The reasons the scintillation efficiency decrease of CsI(Tl) crystals exposed by the high-dosed radiation

Low temperature radioluminescence spectra of CsI:Tl

“…Those data indicate that the sites are not independent and instead there could be conversions or energy transfer between related defect structures associated with these two bands. Trefilova et al [4] found that in the CsI:Tl crystal irradiated with high dose (10 6 Gy), the 488 nm excitation could induce the luminescence at 591 nm and the intensity of the 591 nm band decreased gradually with the increase of temperature from 75 K to about 250 K. Similar features could also occur in the present work, though the dose was much lower. (The dose rate was in the range of 0.3-16 Gy/min.)…”

“…This shift should be considered in the selection of filter and photomultiplier when CsI:Tl is used as the X-ray detector. A more serious shift of the maximum position of thallium emissions has been observed in the highly irradiated samples [4].…”

“…In the past three decades, both theoretical and experimental studies on the optical properties related to defect creation of the thallium doped cesium iodide crystals (CsI:Tl) have been reported [1][2][3][4][5][6][7]. This interest arises because these crystals are widely used as scintillators for photomultiplier detectors for gamma rays and energetic particles from nuclear experiments.…”

“…Besides the typical emission bands at 486 and 551 nm in the irradiated CsI:Tl crystals, the thallium related emissions are at 401, 528, 590, 642, 670 and 932 nm, etc. when produced by UV or X-ray excitation [1][2][3][4].…”

Radiation Tolerance Tests of Small-Sized CsI(Tl) Scintillators Coupled to Photodiodes

“…Alarming results have also been published on the decrease of CsI(Tl) light output already at low absorbed doses [4], [5]. More recent results, however, indicate a higher radiation tolerance [6]- [11] although showing a large scatter depending, e.g., on the purity and the Tl concentration of the material. It has also been concluded that the deterioration of light yield in CsI(Tl) at doses below is caused by the loss of transparency due to color center formation, and that deterioration due to decrease of scintillation efficiency does not set in until above a dose of [8], [11].…”