De. Peplow et al., SODIUM-IODIDE DETECTOR RESPONSE FUNCTIONS USING SIMPLIFIED MONTE-CARLO SIMULATION AND PRINCIPAL COMPONENTS, Nuclear geophysics, 8(3), 1994, pp. 243-259
A new approach has been developed, validated and demonstrated for gene
rating detector response functions for gamma-rays incident on NaI dete
ctors. The approach is demonstrated for gamma-rays with energies from
0.5 to 10.5 MeV incident on 3'' x 3'' and 6'' x 6'' cylindrical detect
ors. The gamma-ray source used here is a point isotropic source locate
d 10 cm from the detector face on the detector axis. However, the appr
oach is very general and could be used for any other geometry desired
and any detector type, with appropriate Monte Carlo simulation. A spec
ific purpose Monte Carlo simulation code called DRFNCS has been design
ed for this purpose and was benchmarked against the general purpose IT
S electron/photon codes developed by Sandia National Laboratories. The
DRFNCS code is orders of magnitude faster than the ITS general purpos
e code and allows one to practically simulate the large number of spec
tra that are required for this purpose. Then the method of principal c
omponents is applied to the Monte Carlo data. This reduces the amount
of data required and allows detector response functions to be generate
d efficiently and accurately for any gamma-ray energy within the speci
fied energy range.