IAEA0833 TREEDE.

1. NAME OR DESIGNATION OF PROGRAM:  TREEDE.

3. DESCRIPTION OF PROBLEM OR FUNCTION

TREEDE is a Monte Carlo transport code based on the Track Rotation estimator, used, in general, to calculate fluxes and currents at a point. This code served as a test code in the development of the concept of the Track Rotation estimator, and therefore analogue Monte Carlo is used (i.e. no importance biasing).

4. METHOD OF SOLUTION

The basic idea is to follow the particle's track in the medium and then to rotate it such that it passes through the detector point. That is, rotational symmetry considerations (even in non-spherically symmetric configurations) are applied to every history, so that a very large fraction of the track histories can be rotated and made to pass through the point of interest; in this manner the 1/r**2 singularity in the uncollided flux estimator (next event estimator) is avoided.

TREEDE, being a test code, is used to estimate leakage or in-medium  fluxes at given points in a 3-dimensional finite box, where the source is an isotropic point source at the centre of the z = 0 surface. However, many of the constraints of geometry and source can be easily removed. The medium is assumed homogeneous with isotropic  scattering, and one energy group only is considered.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

One energy group, a  homogeneous medium, isotropic scattering.

6. TYPICAL RUNNING TIME

For a 10 m.f.p. problem to 5% standard deviation about 3 min on the CDC-6600.

The test case included in this package was executed by  NEA-DB on VAX-11/780 in 2 min. 7 sec. of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:  The track rotation estimator in Monte Carlo.

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES

- Y.S. Horowitz, A. Dubi, S. Mordechai,
  Nucl. Sci. Eng. 59, 427 (1976).

- TREEDE Users Guide.
- A. Dubi, Y.S. Horowitz and H. Rief ;
"Calculation of the Total flux at a Point by the Monte
Carlo Track Rotation Estimator"

11. MACHINE REQUIREMENTS

To execute the test case on VAX-11/780, 17,450 bytes of main storage are required.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

14. OTHER PROGRAMMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHOR

          A. Dubi
          University of California
          Los Alamos Scientific Laboratory
          P.O. Box 1663, Los Alamos
          New Mexico 87545
          USA.

File name	File description	Records
IAEA0833_01.003	TREEDE INFORMATION FILE	56
IAEA0833_01.004	TREEDE SOURCE	298
IAEA0833_01.005	TREEDE TEST CASE OUTPUT	7