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The Nd-doped LaMgAl11O19 single crystals were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, several sharp emission peaks due to the 4f–4f transitions of Nd3+ were observed at 900, 1060, and 1340 nm in the near-infrared range, and the decay curves show the typical decay time for Nd3+. The samples show good afterglow properties comparable with practical X-ray scintillators. The 1% and 3% Nd-doped LaMgAl11O19 samples show a good linearity in the dynamic range from 6–60,000 mGy/h. [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]

0.5, 1, 2, and 5% Er-doped La 3 Ga 5 SiO 14 (LGS) single crystals were synthesized by the Floating Zone method and the photoluminescence (PL) and scintillation properties were characterized. Emission peaks appeared at visible–near-infrared (NIR) regions. Their spectral features matched with those due to the 4f–4f transitions of Er3+. The PL quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.3, 82.5, and 69.4%. The decay times due to the 2H 9/2 –4I 15/2 transitions of Er3+ were obtained when visible ranges were monitored under excitation of both visible lights and X-rays. All the prepared samples showed good linearity between the X-ray exposure dose rate and scintillation signals in NIR ranges. The best lower detection limit in prepared samples was 5 mGy/h recorded by the 2% Er-doped LGS. • Er-doped La 3 Ga 5 SiO 14 single crystals were synthesized by the Floating zone method. • Luminescence due to 4f–4f transitions of Er3+ was observed in both visible and near-infrared regions. • Quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.7, 82.5, and 69.4%. • The best lower detection limit in prepared samples was 5 mGy/h obtained by 2% Er-doped sample. [ABSTRACT FROM AUTHOR]

Scintillators for neutron detection have been required as alternative detectors for 3He gas proportional counters, which are in short supply. Therefore, Eu-doped LiBr single crystals as new scintillators for neutron detection were synthesized by the vertical Bridgman method, and the photoluminescence and scintillation properties were evaluated. Under ultraviolet light and X-ray irradiation, the emission due to 4f65d1–4f7 (8S 7/2) transitions of Eu2+ was observed at 440 nm. According to pulse height spectra under 252Cf neutron irradiation, 0.01 % Eu-doped LiBr showed the highest light yield of 4600 ph/n among the prepared samples, and the α/γ ratio of 0.01 % Eu-doped LiBr was 0.37, which was better than that of commercial GS20 scintillator. • Eu-doped LiBr single crystals were synthesized by the vertical Bridgman-Stockbarger method. • Photoluminescence and scintillation properties under X-, γ-ray, and neutron irradiation were evaluated. • Under UV and X-ray irradiation, the emission due to 4f65 d1–4f7 (8S 7/2) transitions of Eu2+ was observed at 440 nm. • The highest light yield under 252Cf irradiation among the prepared samples were 4600 ph/n, and the α/γ ratio was 0.37. [ABSTRACT FROM AUTHOR]

Optically-stimulated luminescence (OSL) and thermoluminescence (TL) properties of RbI:Eu single crystals synthesized by the vertical Bridgman-Stockberger method were evaluated. OSL peak at 430 nm due to 4f65d1-4f7 transition of Eu2+ was observed under stimulation at 750 nm. The 0.5% Eu-doped sample exhibited the highest OSL intensity among all the sample, and the detection limit was 1 mGy. TL glow peaks at ∼100 and ∼200 °C were observed and were ascribed to F z -center (F-center near Eu2+-cation vacancy dipole) and F-center, respectively. The 0.5% Eu-doped sample showed the highest TL intensity among all the sample, and the detection limit was 0.01 mGy. • RbI:Eu single crystals were synthesized by the vertical Bridgman-Stockbarger method. • Photoluminescence, optically-stimulated luminescence (OSL), and thermoluminescence (TL) properties of RbI:Eu were evaluated. • The optimal concentration turned out be 0.5% for the OSL and TL. [ABSTRACT FROM AUTHOR]

MgAl 2 O 4 translucent ceramics doped with Mn were fabricated by spark plasma sintering, and optical and dosimetric properties were evaluated. The 1% Mn-doped MgAl 2 O 4 translucent ceramic exhibited a photoluminescence emission peak at 520 nm due to Mn2+. Thermally stimulated luminescence (TSL) glow peaks of the Mn-doped MgAl 2 O 4 translucent ceramics were observed at around 60 and 260 °C. Moreover, the TSL intensity increased as the heating temperature rose to 490 °C. TSL spectra confirmed that Mn2+ had a role of recombination centers in the TSL process. The 0.01% Mn-doped MgAl 2 O 4 translucent ceramic showed a proportional relationship between the TSL intensity and irradiation doses ranging from 0.1 to 1000 mGy. • Mn-doped MgAl 2 O 4 translucent ceramics were developed using the SPS technique. • PL and TSL spectra showed the peak due to d-d transitions of Mn2+ ions. • The optimal Mn concentration as TSL materials is less than 0.01%. • The TSL intensity was improved by Mn-doping compared with the undoped MgAl 2 O 4. [ABSTRACT FROM AUTHOR]

(C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 single crystals were synthesized by the slow cooling method, and their optical and scintillation properties were evaluated. Both samples had sharp X-ray diffraction peaks with intervals of (0 0 2 l) (l = 5–7). Absorption edges of (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 were confirmed at 535 and 520 nm, respectively. They showed luminescence due to the recombination of excitons at 500–700 nm. Scintillation decay times at 0.5–0.7 ns were obtained by approximation of decay curves. The light yields of (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 were respectively evaluated to be 1200 and 1500 photons/5.5 MeV-α by measuring full absorption peaks of 241Am α-rays. • (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 single crystals were grown by the slow cooling method. • Luminescence due to the recombination of free excitons was observed. • Scintillation decay times of sub-nanoseconds were observed. • Light yield of (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 was 1500 photons/5.5 MeV-α. [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]

0.1, 0.5, and 1 % Nd-doped Ca 3 Nb 1.6875 Ga 3.1875 O 12 (CNGG) single crystals were successfully synthesized by the Floating Zone method. The optical and scintillation characteristics in ultraviolet–near-infrared (NIR) regions were investigated. All the CNGG crystals showed emissions at 900, 1060, and 1350 nm, which correspond to the typical electronic transitions of Nd3+. The decay times of 200–220 μs were obtained by an approximation of decay curves. The values were valid as the 4f–4f transitions of Nd3+. When relationships between X-ray irradiation dose-rate and output signals in NIR ranges were evaluated, all the prepared samples exhibited good linear responses. The lowest detectable dose-rate in prepared samples was observed by measuring with the 0.5 % Nd-doped sample, and the value was 0.006 Gy/h. [ABSTRACT FROM AUTHOR]

