[en] A hybrid photomultiplier (HPMT) was used to study the scintillation response {N_phels(E) photoelectron and L.Y.(E) light yields and energy resolutions} of various known or newly developed scintillators--namely, Ce-doped crystals (perovskites or garnets), CsI(Tl) and the intrinsic BGO crystal--at different energies in the range 8 keV-1.33 MeV. Detailed comparative studies of the scintillation properties of these crystals are presented. A newly developed fast and heavy LuAG:Ce scintillator is characterized by about a 50% higher L.Y. compared to that of well-known and popular BGO (roughly 12 500 ph/MeV against 8080 ph/MeV, respectively)

[en] Zinc borosilicate glass is studied as a scintillating material. Glass samples with zinc oxide concentrations as high as 60 mol% were prepared successfully without deteriorating the glass-forming ability. Different post-preparation thermal treatments were carried out on the samples in the temperature range of 300-700 deg. C and for 3-8 h duration. A dominant emission band was observed near 400 nm in the luminescence spectra with the excitation peak near 260 nm. Photoluminescence decay kinetics shows dominant decay times of about 7-10 and 170-200 ns with a weak tail down to several tens of microseconds. Thermal treatment was found to enhance the 400 nm emission intensity several times with respect to an as-prepared sample and X-ray diffraction analysis confirmed the presence of ZnO crystallized phase in heavily annealed glass samples

[en] This report presents the luminescence properties of Tb³⁺-doped oxide glasses with high Gd₂O₃ (25 mol%) concentration under UV and X-ray excitation. The intense green ⁵D₄ → ⁷F_J luminescence is observed with strong luminescence quenching of the ⁵D₃ level due to cross-relaxation process. Energy transfer from Gd³⁺ to Tb³⁺ ions is confirmed by both luminescence spectra and decay measurements. The integral scintillation efficiency obtained for the 0.5 wt% Tb³⁺-doped glass under X-ray excitation is of about 40% of that of the reference Bi₄Ge₃O₁₂ crystal. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Ce"3"+,Pr"3"+-codoped SiO_2-Al_2O_3-B_2O_3-Gd_2O_3 glasses (SABG:Ce,Pr) were prepared by melt quenching under a CO reducing atmosphere. Luminescence properties were investigated under UV and X-ray excitations. A dominant emission band at 430 nm belonging to the Ce"3"+:5d_1 → 4f transition was observed in the photo- and radio-luminescence spectra. The energy transfer occurs from this Ce"3"+ band toward the "3P_J levels of Pr"3"+ with an efficiency of up to 24%, followed by the reduction of integrated luminescence intensity with an increasing Pr"3"+ concentration. This result is attributed to the increase in the reabsorption of Ce"3"+ luminescence and the non-radiative energy transfer toward the "3P_J levels of Pr"3"+. The cross-relaxation process within the Pr"3"+ pairs can further diminish the total luminescence yield at high Pr"3"+ concentrations. The integral scintillation efficiency and light yield measurements were carried out and compared to the reference Bi_4Ge_3O_1_2 (BGO) crystal. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Y₃Al₅O₁₂:Ce (YAG:Ce) thin films were grown from PbO-,BaO-, and MoO₃-based fluxes using the liquid phase epitaxy (LPE) method. Photoelectron yield, its time dependence within 0.5-10 μs shaping time, and energy resolution of these samples were measured under α-particle excitation. For comparison a sample of the Czochralski grown bulk YAG:Ce single crystal was measured as well. Photoelectron yield values of samples grown from the BaO-based flux were found superior to other LPE films and comparable with that of the bulk single crystal. The same is valid also for the time dependence of photoelectron yield. Obtained results are discussed taking into account the influence of the flux and technology used. Additionally, α particle energy deposition in very thin films is modelled and discussed. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

