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• The optimal non-stoichiometric ratio for growing Cs 2 LiYCl 6 :Ce crystals was obtained. • High quality Cs 2 LiYCl 6 :Ce single crystals codoped with Ca2+ and Sr2+ ions were grown by the Multi-ampoule Bridgman method. • The energy resolution of Cs 2 LiYCl 6 :Ce was improved from 4.6 % to 3.8 % by co-doping 0.05 % Sr2+. Cs 2 LiYCl 6 :Ce is a novel scintillation crystal with good energy resolution, high light yield, and outstanding neutron/gamma discrimination capability. However, its complex composition and incongruent melting behavior pose many challenges to the crystal growth. In this study, five different compositions of Cs 2 LiYCl 6 :Ce crystals were grown using the vertical Bridgman method. These compositions included LiCl at 57 mol%, 60 mol%, and 63 mol%, as well as CsCl and YCl 3 at ratios of 1.9:1 and 2.1:1. It was found that the highest CLYC phase volume fraction could be obtained in the recipe with a LiCl composition of 60 mol%, while changing the ratio of CsCl to YCl 3 did not show any significant positive effect on crystal growth. In addition, Ca2+/Sr2+ was applied to modify the scintillation performance of CLYC:Ce. A batch of Φ11mm crystals with different co-doping concentrations of Ca2+ and Sr2+ were successfully grown by using the Multi-ampoule Bridgman method, no cracks or inclusions were observed in the grown crystals. Co-doping showed little effect on the radiation luminescence and transmittance spectra of CLYC. The scintillation decay curves demonstrated that the decay times depend on the co-doping concentration. Most notably, the energy resolution of CLYC:Ce is improved from 4.6 % to 3.8 % by co-doping 0.05 % Sr2+ under 662 keV gamma-ray excitation. However, the light yield is reduced because of co-doping of Ca2+ and Sr2+, especially Ca2+ having a more pronounced effect. [ABSTRACT FROM AUTHOR]

• (Gd 1-x Ce x) 3 (Ga 0.995 Cr 0.005) 5 O 12 single crystals were grown by micro-pulling down method. • The emission wavelengths of these crystals were approximately 730 nm. • Cr was segregated in the center part of the crystals. • The relationship between Cr segregation and emission intensity was investigated. • The correlation coefficients of thoes relationships were around 0.9. For the decommissioning of Fukushima Daiichi Nuclear Plants, a novel real-time dose-rate monitor consisting of a scintillator, 100-m long optical fiber and CCD spectrometer has been proposed, and this scintillation material is required to have an emission wavelength of longer than approximately 650 nm. In this paper, as a candidate material for the system, we focused on Ce/Cr co-doped Gd 3 Ga 5 O 12 (Ce/Cr:GGG) single crystals grown by the micro-pulling down method. Since the light output of this material was expected to depend on the Cr3+ concentration, we investigated the relationship between Cr segregation and luminescence properties in Ce/Cr:GGG crystal. Generally, a single photon counting method is not available to evaluate its light output accurately due to the long decay time, we used a novel technique "emission-intensity two-dimensional- mapping method" (2D-image method) to verify the light intensity at each point of the sample. This method realized estimation of the light intensity within the sample, though segregation of Cr3+ is observed. The results showed that Cr was concentrated in the center part along the radial direction in the grown crystals, while all parts had an emission wavelength of approximately 730 nm excited by X-ray. Using the 2D-image method, emission intensity was found to correspond to the Cr concentration, and its correlation coefficients between emission intensity and Cr concentration were over 0.8. We found that our material is available for the monitoring system when the Cr dense part of the crystal is cut and used. [ABSTRACT FROM AUTHOR]