Magnetic fields play such essential roles in star formation as transporting angular momentum and driving outflows from a star-forming cloud, thereby controlling the formation efficiency of a circumstellar disc and also multiple stellar systems. The coupling of magnetic fields to the gas depends on its ionization degree. We calculate the temperature evolution and ionization degree of a cloud for various metallicities of Z /Z⊙ = 10−6, 10−5, 10−4, 10−3, 10−2, 10−1, and 1. We update the chemical network by reversing all the gas-phase processes and by considering grain-surface chemistry, including grain evaporation, thermal ionization of alkali metals, and thermionic emission from grains. The ionization degree at n H ∼ 1015–1019 cm−3 becomes up to eight orders of magnitude higher than that obtained in the previous model, owing to the thermionic emission and thermal ionization of K and Na, which have been neglected so far. Although magnetic fields dissipate owing to ambipolar diffusion or Ohmic loss at n H < 1015 cm−3, the fields recover strong coupling to the gas at n H ∼ 1015 cm−3, which is lower by a few orders of magnitude compared to the previous work. We develop a reduced chemical network by choosing processes relevant to major coolants and charged species. The reduced network consists of 104 (161) reactions among 28 (38) species in the absence (presence, respectively) of ionization sources. The reduced model includes H2 and HD formation on grain surfaces as well as the depletion of O, C, OH, CO, and H2O on grain surfaces. [ABSTRACT FROM AUTHOR]

The photoluminescence and radioluminescence properties of Tb-doped Lu 2 O 3 (Lu 2 O 3 :Tb) single crystals were assessed for scintillator applications. Lu 2 O 3 :Tb exhibits several sharp peaks at 490, 540, 590, and 620 nm attributed to Tb3+, and the decay curves show the typical decay time for Tb3+ in millisecond range. The decay decreases with increasing dopant concentration owing to concentration quenching. Energy distributions under 137Cs γ-rays demonstrate that the 0.1 % Tb-doped Lu 2 O 3 exhibits the highest scintillation light yield (75,000 photons/MeV) among the samples. [ABSTRACT FROM AUTHOR]

Photoluminescence and scintillation properties of Cu-doped LiCl single crystals synthesized by the Bridgman-Stockbarger method were evaluated. Under UV and X-ray irradiation, two emission bands were observed at 325 and 400 nm, and these emissions would be due to 3d94s1-3 d10 transition of Cu+ and Cu+ perturbed by near OH−, respectively. From pulse height spectra under 252Cf neutron irradiation, the 0.1% Cu-doped sample showed the highest light yield (LY) of 5600 photons/neutron among all the samples and the energy resolution of 8.3 %. The LY and the energy resolution of 0.1% Cu-doped LiCl single crystal were comparable with those of commercial Li-glass (GS20). Furthermore, Cu-doped LiCl was not sensitive to γ-ray, and neutron-γ discrimination performance of 0.1% Cu-doped LiCl single crystal was better than that of GS20. • Photoluminescence and scintillation properties of Cu-doped LiCl single crystals were evaluated. • Under UV and X-ray irradiation, an emission peak due to 3d94s1-3d10 transition of Cu+ was observed at 325 nm. • The light yield and energy resolution of 0.1% Cu-doped LiCl single crystal under 252Cf irradiation were comparable with those of commercial Li-glass (GS20). • The neutron-γ discrimination performance of 0.1% Cu-doped LiCl single crystal was better than that of GS20. [ABSTRACT FROM AUTHOR]

Radio-photoluminescence (RPL) phenomenon was observed in CaF 2 transparent and opaque ceramics by X-ray irradiation. The RPL appeared as a formation of photoluminescence (PL) emission bands located around 660 and 720 nm caused by F 2 + and (F 2 +) A centers, respectively. The RPL signal can be deleted by heating, and reusability was observed over ten experimental cycles. The fading of the RPL signal was confirmed to be ~4% in 10 days. The detectable RPL response of CaF 2 transparent ceramics was as low as 1 mGy, and the dynamic ranges were confirmed over 1–10000 mGy with linear response. Image 1 • Radio-photoluminescence (RPL) phenomenon was observed in CaF 2 transparent and opaque ceramics by X-ray irradiation. • The RPL signal can be deleted by heating, and reusability was observed over ten experimental cycles. • The sensitivity of CaF 2 transparent ceramics as RPL dosimeters was confirmed 1 mGy. [ABSTRACT FROM AUTHOR]

Magnetic fields play such roles in star formation as the angular momentum transport in star-forming clouds, thereby controlling circumstellar disc formation and even binary star formation efficiency. The coupling between the magnetic field and gas is determined by the ionization degree in the gas. Here, we calculate the thermal and chemical evolution of the primordial gas by solving chemical reaction network where all the reactions are reversed. We find that at ∼1014–1018 cm−3, the ionization degree becomes 100–1000 times higher than the previous results due to the lithium ionization by thermal photons trapped in the cloud, which has been omitted so far. We construct the minimal chemical network which can reproduce correctly the ionization degree as well as the thermal evolution by extracting 36 reactions among 13 species. Using the obtained ionization degree, we evaluate the magnetic field diffusivity. We find that the field dissipation can be neglected for global fields coherent over ≳ a tenth of the cloud size as long as the field is not so strong as to prohibit the collapse. With magnetic fields strong enough for ambipolar diffusion heating to be significant, the magnetic pressure effects to slow down the collapse and to reduce the compressional heating become more important, and the temperature actually becomes lower than in the no-field case. [ABSTRACT FROM AUTHOR]

Pr-doped CaWO 4 single crystals with dopant concentrations of 0.05–1% were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Emissions due to the 4f–4f transitions of Pr3+ were observed in visible–near-infrared ranges under visible light and X-ray irradiation. The X-ray-induced scintillation decay times were typical values of the transitions of Pr3+ when monitored at 380–900 nm. The afterglow levels when 20 ms passed after X-ray irradiation were calculated to be 573–730 ppm and increased as the dopant concentrations increased. In the integration-type scintillation detector property, 0.05, 0.1, and 0.5% Pr-doped samples showed good linearity between X-ray exposure dose rate and scintillation signals from 0.05 to 5 Gy/h. • Emissions due to 4f–4f transitions of Pr3+ appeared at visible–NIR ranges under visible light and X-ray irradiation. • The scintillation decay times were typical values of the transitions of Pr3+ when monitored at 380–900 nm. • Pr-doped CaWO 4 showed good linearity between X-ray exposure dose rate and scintillation signals. [ABSTRACT FROM AUTHOR]

