Further study on different dopings into PbWO4 single crystals to increase the scintillation light yield

Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO4 scintillators by extending different dopings with an aim to find a possibility of using PbWO4 successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO4 crystals with a size of 10 x 10 x (20-30) mm(3) is 25-35 photolectrons/MeV (phe/MeV) corresponding to 3-4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of similar to 1 mu s. The maximum LY increased to 49 phe/MeV for single doping with Mo6+, 80 phe/MeV for double co-doping of Mo6+ + Sb5+, and similar to 85 phe/ MeV for tripple co-doping of Mo6+ +Cd2+ + Sb5+. The radiation hardness is larger than 10(5) Gy for each of the samples co-doped with Mo6+ + Sb5+ and Mo6+ + Cd2+ + Sb5+, while it is much poorer in PWO:MO6+. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (similar to a few nanoseconds range) blue one, giving a peak at similar to 500 nm in the radioluminescence spectrum similarly as in PWO:Mo6+. (c) 2005 Elsevier B.V. All rights reserved.