CaMoO 4 crystal is a promising scintillator for investigating the neutrinoless double beta decay process and is commonly grown by the Czochralski method. In this study, CaMoO 4 single crystals were grown by the vertical Bridgman method using both spontaneous crystallization and seed crystal approaches. The CaMoO 4 crystal grown using the spontaneous crystallization approach exhibited yellow, light blue, and deep blue colours (from top to middle part of the ingot). The thermal expansion coefficients, α a and α c , were calculated to be 6.11 × 10 −5 /°C, and 23.58 × 10 −5 /°C, respectively. The optical transmission spectra and photo- and thermally stimulated luminescence spectra of the crystals before and after thermal annealing were also investigated. The yellow cubic CaMoO 4 crystal showed the highest x-ray-stimulated luminescence intensity and the best light output under the excitation of a 137 Cs radioactive source. [ABSTRACT FROM AUTHOR]

In this work, Yb-doped Y 3 Al 5 O 12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb 0.1 Y 0.9 ) 3 Al 5 O 12 and (Ca 0.001 Yb 0.1 Y 0.899 ) 3 Al 5 O 12 , respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV–Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca 2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal. [ABSTRACT FROM AUTHOR]

The optical and scintillation characteristics of Gd 2 YAl 2 Ga 3 O 12 :Ce and Lu 2 YAl 2 Ga 3 O 12 :Ce single crystals are investigated. At 662 keV γ-rays, light yield (LY) of 37,900 ph/MeV and energy resolution of 7.0% obtained for Gd 2 YAl 2 Ga 3 O 12 :Ce are superior to those of 18,900 ph/MeV and 11.5% obtained for Lu 2 YAl 2 Ga 3 O 12 :Ce. Scintillation decays are measured using the time-correlated single photon counting technique. A fast component decay time of 45 ns with relative intensity of 88% obtained for Lu 2 YAl 2 Ga 3 O 12 :Ce is superior to that of 50 ns (65%) for Gd 2 YAl 2 Ga 3 O 12 :Ce. The linear attenuation coefficient at 662 keV γ-rays is also determined and discussed. [ABSTRACT FROM AUTHOR]

We have optimized technology of GaN buffer layer growth with respect to the application in fast scintillation structures. The deep defect luminescence so called yellow band (YB) with decay time up to tens of microseconds is undesired for these applications and should be suppressed or at least the ratio of intensities of excitonic to YB maximum has to be considerably increased. The required photoluminescence properties were achieved by optimization of growth parameters of nucleation and coalescence layer on sapphire substrate. We have shown that decrease of NH 3 flow, decrease of coalescence temperature, increase of nucleation time and nucleation pressure lead to improvement of the structure and luminescence properties of the buffer layer. Results indicate a significant increased ratio of excitonic/YB luminescence intensity. [ABSTRACT FROM AUTHOR]

We have investigated Li 4 SiO 4 scintillation crystals for their possible application in neutron detection due to high Li content and low density of 2.35 g/cm 3 . The micro-pulling-down method employing the Ir crucible and afterheater was optimized for crystal growth of Li 4 SiO 4 taking into account the Li evaporation. To grow high-quality crack-free single crystals, the heating power was increased to establish milder temperature gradient, thicker meniscus, smaller crystal diameter and resulting smaller stress in the as-grown crystals. The undoped, Ti-, Cr-, and Al- doped crystals were prepared and studied. Radioluminescence measurements under X-ray excitation showed quite high overall scintillation efficiency of the Ti-doped sample reaching as high as 250% of that of Bi 4 Ge 3 O 12 reference scintillator. The emission spectrum was dominated by one broad band peaking at 350 nm related to Ti 4+ impurity. Reasonable light yield of 10000 photons/neutron was found. However, its long decay time of 54 μs might be a limitation especially for high counting rate applications. The overall scintillation efficiency of the Cr 3+ sample was much lower and the spectrum shows one broad peak at 463 nm which does not correspond to Cr 3+ luminescence. The radioluminescence spectrum of the Al-doped sample resembled to that of the Ti-doped one, just its magnitude is considerably lower, which was explained by Ti contamination. Peculiarities and optimization of crystal growth and a preliminary sketch of luminescence mechanisms and dopant incorporation are discussed. [ABSTRACT FROM AUTHOR]

