Radiation damage study of a thin YAG:Ce scintillator using low-energy protons

by Dr Vladmir Linhart

Thursday 7 Sept 2017, 15:00 → 16:00 US/Eastern

Universe

Radiation hardness of a 50µm thin YAG:Ce scintillator in a form of dependence of a signal efficiency on 3.1MeV proton fluence was measured and analyzed using X-ray beam. The signal efficiency is a ratio of signals given by a CCD chip after and before radiation damage. The CCD chip was placed outside the primary beam because of its protection from damage which could be caused by radiation. Using simplified assumptions, the 3.1MeV proton fluencies were recalculated to: • 150 MeV proton fluencies with intention to estimate radiation damage of this sample under conditions at proton therapy centers during medical treatment, • 150 MeV proton doses with intention to give a chance to compare radiation hardness of the studied sample with radiation hardness of other detectors used in medical physics, • 1 MeV neutron equivalent fluencies with intention to compare radiation hardness of the studied sample with properties of position sensitive silicon and diamond detectors used in nuclear and particle physics. The following results of our research were obtained. The signal efficiency of the studied sample varies slightly (±3%) up to 3.1MeV proton fluence of c. (4 − 8) × 1014 cm−2. This limit is equivalent to 150MeV proton fluence of (5 − 9) × 1016 cm−2, 150MeV proton dose of (350 − 600) kGy and 1MeV neutron fluence of (1 − 2) × 1016 cm−2. Beyond the limit, the signal efficiency goes gradually down. Fifty percent decrease in the signal efficiency is reached around 3.1MeV fluence of (1 − 2) × 1016 cm−2 which is equivalent to 150 MeV proton fluence of around 2 × 1018 cm−2, 150MeV proton dose of around 15 MGy and 1 MeV neutron equivalent fluence of (4 − 8) × 1017 cm−2. In contrast with position sensitive silicon and diamond radiation detectors, the studied sample has at least two order of magnitude greater radiation resistance. Therefore, YAG:Ce scintillator is a suitable material for monitoring of primary beams of particles of ionizing radiation.