The optical, radioluminescence and thermoluminescence properties of Eu-doped BaSi 2 O 5 glass-ceramics were evaluated. The glass samples were synthesized by the conventional melt-quenching technique using a carbon crucible under reductive condition and heat-treated at different temperatures. The samples exhibit photoluminescence and radioluminescence with a broad emission due to Eu2+, and the observed emission peaks are blue-shifted in the crystallized samples. The decay time constants are the typical values of the 5d-4f transitions of Eu2+. The glass sample shows no clear thermoluminescence glow peak while the glass-ceramic samples show an intense thermoluminescence glow peak around 180 °C. The thermoluminescence intensity monotonically increases with the irradiated X-ray dose, which covers from 0.01 to 1000 mGy. [ABSTRACT FROM AUTHOR]

Abstract We synthesized Y 2 O 3 -Al 2 O 3 -SiO 2 glasses doped with various concentrations of Ce (0, 0.03%, 0.10%, 0.30%, and 1.00%). The glasses were obtained by melt-quenching using an IR mirror furnace, and then they were studied in terms of their optical, dosimetric and scintillation properties. The obtained samples indicated photoluminescence (PL) and scintillation due to the 5d–4f transitions of Ce3+ characterized as a broad emission peaking around 350 nm. The PL and scintillation decay times were 35.4–38.1 ns and 47–109 ns, respectively. The 0.10% Ce-doped sample showed the highest PL quantum yield (20%) among the synthesized samples. The quantum yield was well-correlated with the decay time of PL and scintillation. Thermally- and optically-stimulated luminescence were observed after the irradiation of X-rays (10 Gy). The thermally- and optically-stimulated luminescence spectra were confirmed that the luminescence was due to the 5d–4f transitions of Ce3+ in the 0.03% and 0.10% Ce-doped samples. Overall, the samples showed sensitive response of thermally-stimulated luminescence, and it was the highest for the 0.10% and 0.30% Ce-doped samples, having the dynamic range from 0.01 mGy to 1 Gy. Highlights • Ce-doped Y 2 O 3 -Al 2 O 3 -SiO 2 glasses were successfully synthesized by the floating zone furnace. • Scintillation, PL and TSL emissions were predominantly due to the 5d-4f transitions of Ce3+. • Ce-doped Y 2 O 3 -Al 2 O 3 -SiO 2 glasses showed sensitive TSL response to X-ray dose. • Dynamic range as TSL dosimeter was confirmed to be at least 0.01 mGy–1 Gy. [ABSTRACT FROM AUTHOR]

Undoped, Zr-doped and Ti-doped La 2 Hf 2 O 7 single crystals were grown by the optical floating zone technique to evaluate the scintillation properties. The synthesized single crystals show scintillation signals with a broad peak around 450 nm. The scintillation decay curves indicate the decay time constants are in nanoseconds order. Suggested from the pulse height spectra under 241Am alpha-ray irradiation, the scintillation light yields of the undoped, Zr-doped and Ti-doped crystal samples are 270, 180 and 390 photons/MeV. From these results, Ti-doping seems to enhance the scintillation properties of a La 2 Hf 2 O 7 crystal. • Undoped, Zr-doped and Ti-doped La2Hf2O7 single crystals were grown by the optical floating zone technique. • The synthesized single crystals show scintillation signals with a broad peak around 450 nm. • Ti-doping improves the scintillation and afterglow properties of La2Hf2O7. [ABSTRACT FROM AUTHOR]

Abstract Ce- and Eu-doped Ca 2 MgSi 2 O 7 (CMSM) single crystals were synthesized by the Floating Zone method. From the X-ray diffraction patterns, we confirmed that all the CMSM samples have no impurity phases. Under X-ray irradiation, the Ce- and Eu-doped CMSM samples showed scintillation with a broad emission around 390 nm and 530 nm, respectively. The origin of these emissions was considered to be the 5d-4f transitions of Ce3+ and Eu2+, respectively. The absolute light yield of the Eu-doped CMSM sample was 11,000 ph/MeV evaluated under 241Am γ-ray (59.5 keV). In addition, afterglow properties of the Ce- and Eu-doped samples were consistent with the corresponding thermoluminescence properties. Highlights • Ce- and Eu- doped Ca2MgSi2O7 crystals were synthesized by the Floating Zone method. • Ce-doped and Eu-doped crystals showed a broad emission around 400 nm and 530 nm, respectively. • Scintillation light yield was 11,000 ph/MeV for 1% Eu-doped crystal. [ABSTRACT FROM AUTHOR]

Abstract We have investigated radioluminescence and thermoluminescence (TL) properties of the Nd-doped LiCaAlF 6 single crystal. The sample showed the radioluminescence peaks originating from both the 5d-4f and 4f-4f transitions of the Nd3+ ion. The luminescence of Nd-doped LiCaAlF 6 single crystal is detectable with the photodetectors having a sensitivity in the wavelength from the VUV to visible range. The TL intensity monotonically increased as a function of X-ray dose from 100 mGy to 10 Gy. The Nd-doped LiCaAlF 6 single crystal has an advantage in high-dose dosimetry applications. [ABSTRACT FROM AUTHOR]

Abstract Eu-doped Ba x Sr 1- x Al 2 O 4 (x = 0, 0.1, 0.3 and 0.5) single crystals were synthesized by the floating zone method and then characterized for scintillation applications. All the crystal samples exhibit photoluminescence and scintillation with a broad emission around 510 nm. The decay time constants of the latter emission are typical for the 5d-4f transitions of Eu2+. From the pulse height spectra measured under 137Cs gamma-ray, the estimated light yields of Eu:SrAl 2 O 4 , Eu:Ba 0.1 Sr 0.9 Al 2 O 4 Eu:Ba 0.3 Sr 0.7 Al 2 O 4 , and Eu:Ba 0.5 Sr 0.5 Al 2 O 4 crystal samples are 42,000, 30,000, 22,000 and 20,000 photons/MeV, respectively. The observed light yields are notably high, and the fact indicates that Eu:Ba 0.5 Sr 0.5 Al 2 O 4 crystals are good candidates of scintillator materials for gamma-ray measurements. Graphical abstract Image 1 Highlights • Eu-doped (Ba,Sr)Al 2 O 4 single crystals were synthesized by the floating zone method. • The samples exhibit PL and scintillation with a broad emission around 510 nm. • From pulse height spectra, the light yields of Eu:SrAl 2 O 4 and Eu:Ba 0.5 Sr 0.5 Al 2 O 4 crystals are 42,000 and 20,000 photons/MeV. [ABSTRACT FROM AUTHOR]