• K 2 LaBr 5 :Eu2+ single crystal was obtained successfully by vertical Bridgman method without flux for the first time. • The luminescence phenomenon of K 2 LaBr 5 :Eu2+ was studied. • The optical transmission of K 2 LaBr 5 :Eu2+ single crystal was presented and the bandgap was estimated according to Tauc and Menth's law. • For the first time, the decay time of the heterovalently doped K 2 LaBr 5 :Eu2+ single crystal under gamma rays is nanoseconds. Recent researches have shown that Eu2+ ion heterovalently doped rare earth halide scintillators attract the attention of researchers. In this paper, the transparent K 2 LaBr 5 scintillation crystals of centimeter size doped with heterovalent Eu2+ were successfully grow by the vertical Bridgman technique. X-ray powder diffraction analysis shows that the crystal has an orthonormal structure with space group Pnma(62). A small amount of Eu2+ doping does not change the internal structure of the crystal. The transmittance, the UV–visible excited spectrum and emission spectrum, X-ray excited luminescence spectrum, Photoluminescence decay time and scintillation pulse decay time have been measured at room temperature. The results show that the crystal has strong luminescence intensity, and the maximum emission peak is about 430 nm. The photoluminescence decay time of K 2 LaBr 5 :xmol.%Eu2+(x = 0.5, 1, 2) are 5.56 μs, 5.67 μs and 7.03 μs, respectively. The decay time of K 2 LaBr 5 :Eu2+ crystal under 137Cs 662 keV radiation is nanosecond, indicating that the K 2 LaBr 5 :Eu2+ crystal has fast decay characteristics and excellent time resolution performance. [ABSTRACT FROM AUTHOR]

We have successfully grown a SrWO 4 single crystal using the Czochralski pulling method. X-ray diffraction (XRD) showed a single phase of the grown crystal. Luminescence spectrum under X-ray excitation of a bulk SrWO 4 single crystal showed a broad emission band from 300 to 700 nm at room temperature. The decay time spectrum contained two components of 2.6 ns (5.7%) and 522 ns (94.3%) at room temperature. A change in the light yield and decay time is observed between 10 and 300 K. The luminescence yield of SrWO 4 at 125 K is found to be 8 times higher than at room temperature. The decay time gets longer by a factor of 51 as the temperature decreases down to 10 K. [ABSTRACT FROM AUTHOR]

The Ce 3+ doped mixed crystals of Li 6 Y(BO 3 ) 3 and Li 6 Gd(BO 3 ) 3 are grown by Czochralski technique with equal mole ratios of both Yttrium and Gadolinium i.e. Li 6 Y 0.5 Gd 0.5 (BO 3 ) 3 . The grown crystals have the dimensions of ∅10×30 mm 2 . Powder X-ray diffraction (XRD) analysis confirmed single phase of the grown crystals. X-ray and laser induced luminescence spectra are presented. Scintillation properties such as energy resolution, light yield, decay time and α/β ratio under the excitation of 137 Cs γ-ray photons and 241 Am α-particles are also reported in this article. [ABSTRACT FROM AUTHOR]

Ce 1% doped Lu 2 Gd 1 Al 2 Ga 3 O 12 (LGAGG) single crystals with a diameter of 50 mm and length of 150 mm were grown by the Czochralski (Cz) method using an RF heating system. The EPMA techniques is employed to check homogeniousity of chemical composition. Luminescence and scintillation properties were also evaluated. The grown LGAGG showed light yield of around 25,000 photon/MeV and energy resolution was 9.8%@662 keV. The scintillation decay time was 53.6 ns at room temperature. [ABSTRACT FROM AUTHOR]

