**1. NAME AND TITLE**

DTF69: One-Dimensional Multigroup Photon Transport Discrete Ordinates Code System.

**AUXILIARY ROUTINES**

DTFALL: Input Data Generator.

GAMLEG69: Cross Section Generator.

DTF69 is a modified version of DTF-IV (CCC-42), written at LANL for the solution of neutron transport problems. GAMLEG69 is an extensive modification of the LANL-written GAMLEG (also packaged in CCC-42).

**2. CONTRIBUTOR**

Sandia National Laboratories, Albuquerque, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; CDC 6600.

**4. NATURE OF PROBLEM SOLVED**

DTF69 applies the method of discrete ordinates to the gamma-ray transport problem. The major addition required to existing discrete ordinates methods used in neutron transport is a device for processing gamma-ray cross section data. This is provided in GAMLEG69. Provisions are included for external photon sources and the capability to treat secondary radiation such as fluorescence and positron annihilation photons.

**5. METHOD OF SOLUTION**

The main body transport code system, DTF69, is an evolutionary step beyond DTF-IV which is well documented. Apart from its ability to deal with gamma rays, DTF69 has the following distinguishing features: 1) Time dependence is handled by Laplace transform with a newly developed inversion technique; 2) A convergence acceleration scheme using Chebychev polynomials is included; 3) A buckling term to correct for transverse leakage is incorporated; 4) Provision is made for fluorescent and annihilation radiation. (These are particle production processes and ordinarily would introduce an essential complication.); and 5) The source options available are a volume distributed isotropic source, a point isotropic source in the center of a spherically symmetric system, and an angle dependent current falling upon the right boundary.

The gamma ray processing routine GAMLEG69 integrates basic gamma-ray data to produce for each energy group and material the energy deposition, total, absorption (photo electric plus pair production), secondary production cross sections (fluorescence and pair production), and group transfer cross sections representing the Klein-Nishina scattering process.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for DTF69.

**8. COMPUTER HARDWARE REQUIREMENTS**

The codes were designed for the CDC 6600. Standard I-O equipment is used.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The codes will compile and execute on the standard CDC FORTRAN IV Monitor System.

**10. REFERENCES**

Informal Note, "Changes in the December 1969 Version of DTF69."

J. H. Renken and K. G. Adams, "An Improved Capability for Solution of Photon Transport Problems by the Method of Discrete Ordinates," SC-RR-69-739 (December 1969).

J. H. Renken and K. G. Adams, "Application of the Method of Discrete Ordinates to Photon Transport Calculations," SC-RR-67-419 (June 1967).

K. G. Adams, "DTFALL: A Program to Run Photon Transport Problems by the Method of Discrete Ordinates," SC-RR-68-712 (October 1968).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

August 1971; revised December 1984 and September 1991.

**KEYWORDS: ** ONE-DIMENSION; DISCRETE ORDINATES; MULTIGROUP; X-RAY