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PSR-0092 FORIST.

FORIST, Ne-213 Scintillation Detector Neutron Spectra Unfolding

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1. NAME OR DESIGNATION OF PROGRAM:  FORIST. Neutron spectrum unfolding code (FERDOR with optimized resolution using an iterative smoothing  technique).
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2. COMPUTERS
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Program name Package id Status Status date
FORIST PSR-0092/01 Tested 01-FEB-1978

Machines used:

Package ID Orig. computer Test computer
PSR-0092/01 IBM 370 series IBM 370 series
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3. NATURE OF PHYSICAL PROBLEM SOLVED

FORIST solves the matrix unfolding problem for neutron spectrum measurements using NE-213 proton-recoil spectrometry.
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4. METHOD OF SOLUTION

A constrained least-squares unfolding procedure  is used. The response function used in unfolding includes the resolution of the spectrometer, so the unfolded spectrum has large errors initially. The unfolded spectrum must be smoothed to reduce these errors. The smoothing functions are determined iteratively to  optimize energy resolution.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The code is currently dimensioned for a 113 by 77 response matrix. The code is written for measurements consisting of two different gain runs. The iterative procedure used in smoothing is applicable for unfolding neutron spectra. A slight change in the smoothing procedure may be necessary to apply this iterative procedure to unfolding gamma-ray spectra.
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6. TYPICAL RUNNING TIME

The sample problem included (containing two spectra) takes approximately 30 seconds to run on an IBM 360/91.
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7. UNUSUAL FEATURES OF THE PROGRAM
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8. RELATED AND AUXILIARY PROGRAMS

FORIST is a modification of the COOLC code. The smoothing function used in COOLC has been redefined  and an iterative procedure for selecting the widths of the smoothing functions has been added. This iterative procedure optimizes the energy resolution for a given statistical error of the unfolded spectrum. COOLC is an IBM 360 version of the FERDOR code with binning routines. The FERDOR code was developed at ORNL and was written for the IBM 7090 (ORNL-3743, ORNL-TM-2225). A UNIVAC 1108 version of FERDOR was developed at Gulf General Atomic (GA-9751, GA-9882).
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9. STATUS
Package ID Status date Status
PSR-0092/01 01-FEB-1978 Tested at NEADB
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10. REFERENCES

The following references are in addition to those given for COOLC.
- R.H. Johnson, B.W. Wehring, and J.J Dorning:
  'NE-213 Neutron Spectrometry System for Measurements to 15 Mev'
  Proc. Conference on Nuclear Cross Sections and Technology
  Washington, D.C., 3 - 7 March 1975,
  National Bureau of Standards (1975).
- R.H. Johnson, J.J. Dorning, and B.W. Wehring:
  'Integral Test of Cross Sections Using Neutron Leakage Spectra
  from Spheres of Iron, Niobium, Beryllium, and Polyethylene'
  Proc. Conference on Nuclear Cross Sections and Technology
  Washington, D.C., 3 - 7 March 1975
  National Bureau of Standards (1975).
PSR-0092/01, included references:
- R.H. Johnson et al.:
NE-213 Neutron Spectrometry System for Measurements from 1.0 to 20 MeV
Nuclear Instruments and Methods 145 (1977) 337-346
- R.H. Johnson:
A User's Manual for COOLC and FORIST
PE-75-107 (December 1975)
- R.H. Johnson et al.:
Integral Test of Cross Sections Using Neutron Leakage Spectra from
Spheres of Iron, Niobium, Beryllium, and Polyethylene
Proceedings of Conference on Nuclear Cross Sections and Technology
Washington DC (March 1975), to be published by National Bureau of Standards
- D.T. Ingersoll and B.W. Wehring:
Gamma-Ray-Height Response of an NE-213 Scintillation Detector
Nuclear Instruments and Methods 147 (1977) 551-561
- D.T. Ingersoll:
Informal Note on FORIST (July 12, 1976)
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11. MACHINE REQUIREMENTS

(a) IBM 360 - approximately 270k bytes.
(b) IBM 370.
(c) a scratch disc or tape is needed.
(d) reader on logical unit 5
    printer on logical unit 6
    punch on logical unit 7
    scratch on logical unit 2.
(e) The clock is not sampled.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
PSR-0092/01 FORTRAN-IV
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13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

Standard FORTRAN IV compilers for the IBM 360 or 370 systems.
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14. ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHOR

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.
Developed by:   Nuclear Engineering Program, University of Illinois
                at Urbana-Champaign, Urbana, Illinois, USA
                McMaster University, Hamilton, Ontario, Canada
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16. MATERIAL AVAILABLE
PSR-0092/01
File name File description Records
PSR0092_01.001 SOURCE PROGRAM F4-EBCDIC 1207
PSR0092_01.002 DD-CARDS 6
PSR0092_01.003 SAMPLE PROBLEM 1 (NEUTRON) DATA 901
PSR0092_01.004 SAMPLE PROBLEM 1 PRINTED OUTPUT 1556
PSR0092_01.005 SAMPLE PROBLEM 2 (GAMMA) DATA 1476
PSR0092_01.006 SAMPLE PROBLEM 2 PUNCHED OUTPUT 213
PSR0092_01.007 SAMPLE PROBLEM 2 PRINTED OUTPUT 1681
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17. CATEGORIES
  • O. Experimental Data Processing

Keywords: iterative methods, neutron spectra, spectrometers.