Luminescence and scintillation properties of Y 2 SiO 5 :Ce single crystalline film (YSO:Ce-LPE) grown by the liquid phase epitaxy technique are investigated and compared to the bulk Czochralski-grown YSO:Ce single crystal (YSO:Ce-SC). The light yield (LY) and energy resolution are measured using an R6231 photomultiplier under excitation with α - and γ- rays. At 662 keV γ- rays, the LY value of 12,410 ph/MeV obtained for YSO:Ce -LPE is lower than that of 20,150 ph/MeV for YSO:Ce -SC whereas the comparable LY value and energy resolution are obtained under excitation with 5.5 MeV α- rays. The ratio of LY under excitation with α- and γ- rays (α/γ ratio) is determined. Dependence of LY on an amplifier shaping time (0.5–12 µs) is also measured. [ABSTRACT FROM AUTHOR]

• We grew phenanthrene crystals by the using the self-seeding vertical Bridgman technique. • The grown phenanthrene crystals were identified by powder XRD and FTIR. • We evaluated the optical and scintillation properties of grown phenanthrene crystals. Phenanthrene crystals were grown by the self-seeding vertical Bridgman technique as a neutron scintillation material and their luminescence properties were evaluated. As-grown crystals had no secondary phases from the results of the powder X-ray Diffraction and Fourier transform infrared spectrometer measurements. The radioluminescence emission spectrum had a peak at 408 nm and its profile was similar to that of the photoluminescence emission spectrum. The relative light yield under 5.5-MeV alpha-ray was 1.15 times higher than that of lithium glass GS-20. The light yield of phenanthrene under 662 keV gamma-ray is estimated to be 38 ± 2% of NaI:Tl. The scintillation decay time under neutron excitation was estimated to be 7.30 ± 0.14 ns. [ABSTRACT FROM AUTHOR]

• A novel ternary Tb:BaCl 2 /NaCl/KCl eutectic scintillator is reported. • Directionally solidified eutectic was grown by the VB method. • Columnar BaCl 2 fibres with a length of 300 μm were obtained at a growth rate of 0.01 mm/min. • The expected Tb3+ emission was observed only in the BaCl 2 phase. • The decay times of the eutectic were 0.49 ms (7.5%) and 6.64 ms (92.5%) In this study, Tb:BaCl 2 and NaCl/KCl ternary eutectics were grown using quartz ampoules via the vertical Bridgman–Stockbarger method. Each crystal phase had a polygonal columnar shape with a length of 300 µm along the growth direction. The Tb:BaCl 2 scintillator phase grew in the columnar phase. The BaCl 2 scintillator phase is expected to make optical waveguides of the scintillation light. The expected Tb3+ emission peak was observed at approximately 360–630 nm under X-ray irradiation. This emission is mainly attributed to the Tb3+5D 4 →7F 6, 7F 6 , 7F 5 , 7F 4 , and 7F 3 transitions and BaCl 2 host emission transition. The photoluminescence decay times of the Tb:BaCl 2 /NaCl/KCl eutectics was 0.49 ms (7.5%) and 6.64 ms (92.5%). [ABSTRACT FROM AUTHOR]

Abstract: Problems related to the development of physico-technological foundations of preparation of scintillation materials on the basis of zinc selenide with AIIBVI isovalent dopants, as well as complex studies of properties of new semiconductor scintillators are considered. Processes have been studied of formation and transformation of the complex lattice defects that play the role of luminescence centers in AIIBVI-based scintillators. Technological methods have been developed for preparation of a series of practically important scintillation materials of high efficiency, with the absolute light output up to 80,000 photon/MeV, a diversity of spectral-kinetic luminescence properties and up to 109 rad radiation stability. It has been shown that such specific features of scintillators properties as high light output, relatively small atomic number, “fast” or “slow” scintillation kinetics, very low afterglow level (less than 0.01%), allow the development of novel detection systems for multi-energy radiography with improved sensitivity, as well as other radiation sensitive devises. [Copyright &y& Elsevier]

