1. NAME AND TITLE

THRUSH: Calculates Thermal Neutron Scattering Kernel.

2. CONTRIBUTOR

Century Research Center Corporation, Tokyo, Japan.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; Cray-XMP.

4. NATURE OF PROBLEM SOLVED

THRUSH computes the thermal neutron scattering kernel by the phonon expansion method for both coherent and incoherent scattering processes. The calculation of the coherent part is suitable only for calculating the scattering kernel for heavy water.

5. METHOD OF SOLUTION

To evaluate the scattering kernel from the double differential scattering cross section, it is necessary to perform angular integration over scattering angle. This integration is performed analytically in the THRUSH code. A "generalized" spectral density is used from which the coherent as well as the incoherent scattering effect can be calculated. The Sjoelander expansion or short time expansion is used to overcome the poor convergence at high incident neutron energy or high temperature. The inter- molecular elastic scattering from the atom pair of different molecules of heavy water is evaluated using Butler's model.

6. RESTRICTIONS OR LIMITATIONS

Maximum number of frequency mesh points for spectral density is 400 (IMAX). Maximum number of convolution integrals for the n-th phonon term is 8000/IMAX. The maximum number of energy meshes for the scattering kernel is 101.

7. TYPICAL RUNNING TIME

No information on execution times is available.

8. COMPUTER HARDWARE REQUIREMENTS

THRUSH runs on Cray computers.

9. COMPUTER SOFTWARE REQUIREMENTS

The code runs under COS using the CFT 1.11 compiler.

10. REFERENCE

H. Kadotani, "THRUSH: A Code for Calculating Thermal Neutron Scattering Kernel," JAERI-M 8927 (June 1980).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette that contains the source file, sample input and output.

12. DATE OF ABSTRACT

November 1989.