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The aim of this study was to experimentally assess the luminescence efficiency of a cerium fluoride (CeF3) inorganic scintillator in crystal form as a possible alternative to high-luminescence but hygroscopic cerium bromide (CeBr3). The experiments were performed under typical diagnostic radiology X-rays (50–140 kVp). Parameters such as the crystal's absolute luminescence efficiency (AE) and the spectral matching with a series of optical detectors were examined. The replacement of bromine with fluorine appeared to drastically reduce the AE of CeF3 compared to CeBr3 and other commercially available inorganic scintillators such as bismuth germanate (Bi4Ge3O12-BGO). CeF3 reaches a maximum luminescence efficiency value of only 0.8334 efficiency units (EUs) at 140 kVp, whereas the corresponding values for CeBr3 and BGO were 29.49 and 3.41, respectively. Furthermore, the emission maximum (at around 313 nm) moved towards the lower part of the visible spectrum, making CeF3 suitable for spectral coupling with various photocathodes and photomultipliers applied in nuclear medicine detectors, but completely unsuitable for spectral matching with CCDs and CMOS. The obtained luminescence efficiency results denote that CeF3 cannot be applied in medical imaging applications covering the range 50–140 kVp; however, examination of its luminescence output in the nuclear medicine energy range (~70 to 511 keV) could reveal possible applicability in these modalities. [ABSTRACT FROM AUTHOR]

With the rapid development of silicon-based light detectors with high detection efficiency and long-wavelength sensitivity, the development of near-infrared scintillation crystals has become a hotspot. Especially, the Sm2+ doped europium-based halide crystals exhibit excellent near-infrared luminescence properties. In this paper, Cs4 EuI6: Sm near-infrared scintillation crystals with a size of cm-level were successfully prepared by Bridgman method. The composition and structure were discussed by XRD, XPS and ICP-OES methods, indicating that the Sm2+ was introduced and has no obvious effect on the crystal structure of the matrix. Under ultraviolet and X-ray excitation, the crystal has two luminescence centers (Eu2+ and Sm2+), and the emission peaks are located at 450 and 840 nm, respectively, corresponding to the 5d→4f luminescence of Eu2+ and Sm2+. The decay time of Eu2+ and Sm2+ is at the level of microsecond under ultraviolet excitation. The results show that the emission wavelength gradually varies from blue to near infrared as Sm2+ doping concentration increased. The effects of Sm2+ concentration on the luminescence properties, Eu2+ -Sm2+ energy transfer and decay time of the crystals were also studied, which means that the luminescence properties can be tuned by adjusting the Sm2+ doping concentration. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) and scintillation properties of Ce-doped BaHfO3 crystals were investigated. The Ce-doped BaHfO3 crystal is transparent and colorless after annealing treatment under a reduction condition. The broad luminescence band at ~370 nm was observed under ~280 nm excitation with the decay time of ~17 ns. The X-ray-induced scintillation spectra also showed the broad luminescence band at ~380 nm with a fast decay. The origin of the broad luminescence band at ~380 nm is attributed to the 5d-4f transition of Ce3+. The pulse height distribution under 137Cs gamma ray irradiation using Ce-doped BaHfO3 exhibited a distinguishable photoabsorption peak. The light yield of Ce-doped BaHfO3 is ~1600 photons/MeV. [ABSTRACT FROM AUTHOR]

A single crystal of Zn2Te3O8 (ZTO) was grown using the conventional Czochralski technique. TGA analysis showed that the melting point of ZTO is 681 °C, while it exhibits a structural phase transition at 621 °C. The powder X-ray diffraction analysis of ZTO confirmed that it possesses a single crystalline monoclinic structure with the C2/c space group. An indirect band gap of 3.75 eV was estimated for the ZTO crystal based on its absorption spectrum. The X-ray-induced luminescence of the grown crystal comprised a broad band peaking at 565 nm, which can be tentatively assigned to the self-trapped exciton emission from the (Te3O8)4− molecular complexes. The photoluminescence measured under 280 nm excitation showed a broad band luminescence peaking at about 600 nm, and its intensity was significantly enhanced upon cooling the crystal from 300 K to 10 K. The photoluminescence decay time under 280 nm excitation was shown to have two exponential components in the range from 10 K to 175 K, which became a single exponential upon further heating the crystal. Low scintillation light was observed at room temperature both under α- and β-particle excitations from 241Am and 90Sr sources, respectively. The scintillation light yield measured under β-particle excitation from the 90Sr source was enhanced by about five orders of magnitude at 10 K in comparison to that at 300 K. The scintillation light yield measured at 10 K under the same experimental conditions for ZTO in comparison with the well-known cryogenic scintillator Li2MoO4 (LMO) was shown to have four times higher scintillation light. A single-crystal ingot of ZTO was obtained for the first time; however, it had several cracks due to its phase transition. Notably, scintillation at low temperatures for a Te-based crystal was observed for the first time. These preliminary findings are very promising and show that ZTO will be a good candidate for cryogenic phonon scintillation detectors for the 0νββ decay search of 130Te. [ABSTRACT FROM AUTHOR]

This study aims to determine the optimum composition of the CeBr1−xIx compound to achieve the maximum light output. It is based on calculations of the band energy structure of crystals, specifically taking into account the characteristics of the mutual location of local and band 5d states of the Ce3+ ions. The band energy structures for CeBr2I and CeBrI2 crystals were calculated using the projector augmented wave method. The valence band was found to be formed by the hybridized states of 4p Br and 5p I. The 4f states of Ce3+ are located in the energy forbidden band gap. The conduction band is formed by the localized 5d1 states, which are created by the interaction between the 5d states of Ce3+ and the 4f0 hole of the cerium ion. The higher-lying delocalized 5d2 states of Ce3+ correspond to the energy levels of the 5d states of Ce3+ in the field of the halide Cl0 (Br0) hole. The relative location of 5d1 and 5d2 bands determines the intensity of 5d–4f luminescence. The bottom of the conduction band is formed by localized 5d1 states in the CeBr2I crystal. The local character of the bottom of the conduction band in the CeBr2I crystal favors the formation of self-trapped Frenkel excitons. Transitions between the 5d1 and 4f states are responsible for 5d–4f exciton luminescence. In the CeBrI2 crystal, the conduction band is formed by mixing the localized 5d1 and delocalized 5d2 states, which leads to quenching the 5d–4f luminescence and a decrease in the light output despite the decrease in the forbidden band gap. CsBr2I is the optimum composition of the system to achieve the maximum light output. [ABSTRACT FROM AUTHOR]

