In this article, we report the absolute production cross-section of 6.13, 6.92 and 7.12 MeV γ-rays from the 16O(p,p'γ)16O reaction for incident proton energy range of 8-16 MeV. Angular distributions of the three γ-rays have been measured for seven angles at 9 MeV proton energy. A detailed phenomenological optical model potential (OMP) was set up to analyse the cross-section data. The OMP parameters were optimised using elastic, polarization and total reaction data available in the literature for protons and neutrons. Low-lying states of 16O were coupled, the optical potential was deformed using deformation parameters, and several resonances were included in the calculations to account for the nuclear structure effects. The potentials so generated have been used to calculate the differential and total cross sections for both 16O(p,p')16O and 16O(p,p'γ)16O reactions. Our calculated cross-sections are in fairly good agreement with our measured data for 6.13, 6.92 and 7.12 MeV γ-rays. However, there still exist discrepancies in reproduction of the finer details of the cross sections. The comparisons of the calculations with the data bring forth the rather complex roles of channel couplings, resonances in the p+16O system and target deformation in the variation of the cross sections with projectile energy. The increased contribution of nuclear structure effects in light mass nuclei, leads to an apparent loss of predictive power of the theoretical calculation, as we approach the low-energy region of less than 10 MeV projectile energy.

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This communication reports the measurement of direct response for fast and thermal neutrons of a newly marketed scintillation crystal LaBr2.85Cl0.15:Ce, along with the widely used LaBr3:Ce and NaI:Tl crystals. It continues our investigation on the possible utility of LaBr2.85Cl0.15:Ce crystal for the detection of high-energy γ-rays and neutrons. This is the first report of the neutron response of the LaBr2.85Cl0.15:Ce crystal. The neutron response was measured for the three detectors using a calibrated Am-Be source, which emits both neutrons and γ-rays. To eliminate the events due to the interaction of the 4.4 MeV γ-ray emitted from Am-Be, the γ-ray response of all three crystals was simulated using the Monte Carlo simulation toolkit GEANT4. Events due to 2.22 MeV γ-ray produced by the capture of thermal neutrons in the paraffin moderator were also eliminated with the aid of simulations. In addition, the response due to fast neutrons was also simulated using GEANT4 and compared with the measured spectrum. This is the first report of the simulation of fast neutron response of LaBr2.85Cl0.15:Ce using GEANT4. The fast neutron detection efficiency of the three detectors has been obtained from the measured spectra.

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This communication reports about complete characterisation of a small volume 1"x1" cylindrical LaBr2.85Cl0.15:Ce crystal supplied by Scionix Inc. for γ-rays up to 4.4 MeV. The various properties of the crystal studied, are, linearity of response for γ-rays, energy resolution up to 4.4 MeV, timing resolutions, quantification of internal activity, and full energy detection efficiencies for γ-rays from 276 to 4439 keV. Monte Carlo simulation toolkit GEANT4 was used to carry out realistic simulations of the detector’s response for γ-rays. Experimental γ-ray energy spectrum was reproduced in the simulations to estimate the full energy detection efficiency for γ-rays and compared with the measured value. We have obtained energy resolution of ~3.8% at 662 keV using 2" ET-9266B PMT biased at −800 V with the energy signal drawn from the 8th dynode. Timing resolutions of 422 and 364 ps were obtained using 2" ET-9807B PMT for 22Na and 60Co, respectively. To the best of our knowledge, this is the first report on the performance of the newly manufactured and marketed LBC crystal. We do not find any significant difference in the performance of LBC from that of a standard Lanthanum Bromide (Ce activated) crystal of similar volume.

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CeBr3 is emerging as one of the best scintillators having properties almost similar to cerium-doped lanthanum halide scintillators. We have measured, for the first time, the intrinsic energy resolution of Compton electrons in a cylindrical 1"×1" CeBr3 detector using the sources, namely, 137Cs, 22Na, and 60Co employing Compton coincidence technique. We have used the PIXIE-4 data acquisition system that makes the measurement setup quite compact. The measurements of intrinsic energy resolution of Compton electrons were made in the energy range of 0.1-1 MeV. The measurements of intrinsic energy resolution of gamma rays were also made, for the comparison. The preliminary results have clearly suggested that δ-ray component is a major contributor to the intrinsic resolution of CeBr3.

