PSR-0020 LAPHAN0.

1. NAME OR DESIGNATION OF PROGRAM:  LAPHAN0.

3. NATURE OF PHYSICAL PROBLEM SOLVED

LAPHAN0 retrieves photon production cross sections or multiplicities and corresponding neutron interaction cross sections from the ENDF data file, applies  suitable weighting functions over G specified photon groups and N specified neutron broad groups, and constructs A G X N photon production matrix (microscopic and/or macroscopic).
As an option, it operates on this matrix with flux vectors from a neutronics code, as well as with scalar multipliers such as atom number densities and effective photon group energies, to directly provide spatially dependent photon source vectors (number or energy) for transport calculations. Multiple zones can be accommodated, with separate cross-section weighting functions for each zone. Input is in the DTF-IV format and source vector output is also in this format, allowing direct coupling to DTF-IV. Complete freedom is allowed to pick those materials and reaction types for which photon  production matrices are desired.

4. METHOD OF SOLUTION

LAPHAN0 first constructs photon production cross sections, pointwise in neutron and photon energy, from the ENDF data. These cross sections are then integrated over photon energy groups with either constant or direct energy weighting. After integrating over neutron energy in all neutron fine groups, weighting in neutron broad groups is by input fine-group weighting functions, usually the scalar fluxes from a fine-group neutronics calculation. Macroscopic photon production matrices and photon energy production matrices are then computed by scalar multiplication. Photon source vectors are computed by operating on these matrices with spatially dependent neutron flux vectors.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The microscopic pointwise data must be in ENDF format. The code is presently restricted to 99 fine or broad groups, 49 photon groups, and 50 mixture specifications.

6. TYPICAL RUNNING TIME

The central processor time on the CDC 6600 for a sample problem to produce a microscopic matrix for one material (oxygen) using 18 photon groups and 22 neutron fine and broad groups is approximately one minute. The same problem on the CDC 7600 executes in approximately 18 seconds.

7. UNUSUAL FEATURES: UNUSUAL FEATURES OF THE PROGRAM

8. RELATED AND AUXILIARY PROGRAMS

Auxiliary routines data should be preprocessed with the CHECKER code2 and the VIXEN code3 to eliminate errors in format syntax and physical consistency.

10. REFERENCES

- Donald J. Dudziak, Alan H. Marshall, and Robert E. Seamon:
  "LAPH - A Multigroup Photon Production Matrix and Source Vector
  Code for ENDF/B,"
  LA-4337, Los Alamos Scientific Laboratory (1969).
- Henry C. Honeck:
  "Retrieval Subroutines for the ENDF/B System,"
  BNL-13582 (ENDF-110), Brookhaven National Laboratory (1967).
  (Revised CHECKER Code by Oak Ridge National Laboratory, 1970.)
- Donald J. Dudziak and Johnny M. Romero:
"VIXEN, A Physical Consistency Checking Code for Photon Production    Data in Revised ENDF Format,"
  LA-4739, Los Alamos Scientific Laboratory (1971).
- Donald J. Dudziak, Robert E. Seamon, and Dante V. Susco:
  "LAPHAN0 - A P0 Multigroup Photon Production Matrix and Source
  Code for ENDF,"
  LA-4750-MS (ENDF-156), Los Alamos Scientific Laboratory (1971).

11. MACHINE REQUIREMENTS

The code runs under the CDC SCOPE 3.1.2 system (locally modified) for the CDC 6600, and under the LASL CROS system for the CDC 7600.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

A. CDC 6600 and 7600: 65 k   words of memory;
B. One magnetic tape - the ENDF data tape is designated as
   tape 20. All other tapes are virtual tapes on disk,
   extended core storage, or other peripheral storage device.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

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

File name	File description	Records
PSR0020_01.001	SOURCE PROG.+OVERLAY CARDS+INPUT DATA	2351
PSR0020_01.002	PRINTED OUTPUT	153
PSR0020_01.003	LIBRARY DATA	5154