It is well known that scintillator performance, especially its energy resolution, is highly dependent on its homogeneity which is determined through its growth process. Therefore, examination and quality control of synthesized scintillators is an important step towards their improvement. Ionoluminescence (IL) microscopy is a highly sensitive and non-destructive technique which can reveal the texture, chemical composition and distribution of trace elements in the inhomogeneous specimens. In this research work, IL microscopy technique is employed for the first time to provide images of two synthesized CsI(Na) crystals. The results show that IL microscopy is not only capable of determining the distribution of the total luminescence emitted from each point, but can also determine it for individual luminescence bands, which represents special luminescence centers in the sample. Therefore, IL microscopy is introduced as a high potential technique for effective characterization of scintillators. [ABSTRACT FROM AUTHOR]

This research revealed the response of Ga and Al sublattices to the incorporation of mismatching substituents in Gd3Al2Ga3O12:Ce single crystals. Incompatible in size and charge, Li+ and Mg2+ substituents violated configurational entropy. This led to lattice distortion and triggered structural rearrangements. The radial fluctuation of the Ga and Al elements was proven by multi-elemental energy-dispersive X-ray spectroscopy mapping and elemental composition analysis. Further evidence was observed by the shift of the exciton creation energy toward higher energy in the vacuum ultraviolet excitation spectra recorded with synchrotron radiation. In the Li+ and Mg2+ co-doped samples, the crystal core was depleted with Ga atoms and enriched with Al elements. The crystal rim showed the opposite behavior. The change in thermoluminescence peak positions revealed a different mechanism for the formation of localized traps. As a result, Li+ co-doping slightly improved the light yield value, but at the same time decelerated the scintillation decay time. On the contrary, Mg2+ co-doping markedly diminished scintillation parameters. [ABSTRACT FROM AUTHOR]

In this study, the infrared optically stimulated luminescence (IRSL) of single crystals of Ce3+ doped yttrium aluminum garnet (YAG) was investigated for the first time. It was found that infrared stimulation of these crystals, following previous exposure to beta radiation, produces a strong luminescence signal. The highest luminescence efficiency was exhibited by the YAG crystal with 0.1% of Ce. With this crystal, it was possible to measure as low doses as 0.1 mGy. Moreover, IRSL is mainly related to the TL peak at a relatively high temperature of c.a. 175 °C, which leads to quite good stability of the signal in time. These properties create good prospects for potential applications of YAG:Ce in dosimetric radiation measurements [ABSTRACT FROM AUTHOR]

GdTaO4 and LuTaO4 are heavy scintillators with fast decay fluorescence. The photoluminsecence spectra of M phase Nd:GdTaO4 and M′ phase Nd:LuTaO4 excited by a laser diode (LD) of 808 nm were fitted with the full-profile fitting method, and the transition intensity parameters Akt, p were determined. Under the excitation of 808 nm LD laser, the population ratio between the upper and low crystal field energy levels of 4 F3/2 for Nd3+ in GdTaO4 is near to 1, but in LuTaO4 is 1.30 and 1.41, which indicates that the relaxation rate between two crystal field energy levels is nearly equal to the excitation rate of LD. The Judd-Ofelt transition intensity parameters Ωt were calculated with Akt, p, and the transition probabilities from 2 P3/2 of Nd3+ in GdTaO4 and LuTaO4 were computed, which indicates that the fast decay fluorescence of several hundred nanoseconds of Nd3+ in GdTaO4 and LuTaO4 is caused by the high nonradiative transition. [ABSTRACT FROM AUTHOR]

Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 bulk crystals were synthesized using the conventional vertical Bridgman method, and the photoluminescence, radioluminescence, and detector properties were evaluated. The Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 samples show a broad emission band at 750, 690, and 650 nm, respectively, which is attributable to the 5d-4f transitions of Sm2+. The pulse height spectra under 137Cs γ-rays (662 keV) show that the Sm-doped CaCl 2 and SrCl 2 exhibit 9300 and 33000 photons/MeV, respectively. These samples can be used for γ-ray measurements in the red to NIR region. • Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 crystals were synthesized using the conventional vertical Bridgman method. • The photoluminescence, radioluminescence, and detector properties were evaluated. • The samples show a broad emission band at 600–800 nm due to Sm2+. • Sm-doped CaCl 2 , SrCl 2 , and BaCl 2 exhibit light yield of 9300, 33000, and 16000 photons/MeV, respectively. [ABSTRACT FROM AUTHOR]

LaMgAl 11 O 19 :Er single crystals were examined as candidates for scintillators emitting near-infrared luminescence, and their radioluminescence and scintillation detector characteristics were assessed. Upon exposure to X-ray, distinct emission peaks appear at ∼550 and ∼1540 nm and are attributable to Er3+ ions. The decay curves also exhibited characteristic decay times associated with Er3+ ions. Particularly, the 3% Er-doped sample showed a discernible linearity in the dynamic range of dose rate from 1 to 50,000 mGy/h, indicating the potential utility in applications requiring precise and reliable radiation measurements. • Er-doped LaMgAl 11 O 19 crystals were synthesized by the floating zone method. • The samples show a broad emission band at 380 nm due to host and sharp peaks at 550 and 1540 nm due to Er3+. • The 3% Er-doped sample showed a good linearity in the dynamic range of dose rate from 1 to 50,000 mGy/h. [ABSTRACT FROM AUTHOR]

A rare-earth trihalide scintillator, CeBr3, in 1 cm edge cubic monocrystal form, is examined with regard to its principal luminescence and scintillation properties, as a candidate for radiation imaging applications. This relatively new material exhibits attractive properties, including short decay time, negligible afterglow, high stopping power and emission spectrum compatible with several commercial optical sensors. In a setting typical for X-ray radiology (medical X-ray tube, spectra in the range 50–140 kVp, human chest equivalent filtering), the crystal's light energy flux, absolute efficiency (AE) and X-ray luminescence efficiency (XLE) were determined. Light energy flux results are superior in comparison to other four materials broadly used in modern medical imaging (slope of the linear no-threshold fit was 29.5). The AE is superior from 90 kVp onwards and reaches a value of 29.5 EU at 140 kVp. The same is true for the XLE that, following a flat response, reaches 9 × 10−3 at 90 kVp. Moreover, the spectral matching factors and the respective effective efficiencies (EE) are calculated for a variety of optical sensors. The material exhibits full compatibility with all the flat-panel arrays and most of the photocathodes and Si PMs considered in this work, a factor that proves its suitability for use in state-of-the-art medical imaging applications, such as CT detectors and planar arrays for projection imaging. [ABSTRACT FROM AUTHOR]

• 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]