Abstract Eu-doped SrAl 12 O 19 , SrAl 4 O 7 , Sr 4 Al 14 O 25 and SrAl 2 O 4 bulk crystals were successfully synthesized by the floating zone method. The samples exhibit photoluminescence and scintillation with an intense broad emission due to the 5d-4f transitions of Eu2+ in the visible range, and Eu:SrAl 12 O 19 shows additional several sharp emissions owing to Eu3+. The Eu2+ emission blue-shifts as the Al-ratio increases. Pulse height spectrum measurements under 137Cs γ-ray irradiation demonstrated a clear photoabsorption peak, in which the scintillation light yields were estimated to be 6,900 (Eu:SrAl 12 O 19), 700 (Eu:SrAl 4 O 7), 6,500 (Eu:Sr 4 Al 14 O 25) and 42,000 (Eu:SrAl 2 O 4) photons/MeV. [ABSTRACT FROM AUTHOR]

Shocks may have been prevalent in the early Universe, associated with virialization and supernova explosions, etc. Here, we study thermal evolution and fragmentation of shock-compressed clouds, by using a one-zone model with detailed thermal and chemical processes. We explore a large range of initial density (1–105 cm−3), metallicity (0–10−2 Z⊙), UV strength (0–500 times Galactic value), and cosmic microwave background temperature (10 and 30 K). Shock-compressed clouds contract isobarically via atomic and molecular line cooling, until self-gravitating clumps are formed by fragmentation. If the metals are only in the gas-phase, the clump mass is higher than ∼3 M⊙ in any conditions we studied. Although in some cases with a metallicity higher than ∼10−3 Z⊙, re-fragmentation of a clump is caused by metal-line cooling, this fragment mass is higher than ∼30 M⊙. On the other hand, if about half the mass of metals is condensed in dust grains, as in the Galactic interstellar medium, dust cooling triggers re-fragmentation of a clump into subsolar mass pieces, for metallicities higher than ∼10−5 Z⊙. Therefore, the presence of dust is essential in low-mass (≲ M⊙) star formation from a shock-compressed cloud. [ABSTRACT FROM AUTHOR]

Undoped and Ce-doped Sr 2 Al 2 SiO 7 bulk crystals with different concentrations of Ce were synthesized by the floating zone method. Under X-ray irradiation, the both undoped and Ce-doped samples show scintillation with broad emission with decay time constants of approximately 30 and 300 ns. By utilizing photoluminescence (PL) techniques, we attributed the origin of the former emission component is due to the 5d-4f transitions of Ce 3+ while the one of the latter emission is due the host. The scintillation afterglow levels depends on the concentration of Ce and are on an order of ppm. From the pulse height spectrum measured under 241 Am 59.5 keV γ-ray irradiation, the 0.3% Ce-doped Sr 2 Al 2 SiO 7 crystal was revealed to show the absolute scintillation light yield of 1100 ph/MeV, which is the highest among the present samples. In addition, the Ce-doped samples show TL properties with a glow peak at 250 °C and a shoulder around 130 °C. [ABSTRACT FROM AUTHOR]

Tl-doped (0.1, 0.3, 1, and 3%) KI single crystals were synthesized, and photoluminescence and scintillation characteristics of KI:Tl were evaluated. An emission peak at ∼420 nm was observed under ∼300 nm excitation in all the samples. All the synthesized samples exhibited a peak at 420–440 nm and a tail emission at ∼350 nm under X-ray irradiation. These origins would be 3P 1 →1S 0 transitions of Tl+ (420–440 nm) and the off-center configuration of the self-trapped excitons (∼350 nm), respectively. According to pulse height spectra under γ-ray irradiation, scintillation light yield (LY) and the energy response were investigated. The 0.3% KI:Tl showed the highest LY of 7,300 photons/MeV among the prepared samples and ∼11% energy resolution under 137Cs γ-ray (662 keV) irradiation. The energy response of the 0.3% KI:Tl illustrated a good linearity against γ-ray energies from 22 to 1,408 keV. • Tl-doped KI single crystals were grown by the vertical Bridgman-Stockbarger method. • A broad emission band due to Tl+ and the self-trapped excitons were observed at ∼420 nm. • The 0.3% KI:Tl shows the scintillation light yield of 7300 photons/MeV. • The sample shows proportional response in the dynamic range from 22 to 1408 keV. [ABSTRACT FROM AUTHOR]

Ce-doped Lu 2 O 3 –Al 2 O 3 –SiO 2 glasses were prepared using a xenon image furnace and their physical, optical, and scintillation properties were investigated. The photoluminescence (PL) properties were discussed based on the variations in the coordination environment of the different glass compositions. The characteristic shifts of PL spectra were explained in terms of (i) effects of crystal field due to the presence of different coordination environments which Ce3+ can take and (ii) effects of self-absorption due to the increase in Ce4+ based on the results of Raman spectra, transmission spectra, and PL lifetimes. The PL quantum yield (QY) tends to be higher for specimens with the emission peak located on the relatively shorter wavelength side, i.e., those with significant Ce3+ in the 6-coordinated environment and low Ce4+ content. This tendency also affects scintillation properties, with both scintillation spectral intensity and light yield under γ-ray irradiation showing characteristics that correlate positively with PL QY. [ABSTRACT FROM AUTHOR]

Sn-doped Ga 2 O 3 single crystals were synthesized by the Floating Zone (FZ) method. In photoluminescence (PL) under the excitation wavelength of 280 nm, we observed two types of luminescence: (1) defect luminescence due to recombination of the donor/acceptor pairs which appears at 430 nm and (2) the nsnp-ns 2 transitions of Sn 2+ which appear at 530 nm. The PL and scintillation decay time curves of the Sn-doped samples were approximated by a sum of exponential decay functions. The faster two components were ascribed to the defect luminescence, and the slowest component was owing to the nsnp-ns 2 transitions. In the pulse height spectrum measurements under 241 Am α-rays irradiation, all the Sn-doped Ga 2 O 3 samples were confirmed to show a full energy absorption peak but the undoped one. Among the present samples, the 1% Sn-doped sample exhibited the highest scintillation light yield (1,500 ± 150 ph/5.5 MeV-α). [ABSTRACT FROM AUTHOR]

