Computer Programs
NESC0263 GASKET-2.
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NESC0263 GASKET-2.

GASKET-2, Thermal Neutron Scattering Law for Moderators, Harmonic Vibrations and Gaseous

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1. NAME OR DESIGNATION OF PROGRAM:  GASKET-2
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2. COMPUTERS
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Program name Package id Status Status date
GASKET-2 NESC0263/01 Tested 01-DEC-1973

Machines used:

Package ID Orig. computer Test computer
NESC0263/01 CDC 6600 CDC 6600
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3. DESCRIPTION OF PROBLEM OR FUNCTION

GASKET calculates the thermal neutron scattering law, s(alpha,beta), for a large class of moderators. Provision has been made in GASKET for the following dynamical modes of the scatterer -
(1) free translation (gas),
(2) diffusive or Brownian motion,
(3) harmonic isotropic vibrations with continuous frequency spectrum,
(4) harmonic anistropic vibrations with continuous frequency spectrum (as applied for instance to graphite),
(5) harmonic isotropic vibrations with discrete frequency spectrum.
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4. METHOD OF SOLUTION

Neutron scattering kernels are obtained from the scattering law using the relation
  sigma(e0 to e,theta) = (sigmab/4pi)*sqrt(e/e0)*exp(-beta/2)*
where e0 and e are, respectively, initial and final neutron energies, theta is the cosine of the neutron scattering angle in the laboratory, and alpha and beta respectively, dimensionless momentum and energy transfers. GASKET calculates s at points of a 2-dimensional alpha,beta mesh. Numerical methods are used to evaluate Fourier transforms of s. For very large values of alpha and beta an option is included to use Wick's short collision approximation for s.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of -
   100 points in distributed frequency spectrum
   100 points in anisotropic part of the frequency spectrum
     2 discrete oscillators if w sub 1 does not equal zero, otherwise 20
    20 phonon terms calculated for each delta line
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6. TYPICAL RUNNING TIME

10 minutes are required  on the UNIVAC1108; 8 on the CDC6600.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS

An auxiliary code, FLANGE  (NESC Abstract 247), is used to generate cross section information from the scattering law.
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9. STATUS
Package ID Status date Status
NESC0263/01 01-DEC-1973 Tested at NEADB
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10. REFERENCES

- J. U.  Koppel, J.  R. Triplett,  and Y.  D. Naliboff,
GASKET, A  Unified Code  for Thermal  Neutron Scattering,  GA-7417
Revised, March 10, 1967.
- GASKET Update Note, GGA Note.
- Integral  Neutron Thermalization,  Annual Summary Report, GA-8280, pp. 146-152, September 30, 1967.
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11. MACHINE REQUIREMENTS

32K machine with about 26K available for the program and one scratch unit (drum, disk, or tape).
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0263/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   EXEC2.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHORS

   Program       J. U. Koppel, J. R. Triplett, and Y. D. Naliboff
   Abstract      D. H. Houston
                 General Atomic Company
                 P. O. Box 81608
                 San Diego, California  92138
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16. MATERIAL AVAILABLE
NESC0263/01
File name File description Records
NESC0263_01.001 SOURCE PROGRAM (FORTRAN) 1460
NESC0263_01.002 SAMPLE PROBLEM 64
NESC0263_01.003 OUTPUT LIST OF SAMPLE PROBLEM 1381
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17. CATEGORIES
  • A. Cross Section and Resonance Integral Calculations

Keywords: incoherent scattering, moderators, scattering law.