The photoluminescence and scintillation properties of n-bromophenethylammonium lead chloride ((n-BrPEA) 2 PbCl 4) (n = 4, 3, and 2) and phenethylammonium lead chloride ((PEA) 2 PbCl 4) have been investigated. All the samples showed broad emission peaks at 400–700 nm upon excitation by UV light or X-ray. The decay time constants of 8–28 ns were obtained which originated from the recombination of self-trapped exciton (STE) within inorganic layers. The afterglow levels at 20 ms after 2 ms of X-ray irradiation of (4-BrPEA) 2 PbCl 4 and (3-BrPEA) 2 PbCl 4 (76 and 55 ppm) were better than (PEA) 2 PbCl 4 (379 ppm). The light yield of (4-BrPEA) 2 PbCl 4 (3100 photons/5.5 MeV-α) was higher than (PEA) 2 PbCl 4 (1400 photons/5.5 MeV-α). • (BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystals were grown by the slow cooling method. • All the crystals showed the luminescence due to the recombination of the self-trapped excitons confined in inorganic layers. • The (4-BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystal showed the highest QY in the present crystals. • The light yields of the (4-BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystals surpassed that of the unsubstituted crystal. [ABSTRACT FROM AUTHOR]

(n-ClC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 ((n-ClPEA) 2 PbCl 4) (n = 2, 3, and 4) and (n-C 6 H 5 C 2 H 4 NH 3) 2 PbCl 4 ((PEA) 2 PbCl 4) crystals were synthesized by the slow-cooling method, and the photoluminescence (PL) and scintillation properties were evaluated. All the samples showed self-trapped excitons luminescence at 400–700 nm. The PL quantum yields of the (n-ClPEA) 2 PbCl 4 (n = 2, 3, and 4) and (PEA) 2 PbCl 4 crystals were 2.2, 0.9, 11.2, and 2.2 %, respectively. In the pulse-height spectra of 241Am α-rays (5.5 MeV), full energy absorption peaks were observed, and the light yields of (n-ClPEA) 2 PbCl 4 (n = 2, 3, and 4) and (PEA) 2 PbCl 4 crystals were respectively calculated to be 530, 490, 2,800, and 1,400 photons/5.5 MeV-α with typical errors of ± 10 %. [ABSTRACT FROM AUTHOR]

Ce‐doped yttrium aluminum garnet (YAG) is among the efficient rare‐earth garnet scintillators and phosphors. Herein, a computational and experimental study of complex F‐type defect centers formed in YAG by doping with cerium and carbon is addressed. The formation energies determined by ab initio calculations of different defects and atomic chemical potentials in YAG:Ce,C are discussed in O‐poor and O‐rich conditions corresponding to the crystal growth under Ar+CO reducing atmosphere, and postgrowth annealing in air, respectively. It is shown that as‐grown crystals contain numerous positively charged defects responsible for F‐type center formation, whereas mainly negative‐charged defects are remained after the annealing in air. The negatively charged defects located nearby Ce luminescence center occupying Y site may stabilize cerium in the tetravalent state and promote a hole transport to this luminescence center. This describes a high scintillation efficiency of Ce,C‐doped garnets. Furthermore, YAG:C and YAG:Ce,C with a high carbon concentration, in addition to luminescence peaked at 400 ns ascribed to F+‐type centers, possess a fast luminescence peaked around 650 nm that may be attributed to the complex defect centers. These unveiled features of the luminescence process in rare‐earth garnets may contribute to the development of efficient luminescence materials. [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]

This work is dedicated to investigation of the luminescent properties of the prospective photoconversion material based on the crystal of Ce3+ doped Ca 3 Sc 2 Si 3 O 12 (CSSG) garnet. The GSSG:Ce crystal was grown using the micro-pulling-down (μPD) method. The CSSG:Ce crystal exhibited an intensive photoluminescence (PL) emission band with two sub-bands peaked at 504 and 545 nm, corresponding to 5d-4f (2F 5/2;7/2) transitions. Furthermore, we have investigated also the formation of cerium multicenters in the GSSG:Ce crystal using analyses of the structure of Ce3+ photoluminescence emission and excitation spectra under excitation of the luminescence of this crystal by synchrotron radiation. The formation of Ce3+-multicenters in CSSG:Ce garnet is caused by the local inhomogeneity of the dodecahedral sites of garnet lattice due to localization of the hetero-valent Sc3+ and Si4+ cations in the octahedral and tetrahedral positions of the garnet host. The existence of Ce3+ multicenters resulted in a significant enhancement of the Ce3+ emission band in the red range and improving the performance of conventional YAG:Ce phosphor. The next task of our work was to evaluate the possibility of application of the GSSG:Ce crystal as a light phosphor-converter (pc) for white light-emitting diodes (WLEDs). In the frame of this task, we have successfully developed a prototype of WLED by employing the CSSG:Ce crystal as a phosphor-converter (pc) with blue 450 emitting LED as well as investigated the color characteristics of this pc-WLED. • Ca 3 Sc 2 Si 3 O 12 :Ce (CSSG:Ce) crystal was grown by micropulling down method. • Presence of two different Ce1 and Ce2 emission centers was detected CSSG:Ce crystals. • Luminescent properties and energy structure of F+ and F centers in CSSG host were studied. • Prototypes of a white LED based on CSSG:Ce phosphor and blue LED were developed. [ABSTRACT FROM AUTHOR]

(C 6 H 5 C 2 H 4 NH 3) 2 Pb 1- x Ca x Br 4 (x = 0.05, 0.1, and 0.25) crystals were grown by the solvent diffusion method and evaluated for the photoluminescence and scintillation properties. When irradiated by X-rays, emission peaking at 440 nm due to exciton emission was observed. The pulse height spectra of (C 6 H 5 C 2 H 4 NH 3) 2 Pb 1- x Ca x Br 4 under 137Cs γ-ray irradiation demonstrate that the light yields were 20,000, 17,000, and 16,000 ph/MeV in x = 0.05, 0.1, and 0.25 samples, respectively. Ca-substitution significantly enhances the photoluminescence quantum yield and scintillation light yield. • (C 6 H 5 C 2 H 4 NH 3) 2 (Pb,Ca)Br 4 crystals were evaluated for the photoluminescence and scintillation properties. • (C 6 H 5 C 2 H 4 NH 3) 2 (Pb,Ca)Br 4 crystals exhibit a sharp emission peaking at 440 nm due to exciton luminescence. • Pulse height spectra under 137Cs γ-rays demonstrate the light yields was 20,000 ph/MeV. • Ca-substitution enhances both the photoluminescence and scintillation properties. [ABSTRACT FROM AUTHOR]

