Irradiation of luminescence dosimeters in pulsed mixed radiation fields

UHDpulse - Metrology for Advanced Radiotherapy using beams with Ultra-High Pulse Dose Rates is a European project aimed at developing novel dosimetry standards, as well as improving existing ones, for FLASH radiotherapy, very high energy electrons radiotherapy, and laser-driven medical accelerators. Within the scope of this project, Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) detectors are used to measure stray radiation fields. Experiments performed with conventional pulsed particle-beams allow to characterize the dosimeters in known and controllable radiation fields. In turn, this allows to develop models and predict their behavior in complex radiation fields, such as those at laser-driven and FLASH facilities. TL and OSL detectors were irradiated at the Microtron MT25 electron accelerator in Prague, Czech Republic. GAFChromicTM films and plastic nuclear track detectors were used to study the beam profile and the neutron background respectively. The responses of the different detector to the pulsed mixed radiation fields of the Microtron MT25 are compared among each other and presented in this paper

Detection of fast neutrons with the pixel detector Timepix3

We examined the response of the pixel detector Timepix3 with silicon sensor to well-defined fast neutron fields. Part of the pixel detector silicon sensor was additionally equipped with a neutron mask of distinct converter regions. The mask consists of separate thermal and fast neutron regions using 6LiF and hydrogen (plastic) converters, respectively. Measurements were performed with mono-energetic fast neutrons produced at D-D and D-T sources from a Van de Graaff accelerator and a neutron generator, respectively. Data were collected with low background including measurements with moderator material to provide a thermalized neutron component. All the signals produced in the detector were analyzed and decomposed in terms of the spectral -tracking response of the pixel detector. The effect of the fast and thermal components of the neutron converter were determined and compared with direct interactions in the silicon sensor which are significant and can be dominant for fast neutrons. We identify and classify the neutron-induced tracks in terms of the broad-type particle-event track classes. A partial overlap is unavoidable with tracks from direct detection of other radiations in particular protons and low-energy light ions as well as X rays. This will limit the neutron-event discrimination in mixed-radiation fields. The detection response according sensor-mask region was examined and calibrated for the investigated neutron fields. The neutron detection efficiency is selectively derived for the detector particle-event classes. This approach enables to enhance the neutron-discrimination and suppress background and unwanted events. This work enables to extend the response matrix of the detector for broad-type radiations to include neutrons both fast and thermal. The results serve to enhance the sensitivity and determine the neutron component in unknown and mixed-radiation fields such as outer space and particle radiotherapy environments.Web of Science181art. no. P0100