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S.M. Patel

Bio: S.M. Patel is an academic researcher from Tata Institute of Fundamental Research. The author has contributed to research in topics: Inelastic scattering & Big Bang nucleosynthesis. The author has an hindex of 3, co-authored 10 publications receiving 94 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a review summarizes the synthesis of 2D transition metal dichalcogenides (TMDCs) by several techniques, i.e., mechanical and chemical exfoliation, RF-sputtering, atomic layer deposition (ALD) and chemical vapor deposition (CVD), etc.

103 citations

Journal ArticleDOI
TL;DR: In this article, the performance of a large volume (946 cm3) cylindrical (3.5 in. diameter × 6 in. length) LaBr3:Ce detector has been studied using γ - rays from radioactive sources and in-beam reaction, from few hundred keV to 22.5
Abstract: This paper presents the results of our measurements and detailed simulations using GEANT4 to investigate the performance of a large volume (946 cm3) cylindrical ( 3.5 in . diameter × 6 in . length) LaBr3:Ce detector. The properties of the detector have been studied using γ - rays from radioactive sources and in-beam reaction, from few hundred keV to 22.5 MeV. The salient features, which have been studied in-depth, are the uniformity and internal activity of the crystal, the energy and timing resolutions, linearity of the response up to 22.5 MeV, and efficiencies. A highly linear response has been observed by extracting the energy signal from a lower dynode and operating the PMT at a low voltage. The detector is to be primarily used for measuring high energy γ - rays spectra from Giant Dipole Resonance (GDR) decay studies.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the properties and response of large volume square bars (2 ′ ′ × 2 ′ γ × 8 ′ ) of LaBr3:Ce detectors, individually, and in a compact array of four square bars, with gamma-rays up to 22.5 MeV were investigated.
Abstract: LaBr3:Ce scintillators have recently become commercially available in sizes large enough for measurements of high energy gamma-rays. In this communication, we report our studies on properties and response of large volume square bars ( 2 ′ ′ × 2 ′ ′ × 8 ′ ′ ) of LaBr3:Ce detectors, individually, and in a compact array of four square bars, with gamma-rays up to 22.5 MeV. The properties studied are, uniformity of the crystal, internal radioactivity, energy resolution, timing resolution, linearity of the response and detection efficiencies. The response of the detectors for 22.5 MeV γ -rays produced from 11B( p , γ )12C capture reaction and for 15.1 MeV γ -rays produced from 12C( p , p ′ γ )12C inelastic scattering reaction are studied in detail. The measured absolute efficiencies (both total detection and photo-peak) for 662 keV gamma-rays from 137Cs are compared to those obtained using realistic GEANT4 simulations. The primary aim of the array is to measure high energy gamma-rays (5–50 MeV) produced from the de-excitation of excited Giant Dipole Resonance (GDR) states, radiative capture reactions, nuclear Bremsstrahlung process and inelastic scattering process. The highly satisfactory performance of the array provides the impetus for future efforts toward building a bigger array.

9 citations

Journal ArticleDOI
TL;DR: In this paper, the spectral properties of co-doped LaBr3:Ce have been investigated using multiple γ-ray sources and the results showed that the energy resolution of the co-decay-time co-depletion of a single crystal at 661.7 keV is the same as that of a regular crystal of similar size and does not show any significant improvement.
Abstract: In this paper we report about thorough characterization of Sr 2 + 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 possibilities of improving them further by Sr 2 + co-doping is a fledgling field of research. The primary aim of this work is to check whether 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 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 reported measurement of spectral shape showing 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 Sr 2 + 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 the volume and use of PMTs or APDs and is required to be significantly better to compensate for the deterioration in timing.

6 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a textbook of oral pathology is used to take advantage of limited budget to obtain knowledge and experience in a more practical way, by reading a textbook instead of traveling to experience directly.
Abstract: Make more knowledge even in less time every day. You may not always spend your time and money to go abroad and get the experience and knowledge by yourself. Reading is a good alternative to do in getting this desirable knowledge and experience. You may gain many things from experiencing directly, but of course it will spend much money. So here, by reading a textbook of oral pathology, you can take more advantages with limited budget.