ZnO:Ga (GZO), as well as other band-edge luminous materials, exhibits fast time response properties, which makes it suitable for application as an ultraviolet scintillator for transient radiation detection. However, due to the serious self-absorption problem and low external quantum efficiency, the luminescence intensity cannot be intensified by increasing the volume of the crystals. To alleviate this problem, CsPbBr 3 quantum dot (QD) films were used to enhance the radioluminescence (RL) intensity of GZO. The effects of CsPbBr 3 QD films on the emission spectrum, intensity and angular distribution were experimentally analyzed under three different modes, namely, coating on the imaging surface, incident surface and both surfaces. The CsPbBr 3 QD film on the imaging surface could change the external quantum efficiency and luminescence angular distribution of GZO via its various surface morphologies. When CsPbBr 3 QD films were coated on both surfaces, the luminescence intensity reached 2.43 times that of GZO, while the proportion of emitted light from GZO was less than 6 %. Based on the experimental results, the principle of the enhancement and the difference among the three coating modes were discussed. The enhancement caused by CsPbBr 3 QD films on GZO was considerable and could be simply duplicated on many other materials, expanding their application in the field of detection and imaging. • Radioluminescence intensity of ZnO:Ga can be enhanced by coating perovskite films. • Scintillation performance of CsPbBr 3 QD film-coated ZnO:Ga was investigated. • Tuning the angular distribution by CsPbBr 3 QD film is beneficial for X-ray imaging. [ABSTRACT FROM AUTHOR]

Luminescence and scintillation properties of Lu 2 YAl 2.5 Ga 2.5 O 12 :Ce,Mg (0.02, 0.05 %) garnet crystals grown by the micro-pulling down method were investigated. The onset temperature for luminescence quenching at ∼365 K is determined from the temperature dependence of photoluminescence decay time. At room temperature, the Mg (0.05 %) sample exhibits high integral scintillation efficiency of ∼445 % of BGO crystal, light yield value of 23,500 photons/MeV, and fast scintillation decay times of 20 ns (15 %) + 54 ns (85 %). The higher radioluminescence intensity of the Mg (0.05 %) sample correlates with an appearance of its lower themally-stimulated luminescence intensity in 77–500 K range. • Luminescence and scintillation properties of Lu 2 YAl 2.5 Ga 2.5 O 12 :Ce,Mg (Mg = 0.02 %, 0.05 %) crystals are investigated. • Both crystals show onset of luminescence quenching at 365 K. • Lu 2 YAl 2.5 Ga 2.5 O 12 :Ce,0.05%Mg shows light yield of 23,500 photons/MeV. • Lu 2 YAl 2.5 Ga 2.5 O 12 :Ce,0.05%Mg shows scintillation decay time of 20 ns (14 %) + 54 ns (86 %). • Thermoluminescence characteristics are investigated. [ABSTRACT FROM AUTHOR]

The HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder mission aims to develop a constellation of nanosatellites to study astronomical transient sources, such as gamma-ray bursts, in the X and soft γ energy range, exploiting a novel inorganic scintillator. This study presents the results obtained describing, with an empirical model, the unusually intense and long-lasting residual emission of the GAGG:Ce scintillating crystal after irradiating it with high energy protons (70 MeV) and ultraviolet light (∼ 300 nm). From the model so derived, the consequences of this residual luminescence for the detector performance in operational conditions has been analysed. The suitability of this detector for the HERMES Pathfinder nanosatellites was demonstrated by the low contribution of the afterglow, 1–2 pA at peak, to the input current of the front-end electronics. [ABSTRACT FROM AUTHOR]

(K,Rb) 2 CuBr 3 crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K 2 CuBr 3 , (K 0.25 ,Rb 0.75) 2 CuBr 3 , (K 0.5 ,Rb 0.5) 2 CuBr 3 , (K 0.75 ,Rb 0.25) 2 CuBr 3 , and Rb 2 CuBr 3 were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K 2 CuBr 3 and Rb 2 CuBr 3. Among these samples, (K 0.75 , Rb 0.25) 2 CuBr 3 showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of 137Cs γ-rays (662 keV). • (K,Rb) 2 CuBr 3 crystals were synthesized by the slow cooling method. • The afterglow levels of the (K,Rb) 2 CuBr 3 were 10–40 ppm. • (K 0.75 ,Rb 0.25) 2 CuBr 3 showed the highest light yield (7400 ph/MeV) in prepared samples. [ABSTRACT FROM AUTHOR]

In this study, we fabricated Cs 3 ScCl 6 crystals doped with different concentrations of Ce and investigated their luminescence properties. In both the photoluminescence (PL) and scintillation spectra, emission bands attributable to Ce3+ 5d–4f transition were observed. The PL temporal profiles revealed decay time constants of ~35 ns, which are typical values for Ce3+ 5d–4f transition. In the scintillation temporal profiles, two decay components were observed. The fast and slow components could be attributed to Ce3+ 5d–4f luminescence and self-trapped excitons (STEs) or a slow energy transfer from STEs to Ce3+, respectively. The maximum light yield was 9200 photons/MeV for a Ce concentration of 0.5 mol%. [ABSTRACT FROM AUTHOR]

The scintillation characteristics of Lu0.8Gd2.2 (Al5–xGax)O12:Ce,Mg (x = 2.6 and 3) single crystals grown by the micropulling down method are investigated. The light yield of 27600 photons/MeV obtained for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg is higher than that of 25 400 photons/MeV obtained for Lu0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. The photoluminescence and scintillation decays measured at room temperature (RT) for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg are faster than those for Lu0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. Temperature dependence of radioluminescence (RL) intensity indicates a lower quenching temperature for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg. Coincidence time resolution of a Lu0.8Gd2.2Al2Ga3O12:Ce,Mg detector in coincidence experiment with a BaF2 detector was measured to be 410 ps. The afterglow and thermally stimulated luminescence (TSL) characteristics below RT are also measured. [ABSTRACT FROM AUTHOR]

Eu‐doped CaF2 is studied for use as a scintillator. Herein, the 3D spatial distribution of Eu ions doped in CaF2 crystal is evaluated. It is confirmed that both divalent and trivalent Eu ions are doped in CaF2 crystals from the luminescence spectra of the Eu‐doped CaF2 crystals. Using bandpass filter, the 3D spatial distribution of divalent and trivalent Eu ions is measured, respectively. The 3D spatial distribution of divalent Eu ions with ionic radius larger than that of Ca site is nonuniform with mesh‐like pattern. In contrast, the 3D spatial distribution of trivalent Eu ions with ionic radius smaller than that of Ca site is uniform. In Eu‐doped CaF2 crystals grown by micropulling down method, strain caused by the difference in lattice constants between CaF2 and a seed crystal is confirmed. [ABSTRACT FROM AUTHOR]