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This paper reviews our work on the measurements of absolute production cross sections of γ-rays from the (p,p'γ) reactions on ¹²C and 16O. The measurements cover a range of 8–16 MeV for the incident proton beam. The angular distributions of the γ-rays have been measured. A detailed phenomenological analysis within the framework of optical model formalism has been carried out to reproduce the experimental data. The existing global set of elastic, polarization and total reaction data for protons and neutrons have been used to generate the optical model potential. The nuclear structure effects have been included in the calculations by considering the roles of coupling of the low-lying states, the presence of resonances and nuclear deformations. The potentials so generated have been used to calculate the differential and total cross sections for both (p,p') and (p,p'γ) reactions. The results of the analysis are in good agreement with the measured data for the observed γ-rays. However, discrepancies still exist in reproducing the finer details of the cross sections. The existing discrepancies between our phenomenological analysis and the experimental data demonstrate the rather complex roles of channel couplings, resonances in the compound nuclear system and target deformation. The significant contribution of nuclear structure effects in light mass nucleus like 12C and 16O, leads to an apparent loss of predictive power of the theoretical calculation for low-energy region (less than 10 MeV) of the projectile energy. 

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In this paper, we report about thorough characterization of Sr²⁺ co-doped LaBr3:Ce single crystal of dimensions 1.5′′×1.5′′. The properties studied include energy resolution, timing resolution, internal activity, intrinsic photo-peak efficiency and linearity over a range of 661.7 keV to 4.43 MeV using multiple γ-ray sources. While characteristics of regular Ce-doped LaBr3 and its superiority over other inorganic crystals are now well established, the possibility of improving them further by Sr²⁺ co-doping is a fledgling field of research. The primary aim of this work is to check whether the addition of Sr by the manufacturer results in better performance than standard Lanthanum Bromide doped with Cerium. The results obtained were compared with measurements with standard LaBr3:Ce of similar size. The energy resolution of the co-doped crystal at 661.7 keV is the same as that of a regular crystal of similar size and does not show any significant improvement. However, the timing resolution is found to be inferior to a similar LaBr3:Ce crystal. This is in conformity with the reported measurement of spectral shape, showing a lengthening of decay time. Our result on energy resolution is at variance with previously published reports on very small-volume co-doped crystals. Two very recent measurements with larger volume Sr co-doped crystals (1.5′′×1.5′′ and 3.0′′×3.0′′) have also shown improvement in energy resolutions. We conclude that more measurements are probably required to proclaim Sr²⁺ co-doped LaBr3 as significantly superior to LaBr3:Ce, irrespective of the shape, size and PMTs used. The observed improvement in energy resolution has to be consistent regardless of the volume and use of PMTs or APDs and is required to be significantly better to compensate for the deterioration in timing.

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This paper reports about complete characterization of a small volume, cylindrical (1'' × 1'') CeBr3 crystal. The measurements include determination of energy and timing resolutions, absolute photo-peak detection efficiency, internal activity and linearity of response up to 4.43 MeV gamma-ray energy. The results, so obtained, have been compared with the performance of NaI(Tl) and LaBr₃:Ce crystals of similar volume. Realistic Monte Carlo simulations were carried out using GEANT4 package to reproduce the experimental spectra and photo-peak detection efficiency. We have obtained best energy resolution of 4.7% at 662 keV for −800 V using a 2'' ET9266B tube. A somewhat better value of 4.3% is obtained using Hamamatsu R10233 tube. On the timing front we have obtained a resolution of 310ps at Co energy. We have determined the absolute photo-peak efficiency of the crystal for 662 keV to be 13.2%, in very close conformity with our Geant4 simulated value of 13.8%. We have estimated from the measurements the actual internal activity of the crystal to be less than 0.045 counts cm⁻³ s⁻¹. It has been concluded that while CeBr3 is just marginally inferior to LaBr3:Ce in terms of energy and timing resolutions, it scores over LaBr3:Ce in terms of internal activity. Unlike LaBr3:Ce, CeBr3 is much purer and has no significant gamma and beta activity.