Undoped and Ce-doped Ca 2 Al 2 SiO 7 single crystals with different Ce concentrations were prepared by the floating zone method. From the X-ray diffraction patterns, we confirmed that all the grown crystals have no impurity phases. The undoped sample shows scintillation induced by X-rays, and the spectrum consists of two broad emission bands peaking at 350 and 400 nm. The decay curve appeared to consist of only single exponential decay with the decay constant of 51 ns. In contrast, Ce-doped samples show a broad scintillation peaking around 400 nm, in which the decay curve consists of two exponential decay functions with the decay times of approximately 30 and 100 ns. From the pulse height spectra measured using the present samples under 241 Am 59.5 keV γ-ray irradiation, we confirmed that the 0.3% Ce-doped sample exhibits the highest absolute scintillation light yield of 16,000 ph/MeV. The samples also exhibit thermoluminescence (TL). The glow curves appear to have a broad feature with the peak temperature from 100 to 500 °C for undoped and from 50 to 400 °C for Ce-doped samples. Among the present samples, the 0.3% Ce-doped sample shows the highest sensitivity, and a linear response to the irradiation dose was confirmed in the dose range of 0.01–100 mGy. [ABSTRACT FROM AUTHOR]

We investigated the photoluminescence (PL), radioluminescence (RL) and thermally-stimulated luminescence (TSL) properties of Pr:CaSiO 3 crystals grown by the floating zone method. In both the PL and RL spectra, a broad emission band are observed around 300 nm due to the 5d-4f transitions of Pr 3+ , whose decay time constants are 16–20 ns and 140–260 ns. In TSL, multiple glow peaks are observed over 50–250 °C, and the response intensity increases linearly proportional to the X-ray dose. [ABSTRACT FROM AUTHOR]

We have investigated thermally-stimulated luminescence (TSL) properties of Ce-doped LiCaAlF 6 crystals irradiated with ionizing radiations of different linear energy transfers (LET) – X-rays and He ion beams. It was found that the TSL glow peaks mainly appeared around 120 and 250–400 °C, and the ratio of the former peak intensity to the latter was found to decrease with increasing the LET. Furthermore, together with the TSL properties measured with X-rays, diffusion length of electron-hole pairs was estimated to lie in a range of 30–120 nm depending on the LET and concentration of Ce. [ABSTRACT FROM AUTHOR]

Optical, radioluminescence (RL) and thermoluminescence (TL) properties of magnesium aluminoborate glasses were evaluated. The samples were synthesized by the conventional melt-quenching technique using an alumina crucible under ambient atmosphere. After polishing, all the samples show good transparency. In photoluminescence, RL and TL, the emission is predominantly due to the 5d-4f transitions of Ce 3+ appearing as a broad feature peaking around 300–500 nm, and the decay time constants are affected by concentration quenching but on the typical range for the 5d-4f transitions of Ce 3+ . TL glow curves are characterized as a single but broad glow peak over 100–300 °C, and the TL intensity monotonically increases with the X-ray dose irradiated over 1–10000 mGy. [ABSTRACT FROM AUTHOR]

Tb 3 Al 5 O 12 (TbAG) crystalline materials doped with different concentrations of Ce were prepared by the floating zone (FZ) method to evaluate their basic optical and scintillation properties. In photoluminescence (PL), a broad emission due to the 5d-4f f transition of Ce 3+ appeared around 550 nm, and the decay time was approximately 40 ns. Under X-ray irradiation, the scintillation due to the 5d-4f transition of Ce 3+ was also observed around 550 nm, but the decay time appeared to be much longer 376–599 ns than that of PL and it depended on the concentration of Ce. The pulse height spectroscopy analyses revealed that 3.0% Ce-doped TbAG showed the highest light yield of 30,100 ph/MeV under 137 Cs γ -ray irradiation among the samples investigated in this work. [ABSTRACT FROM AUTHOR]

Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were grown by the xenon lamp equipped floating zone method. The synthesized crystals were in the single phase of SHO crystal structure, and no impurity phases such as HfO 2 were evident by the X-ray diffraction analysis. The Ce:SHO shows blue luminescence peaking at 410 nm in both the PL and scintillation spectra, and the decay time constant was approximately 14 ns. The PL QY increases with the Ce concentration, which was confirmed up to 5%. The afterglow level is the lowest when the Ce concentration is 3%. The full energy peak can be demonstrated with all the Ce:SHO single crystals prepared in this study under 241Am alpha-ray irradiation, and the estimated light yield is 396 photons/MeV for the 3% Ce:SHO, which is the highest among the samples studied. • Transparent and yellowish Ce-doped SrHfO 3 (Ce:SHO) single crystals were synthesized by the xenon lamp equipped floating zone method. • Ce:SHO showed blue luminescence with the maximum peak at 410 nm in both the photoluminescence and X-ray-induced scintillation spectra. • The full energy peak was observed in all the Ce:SHO single crystals under 241Am alpha-ray irradiation. [ABSTRACT FROM AUTHOR]

The single crystals of 0, 0.6, 1, 1.6 and 2 mol% Ce doped CaGdAl 3 O 7 (Ce:CGAM) were grown by the Floating Zone method, and investigated on photoluminescence (PL) and scintillation properties. In the PL spectra, a broad emission appeared over 380–500 nm under 280 and 360 nm excitations with the quantum yield of 33.8–38.8%. Under a vacuum ultraviolet excitation (90 nm) using a synchrotron source, non-doped CGAM single crystal showed broad emissions over 250–650 nm. The PL decay time profiles followed a monotonic exponential decay with a decay time constant of around 33 ns. The scintillation spectra were similar to those of PL. All of the samples exhibited a clear photoabsorption peak and Compton edge in the pulse height spectra measured under 137 Cs γ-ray irradiation, and the absolute scintillation light yield (LY) was highest for the 2% Ce-doped sample with the value of 3300±300 ph/MeV. The scintillation decay profiles were approximated by a third order exponential decay function, and the extracted decay time of Ce 3+ emission component was around 36–44 ns. Among all the samples, 2%Ce:CGAM single crystal sample showed the best afterglow level as a scintillator under X-ray irradiation. [ABSTRACT FROM AUTHOR]

