Dosimetry of Photons with Low Pressure Proportional Counters

Publisher Website
Google Scholar
Abstract
Low pressure proportional counters are established as dosimetric tools in neutron dosimetry. The method is applied in precision measurements of kerma factors and in dosimetric investigations of low energy neutrons and complex radiation fields. The question addressed in this paper is whether the particular properties of proportional counters can also be used as dosimetric tools in scientific photon dosimetry. The measurements were performed using counters with walls of A-150 plastic, aluminium and iron in monoenergetic photon fields (nuclide sources) of 140 keV, 660 keV and 1.2 MeV. The simulated diameters used were 1 and 5 µm. The microdosimetric spectra measured with the metal counters differ distinctly from those measured with the A-150 plastic counter. The main difference is that the maximum lineal energies for metal counters are a factor of approximately 2 higher. This effect is explained by the re-entry effect related to electron backscattering which in turn appears to influence the measurement of absorbed dose and thus the applicability of the Bragg-Gray relation.

This publication has 0 references indexed in Scilit: