Visible to infrared low temperature photoluminescence of rare earth doped bismuth germanate crystals.
In this paper, the influence of a series of rare earth (Eu, Tm, Nd) and Cr ion doping on the optical properties of BGO was investigated by means of photoluminescence (PL) from visible to IR region in the 10-300K temperature range using different types of detectors, namely, photomultiplier tube (PMT), InGaAs (IGA), and Si. Several samples were investigated having dopants concentrations of 0.3wt%Nd, 0.4wt%Tm, 0.06wt% Cr and 3ppm Eu. The PL spectra of the samples showed different luminescence behaviour which is assigned to the 4f intra shell transition from rare earth ions. The temperature dependence of the PL from rare earth doped BGO crystals is also examined.
Luminescence, radiation damage, and color center creation in Eu3+doped Bi4Ge3O12 fiber single crystals
Doped Bi4Ge3O12 (BGO) fiber single crystals were grown by the micro-pulling-down method with the resistance heating system. Optical absorption measurements before and after x-ray irradiation (induced absorption) were performed in order to investigate the radiation damage of the crystals. The Eu3+-doped BGO has shown higher radiation resistance with respect to the equivalently grown undoped BGO fibers. Radio- and photoluminescence characteristics were obtained to clarify the role of Eu3+ in luminescence and scintillation mechanism. Radioluminescence spectra show the intense and slow (decay time of 1.61 ms) 5D0,1−7Fx(x=0−6) radiative transitions of Eu3+, while the intrinsic BGO emission becomes weaker with respect to the undoped BGO. Photoluminescence decay of the intrinsic BGO emission becomes nonexponential and noticeably faster in Eu-doped samples, which evidences the nonradiative energy transfer from intrinsic emission centers to Eu3+ ions. Thermally stimulated luminescence (TSL) measurements above room...
Radiation damage of bismuth germanate crystals
Abstract Recent CERN results on BGO radiation damage tests are presented, where the behaviour of different optical parameters like excitation, fluorescence and transmission spectra, is analysed as a function of photon irradiation at different wavelengths (from 1.88 eV to 1.33 MeV). Some attempts to cure damaged crystals, either by exposure to visible light or by annealing are also discussed. In the last section a qualitative model of the damage mechanism is described.