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CCC-0233 CRYSTAL-BALL.

CRYSTAL-BALL, Neutron Spectra Calculation from Activation Experiment with Error Estimate

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1. NAME OR DESIGNATION OF PROGRAM:  CRYSTAL-BALL.
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2. COMPUTERS
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Program name Package id Status Status date
CRYSTAL-BALL CCC-0233/01 Tested 01-APR-1977

Machines used:

Package ID Orig. computer Test computer
CCC-0233/01 IBM 370 series IBM 370 series
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3. DESCRIPTION OF PROBLEM OR FUNCTION

CRYSTAL-BALL is a program for determining neutron spectra from activation measurements and their associated errors.

A subsidiary program, XSTAPE, converts activation cross sections from the SAND-II data library into pointwise cross sections in a format that can be read by the main program. An energy grid consistent with the SAND-II grid (2) is used, however the subroutine specifying the energy spacings can be easily changed.

CRYSTAL-BALL itself uses the cross section data, together with an initial guess of the neutron spectrum to calculate the integral and differential spectrum and the corresponding reaction rates and monitor responses. An option to plot spectrum data using CALCOMP plotter routines is included.
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4. METHOD OF SOLUTION

Measured activities are related to the neutron  flux and cross section by an integral equation of the first kind. CRYSTAL-BALL uses the method of F.W. Stallman (1) to solve a set of  these equations.

The method is based on a direct approximation of the Dirac delta operator by a linear combination of integral operators. It involves  minimizing an integral expression involving both the true spectrum and a user-supplied estimate, subject to a tolerance limit.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:
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6. TYPICAL RUNNING TIME:
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7. UNUSUAL FEATURES OF THE PROGRAM

Techniques solving these integral  equations by expanding the neutron spectrum in terms of some set of  functions frequently result in numerical oscillations and instabilities, and they tend to calculate spectrum shapes which are  characteristic of the expansion function. The CRYSTAL-BALL technique, using experimental data, has been found to be highly stable unless very low convergence criteria are requested.
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8. RELATED AND AUXILIARY PROGRAMS

The subsidiary program, XSTAPE, which generates an appropriate activation cross section data set, is a modification of the SAND-II CSTAPE program.
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9. STATUS
Package ID Status date Status
CCC-0233/01 01-APR-1977 Tested at NEADB
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10. REFERENCES

- F.W. Stallman:
  Numerical Solution of Integral Equations
  Numerische Mathematik vol. 15 pp. 297-305 (1970).
- W.N. McElroy, S. Bert, T. Crockett, R.G. Hawkins:
  SAND-II - A Computer Automated Iterative Method for Neutron Flux
  Determination by Foil Activation
  AFWL-TR-67-41 vol. 1-4.
CCC-0233/01, included references:
- F.B.K. Kam and F.W. Stallmann:
  CRYSTAL BALL - A Computer Program for Determining Neutron Spectra
  from Activation Measurements
  ORNL-TM-4601 (June 1974).
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11. MACHINE REQUIREMENTS:
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
CCC-0233/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The plotting option utilises the plot package INTRIGUE-II, and the CALCOMP plotter routines. Three subprograms of INTRIGUE-II, namely GRID, XTENS and TENS, have been modified slightly.
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15. NAME AND ESTABLISHMENT OF AUTHOR

   F.B.K. Kam
   Operations Division
   Oak Ridge National Laboratory
   Oak Ridge, Tennessee 37830, U.S.A.

   F.W. Stallman
   University of Tennessee
   Knoxville, Tennessee, U.S.A.
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16. MATERIAL AVAILABLE
CCC-0233/01
File name File description Records
CCC0233_01.001 CROSS SECTION LIBRARY 2599
CCC0233_01.002 XSTAPE SOURCE F4 EBCDIC 504
CCC0233_01.003 XSTAPE DD CARDS 2
CCC0233_01.004 CRYSTAL-BALL SOURCE F4 EBCDIC 816
CCC0233_01.005 CRYSTAL-BALL DD CARDS 2
CCC0233_01.006 CRYSTAL-BALL INPUT DATA 34
CCC0233_01.007 XSTAPE OUTPUT 5925
CCC0233_01.008 CRYSTAL-BALL OUTPUT 334
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17. CATEGORIES
  • O. Experimental Data Processing

Keywords: activation analysis, neutron spectra, reaction rates.