415 citations

01 Sep 2016
TL;DR: Using novel porous (holey) metallic 1T phase MoS2 nanosheets synthesized by a liquid-ammonia-assisted lithiation route, this study systematically investigated the contributions of crystal structure, edges, and sulfur vacancies to the catalytic activity toward HER and revealed that the phase serves as the key role in determining the HER performance.
Abstract: Molybdenum disulfide (MoS2) is a promising nonprecious catalyst for the hydrogen evolution reaction (HER) that has been extensively studied due to its excellent performance, but the lack of understanding of the factors that impact its catalytic activity hinders further design and enhancement of MoS2-based electrocatalysts. Here, by using novel porous (holey) metallic 1T phase MoS2 nanosheets synthesized by a liquid-ammonia-assisted lithiation route, we systematically investigated the contributions of crystal structure (phase), edges, and sulfur vacancies (S-vacancies) to the catalytic activity toward HER from five representative MoS2 nanosheet samples, including 2H and 1T phase, porous 2H and 1T phase, and sulfur-compensated porous 2H phase. Superior HER catalytic activity was achieved in the porous 1T phase MoS2 nanosheets that have even more edges and S-vacancies than conventional 1T phase MoS2. A comparative study revealed that the phase serves as the key role in determining the HER performance, as 1T phase MoS2 always outperforms the corresponding 2H phase MoS2 samples, and that both edges and S-vacancies also contribute significantly to the catalytic activity in porous MoS2 samples. Then, using combined defect characterization techniques of electron spin resonance spectroscopy and positron annihilation lifetime spectroscopy to quantify the S-vacancies, the contributions of each factor were individually elucidated. This study presents new insights and opens up new avenues for designing electrocatalysts based on MoS2 or other layered materials with enhanced HER performance.

175 citations

Journal ArticleDOI
TL;DR: This work verified that the synthesis of Ni-doped In2O3/WS2 nanofilm provides a new avenue to develop promising hybrids for formaldehyde sensing.
Abstract: A high-performance formaldehyde sensor based on nickel (Ni)-doped indium trioxide (In2O3)/tungsten disulfide (WS2) nanocomposite was demonstrated. An epoxy substrate served as matrix of the Ni-In2O3/WS2 nanocomposite sensor. The material properties of self-assembled Ni-In2O3/WS2 nanoheterostructure were fully characterized and confirmed. The formaldehyde-sensing properties of the Ni-In2O3/WS2 composite were tested at 25 °C. Compared to the In2O3, WS2, and their composite, the Ni-In2O3/WS2 sensor demonstrated significant improvement on the formaldehyde-sensing performance, including a low detection limit of 15 ppb, good selectivity, repeatability, fast detection rate, and a fair logarithmic function toward formaldehyde concentration. The dramatically enhanced sensing performance of Ni-In2O3/WS2 film sensor can be attributed to the Ni ion doping and synergistic interfacial incorporation of In2O3/WS2 heterojunction. The sensitive mechanism of the Ni-In2O3/WS2 film sensor toward formaldehyde is explored through density functional theory (DFT) simulation. This work verified that the synthesis of Ni-doped In2O3/WS2 nanofilm provides a new avenue to develop promising hybrids for formaldehyde sensing.

124 citations

Journal ArticleDOI
TL;DR: MoS2, the second most widely studied two-dimensional nanomaterial, has fascinating physical and chemical properties and thus has a wide variety of applications as mentioned in this paper, and has been getting much attention.
Abstract: MoS2, the second most widely studied two-dimensional nanomaterial, has fascinating physical and chemical properties and thus has a wide variety of applications. MoS2 has been getting much attention...

114 citations

Journal ArticleDOI
TL;DR: In this paper, the properties of large volume cylindrical 3.5″×8″ (89mm×203mm) LaBr 3 :Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL photo-multiplier tube were investigated.
Abstract: The properties of large volume cylindrical 3.5″×8″ (89 mm×203 mm) LaBr 3 :Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL photo-multiplier tube were investigated. These crystals are among the largest ones ever produced and still need to be fully characterized to determine how these detectors can be utilized and in which applications. We tested the detectors using monochromatic γ–ray sources and in-beam reactions producing γ rays up to 22.6 MeV; we acquired PMT signal pulses and calculated detector energy resolution and response linearity as a function of γ-ray energy. Two different voltage dividers were coupled to the Hamamatsu R10233-100SEL PMT: the Hamamatsu E1198-26, based on straightforward resistive network design, and the “LABRVD”, specifically designed for our large volume LaBr 3 :Ce scintillation detectors, which also includes active semiconductor devices. Because of the extremely high light yield of LaBr 3 :Ce crystals we observed that, depending on the choice of PMT, voltage divider and applied voltage, some significant deviation from the ideally proportional response of the detector and some pulse shape deformation appear. In addition, crystal non-homogeneities and PMT gain drifts affect the (measured) energy resolution especially in case of high-energy γ rays. We also measured the time resolution of detectors with different sizes (from 1″×1″ up to 3.5″×8″), correlating the results with both the intrinsic properties of PMTs and GEANT simulations of the scintillation light collection process. The detector absolute full energy efficiency was measured and simulated up to γ-rays of 30 MeV

85 citations