Abstract: In this study, (Gd1−x Y x )F3 (x=0.2, 0.4, 0.5 0.6 and 0.8) crystals were grown by the μ-PD method. Neither visible inclusions nor cracks were observed in (Gd1−x Y x )F3 (x=0.4, 0.5 and 0.6) crystals. Lattice constants increase linearly as the Y3+ concentration decreases. Using (Gd1−x Y x )F3 as a host material, the Sr0.5% Ce1%, 3%, 5% and 7% co-doped Gd0.5Y0.5F3 single crystal was prepared. In this crystal, Ce3+-perturbed luminescence at 380nm is observed with 31.8ns photoluminescence decay time. Under X-ray excitation rather high radioluminescence intensity of this band was obtained exceeding that of BGO scintillator. The energy transfer in the sequence of regular Ce3+→ (Gd3+) n → perturbed Ce3+ sites was evidenced though observation of decay time shortening of the regular Ce3+ and Gd3+ centers and intensity change between Gd3+ and Ce3+-perturbed emission. [ABSTRACT FROM AUTHOR]

Abstract: The epitaxial films of Ce3+-doped yttrium and lutetium aluminum garnets, Y3Al5O12 and Lu3Al5O12, were grown by the liquid phase epitaxy from fluxes of various compositions, i.e. PbO–B2O3, BaO–BaF2–B2O3, and MoO3–Li2MoO4. Growth, film morphology, and structural, optical and emission properties of the films were studied using optical microscopy, XRD, interferometric surface profilometry, optical absorption spectroscopy, luminescence emission and excitation spectroscopy, and kinetics of luminescence. The properties of measured films were analyzed and mutually compared. [Copyright &y& Elsevier]

Abstract: In this paper, we report on the improved scintillation properties of Cs2NaCeCl6 crystal. The Cs2NaCeCl6 crystal was grown by the Czochralski technique in the dimensions of ⊘10×4mm3. X-ray excited luminescence measurements of the Cs2NaCeCl6 crystal showed a doublet emission spectrum in the wavelength range from 370 to 440nm, peaking at 380 and 410nm. An energy resolution (FWHM of peak position) for the 662-keV full energy peak of 8.3% was observed at room temperature. The scintillation properties were studied by using different gamma ray sources. We measured an absolute light yield of 20,000 photons/MeV of absorbed γ-ray energy. The crystal shows three main scintillation decay time components of 91ns (36%), 601ns (33%) and 3.2μs (31%). The results show a good proportionality for light output versus γ-ray energy. The light output deviates from the linear response of 8% between the measured range of energy. [Copyright &y& Elsevier]

Abstract: Effect of Ga substitution in a (Ce,Lu)3Al5O12 scintillator was examined at the crystals grown by the micro-pulling down(μ-PD) method. Strong suppression of unwanted host luminescence due to an exciton localized around Lu–Al antisite defect was observed even at the Ga concentration of 10mol%. Less-intense slower components in scintillation decay were obtained upon increasing the amount of Ga. While the radioluminescence intensities of the 5d–4f luminescence of Ce3+ were not strongly changed, light yield was increased by Ga substitution. The 20% Ga-substituted sample showed even higher light yield than typical Czochralski-grown Ga-free LuAG:Ce. [Copyright &y& Elsevier]

Abstract: In this work, we present results of studies aimed at optimization of scintillation performance of fast but low-light yield YAlO3:Pr scintillator. We applied co-doping with trivalent ions Mo3+ and Ga3+ in attempts to reduce the concentration of charge trapping centers that may exist in this material. Systematic study was performed by using the micro-pulling-down method for single crystal growth. Square-shaped YAlO3:(Pr,Mo) and YAlO3:(Pr,Ga) crystals with selected co-dopant concentrations were grown. Experimental results including absorption spectra, luminescence under X-ray excitation and scintillation decay are presented. No positive contribution of the co-dopant ions was found. Complicated co-dopant behavior makes the improvement of scintillation parameters difficult. [Copyright &y& Elsevier]

