PSR-0092 FORIST.

1. NAME OR DESIGNATION OF PROGRAM:  FORIST. Neutron spectrum unfolding code (FERDOR with optimized resolution using an iterative smoothing  technique).

3. NATURE OF PHYSICAL PROBLEM SOLVED

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

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.

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.

6. TYPICAL RUNNING TIME

The sample problem included (containing two spectra) takes approximately 30 seconds to run on an IBM 360/91.

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).

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).

- 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)

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.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

Standard FORTRAN IV compilers for the IBM 360 or 370 systems.

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

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