X-ray induced radiation damage in CLYC(Ce)

Abstract

The radiation hardness of the 6Li loaded scintillator CLYC(Ce) to X-rays was investigated. Two crystals were studied; one crystal was irradiated with X-rays and one was kept as a control and only exposed to a moderated 241Am–Be source. The control crystal was used as a reference sample for photoluminescence excitation and emission measurements. The exposed crystal was given two doses of X-rays, the first was 2.3 Gy and the second was 118.2 Gy after a 22 week annealing period. The total dose was 120.5 Gy and was found to significantly reduce the light yield of the crystal. Pulse height spectra from the moderated 241Am–Be taken with the irradiated crystal showed a 54% decrease in pulse height and a broadening of the FHWM of the peak from 14.6 % to 44.2%. Analysis of the pulse shapes showed no change to the median decay time to 37% of the scintillator, with values of ∼350 ns for the irradiated and control crystal. Photoluminescence excitation and emission measurements revealed a reduction in the relative intensity of the main Ce3+ emission with respect to the self-trapped exciton luminescence. This indicated a modification to the Ce3+ luminescence center. There was little recovery at room temperature over the course of 22 weeks after the first irradiation. The irradiated crystal was also found to display significant room temperature luminescence after X-ray irradiation with it being measurable up to 120 min after the X-ray irradiation.