RSIC COMPUTER CODE PSR-095
1. NAME AND TITLE
GAMMA: Monte Carlo Code System for Calculating Efficiencies and Response Functions of
NaI(Tl) Crystals for Gamma Rays from Thick Disk Sources.
Istituto Nazionale de Fisica Nucleare, Sezione di Bari, Bari, Italy.
3. CODING LANGUAGE AND COMPUTER
Fortran IV; IBM 360/370.
4. NATURE OF PROBLEM SOLVED
GAMMA evaluates the efficiencies and the response functions of NaI(Tl) crystals for gamma rays
from thick disk sources. It considers the effective contribution of the secondary electrons with their
possible bremsstrahlung radiation; the secondary electrons are followed in the source and in the
5. METHOD OF SOLUTION
The calculation is performed using Monte Carlo methods. A primary photon is followed both in
the source and in the detector. The electrons produced in photoelectric, Compton, and pair-production
events are also followed with their possible bremsstrahlung or annihilation radiation, and the electron
energy deposit in the detector is stored. In order to save computation time, the path of the electrons
is assumed to be straight. A more realistic and costly simulation of the electron path gives
improvements masked by statistic uncertainties with the commonly used gamma ray energies and
detector dimensions. This becomes necessary for secondary electron ranges which are much greater
than the source and detector dimensions.
6. RESTRICTIONS OR LIMITATIONS
Reliable results are obtained even for high energy gamma rays, provided the dimensions of the
source and/or the detector are not too much smaller than the range of the secondary electron within.
7. TYPICAL RUNNING TIME
No study has been made by RSIC of typical running times for GAMMA.
8. COMPUTER HARDWARE REQUIREMENTS
GAMMA is operable on the IBM 360/370 computers.
9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran IV compiler is required.
"GAMMA Code Input-Output Instructions," Informal Note.
M. Belluscio, R. de Leo, A. Pantaleo and A. Vox, "Efficiencies and Response Functions of
NaI(Tl) Crystals for Gamma Rays from Thick Disk Sources," Nucl. Instr. Meth. 118 (1974) 553-563.
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
KEYWORD: DETECTOR RESPONSE