Abstract: We report on a new scintillation crystal, CsCe2Cl7, for γ-ray spectroscopy. The crystal was grown using the Czocralski pulling method. X-ray excited luminescence measurements of the CsCe2Cl7 showed a broad emission band in the wavelength range from 370 to 470nm with a peak centre at 410nm. An energy resolution (FWHM of peak position) for the 662keV full energy peak of 5.5% was observed at room temperature. The results showed a good proportionality for light output versus γ-ray energy. The light output deviation from the linear response is about 10% between the energy range of 31 and 1333keV. We measured a light yield of 28,000photons/MeV of absorbed γ-ray energy. The scintillation decay curve of CsCe2Cl7 can be described by a single exponential decay function with a decay time of 50ns. Overall, these measurements clearly indicate that CsCe2Cl7 can exhibit attracting scintillation properties, and we believe that the CsCe2Cl7 crystal is a promising material for medical imaging and radiation detection. [Copyright &y& Elsevier]

Abstract: Single crystals of LaBr3:Ce and LaCl3:Ce have been grown by the vertical Bridgman technique. Crystals of these scintillators are used in the fabrication of high-resolution, gamma-ray spectrometers. The LaBr3:Ce and LaCl3:Ce crystals we have grown have high light outputs of ∼80,000 and 50,000 photons/MeV, respectively, and fast principal decay constants of <30ns. The emission wavelength for the LaBr3:Ce and LaCl3:Ce scintillators are and 350nm, respectively. Both materials have excellent energy resolutions of ∼3% FWHM for 662keV photons at room temperature. In this paper, we will report on our results to date for vertical Bridgman crystal growth and characterization of Ce-doped LaBr3 and LaCl3 crystals. We will also describe the handling and processing procedures developed for these oxygen and moisture sensitive materials. [Copyright &y& Elsevier]

Abstract: In this paper, high optical quality cerium-doped lutetium pyrosilicate(LPS:Ce) crystal has been grown by Czochralski method with the seed oriented along cleavage plane (110). The structure, segregation coefficient of Ce3+ and optical characterization of LPS:Ce crystal have been compared with those of LSO:Ce crystal. The results show that LPS:Ce has the advantage over LSO:Ce by having a larger segregation coefficient of Ce3+, lower cost of starting material, lower melting point and only one luminescence mechanism. Thus, LPS:Ce crystal offers an attractive alternative to LSO:Ce for scintillator applications. [Copyright &y& Elsevier]

Trivalent ions codoping Mo:PWO boules were grown along the c-axis using the Czochralski technique. Trivalent ions codoping improved the fast components of luminescence for Mo:PWO due to suppression/compensation of hole-trapping centers. Correspondingly, trivalent ions codoping increased the fast components of the light yield. The La3+ and Gd3+ concentration in the crystal gradually decreased along the growth direction because they increased the melting point. The Y3+ concentration increased along this direction due to the different influence on the melting point. Compared with La:Mo:PWO, Y:Mo:PWO shows a more uniform transmittance along the growth direction. [Copyright &y& Elsevier]

Abstract: In this paper we report on the crystal growth and characterization of 9,10-diphenylanthracene. Crystals of 9,10-diphenylanthracene (DPA) were grown by the solution growth technique as well as the vertical Bridgman method. In case of the solution growth technique, several organic solvents were investigated including heptane, cyclohexane, toluene, and p-xylene. The largest crystals of the highest quality were obtained from toluene and xylene. In the case of vertical Bridgman, evacuated silica ampoules were used to grow large single crystals of DPA. Crystals grown by this method exhibit excellent scintillation properties. Radioluminescence spectra of DPA crystals exhibit a broad emission band peaking at 475nm. DPA crystals show high light yields of up to 20,000ph/MeV and a fast scintillation decay of less than 20ns. Fast neutron detection was achieved using a 252Cf source. [Copyright &y& Elsevier]