In this article, single crystals of a new nonhygroscopic scintillating material of tetrafluoroaluminate (TlAlF4) were grown using the Bridgman–Stockbarger technique. The diffraction pattern obtained from powder X-ray diffraction was found to be in good agreement with the reference data. The X-ray-induced luminescence measurements of the grown crystal sample exhibit a very strong intrinsic emission band in the wavelength range from 300 to 450 nm, with a peak maximum at 390 nm. Scintillation properties, such as pulse height spectra and decay time of the grown crystals, were investigated using γ-rays from the 137Cs radiation source. The scintillation light yield was found to be ~11 800 ph/MeV. At room temperature, the measured decay time profile was fitted with three exponential functions; the result showed a fast component of 194 ns (13.1%), a medium component of 992 ns (84.6%), and a slow component of 3.5 μs (2.3%). Trap centers were studied using the results obtained from thermally stimulated luminescence. The temperature dependence of the scintillation light yield and decay time was also studied. The results showed that TlAlF4 is a promising scintillator crystal, and thus, a potential candidate for X-ray and γ-ray detection. [ABSTRACT FROM AUTHOR]

The scintillation properties of Mg2+-codoped Lu0.6Gd2.4Al2Ga3O12:Ce (LGAGG:Ce,Mg) single crystal grown by Czochralski’s method are investigated. The light yield (LY), scintillation decay time, and coincidence time resolution are presented in comparison with a GAGG:Ce,Mg reference crystal. The LY of 26 200 photons/MeV obtained for LGAGG:Ce,Mg is lower than that of 39 600 photons/MeV for GAGG:Ce,Mg. Despite a lower LY value, the time resolution of LGAGG:Ce,Mg is comparable to that of GAGG:Ce,Mg due to its faster scintillation decay time. LGAGG:Ce,Mg exhibits a much faster afterglow decay and a lower thermally stimulated luminescence intensity with respect to GAGG:Ce,Mg. [ABSTRACT FROM AUTHOR]

The lead tungstate crystal (PbWO4, PWO) is one of the widely used scintillation materials for electromagnetic calorimeters (EMCs) in high-energy physics experiments. The degradation of the optical transmittance in the range of the luminescence spectrum under ionizing radiation leads to losses of the light output resulting in the deterioration of the energy resolution and limiting the lifetime of the calorimeter. A possible way to restore radiation damage is the in situ illumination by visible or near-infrared light of the whole crystal volume. It allows recovering the transmittance losses due to the depopulation of the color centers. Such a kind of stimulated recovery subsystem based on a blue light-emitting diode is considered for the EMC of the PANDA detector at Facility for Antiproton and Ion Research (FAIR) (Darmstadt, Germany). Here, we report on the stimulated recovery studies of the lead tungstate radiation damage induced by external light from laser diodes at different wavelengths. The level of technological development of laser diodes allows increasing the efficiency of the stimulated recovery. [ABSTRACT FROM AUTHOR]

Scintillation characteristics of Y0.8Gd2.2 (Al5–xGax)O12:Ce,Mg (x = 2.6 and 3) single crystals are presented. At 662-keV γ-rays, the light yield of 35 600 photons/MeV obtained for Y0.8Gd2.2Al2Ga3O12:Ce,Mg is higher than that of 32 600 photons/MeV for Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. Scintillation decay components of 32.3 ns (52.4%) + 104 ns (47.6%) obtained for Y0.8Gd2.2Al2Ga3O12:Ce,Mg are faster than those of 11.5 ns (5%) + 51.2 ns (69%) + 302 ns (26%) obtained for Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. The coincidence time resolution of 336 and 389 ps was obtained, respectively, for Y0.8Gd2.2Al2Ga3O12:Ce,Mg-photomultiplier (PMT) and Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg-PMT, in coincidence experiment with a BaF2-PMT detector. The radioluminescence yield at room temperature (RT) is comparable for both crystals while the yield below 130 K is about 20% higher for Y0.8Gd2.2Al2Ga3O12:Ce,Mg. Afterglow and thermally stimulated luminescence (TSL) below RT are also measured. [ABSTRACT FROM AUTHOR]

This article presents the measurements of the luminescence and scintillation under X-ray of undoped, Si-doped, and Si, B codoped gallium-arsenide (GaAs) samples at cryogenic temperature over a wide infrared (IR) region using Si and InGaAs photodetectors. The undoped GaAs has a narrow emission band at 838 nm (1.48 eV) and a low light output of about 2 ph/keV. The GaAs:Si has three broad luminescence bands at 830 nm (1.49 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) and a light output of about 67 ph/keV. GaAs:(Si, B) has four luminescence bands at 860 nm (1.44 eV), 930 nm (1.33 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) with a light yield of approximately 119 ph/keV. With advances in photodetection, GaAs promises to be a useful cryogenic scintillator for the detection of electron recoils from MeV/c2 dark matter. [ABSTRACT FROM AUTHOR]

Scintillation and luminescence properties of a novel organic crystal scintillator, 1,4-bis(2-methylstyryl) benzene (bis-MSB), were measured and compared with those of the conventional trans-stilbene organic crystal scintillator. Although trans-stilbene has been used for beta or neutron detection, trans-stilbene cannot be applied at high temperature conditions due to a lower melting point (124 °C). Liquid scintillators or plastic scintillators also cannot be used at high temperature. Usually, bis-MSB has been used as dopant in liquid scintillators to obtain fast scintillation decay and high luminescence quantum yield, and its melting point is 181 °C higher than that of trans-stilbene. In this paper, we focused on bis-MSB in solid state. The bis-MSB and trans-stilbene crystals were grown by the self-seeding vertical Bridgman method using double quartz ampoules. The bis-MSB crystal had the fast decay time of ∼4.2 ns and the increased light yield of ∼12,000 ph/5.5 MeV(α), while trans-stilbene had the decay time of ∼8.5 ns and the light yield of ∼8500 ph/5.5 MeV(α). The photoluminescence quantum yield was almost constant up to 125 °C for bis-MSB and only up to 50 °C for trans-stilbene. We succeeded in obtaining the novel organic crystal scintillator which can operate even at higher temperature up to 125 °C. • The scintillation properties of the bis-MSB crystal were investigated. • Transparent crystals were grown by self-seeding vertical Bridgman method. • Bis-MSB had better scintillation properties compared to trans-stilbene. • The temperature dependence of luminescence quantum yield of bis-MSB was studied. [ABSTRACT FROM AUTHOR]

