Experimental study for improving the angle dependence of the response of PADC-based personal neutron dosemeters

The large angle dependence of the Hp(10) response in PADC-based personal neutron dosemeters constitutes a serious concern in operational radiation protection dosimetry. For planar dosemeters, the typical Hp(10) response falls by half or more when the incidence angle changes from 0° to 60°. To reduce this source of systematic uncertainty, configurations based on multiple detectors at different angles have been developed, but their complex geometries constitute an important obstacle to the implementation in routine services.This works proposes a simplified configuration, based on two orthogonal PADC detectors, which is suitable for the implementation in the routine service of INFN-LNF (Frascati).This system was tested, using a ISO slab standard phantom, in the following reference neutron fields: 241Am–Be and 252Cf(D2O) available at ENEA-Bologna, and 1.2 MeV, 5 MeV and 14.8 MeV mono-chromatic beams available at PTB Braunschweig. Incidence angles of 0°, ±15°, ±30°, ±45° and ±60° were chosen. The sum of the track density in the PADC parallel to the phantom and that in the detector normal to the phantom face, was regarded as “dosemeter reading”. On this basis the Hp(10) response was calculated for different energies and incidence angles. As expected, the angular response of the two-orthogonal-element dosemeter is highly improved with respect to that of a single planar PADC.

► The response of a two-orthogonal-element PADC personal neutron dosemeter have been studied.
► The angle response is greatly improved with respect to a single element planar configuration.
► The new configuration is suitable for ready implementation in dosimetry services.