[en] Low-dimensional halide perovskites with highly efficient luminescent properties have attracted huge attention in optoelectronic and radiation detection applications in recent years. Herein, a highly efficient 0D $C{s}_{3}C{u}_2{I}_5$ perovskite crystal is presented for X-ray and $\mathrm{\gamma <!--\; ??\; -->}$-ray detection that can be easily grown from the melt by the Bridgman method. The crystal structure of $C{s}_{3}C{u}_2{I}_5$ belongs to an orthorhombic system with a space group of Pnma. The $C{s}_{3}C{u}_2{I}_5$ crystal is nonhygroscopic and self-absorption free due to a large Stokes shift of 120 nm originated from its self-trapped exciton emission. Its scintillation emission centers at 440 nm with a principal decay time of 967 ns. The $C{s}_{3}C{u}_2{I}_5$ crystal not only demonstrates a high scintillation yield of about 32 000 photons MeV${}^{-<!--\; ???\; -->1}$ and an extremely low afterglow of 0.03% at 10 ms under X-ray radiation, but also possesses a high light yield of 29 000 photons MeV${}^{-<!--\; ???\; -->1}$ with an excellent energy resolution of 3.4% at 662 keV under $\mathrm{\gamma <!--\; ??\; -->}$-ray radiation. (© 2020 Wiley‐VCH GmbH)

[en] Highlights: • Morphology of the grown rare-earth-doped LaAlO3 crystals was studied. • Role of the growth atmosphere explained by its influence on Ce valence state. • Origin of radioluminescence explained by defect emission in Ce-doped crystals. • High radioluminescence efficiency found for Eu-doped crystals. -- Abstract: LaAlO₃ perovskite single crystals doped with Ce, Eu or Tb have been grown by micro-pulling-down method. X-ray diffraction analysis confirmed low-temperature rhombohedric phase. Energy-dispersive Laue mapping revealed sub-grains in the grown crystals. For the Ce-doped crystals, very low radioluminescence efficiency was found and the observed emission was ascribed to defects. Photoluminescence spectra were significantly different from the radioluminescence ones. They were significantly quenched at room temperature and the related luminescence showed also unusually high Stokes shift. High radioluminescence efficiency was found for the Tb-doped samples and especially for the Eu-doped ones, which would point to the fact that in LaAlO₃ the scintillation process is more favorable for the luminescence ions which tend to capture an electron first.

[en] Liquid phase epitaxy method was used to prepare YAG:Ce and YAG films (thickness 2-25μm) from the fluxes based either on PbO or BaO. 4f→5d bands of Ce³⁺ ions were observed peaking at 340 and 457 nm. A hybrid photomultiplier was used to measure scintillation response of the LPE films using ²³⁹Pu alpha particle source. Some of YAG:Ce films show photoelectron yield close to that of YAG:Ce single crystal. Iron contamination degrades significantly the film scintillation performance

[en] Yttrium-aluminium garnet powders were prepared from aqueous solutions containing yttrium nitrate and aluminium chloride or nitrate via irradiation with accelerated electrons or UV light and via consequent calcination of formed solid phase. UV light seems to be more convenient for yttrium-aluminium garnet preparation; both types of irradiation yield crystalline Y₃Al₅O₁₂ phase after 1 h calcination at 1000 deg. C in air, but some amounts of yttrium oxide and aluminium oxide were also detected in calcinated solid phase formed under accelerated electrons irradiation. Preliminary radioluminescence and thermoluminescence measurements were performed to further evaluate prepared materials. Intensive radioluminescence typical for Ce³⁺ doped structure was observed; thermoluminescence glow curves show distinctive peaks at 135-140 and 240-250 deg. C. - Highlights: → YAG and YAG:Ce were synthesized via irradiation of aqueous solutions of precursors. → Ionizing and/or non-ionizing radiation were used for the synthesis. → Calcination for 1 h at 1000 deg. C leads to well developed crystalline YAG phase. → Synthesized powder YAG consists of 50 nm nanocrystals. → The best prepared materials have very intensive radioluminescence.

[en] Scintillating properties of Ce³⁺-doped (Lu,Y) aluminum garnet single crystalline films (SCF) were investigated. Thin SCF films of thickness between 1 and 30 μm were grown by a liquid phase epitaxy (LPE) method in various fluxes. The α-particle excitation (mainly 5.4857 MeV line of ²⁴¹Am) of pulse height spectra is used to measure scintillation response of SCF, especially peak of those α-rays which are totally absorbed in the films. Detailed studies and evaluation of scintillation measurements of large sets of Ce³⁺-doped SCF (Lu,Y) aluminum garnets showed that at present time (i) YAG:Ce SCF have comparable scintillation properties as YAG:Ce single crystals, especially their N_phels photoelectron yields are the same while (ii) scintillation properties of LuAG:Ce SCF do not reach those of LuAG:Ce single crystal.