Photon Energy and Angular Response of Individual Dosemeters with Respect to Directional Dose Equivalent

Abstract

In personnel monitoring, the directional dose equivalents H'(0.07) and H'(10) based on ICRU 39 became the dose quantities of interest. Energy compensation filters have been optimised by calibrating the dosemeters on the surface of the ICRU sphere with photons in the energy range 12 keV to 1.2 MeV. Conversion factors H'(10)/X have been taken from ICRP 51 and the report PTB-Dos-11. The paper discusses the energy and angular response of: (i) new designed filters for LiF detectors in commercial capsules such as the universal albedo neutron dosemeter, the official neutron personnel dosemeter in the FRG; (ii) a new commercially available flat phosphate glass dosemeter for automatic readout; and (iii) pocket ionisation chambers of the type FH39U and SEQ 5. In the energy range 12 keV to 1.2 MeV, the energy response for H'(10) is energy independent for LiF dosemeters within ± 25%, for pen dosemeter type FH39U within ± 10% and for the flat glass dosemeter within ± 10% for frontal irradiation. For angles up to 60 o, the flat glass dosemeter indicates H'(10) within ± 30%, whereas for the other dosemeter types investigated over-estimation up to a factor of 3 were found at lower energies.