Light Output and Radiation Damage in A YAIO 3 :Ce Crystal
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ABSTRACT The optical absorption, light output and effects of radiation damage have been studied
in a 2.1 x 2.1 x 2.1 cm
3
crystal of YA10 3 :Ce. The light yield produces approximately
2867 photoelectrons per MeV on a photomultiplier tube with a bialkali photocathode. The scintillation and light transmission properties of the crystal were characterized before 6 and after exposure to 1 Mrad of "Co gamma rays. Significant radiation induced optical absorption was observed near the optical band edge of the crystal, along with an extremely intense phosphorescence after irradiation. Partial spontaneous recovery from the damage occurred at room temperature, and it was possible to induce additional recovery by optical bleaching.
INTRODUCTION Cerium doped yttrium aluminum oxide (YA103:Ce) has recently been investigated as a new scintillating material for X-ray and low energy gamma ray detection [1-3],and has also been developed for use as a stable calibration source for monitoring of calorimeters and 6 3 other devices with optical readout [4-5].It has a reasonably high density (p=5. gm/cm ) and has a scintillation emission in the near UV (, -- 347 nm) with a fast decay time (r 28 ns) and high light yield. With its scintillation properties resembling that of undoped cesium iodide, it is particularly useful as a calibration source for CsI calorimeters. However, for may high energy physics applications, calorimeters are required to operate in a high radiation environment, and therefore the radiation damage properties of the calorimeter materials are important. This paper reports on the results of an investigation of the optical absorption, light output and radiation damage in a YA10 3 crystal in order to better evaluate its potential use in high energy physics applications. The YA10 3 sample used in this study was produced at the Institute of Nuclear Problems in Minsk, Belarus. The sample is approximately cubic with dimensions 2.1 x 2.1 x 2.1 cm 3 . Two parallel surfaces were well polished and the other four surfaces had a ground finish. The absorbance was measured as a function of wavelength along the 2.1 cm path length between the two polished surfaces using an Hitachi model 3210 double-beam spec60 trophotometer. The crystal was exposed to a high intensity Co radiation source in order to study the effects of radiation damage. The absorbance and scintillation light output were measured initially, and then after incremental radiation doses, up to a cumulative total dose of 1 Mrad. Following the last irradiation, the natural recovery of the crystal was measured as a function of time at room temperature after irradiation, and optical bleaching was used to try to induce additional recovery from damage.
469 Mat. Res. Soc. Symp. Proc. Vol. 348. 01994 Materials Research Society
600
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