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Quasi-elastic (QEL) scattering measurements have been performed using a ²⁸Si projectile off a ⁹⁰Zr target at energies around the Coulomb barrier. A Bayesian analysis within the framework of coupled channels (CC) calculations is performed in a large parameter space of quadrupole and hexadecapole deformations ( β₂ and β₄) of ²⁸Si. Our results unambiguously show that ²⁸Si is an oblate shaped nucleus with β₂ = -0.38±0.01 which is in excellent agreement with results from electromagnetic probes. The sign and magnitude of quadrupole deformation along with a precise value of hexadecapole deformation (β₄ = +0.03±0.01) of ²⁸Si have been determined for the first time using QEL scattering. A remarkable agreement is obtained between the experimental and calculated β₄ values of ²⁸Si based on Skyrme-Hartree-Fock method. The present results demonstrate the strong sensitivity of the quasi-elastic scattering to the sign and magnitude to the ground state deformation parameters, thus affirming its suitability to be used for rare exotic nuclei using low intensity RIBs.

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Evaporation residue (ER) cross sections and ER-gated 𝛾-ray fold distributions are measured for the ³²S+154Sm nuclear reaction above the Coulomb barrier at six different beam energies from 148 to 191 MeV. 𝛾-ray multiplicities and spin distributions are extracted from the ER-gated fold distributions. The ER cross sections measured in the present work are found to be much higher than what was reported in a previous work using a very different target-projectile (48Ti+138Ba) combination, leading to the same compound nucleus 186Pt, with much less mass asymmetry in the entrance channel than the present reaction. This clearly demonstrates the effect of the entrance channel on ER production cross section. The ER cross sections measured in the present work are compared with the results of both the statistical model calculations and the dynamical model calculations. Statistical model calculations have been performed to generate a range of parameter space for both the barrier height and Kramers's viscosity parameter over which the ER cross-section data can be reproduced. The calculations performed using the dinuclear system (DNS) model reproduce the data considering both complete and incomplete fusion processes. DNS calculations indicate the need for the inclusion of an incomplete fusion channel at higher energies to reproduce the ER cross sections. 

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Quasi-elastic (QEL) scattering measurements have been performed using the ²⁸,³⁰Si projectiles off the ⁹⁰Zr target at energies around the Coulomb barrier. Coupled-channels (CC) calculations were carried out in a large parameter space of quadrupole and hexadecapole deformations for the N=Z, ²⁸Si and N=Z+2, ³⁰Si nuclei. ²⁸Si at the N=Z line is observed to be uniquely oblate shaped in its ground state. In contrast, for ³⁰Si with just two additional neutrons- oblate, prolate, and spherical CC descriptions are equally compatible with the measurements. To further investigate the nuclear structure evolution with varying neutron number, shell-model calculations were performed. These calculations reveal a sudden change in the nuclear structure aspects at ³⁰Si in going from ²⁸Si to ³²Si. Combined reaction and structure analyses consistently indicate that ³⁰Si does not possess a well-defined intrinsic shape, and it is a potential candidate for “shape fluctuations” in its ground state.

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The concept of a heterostructure-based scintillation detector has been proposed as a potential alternative to current time-of-flight positron emission tomography (TOF-PET) detectors. In a heterostructure design, a dense scintillator (matrix) works in synergy with a fast-timing light scintillator (filler). The design often includes complex geometries, necessitating precise machining. The application of 3D printing technology can facilitate the fabrication of such complex geometries. This study presents the formulation and fabrication of a 3D-printed plastic scintillator, which has been identified as a potential filler material. The developed scintillator shows better rise and decay times compared to commercial plastic scintillators such as EJ-200. We have measured a coincidence time resolution (CTR) of 225 ps using γ−γ coincidence. Monte-Carlo simulations were performed using the Geant4 toolkit to validate the advantages of using complex filler material designs. The simulation outcomes demonstrate significant improvement in the performance of heterostructures in the case of complex designs over simpler ones. The findings of this study underscore the promise of using 3D printing technology for producing complex heterostructures. This can help in advancing the development of TOF-PET detectors with comparatively reduced effort.

