**RSIC COMPUTER CODE PSR-020**

**1. NAME AND TITLE**

LAPHANO: P_{O} Multigroup Photon Production Matrix and Source Vector Code for ENDF
Data.

This code replaces LAPH.

**AUXILIARY ROUTINES**

Data should be preprocessed with CHECKER and with VIXEN to eliminate errors in format syntax
and physical consistency.

**2. CONTRIBUTOR**

Los Alamos National Laboratory, Los Alamos, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; CDC 6600 or IBM 360.

**4. NATURE OF PROBLEM SOLVED**

LAPHANO retrieves photon production cross sections or multiplicities and corresponding neutron
interaction cross sections from the ENDF/B 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 CCC-42/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.

**5. METHOD OF SOLUTION**

LAPHANO first constructs photon production cross sections, pointwise in neutron and photon
energy, from the ENDF/B 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.

**6. RESTRICTIONS OR LIMITATIONS**

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.

**7. 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 18 seconds.

**8. COMPUTER HARDWARE REQUIREMENTS**

LAPHANO is operable on the CDC 6600 or the IBM 360 computers. The CDC 6600 requires
65 k_{10} words of memory. One magnetic tape is required--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.

**9. COMPUTER SOFTWARE REQUIREMENTS**

LAPHANO runs under the CDC SCOPE 3.1.2 System (locally modified) for the CDC 6600.

**10. REFERENCES**

**a. Included in documentation:**

D. J. Dudziak, R. E. Seamon, and D. V. Susco, "LAPHANO: A PO Multigroup Photon Production Matrix and Source Code for ENDF," LA-4750-MS (ENDF-156) (1971).

D. J. Dudziak, A. H. Marshall, and R. E. Seamon, "LAPH: A Multigroup Photon Production
Matrix and Source Vector Code for ENDF/B," LA-4337 (1969).

**b. Background information:**

H. C. Honeck, "Retrieval Subroutines for the ENDF/B System," BNL-13582 (ENDF-110) (1967). (Revised CHECKER code by Oak Ridge National Laboratory, 1970).

D. J. Dudziak and J. M. Romero, "VIXEN, A Physical Consistency Checking Code for Photon
Production Data in Revised ENDF Format," LA-4739 (1971).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents (10.a) and one (1.2MB) DOS diskette which contains the
source code and sample problem input and output.

**12. DATE OF ABSTRACT**

September 1972; updated November 1983.

**KEYWORD: ** GAMMA-RAY PRODUCTION CROSS SECTION PROCESSING