Abstract: In this paper, we grew 1.0mol% Ce doped Cs2LiLuBr6 material as a bromo-elpasolite structured crystal. The Cs2LiLuBr6:Ce3+ crystal was grown by the Bridgman method using a two-zone vertical furnace. We measured the luminescence and scintillation properties of the grown crystal under X-ray and γ-ray excitations at room temperature. Under X-ray excitation the emission spectrum of the Cs2LiLuBr6:Ce3+ was observed in the range of 360–540nm, peaking at 394 and 426nm. This emission is attributed to the 5d→4f transitions of the Ce3+ ion. The decay time of the crystal was composed of three components. The fast component is 37ns (35%), the intermediate component is 337ns (25%), and the slow component is about 1.7μs (40%). The relative light yield of the crystal was found to be 46% to that of CsI(Tl) using a bi-alkali photomultiplier tube. [Copyright &y& Elsevier]

• Growth melt KCl-SrCl 2 -EuCl 2 was made by carbochlorination of KCl-SrCl 2 -Eu 2 O 3 mixture. • In the carbochlorinated KCl-SrCl 2 -EuCl 2 melt admixture of Eu3+ is present. • Addition of KI to the KCl-SrCl 2 -EuCl 2 melt favors complete transfer of Eu3+ to Eu2+. • Crystals of new incongruently melting scintillation material KSr 2 Cl 5 :Eu2+ were grown. • Light yield of KSr2Cl5:0.5 mol% Eu2 + is 70% vs. NaI:Tl, energy resolution is 8–9%. The peculiarities of direct incorporation of Eu2+ (via Eu 2 O 3) in KCl-SrCl 2 (1:1.99) melt for the growth of Eu2+-activated scintillation material of K(Sr 0.995 Eu 0.005) 2 Cl 5 composition were studied. When added to the chloride melt at 973 K Eu 2 O 3 starts to transform into EuOCl immediately and the process is essentially incomplete. The complete dissolution of Eu oxocompounds (Eu 2 O 3 , EuOCl) in the melt was provided by the application of the carbochlorination process (the action of CCl 4 vapor) which is a special case of the reactive atmosphere processing (RAP). A scintillation material of K(Sr 0.995 Eu 0.005) 2 Cl 5 composition was grown from the obtained melt with an application of the Bridgman technique. The boule included long opaque end sections and transparent medium section with the composition of K(Sr 0.995 Eu 0.005) 2 Cl 5. The luminescence studies of the obtained samples confirmed coexistence of both Eu2+ and Eu3+ in the growth melt. The non-isomorphic Eu3+ is displaced to the top section of the boule as a result of directional crystallization. An amount of KI was added to the growth melt to provide complete reduction of Eu3+ into Eu2+. Scintillation parameters of all the obtained crystals are close: the relative light yield values are ca.70% vs. NaI:Tl and the energy resolution is within 8–9%. [ABSTRACT FROM AUTHOR]

• Tl-, Hf- and Zr-based scintillator crystals with high density and high light yield. • Intrinsic scintillator crystals with simple cubic crystal structures. • Energy resolutions below 3.8% at 662 keV and good proportional responses to photon energies. The re-discovery of Cs 2 HfCl 6 (CHC) as a scintillator has lately generated much interest in this material and its family, which belongs to the K 2 PtCl 6 cubic crystal structure [1]. CHC is an intrinsic scintillator that is non-hygroscopic, has no self-radioactivity, provides good energy resolution, and has good non-proportionality. In this paper we are reporting growth and scintillation properties of two new and Tl-, Hf- and Zr-based compounds of Tl 2 HfCl 6 and Tl 2 ZrCl 6 , with physical densities of 5.1 g/cm3 and 4.5 g/cm3, respectively and effective atomic numbers (Z eff) of 71 and 69, respectively. Samples from successfully grown 16 mm diameter boules were cut, processed, and characterized for their scintillation and radiometric properties. Energy resolutions of 3.7% (FWHM) for THC and 3.4% for TZC (FWHM) at 662 keV are measured. Primary luminescence decay times of 1.1 μs and 2.3 μs, for Tl 2 HfCl 6 and Tl 2 ZrCl 6 , respectively, as well as good proportionality for both materials have been observed. [ABSTRACT FROM AUTHOR]