USCD1040 BAYESZ.

BAYESZ, S-Wave, P-Wave Resonance Level Spacing and Strength Functions

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHOR, MATERIAL, CATEGORIES

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1. NAME OR DESIGNATION OF PROGRAM: BAYESZ.

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2. COMPUTERS

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Program name	Package id	Status	Status date
BAYESZ	USCD1040/02	Tested	07-OCT-1982

Machines used:

Package ID	Orig. computer	Test computer
USCD1040/02	CRAY 1	CRAY 1

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3. DESCRIPTION OF PROBLEM OR FUNCTION

BAYESZ calculates average s- and p-wave level spacings, strength functions, and average radiation widths of a mixed sequence of s- and p-wave resonances whose parameters are supplied as input. The code is based on two physical  assumptions:

1) The neutron reduced width distribution for each open channel is  a chi-squared distribution with one degree of freedom, i.e.     Porter-Thomas.

2) The spacing distribution follows the Gaussian Orthogonal  Ensemble. This property is used, however, only to fix the s- to  p-wave level density ratio as proportional to (2J+1) with a spin     cut-off correction.

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4. METHOD OF SOLUTION

The method used is an extension of that described by Moore et al. in reference (1), and is based on the method of moments of a truncated Porter-Thomas distribution.

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Parameters for a maximum of 500 individual resonances can be specified. This restriction can be relaxed by increasing array dimensions.

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6. TYPICAL RUNNING TIME

About 2 seconds of CRAY-1 CP time are required for 10 iterations on a set of parameters for 273 resonances. A similar problem required 18 seconds on a CDC-7600 to perform 20 iterations.

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7. UNUSUAL FEATURES OF THE PROGRAM

The program requires no subjective judgement on the part of the user to interpret the results; all input initial guess values for average parameters are automatically adjusted during the iteration procedure.

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8. RELATED AND AUXILIARY PROGRAMS: BAYESZ is an extension of BAYESX.

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9. STATUS

Package ID	Status date	Status
USCD1040/02	07-OCT-1982	Tested at NEADB

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10. REFERENCES

(1) M.S. Moore et al.:
    Spin Determination of Resonance Structure in (U-235 + n)
    Below 25 keV.
    Phys. Rev. C18, 1328 (September, 1978).

USCD1040/02, included references:

- Program Description, BAYESZ
P-3/81-886 0372R (December 4, 1981).

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11. MACHINE REQUIREMENTS: 51200 words on a CRAY-1.

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12. PROGRAMMING LANGUAGE(S) USED

Package ID	Computer language
USCD1040/02	FORTRAN-IV

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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED: COS.

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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

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15. NAME AND ESTABLISHMENT OF AUTHOR

          Dr. M.S. Moore
          Los Alamos National Laboratory
          Los Alamos
          New Mexico 87545
          USA

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16. MATERIAL AVAILABLE

USCD1040/02

File name	File description	Records
USCD1040_02.003	BAYESZ INFORMATION FILE	83
USCD1040_02.004	BAYESZ SOURCE (FORTRAN-4)	443
USCD1040_02.005	BAYESZ JCL FOR COMPILATION & LINKEDIT	10
USCD1040_02.006	BAYESZ JCL TO RUN TEST CASES	12
USCD1040_02.007	BAYESZ INPUT DATA FOR TEST CASE 1	262
USCD1040_02.008	BAYESZ OUTPUT OF TEST CASE 1	695
USCD1040_02.009	BAYESZ INPUT DATA FOR TEST CASE 2	260
USCD1040_02.010	BAYESZ OUTPUT OF TEST CASE 2	1121

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17. CATEGORIES

A. Cross Section and Resonance Integral Calculations

Keywords: nuclear models, porter-thomas distribution, resolved region, resonance.