Influence of variable tungsten valency on optical transmittance and radiation hardness of lead tungstate (PWO) scintillation crystals

Temperature dependence of radiation hardness of lead tungstate (PWO) scintillation crystals

“…In the table, crystal color is indicated together with the corresponding formulae WO 3Àx for certain typical values of a and b. As demonstrated in (Burachas et al, 2003, the colorless crystals fabricated for CERN projects CMS and ALICE had an optimal x value of w0.11 at a z 0.11, b ¼ 0.…”

“…Such annealing results in reduction of induced optical absorption and in shortening of the time necessary for recovery of the initial transparency. Meanwhile, annealing in reductive environment or at lower temperature has an opposite effect (Burachas et al, 2003).…”

“…The initial transparency spontaneously recovers after termination of the irradiation, and two components, fast and slow, are observed in the recovery kinetics (Annenkov et al, 1997). The recovery rate is enhanced by higher crystal temperature and illumination at certain wavelengths in visible spectrum (Bondar et al, 1998) and depends on conditions of growth and after-growth annealing (Zhu, 1998a,b;Burachas et al, 2003). Interpretation of the experimental results has usually been based on the model of point defects (Annenkov et al, 2002).…”

“…These changes in composition of the clusters result in variation of transparency of the entire PWO crystal. The cluster model is adequate to explain all the experimental data available on changes in PWO properties under annealing and irradiation (Burachas et al, 2003(Burachas et al, , 2006.…”

Structure of Centers of Matrix Emission of the Undoped and RE-Doped Scheelite-Type Lead Tungstate Crystals

“…One should remember the necessity of the charge compensation in the crystal lattice. Therefore, some authors consider that the second type of RE centers in the PWO crystals could arise whether the impurity RE ions occupy W positions [10,11,[41][42][43][44][45]. Such replacement is accompanied by comparable large differences of charges and ionic radii.…”