.A.

Atomics International
North American Rockwell

File name	File description	Records
PSR0302_01.001	Information file	54
PSR0302_01.002	JCL and control information	4
PSR0302_01.003	COMNUC3B FORTRAN 77 source program	6889
PSR0302_01.004	TAPE 10 library input	674
PSR0302_01.005	Sample problem input	110
PSR0302_01.006	Sample problem output (tape 4)	1680
PSR0302_01.007	Sample output summary (tape 2)	36
PSR0302_01.008	Logfile from sample problem	66