Sc. Sabharwal et al., PREPARATION AND CHARACTERIZATION OF RADIATION-HARD PBWO4 CRYSTAL SCINTILLATOR, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 381(2-3), 1996, pp. 320-323
The selective loss of one of the crystal constituents is found to be r
esponsible for the yellowish coloration of PbWO4 crystals. However, us
ing the already pulled crystals as the starting charge for the subsequ
ent growth, colorless crystals can be grown. The crystals exhibiting e
xcellent transmission characteristics have been grown employing a low
temperature gradient, a moderate rotation rate of 15 rpm and a pull sp
eed of 1 mm/h. The colored crystals show some radiation damage on gamm
a irradiation, while the colorless ones remain unaffected even for irr
adiation doses as high as 10 Mrad. Both the types of crystals show the
presence of weak thermoluminescence (TL) emission when high irradiati
on doses (similar to 10 Mrad) are given. Only one TL glow peak is obta
ined in both the cases but the peak temperatures are different. The em
ission centers responsible for the TL emission are found to be the one
s which give rise to the scintillation emission in the crystal.