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NEA-1652 GEM.

GEM, Monte-Carlo Code for Simulating a Decaying Process of an Excited Nucleus

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1. NAME OR DESIGNATION OF PROGRAM:  GEM.
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2. COMPUTERS
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Program name Package id Status Status date
GEM NEA-1652/01 Tested 20-JUN-2003

Machines used:

Package ID Orig. computer Test computer
NEA-1652/01 Linux-based PC Linux-based PC,PC Pentium 2GHz
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3. DESCRIPTION OF PROGRAM OR FUNCTION

GEM is a Monte Carlo code which simulates a decaying process of an excited nucleus. GEM calculates the types, numbers, and kinetic energies of particles emitted from an excited nucleus. Input file which includes the mass, charge, excitation energy, kinetic energy and the direction of motion of the excited nuclei produced after cascade or preequilibrium stage, is needed for execution.  In order to estimate cross sections of particle productions, output file needs to be edited.
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4. METHODS

The code is based on the generalised evaporation model [1] and the Atchison fission model [F. Atchison, Jul-conf-34 KFA-Julich, Germany (1980)].  Type and kinetic energy of an emitted particle are randomly selected according to the probability distribution.  A simulation continues as far as evaporation is energetically possible.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  None.
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6. TYPICAL RUNNING TIME:  Depends on the mass and excitation energy of a target.
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7. UNUSUAL FEATURES:  None.
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8. RELATED OR AUXILIARY PROGRAMS:  None.
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9. STATUS
Package ID Status date Status
NEA-1652/01 20-JUN-2003 Tested at NEADB
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10. REFERENCES

[1] S. Furihata, "Statistical analysis of light fragment production from medium energy proton-induced reactions", Nucl. Inst. Meth. in Phys. Res. B 171 (2000)251--258.
[2] S. Furihata, Proceedings of Monte Carlo 2000, Lisbon (2000) to be published by Springer Verlag.
[3] S. Furihata and H. Nakashima, "Analysis of activation yields by INC/GEM", JAERI-Conf 2001-006 (2001) 236.
NEA-1652/01, included references:
- K. Niita, S-i. Meigo, Y. Ikeda, S. Furihata and F. Maekawa:
The GEM Code - A Simulation program for the Evaporation and the Fission
Process of an Excited Nucleus
Jaeri-Data/Code 2001-015 (March 2001)
- S. Furihata:
The GEM code users manual
The Generalized Evaporation Model and the fission model for a Monte Carlo
simulation (September 5, 2001)
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11. HARDWARE REQUIREMENTS
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-1652/01 FORTRAN-77
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13. SOFTWARE REQUIREMENTS
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The excited energy of a residual nucleus produced after evaporation process is not written in an output file.  To write this value in the output file, the following lines in 'main.f' should be modified. Add 'e1' in the write statements on line 165 and 187 (just before format statement 602 and 604), then the excitation energy of a residual nucleus can be obtained.

     &         write(70,602)izr,iar,erec,bet0,nocas,e1 <--
602         format(2i4,1pe13.5,3e13.5,i7,3h B )

     &        write(70,604)izr,iar,erec,bet0,nocas,e1 <--
604     format(2i4,1pe13.5,3e13.5,i7,3h D )
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15. NAME AND ESTABLISHMENT OF AUTHORS

     Shiori Furihata
     Mitsubishi Research Institute INC.,
     2-3-6 Otemachi, Chiyoda-ku, Tokyo, 100-8141, Japan.
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16. MATERIAL AVAILABLE
NEA-1652/01
\for\*.f source files
\data\level.tbl Data library
\data\mass.tbl Data library
\data\shell.tbl Data library
sample\in sample input file
sample\nucl.in sample input file
sample\sample.gem.out output file
GEM-abstract.txt Abstract of GEM
NEA_1652_1_V1.PDF documentation
NEA_1652_1_V2.PDF documentation
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17. CATEGORIES
  • A. Cross Section and Resonance Integral Calculations

Keywords: Monte Carlo method, cascade, decay, nuclear models, preequilibrium, simulation.