Pr:Li 6 Y(BO 3) 3 and Pr,Ce:Li 6 Y(BO 3) 3 crystals were grown by the Czochralski method. The luminescence properties of the Pr:Li 6 Y(BO 3) 3 and Pr,Ce:Li 6 Y(BO 3) 3 crystals, such as their optical transmission, photoluminescence and X-ray induced luminescence spectra were investigated. The scintillation properties of the multi-channel energy spectrum of the Pr,Ce:Li 6 Y(BO 3) 3 crystal under thermal neutrons and gamma-ray excitation were also studied. The energy resolutions of the Pr,Ce:Li 6 Y(BO 3) 3 crystal, which had a size of 8 × 7 × 2 mm3 , excited by moderated 252Cf for the 10B (n,α)7Li and 6Li (n,α)3H reactions were determined to be 42% and 16%, respectively. The decay time under 320 nm UV light excitation was fitted to be 27 ns. Therefore the Pr,Ce:Li 6 Y(BO 3) 3 crystal is a promising fast scintillator for thermal neutron detection with good energy resolution, fast decay time and possible pulse-height discrimination ability. • Pr3+, Ce3+ co-doped Li 6 Y(BO 3) 3 crystals were grown using Czochralski method. • The energy resolution of Pr,Ce:LYBO crystal for 10B (n,α)7Li reaction is 42%. • The energy resolution of Pr,Ce:LYBO crystal for 6Li (n,α)3H reaction is 16%. • The photoluminescence decay time of Pr,Ce:Li 6 Y(BO 3) 3 crystal is 27 ns. [ABSTRACT FROM AUTHOR]

Eu-doped CaAl2O4 bulk crystals were synthesized by the floating zone (FZ) method, and their photoluminescence (PL) and scintillation properties were investigated firstly in a bulk crystal. The crystal samples exhibit PL and radioluminescence (RL) with a broad emission peaking around 440 nm as well as sharp peaks appearing around 600 nm, which are similarly observed for powder samples. Suggested from the decay time constants, they are attributed to the 5d-4f transitions of Eu2+ and the 4f-4f transitions of Eu3+, respectively. From the pulse height spectrum under 241Am γ-ray (59.5 keV) exposure, the light yield (LY) of a 3.0% Eu:CaAl2O4 bulk crystal is approximately 12000 ph/MeV. [ABSTRACT FROM AUTHOR]

The luminescence and scintillation properties of Ce3+-doped Gd 3 (Al 5-x Sc x)O 12 (x = 1, 1.5, 2, 2.5, 3) garnet crystals grown by the floating zone method were investigated. With increasing Sc content, the Ce3+ 5d 1 → 4f luminescence was blue shifted due to a decrease in 5d 1 -5d 2 crystal field splitting (Δ 12) of the 5d e doublet state. The Sc content showed a strong influence on purity of garnet phase in the Gd 3 (Al 5-x Sc x)O 12 :Ce crystals. The presence of secondary phase (perovskite and/or α-Al 2 O 3) results to a poor transparency and a lower light yield (LY) value. The Gd 3 Al 3 Sc 2 O 12 :Ce crystal exhibited pure garnet phase, highest quantum yield (∼76 %) and transmittance (∼80 %), and highest LY value (6,850 photons/MeV at 662 keV γ rays) among the studied samples. Above RT, a decrease of radioluminescence (RL) yield occurs for all samples due to the thermal ionization process. A decrease of the RL yield at low temperature observed in correlation with the intense thermoluminescence peaks can be explained by the localization of electrons at intrinsic shallow traps. • Luminescence and scintillation characteristics of Gd 3 (Al 5-x Sc x)O 12 :Ce crystals are investigated. • Temperature dependence of radioluminescence yield is measured in 10–350 K range. • Gd 3 Al 3 Sc 2 O 12 :Ce shows highest quantum yield and light yield. • Thermoluminescence and low-temperature afterglow are investigated. [ABSTRACT FROM AUTHOR]

Nondoped Cs2HfCl6 (CHC) and alkaline earth metal-doped CHC (AE:CHC) crystals were grown by the vertical Bridgman–Stockbarger method. The spectra of the AE:CHC under X-ray excitation were similar to those for the AE-free crystal; thus, AE doping did not change emission wavelength of CHC. We determined the light outputs and energy resolutions of nondoped CHC and AE:CHC by measuring pulse-height spectra under 662-keV gamma-ray excitation of a 137Cs source. Both light output and energy resolution were deteriorated with AE doping. For example, nondoped CHC had a light output of ~44 000 photons/MeV and energy resolution of ~5.2%; on the other hand, Sr 0.5 at.%-doped CHC had a light output of only ~28 000 photons/MeV and energy resolution of ~10%. Scintillation decay also did not change. The nonproportional response values of light output versus gamma-ray energy did not improve in AE:CHC either. Therefore, doped AEs can be responsible for creation of defect trap levels which would hamper the carrier transport in CHC structure. [ABSTRACT FROM AUTHOR]

A novel TlGd2Cl7 single crystal with scintillation properties is presented. TlGd2Cl7 single crystals with different Ce3+-doping concentrations (0, 0.5, 1, and 5 mol%) are grown using the vertical Bridgman technique. All doped samples exhibit typical Ce3+ emission under X-ray excitation between 350 and 550 nm. Among all grown samples, the best light yield (LY) of ~49 700 photons/MeV and good energy resolution of 6% (full-width at half-maximum) are observed for the 5-mol%-Ce3+-doped TlGd2Cl7 crystal under an excitation of 662-keV $\gamma $ -rays at room temperature. Three exponential decay components are observed for all Ce3+- doped samples at room temperature. Faster decays are observed with the increase in the Ce3+ concentration. The effective atomic (Z) number of the proposed crystal is 64; therefore, efficient X- and $\gamma $ -ray detections could be performed with the proposed scintillator. The high LY, high effective Z number, good energy resolution, and fast scintillation response suggest that this scintillator could be employed in various applications. Further investigations are ongoing for the improvement of its scintillation properties with a higher Ce3+ concentration. [ABSTRACT FROM AUTHOR]

