Influence of non‐stoichiometry and doping on scintillating response of PbWO ₄ crystals

Abstract

Systematic scintillation response studies dealing with photoelectron yield (N phels (E)), energy resolution (En.Res.(E)) and radio-luminescence (RL) measurements were accomplished on non-stoichiometric and/or (Ba, Mo) doped PbWO 4 single crystals. We used a new experimental set-up with a Hybrid Photomultiplier (HPMT) to measure γ-ray pulse height spectra of some lines in the energy range 500 -1300 keV. Scintillation responses of PbWO 4 crystals were compared with that of a BGO crystal of the same shape and dimensions. PbWO 4 crystals, which show mainly blue emission, (λ p ≈ 410 nm) provide N phels (E) between 2.4 -4.4 % of BGO. In non-stoichiometric PbWO 4 (≈ 49 % of PbO in the melt) green emission (λ p ≈ 500 nm) dominates and N phels (E) reaches ≈ 8 % of BGO. Non-stoichiometric crystals doped with Mo show the highest N phels (E) (almost 10 % of that of BGO) while En.Res. at 662 keV reaches 20 %.

Microstructure, optical, and scintillation characteristics of Pr3+ doped Lu3Al5O12 optical ceramics

“…and energy resolution ͓full width at half maximum ͑FWHM͔͒ were evaluated from the pulse height spectra measurements using different x-or ␥-ray lines of radioisotope sources ͑ 109 Cd, 210 Pb, 241 Am, 57 Co, 22 Na, and 137 Cs͒ in the energy range 20-1275 keV. 22,23 To compare properly the Pr-doped LuAG and BGO samples for scintillation efficiency, we evaluated L.Y. 22,23 To compare properly the Pr-doped LuAG and BGO samples for scintillation efficiency, we evaluated L.Y.…”

Time development of scintillating response in Ce‐ or Pr‐doped crystals

“…Experimental (Y,Lu) aluminium garnet and perovskite crystals were grown by the Czochralski method (by the company Crytur Ltd. in Turnov, Czech Republic), the LSO:Ce and GSO:Ce were obtained from CTI, USA or Hitachi, Japan companies, respectively, BGO from prof. Ishii, SIT, Japan and PWO from P. Bohacek of the Institute of Physics in Prague [12]. Samples for scintillating measurements were mainly plates of 1 mm thick and only low light yield PWO crystal was cylinder of ∅ 13 × 13 mm.…”

“…Its inner walls reflect scintillating photons back to the photocathode. Scintillation response and its time development was measured using HPMT (PPO 475B, DEP, Roden, The Netherlands) in the energy range 8 keV -2 MeV from pulse height spectra (details are given in [1,3,7,11,12]). This HPMT has the highest quantum efficiency ~ 25 % at 380 nm while in the green range it decreases to ~ 10 %.…”

“…Table 1 shows basic differences between crystals containing Y and Lu as lattice ions. An explanation of these difference can be given from TSL measurements more precisely [8][9][10]12]. Slow decay components can be mostly caused by shallow electron or hole traps causing TSL glow peaks below RT.…”

“…1 it belongs to the group of crystals with lower portion of slow components (the increase of N phels /MeV is about 27 % up to 5 µs). Detailed measurements of PWO co-doped with Mo [12] have shown that Mo presence in PWO causes an higher re-trapping or migrating of electrons and/or holes delaying their radiative recombination at green emission centres but N phels /MeV time development shows N phels /MeV increase does not exceed 30 %.…”