RSIC COMPUTER CODE PSR-099
1. NAME AND TITLE
SPEC-4: Calculated Recoil Proton Energy Distributions from Monoenergetic and Continuous
Atomic Weapons Research Establishment, Aldermaston, England.
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
3. CODING LANGUAGE AND COMPUTER
Fortran IV; IBM 360/370.
4. NATURE OF PROBLEM SOLVED
SPEC-4 calculates the neutron spectrum incident on a spherical proportional counter containing
hydrogen. It allows a complete analysis of an experimental recoil proton spectrum obtained from a
spherical gas filled proportional counter. The only input data required in addition to the experimental
spectrum are the counter parameters and an estimate of the neutron spectrum above the highest energy
to be analyzed. The answer is presented as neutron flux per unit lethargy interval in groups of width
equal to the counter resolution.
5. METHOD OF SOLUTION
The basis of the method is a knowledge of the pulse height distribution produced in the counter by
mono-energetic neutrons (including "wall effect"). An analytical expression is used to generate this
"response function" for the given neutron energy. The integrated response to neutrons above EMAX
can now be calculated and subtracted from the measured pulse height distribution. The neutron
spectrum in defined energy groups is then found by unfolding a matrix of response functions at the
specified energies, using "back substitution." To reduce oscillations, the response function matrix is
differentiated and unfolded from the differentiated data.
6. RESTRICTIONS OR LIMITATIONS
The neutron spectrum above a maximum energy EMAX (depending on gas pressure) must be known. The measured proton range v energy data is also required.
Storage and time restrictions can be neglected compared with the need to get reasonable statistical
accuracy on the input data. This has been found to restrict the number of energy groups to
7. TYPICAL RUNNING TIMES
SPEC-4 ran in 45 seconds on the IBM 360.
8. COMPUTER HARDWARE REQUIREMENTS
SPEC-4 is operable on the IBM 360/370 computers. A card or tape reader and printer are
required; auxiliary storage is not.
9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran IV compiler is required.
P. W. Benjamin, C. D. Kemshall, and A. Brickstock, "The Analysis of Recoil Proton Spectra," AWRE 09/68.
C. D. Kemshall, "The Use of Spherical Proportional Counters for Neutron Spectrum Measurements," AWRE 031/73.
11. CONTENTS OF CODE PACKAGE
Included are the referenced documents and one (1.2MB) DOS diskette which contains the source
code and sample problem input and output.
12. DATE OF ABSTRACT
KEYWORDS: DETECTOR RESPONSE; UNFOLDING