We have investigated the photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimeter properties of Pr-doped 12CaO·7Al 2 O 3 (Pr:C12A7) crystals prepared by the floating zone (FZ) method. In PL emission and excitation spectral measurements, some emission bands around 600–650 and 850–950 due to the 4f-4f transitions of Pr 3+ were observed under excitation at 450–500 nm. The decay time constants of these emissions were approximately 78 μs. The scintillation spectra showed the 4f-4f transition related emissions of Pr 3+ at similar wavelengths with those in PL. The scintillation decay time constants of Pr-doped samples except 0.1% Pr-doped one were around 50 μs, and the latter value was shorter than those of PL. In contrast, the 0.1% Pr-doped sample showed the scintillation decay time constant about 80 μs. The PL quantum yield of 0.5% Pr:C12A7 crystal was the highest among the present samples. After X-ray irradiations, the 0.5, 1.0 and 2.0% Pr-doped samples showed intense and broad TSL glow peak around 95 °C while the undoped and 0.1% Pr-doped samples showed no significant signal. [ABSTRACT FROM AUTHOR]

We investigated photoluminescence, scintillation and dosimeter properties of (Y 1- x Eu x )AlO 3 ( x = 0.001, 0.5 and 1) single crystals (hereafter denoted as Eu:YAP for x = 0.001, EYAP for x = 0.5 and EAP for x = 1). The samples were prepared by the Floating Zone method. In photoluminescence (PL), we observed a broad emission around 300–400 nm due to host under excitation of 280 nm, and emissions due to the 4f state transitions of Eu 3+ appeared around 590 nm and 615 nm. Scintillation spectra also show emission peaks around 590 and 615 nm due to the 4f state transitions of Eu 3+ in all the samples. In addition, emissions around 300–400 nm due to YAP host and around 550–700 nm due to 5d-4f transitions of Eu 2+ appeared in Eu:YAP. The PL and scintillation decay time profiles consisted of several exponential decay components. The fast (ns) component group was possibly due to host emission, and especially Eu:YAP demonstrated a very fast PL decay time of 16 ns. The intermediate (μs) component group was due to the 5d-4f transitions of Eu 2+ . The slow (ms) component group was ascribed to the 4f state transitions of Eu 3+ ion. The Eu:YAP sample showed intense thermally-stimulated luminescence (TSL) with peaks at 46, 155, 255 and 443 °C. The intensity was much higher than those of EAP and EYAP. In particular, the peak at 254 °C, which showed the highest intensity, was due to doping with Eu. The TSL dose response function showed a good linearity (R 2 > 0.99) over a wide dose range from 0.1 mGy to 100 mGy for Eu:YAP, which showed the highest sensitivity among the present samples. [ABSTRACT FROM AUTHOR]

(C 6 H 5 C 2 H 4 NH 3) 2 PbBr 4 single crystals substituted with various concentrations of In (5, 10, 25, and 50%) were grown by the solvent diffusion method, and the effect of In-substitution on photoluminescence (PL) and scintillation properties were investigated. PL and scintillation peaks due to excitons confined in inorganic layers were observed, and the decay times were consistent with those of the free excitonic luminescence. The photoluminescence quantum yields of the 5, 10, 25, and 50% In-substituted crystals were respectively 23.0, 24.7, 26.0, and 25.2%. The light yield of the 25% In-substituted crystal was estimated to be 14100 photons/MeV from the pulse height spectrum under 137Cs γ-rays irradiation. • In:(C 6 H 5 C 2 H 4 NH 3) 2 PbBr 4 crystals were grown by the solvent diffusion method. • Free excitonic luminescence was observed. • Light yield of the 25% In-substituted crystal was 14,100 photons/MeV. [ABSTRACT FROM AUTHOR]

Eu-doped SrAl 2 O 4 (Eu:SrAl 2 O 4 ) crystals are prepared by a floating zone (FZ) method. In photoluminescence (PL), an intense broad emission peak around 510 nm due to 5d-4f transition of Eu 2+ appear under excitation at 250–450 nm. The PL decay time constants are about 800 ns due to the 5d-4f transitions of Eu 2+ . In the nondoped sample, emission peaks around 480 and 560 nm are observed upon excitation at 316 nm. The X-ray induced scintillation spectra also show an intense broad emission peak around 510 nm, and the decay time constants are approximately 500 ns. In the pulse height spectra of the 2.5% Eu:SrAl 2 O 4 crystal, the absolute light yield is ~46,000 ph/MeV. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 120 and 400 °C. In optically stimulated luminescence (OSL) after X-ray irradiation, emission peaks are observed around 510 nm while exposing the samples to the stimulation light at 800 nm. [ABSTRACT FROM AUTHOR]

Eu-doped MgAl 2 O 4 transparent ceramics were synthesized by the spark plasma sintering technique as a new dosimetric material. The MgAl 2 O 4 ceramics doped with Eu had the diffuse transmittance of 40–60% at longer wavelengths than 500 nm. The 0.01% Eu-doped MgAl 2 O 4 showed the photoluminescence (PL) emission peak at 500 nm under the excitation at 300 nm, while the 0.1% Eu-doped MgAl 2 O 4 clearly showed the PL emission peak at 600 nm under the excitation at 400 nm. These PL were due to 5d-4f transitions of Eu2+ ions and decayed within a few microseconds. The Eu-doped MgAl 2 O 4 exhibited TSL glow peaks at 70, 250, 300, and 440 °C. The relative TSL intensity decreased to 95% within 1 day and was stable for 5 days. The TSL intensity of the 0.01 and 0.1% Eu-doped MgAl 2 O 4 was detectable from 0.01 mGy and increased up to 1000 mGy with a linear relation. • Transparent ceramics of Eu-doped MgAl 2 O 4 were synthesized by the spark plasma sintering method. • Eu-concentration dependence on optical and dosimetric properties were investigated. • The optimal concentration turned out to be 0.1% for the TSL intensity. [ABSTRACT FROM AUTHOR]