We are in the process of developing novel thallium-based inorganic halide compounds for X- and $\gamma $ -ray radiation detections. In this paper, novel cerium-activated single crystals of Tl2GdCl5 are reported along with a pure Tl2GdCl5. The two-zone vertical Bridgman method is used to grow this scintillator from its melt. Luminescence studies are performed under ultraviolet and X-ray excitations at room temperature. All of the Ce-activated samples exhibit similar emission bands in the range of 350–430 nm, with a peak around 388 nm, attributed to the $5d~\to ~4f$ radiative transition of the Ce3+ ion. In the pure sample, an intense luminescence band appeared owing to the presence of the Tl+ ion in the host lattice, along with the typical Gd3+ emission (~310 nm). Scintillation properties, such as energy resolution, light yield, and decay time, are evaluated under the $\gamma $ -ray excitation. The scintillation properties vary with the Ce3+-concentration. The best performances are obtained for the 5-mol% Ce-activated crystal, which, under a 662-keV $\gamma $ -ray excitation, exhibited an energy resolution of 5% (full-width at half-maximum) and light yield of 53 000 ± 5300 ph/MeV. Fast scintillation decay components followed by slow components are observed for all grown samples. The measured scintillation properties of Tl2GdCl5, which has high density and effective Z-number, reveal its large potentials as a radiation detector in medical imaging techniques. [ABSTRACT FROM AUTHOR]

The luminescence and scintillation properties of novel Na2Mo2O7 (NMO) crystals grown by two different techniques, the conventional Czochralski and the low-thermal-gradient Czochralski techniques, were studied. The transmittances of the NMO crystals were measured at room temperature. The luminescence properties and decay times of the crystals from room temperature 300 to 10 K were measured by using an LED diode emitting at the wavelength of 280 nm. Very weak luminescence was observed at the room temperature. The luminescence, however, was enhanced significantly at lower temperatures. The crystals showed a red emission peak of 663 nm at 10 K. The scintillation decay time was $2~\mu \text{s}$ at room temperature and was increased to $\sim 750~\mu \text{s}$ at 10 K. Low-temperature thermally stimulated luminescence measurements were carried out to investigate the presence of trap centers in the grown crystal. The scintillation light yield of the scintillator was measured by a photon counting technique using a 90Sr beta source in the same temperature range from 300 to 10 K. The light yields of the NMO crystals grown at two different institutes were also compared with a standard CaMoO4 crystal. [ABSTRACT FROM AUTHOR]

A Cs2Mo2O7 single crystal, a molybdenum-based crystal as research and development scintillation material for future neutrinoless double beta decay experiments under milli-Kelvin temperatures, was grown by the Czochralski method. The grown crystal was prepared as a sample for measurements of its optical properties. The sample was cooled down from room temperature to 10 K, and temperature dependence of emission spectrum and decay time were measured. We used a light emitting diode as an excitation source for the emission spectra measurements and a pulsed-type laser for the decay time due to its high intensity. The intensity of emission spectrum and the decay time increased as the temperature decreased. We estimated the optical energy bandgap via a transmittance measurement at room temperature. As far as we know, it is the first time to grow a large Cs2Mo2O7 crystal and to study its luminescence properties. Moreover, we grew a well-studied Li2MoO4 crystal as a reference to compare the light output of the Cs2Mo2O7 at 10 K. Through these results, the Cs2Mo2O7 crystal found to be a candidate scintillator for the future neutrinoless double beta decay experiments. [ABSTRACT FROM AUTHOR]

Scintillation performances of carbon-doped YAG and YAG:Ce crystals obtained by the Czochralski method under novel conditions of Ar+CO reducing atmosphere is compared to their counterparts obtained by conventional technologies. While light yield and energy resolution in YAG crystals grown under different conditions is similar, a fast luminescence decay component of 4-6 ns is observed in YAG:C grown by the new procedure. Optimization of post-growth thermal annealing procedure of YAG:Ce,C scintillator provides the very high light yield of 28 200 phot MeV-1, and the energy resolution of 7.8-8.5% at 662 KeV. [ABSTRACT FROM AUTHOR]

Optical absorption, luminescence spectra, scintillation decay curves, and scintillation light yield were measured in a series of undoped yttrium–aluminum garnet (YAG) crystals of different origins. This paper reveals a correlation between luminescent properties and scintillation efficiency of undoped YAG crystals. All the samples were separated into three groups, Type I, Type II, and Type III, based on their optical properties and scintillation efficiency. The intrinsic ultraviolet luminescence band peaking around 300 nm is found in the samples with high scintillation yield (Type I). Luminescence intensity of this band depends on the crystal purity and on the stoichiometry of the garnets. The UV emission may be related to e–h recombination in vicinity of vacancies. The garnets of Type II contain more impurities which quench the 300-nm emission. The samples of Type III do not exhibit any significant radioluminescence. Light yield of the finest undoped YAG samples in the series, Type I, is similar to the yield of Ce-doped YAG. This Type of crystals can potentially be used in scintillation detectors. [ABSTRACT FROM AUTHOR]

The study of optical and photoluminescence properties of codoped Lu 2 SiO 5 :Ce, Yb single crystals was performed using conventional spectroscopy as well as time-resolved spectroscopy under excitation by pulsed synchrotron radiation. It was shown that the quenching of cerium luminescence is due to the nonradiative energy transfer from Ce3+ to Yb3+ ions. It was confirmed also that such energy transfer is not cooperative process. According to the constructed vacuum referred binding energy diagram the possible mechanism of quenching of cerium luminescence is the metal-to-metal electron transfer from Ce3+ to Yb3+. • The formation of luminescence properties of LSO:Ce,Yb crystals were studied at UV-VUV excitation. • The nonradiative energy transfer from the cerium to ytterbium has been shown. • The energy transfer mechanism is not cooperative. • Vacuum referred binding energy diagram for Lu 2 SiO 5 :Ce,Yb was constructed. [ABSTRACT FROM AUTHOR]

Over the past two decades, substantial research has been done on the typical elpasolite scintillators Ce:Cs 2 LiYCl 6 (CLYC) and Ce:Cs 2 LiLaBr 6 (CLLB) for their potential use as neutron/gamma dual-mode detectors. Commonly, the cation or anion alloying will change the luminescence and scintillation properties of the scintillators, such as the good energy resolution of the Ce:Cs 2 LiLa(Br–Cl) 6 (CLLBC) crystal. In this work, ⌀8 mm Ce:Cs 2 Li(LaBr 6) x (YCl 6) 1-x crystals with x = 0.1, 0.2, 0.3 and 0.4 were grown by the vertical Bridgman technique. Then, ⌀25 mm Ce:Cs 2 LiLa 0.1 Y 0.9 Br 0.6 Cl 5.4 crystal was grown for its relatively high optical quality and phase purity. The luminescence and scintillation properties were also investigated. The energy resolution of Ce:Cs 2 LiLa 0.1 Y 0.9 Br 0.6 Cl 5.4 crystal was calculated to be 9.3%. The scintillation decay time were 38 ns and 623 ns under 137Cs irradiation. • Ce: Ce:Cs 2 Li(LaBr 6) x (YCl 6) 1-x crystals were grown using vertical Bridgman method. •⌀25 mm Ce:Cs 2 LiLa 0.1 Y 0.9 Br 0.6 Cl 5.4 crystal with good optical quality was obtained. • Energy levels were calculated and CVL mechanism was displayed. •The photoluminescence decay time of Ce:Cs 2 LiLa 0.1 Y 0.9 Br 0.6 Cl 5.4 crystal was 36.9 ns. •Energy resolution of 9.3% under 137Cs irradiation was obtained. [ABSTRACT FROM AUTHOR]