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Metal halide perovskites have received great interest in developing scintillator materials. Among various types of perovskites, low dimensional metal halide perovskites have high exciton binding energy and photo-luminescence quantum yield (PLQY), making them suitable for X-ray and γ-ray detection. In this work, we report the growth and characterization (structural and optical) of 1-D CsCu2I3 single crystal (SC). The SC was grown using the solvent evaporation method at room temperature. The crystal exhibits an orthorhombic structure with Cmcm space group. The optical characterizations show a yellow photoluminescence (PL) with a large Stoke’s shift (~230 nm) that originate from self-trapped exciton (STE) emission. The X-ray photoelectron spectroscopy (XPS) results indicate that the addition of oleic acid (OA) prevents the oxidation of Cu⁺. Further, we coupled the SC with a silicon photomultiplier (SiPM) to study the scintillation properties. The grown crystal has been characterized for light output, energy resolution, linearity, and non-proportionality. The CsCu2I3 SC grown for this study exhibits a comparable light output of ~20000 ph/MeV to those grown using inverse temperature crystallization (ITC), as reported in the literature. However, the energy resolution reported in this study (11.57% at 662 keV) is better than the values reported for ITC-grown crystals in the literature. GEANT4 simulation toolkit has been used to perform the simulations, and the simulated intrinsic photopeak efficiencies for different volumes of CsCu2I3 scintillator have been obtained and compared with NaI:Tl and bismuth germanate (BGO) scintillators.

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Metal halide perovskites, particularly zero-dimensional (0D) variants, have garnered significant attention as scintillator materials for various applications such as γ-ray spectroscopy, X-ray imaging, and security. Among these, Cs3Cu2I5 has emerged as a promising candidate owing to its exceptional characteristics, such as good energy resolution, high light output, and high stopping power. Although there is sufficient data available on the scintillation properties of Cs3Cu2I5 Single Crystal (SC) grown using various methods, there still remains a scarcity of data on the scintillation properties of SCs grown using solvent evaporation method at room temperature. In the present work, Cs3Cu2I5 SCs have been grown using the solvent evaporation method at room temperature and characterized for their structural, optical, and scintillation properties. The SC shows an orthorhombic structure with a bandgap of 3.58 eV. The optical properties of the SC reveal the existence of Self-Trapped Exciton (STE). The SC exhibits an energy resolution of 5.80±0.05% at 662 keV and a light output of 41,000 photons/MeV, making it suitable for γ-rays detection. The intrinsic photopeak efficiencies of Cs3Cu2I5 SC for γ-rays are reported for the first time. GEANT4 simulation toolkit has been used to perform realistic simulations, and the simulated and experimental efficiencies are compared. Simulations show that Cs3Cu2I5 scintillator has twice the efficiency of the NaI:Tl scintillator.

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In this study, we present the results of measurements and radiological impact of natural radioactivity in soil and groundwater of the Himalayan region in the Uttarakhand State of India. The concentrations of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K ) in soil samples of the study area were determined using gamma-ray spectrometry by employing the NaI(Tl) detector. The concentrations of radon and uranium were also measured in potable groundwater samples using RAD7 and Inductively Coupled Plasma Mass Spectrometry (ICPMS) techniques, respectively. The average specific activities of ²²⁶Ra (116 Bq kg⁻¹ ), ²³²Th (137 Bq kg⁻¹) and ⁴⁰K (735 Bq kg⁻¹) in soil were found considerably higher than the corresponding global average values. The average concentrations of radon (35 Bq l⁻¹) and uranium (1.3 µg l⁻¹) in potable groundwater were found well within the safe limits recommended by the World Health Organization. The effects of natural radioactivity in soil and groundwater are discussed in terms of different risk assessment parameters and dose quantities.

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Cerium doped Lanthanum halide scintillators are useful in γ-ray spectroscopy due to their excellent energy resolution and high stopping power. The response of Compton electrons in 1″ × 1″ cylindrical LaCl3:Ce scintillator was recorded using a PIXIE-4 digital data acquisition system having no requirement of any external pulse-processing unit and coincidence unit, which makes the whole measurement setup very compact. The intrinsic energy resolution of Compton electrons in LaCl3:Ce was measured employing the Wide Angle Compton Coincidence Technique (WACCT) for energies ranging from 100 keV to 1 MeV by using ¹³⁷Cs, ⁶⁰Co and ²²Na γ-ray sources. The effect of coincidence energy gating window was also studied. A good agreement between the present results obtained using a digital method and the results reported in the literature with the analogue method has been observed.

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