Hafnium-based materials are attractive for a scintillator owing to their high density and effective atomic number. In this study, single crystals of Ce-doped calcium hafnate perovskite (Ce:CaHfO 3) were synthesized from a Ca-rich composition, and photoluminescence (PL) and scintillation properties were investigated. The X-ray diffraction patterns revealed that the synthesized single crystals were a single phase of CaHfO 3. The Ce:CaHfO 3 exhibited blue luminescence at 430 nm and fast decay due to the 5d–4f transition of Ce3+ in both PL and scintillation. From the measurement of pulse height spectra under 137Cs irradiation, the highest light yield of 7800 photons/MeV was observed in the 3% Ce:CaHfO 3. • Single crystals of Ce-doped calcium hafnate perovskite (Ce:CaHfO 3) were successfully synthesized from a Ca-rich composition. • Ce:CaHfO 3 exhibited blue luminescence and fast decay due to the 5d–4f transition of Ce3+ in both PL and scintillation. • The light yield of 7800 photons/MeV was observed in the 3% Ce:CaHfO 3 under 137Cs gamma-ray irradiation. [ABSTRACT FROM AUTHOR]

In this study, we synthesized Dy-doped CaF 2 transparent ceramics with several concentrations and evaluated optical, thermally stimulated luminescence (TSL), and optically stimulated luminescence (OSL) properties. The 0.05, 0.1, and 0.5% Dy-doped samples had diffuse transmittance of approximately 60% at 500 nm, and the absorption band appeared at around 280 nm after X-ray irradiation. The photoluminescence (PL) excitation wavelengths were 255, 295, 325, 350, 360, and 390 nm. When Dy concentration was 0.1%, the PL quantum yield was maximum. The OSL peaks of the Dy-doped samples was observed at 480, 570, and 660 nm by the optical stimulation at 280 nm. The TSL glow curves of the 0.5 and 1.0% Dy-doped samples consisted of the glow peaks at 75, 160, and 200 °C. The minimum detectable dose of the 0.5% Dy-doped sample as the OSL and TSL dosimeters was 15 mGy and 0.28 μGy, respectively. • Transparent ceramics of Dy-doped CaF 2 were synthesized by the spark plasma sintering method. • Dy-concentration dependence on dosimetric properties were investigated. • The optimal concentration turned out to be 00.5% for the OSL and TSL intensities. [ABSTRACT FROM AUTHOR]

In this study, Ce-doped SrAl 2 O 4 (Ce:SrAl 2 O 4 ) crystals were prepared by a floating zone (FZ) method and experimental evaluations were performed for scintillator applications. In photoluminescence (PL) with an excitation around 320 nm, an intense broad emission peak appears around 380 nm due to the 5d-4f transitions. The PL decay time constants are approximately 30 ns. The X-ray induced scintillation spectrum also shows an intense broad emission peak around 380 nm. Among the samples evaluated with different concentrations of Ce, the absolute light yield under 137 Cs is considerably high (∼3900 ph/MeV) when the concentration of Ce is 1.0%. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 110, 210 and 330 °C. The samples also shows optically stimulated luminescence (OSL) after X-ray irradiation, in which the emission appears around 380 nm due to the 5d-4f emission bands of Ce 3+ while the samples is exposed to the stimulation light at 655 nm. [ABSTRACT FROM AUTHOR]

We investigated the scintillation and dosimeter properties of yttria stabilized zirconia (YSZ, Y 2 O 3 –ZrO 2 ) crystal. It showed 70–80% in-line transmittance at wavelength longer than 300 nm. Under excitations around the bandgap energy, several intense photoluminescence (PL) emission peaks appeared at 450, 550, 570 and 600 nm, and the PL decay time constants were 5.5 and 20.7 ns. In the X-ray induced scintillation spectrum, an intense emission peak around 450 nm was observed, and the scintillation decay time constants were 14.4 and 169.8 ns. After irradiations with X-rays, thermally stimulated luminescence (TSL) glow peaks appeared at 100, 200 and 450 °C. Also, after X-ray irradiations, optically stimulated luminescence (OSL) was detected around 500 nm with 650 nm stimulation. [ABSTRACT FROM AUTHOR]

Tellurite glass (TeG) and its glass-ceramics (TeGC435 and TeGC455), with a composition of 10Eu 2 O 3 –10BaO–80TeO 2 , were prepared and their luminescence properties were evaluated. TeG was prepared via the melt quenching technique, while TeGC435 and TeGC455 were fabricated by heat treating TeG at 435 and 455 °C, respectively, for 5 h each. The Eu 2 Te 6 O 15 crystal phase was formed in TeGC435 and TeGC455. Both the glass and glass-ceramics showed sharp photoluminescence and scintillation peaks, attributed to the 4f→4f transitions of Eu3+. The highest quantum yield was obtained for TeG, whereas the highest integrated scintillation intensity was obtained for TeGC455. The scintillation intensity of TeGC455 was approximately 10% of that of the Bi 4 Ge 3 O 12 single crystal. Furthermore, typical decay times derived from the 4f→4f transitions were obtained for TeG, TeGC435, and TeGC455 during photoluminescence and scintillation. [ABSTRACT FROM AUTHOR]

Translucent ceramics of undoped and Eu-doped NaMgF 3 were synthesized by the spark plasma sintering method. Their optical, scintillation, thermally stimulated luminescence (TSL), and optically stimulated luminescence (OSL) properties were examined. In photoluminescence and scintillation spectra, Eu-doped NaMgF 3 mainly showed the emission peaks at 360 and 375 nm, ascribed to 4f-4f and 5d-4f transitions of Eu2+, respectively. The TSL glow curve consists of the glow peaks at 94, 132, 166, 203, 249, 316, and 377 °C. The OSL signal could be detected by stimulation at 415 nm. The dominant luminescence center in TSL and OSL processes was Eu2+ ions, showing the emission peaks at 360 and 375 nm. The Eu-doped NaMgF 3 had linear TSL and OSL responses from an irradiation dose of 0.01 mGy. • Translucent ceramics of undoped and Eu-doped NaMgF 3 were synthesized by the spark plasma sintering method. • The photoluminescence quantum yield, TSL, and OSL are largest for 0.5–1% Eu. • The TSL is linear from 0.01 to 100 mGy, and the OSL is linear from 0.01 to 1000 mGy. [ABSTRACT FROM AUTHOR]