In the present study, the response of the crystalline scintillator LaBr3:Ce when excited with X-rays at tube voltages from 50 kVp to 150 kVp was investigated, for possible use in hybrid medical-imaging systems. A single crystal (10 × 10 × 10 mm3) was irradiated by X-rays within the aforementioned tube-voltage range, and the absolute efficiency (AE), as well as the detective quantum efficiency for zero spatial-frequency (DQE(0)), were measured. The energy-absorption efficiency (EAE), the quantum-detection efficiency (QDE) and the spectral compatibility with various optical photodetectors were also calculated. The results were compared with the published data for the LaCl3:Ce, Bi4Ge3O12 (BGO), Lu2SiO5:Ce (LSO), and CdWO4 single crystals of equal dimensions. The AE values of the examined crystal were found to be higher than those of the compared crystals across the whole X-ray tube-voltage range. Regarding the EAE, LaBr3:Ce demonstrated a comparatively better performance than the LaCl3:Ce crystal. The emitted-light spectrum of LaBr3:Ce was found to be compatible with various types of photocathodes and silicon photomultipliers. Moreover, the LaBr3:Ce crystal exhibited excellent performance concerning its DQE(0). Considering these properties, the LaBr3:Ce crystal could be considered as a radiation-detector option for hybrid medical-imaging modalities, such as PET/CT and SPECT/CT. [ABSTRACT FROM AUTHOR]

Optical and scintillation characteristics of Mg2+-codoped Lu 2 Y(Al 5-x Ga x)O 12 :Ce (x = 2, 3) multicomponent garnet crystals grown by the micro-pulling down method were investigated. At RT, the shortening of scintillation decay time and a decrease of light yield (LY) value measured for a higher Ga containing samples can be explained by thermal ionization of the Ce3+ 5d 1 excited state. At 662 keV γ-rays, Lu 2 YAl 3 Ga 2 O 12 : Ce, 0.05%Mg exhibits high LY value of 29,000 ph/MeV along with scintillation decay times of 50 ns (86%) + 73 ns (14%). Co-doping with larger Mg2+ content leads to a decrease of LY value, scintillation decay time, and afterglow level. Radioluminescence quenching observed at low temperature region in correlation with large thermoluminescence peaks can be caused by trapping of electrons at intrinsic shallow traps. • Luminescence and scintillation properties of Lu 2 Y(Al 5-x Ga x)O 12 :Ce,Mg (x = 2, 3) crystals are investigated. • Temperature dependencies of photo-and radioluminescence are presented. • Lu 2 YAl 3 Ga 2 O 12 :Ce,0.05%Mg shows high light yield of 29,000 photons/MeV. • Lu 2 YAl 3 Ga 2 O 12 :Ce,0.05%Mg shows quenching temperature at 435 K due to thermal ionization. • Afterglow and thermoluminescence characteristics are investigated. [ABSTRACT FROM AUTHOR]

Optical, scintillation, and dosimetric properties of the undoped and Tb-doped CaYAlO 4 single crystals grown by the floating zone method were evaluated. Several photoluminescence (PL) emission peaks due to the 4f–4f transitions of Tb3+ ion were observed at 385–620 nm under excitation at 250 nm in Tb-doped CaYAlO 4 samples. Under X-ray irradiation, scintillation peaks of the Tb-doped CaYAlO 4 crystals were consistent with the PL emission peaks. In terms of a dosimetric property, the 0.1% Tb-doped crystal exhibited the highest thermally stimulated luminescence intensity and the widest linear responses in the range of 0.01–1000 mGy among the samples. • The undoped and Tb-doped CaYAlO 4 single crystals were synthesized by the floating zone method. • The Tb-doped samples exhibited luminescence due to the 4f-4f transitions of Tb3+. • The 0.1% Tb-doped crystal exhibited the widest linear responses in the range of 0.01–1000 mGy among the samples in TSL. [ABSTRACT FROM AUTHOR]

A novel NIR emitting scintillator with 825 nm was developed by doping Sm2+ in Cs 4 Eu(Br,I) 6 crystal. The single crystals of Cs 4 Eu(Br,I) 6 :Sm were successfully grown by the Bridgman method. The crystal structure and valence state was approved by XRD and XPS methods. The luminescence properties and energy transfer were systematically investigated. The energy transfer mechanism is variable for different Sm2+ concentration. The PL decay profiles show that the Sm2+-related emission has fast decay of nanosecond. The proportion of fast decay can be tunable by adjusting Sm2+ doped concentration. The Sm2+ doped europium -host material will have a potential application for unclear detection as near-infrared (NIR) scintillators. • The novel NIR emitting Cs 4 Eu(Br,I) 6 :Sm scintillation crystals were successfully grown by the Bridgman method and the luminescence properties is tunable. • The proportion of nonradiative energy transfer from Eu2+ to Sm2+ was improved and the PLQY of Sm2+-related is up to 42.1%. • The fast decay time component of Sm2+ (50 ns) is up to 31.8% for Cs 4 Eu(Br,I) 6 : 3 mol%Sm crystal. • The proposed Sm2+ doped europium -host material principle is an effective method to develop near-infrared (NIR) scintillators for nuclear radiation detection. [ABSTRACT FROM AUTHOR]

Mixed crystals Li6YxGd1–x(BO3)3:Ce3+ (LYGBO) (where, x = 0.0, 0.2, 0.5, 0.8, 1.0) are grown by using Czochralski method with different proportions of Li6Y(BO3)3 and Li6Gd(BO3)3. All crystals are doped with 3 mole% optimized concentrations of Ce3+ ions. The grown crystals are 20–70 mm in length and 5–10 mm in diameter. Detailed sintering and crystal growth procedure is presented in this study. The required phase of the grown crystals is confirmed by powder X-ray diffraction (XRD) analysis. Ultraviolet (UV) photoluminescence and X-ray induced luminescence of the grown crystals at room temperature are measured. Various scintillation properties such as energy resolution, light yield, $\alpha /\beta $ ratio and fluorescence decay time under the excitation by ^{137}\mathrm {Cs}~\gamma -ray and 241Am particles are also presented. [ABSTRACT FROM PUBLISHER]