Comparison of superheated drop detector with phosphorous pentoxide powder for the detection of neutrons in 18 MV x rays.

Abstract

Neutron dose equivalent measurements were performed in and around an 18 MV x-ray beam using superheated drop detectors (SDD) and phosphorous pentoxide (P2O5) powder. The neutron dose equivalent profiles for various field sizes of 10 X 10 cm2, 20 X 20 cm2, and 30 X 30 cm2 were measured. The results measured with the P2O5 were checked for any gross systematic errors by comparing with the published results computed by using Monte Carlo calculations. A comparison was then made between the neutron dose equivalent profiles measured with the P2O5 and the SDD. The results of this comparison show that the neutron dose equivalents measured with the two types of detectors agree with each other for measurements about 20 cm away from the beam edges. However, in and near the beam edges the SDD measurements are upto 50% less than the neutron dose equivalents measured using P2O5 for the 18 MV x-ray beam.