As an investigation of Lu-based scintillators, the 0.05, 0.1, 0.5, and 1.0% Pr:SrLu 2 O 4 single crystals were synthesized by the floating zone method. Pr:SrLu 2 O 4 exhibited the broad and sharp luminescence peaks due to the 5d–4f and 4f–4f transitions of Pr3+, respectively. Pr:SrLu 2 O 4 showed fast decay time constant of ∼18 ns due to the 5d–4f transition of Pr3+. The 0.05 and 0.1% Pr:SrLu 2 O 4 exhibited clear photoabsorption peak under 137Cs gamma-ray irradiation. The 0.1% Pr:SrLu 2 O 4 exhibited the highest quantum yield, luminescence intensity, and light yield among the samples. • Pr:SrLu 2 O 4 exhibited the broad and sharp luminescence peaks due to the 5d–4f and 4f–4f transitions of Pr3+, respectively. • Pr:SrLu 2 O 4 exhibited the broad emission bands at 320 and 360 nm with fast decay time constants of about 18–19 ns. • The PL decay time constants, QY , and light yield loosely depended on concentration of Pr. • The 0.1% Pr:SrLu 2 O 4 exhibited the best QY of 18.4% and light yield of 2100 photons/MeV among the samples. [ABSTRACT FROM AUTHOR]

HD dominates the cooing of primordial clouds with enhanced ionization, e.g. shock-heated clouds in structure formation or supernova remnants, relic H ii regions of Pop III stars and clouds with cosmic ray (CR) irradiation. There, the temperature decreases to several 10 K and the characteristic stellar mass decreases to ∼10 M⊙, in contrast with first stars formed from undisturbed pristine clouds (∼100 M⊙). However, without CR irradiation, even weak far-ultraviolet (FUV) irradiation suppresses HD formation/cooling. Here, we examine conditions for HD cooling in primordial clouds including both FUV and CR feedback. At the beginning of collapse, the shock-compressed gas cools with its density increasing, while the relic H ii region gas cools at a constant density. Moreover, shocks tend to occur in denser environments than H ii regions. Owing to the higher column density and the more effective shielding, the critical FUV intensity for HD cooling in a shock-compressed gas becomes ∼10 times higher than that in relic H ii regions. Consequently, in the shock-compressed gas, the critical FUV intensity exceeds the background level for most of the redshift we consider (6 ≲ z ≲ 15), while in relic H ii regions, HD cooling becomes effective after the CR intensity increases enough at z ≲ 10. Our result suggests that less massive (∼10 M⊙) Pop III stars may be more common than previously considered and could be the dominant population of Pop III stars. [ABSTRACT FROM AUTHOR]

We fabricated organic–inorganic perovskite nanocrystals in nanoporous glasses (OIPiG) where (C6H5C2H4NH3)2PbBr4 (Phe) was incorporated into about 4 nm diameter pores and evaluated their photoluminescence and scintillation properties, compared with the Phe single crystal. Both the samples showed emissions due to the recombination of free excitons in the inorganic layer under 280 nm excitation light. In scintillation, a weak and broad scintillation peak possibly due to the free excitons and bound excitons was observed in the OIPiG, while the Phe single crystal showed efficient scintillation due to free exciton emissions with a peak approximately at 435 nm. The scintillation decay time constant (4.4 ns) due to the free excitons for the OIPiG was found to be faster than that (6.6 ns) for the Phe single crystal. In addition, the afterglow levels were confirmed to be 340 ppm for the OIPiG and 20 ppm for the Phe single crystal. The afterglow level of the OIPiG was higher than that of the Phe single crystal but was almost equivalent to that for the commonly used inorganic scintillator CsI:Tl. [ABSTRACT FROM AUTHOR]

Long gamma-ray bursts (LGRBs) have a typical duration of ∼30 s, and some of them are associated with hypernovae, such as Type Ic SN 1998bw. Wolf-Rayet stars are the most plausible LGRB progenitors, since the free fall time of the envelope is consistent with the duration, and the natural outcome of the progenitor is a Type Ic SN. While a new population of ultra-long GRBs (ULGRBs), GRB 111209A, GRB 101225A, and GRB 121027A, has a duration of ∼104 s, two of them are accompanied by superluminous-supernova-like (SLSN-like) bumps, which are ≲ 10 times brighter than typical hypernovae. Wolf-Rayet progenitors cannot explain ULGRBs because of durations that are too long and SN-like bumps that are too bright. A blue supergiant (BSG) progenitor model, however, can explain the duration of ULGRBs. Moreover, SLSN-like bumps can be attributed to the so-called cocoon fireball photospheric emissions (CFPEs). Since a large cocoon is inevitably produced during the relativistic jet piercing though the BSG envelope, this component can be smoking gun evidence of the BSG model for ULGRBs. In this paper, we examine u-, g-, r-, i-, and J-band light curves of three ULGRBs and demonstrate that they can be fitted quite well by our BSG model with the appropriate choices of the jet opening angle and the number density of the ambient gas. In addition, we predict that for 121027A, SLSN-like bump could have been observed for ∼20-80 days after the burst. We also propose that some SLSNe might be CFPEs of off-axis ULGRBs without visible prompt emissions. [ABSTRACT FROM AUTHOR]

Crystals of organic–inorganic layered perovskite-type compounds with a methoxyphenethylamine (nOCH 3 -C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 (n = 2, 3, 4) were synthesized by a temperature gradient method, and their radiation response properties were evaluated for scintillator applications. The perovskite-type compounds with a methoxyphenethylamine exhibited luminescence due to the exciton recombination when excited by ultraviolet light and X-ray. The quantum efficiency (0.12) of the perovskite-type compound with a 4-methoxyphenethylamine was the highest among the fabricated crystals. Furthermore, scintillation light yields of the perovskite-type compounds with a methoxyphenethylamine were evaluated by pulse height spectra using 241Am gamma-ray source. Their obtained yields of (2OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 , (3OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 , and (4OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 crystals were 3600, 6100 and 11,000 photons/MeV, respectively. In addition, fast decay times on the order of a few nanoseconds under X-ray irradiation were observed in the (2OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 (6.7 ns), (3OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 (4.5 ns), and (4OCH 3 –C 6 H 4 C 2 H 4 NH 3) 2 PbBr 4 crystals (6.8 ns) owing to the free exciton recombination. • The organic–inorganic compounds with a methoxyphenethylamine were synthesized by the temperature gradient method. • An emission peak due to exciton emissions with a decay time constant of several nanoseconds was detected. •The scintillation light yield of the compound with a 4-methoxyphenethylamine was about 11,000 photons/MeV. [ABSTRACT FROM AUTHOR]