This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators ${\rm SrI}_{2}$ (Eu), GYGAG(Ce) and CsI(Na).

Nonproportionality of Scintillator Detectors. V. Comparing the Gamma and Electron Response

Significance of thoron measurements in indoor environment.

Quantification of radiological dose and chemical toxicity due to radon and uranium in drinking water in Bageshwar region of Indian Himalaya

The measurements of primordial radionuclides (226Ra, 232Th and 40K) and radon exhalation rates in soil samples were performed in Bageshwar region of Kumaun Himalaya, India using gamma-ray spectrometry and scintillation detector based radon monitor, respectively. The average concentrations of 226Ra, 232Th and 40K in the investigated region were found to be 36 Bq kg−1, 50 Bq kg−1 and 1595 Bq kg−1, respectively. The average values of radon and thoron mass exhalation rates were observed to be 29 mBq−1 kg−1 s−1 and 256 mBq−1 kg−1 s−1, respectively. The average value of thoron surface exhalation rates was observed to be 2281 mBq−1 m−2 s−1. The external exposure to 226Ra, 232Th and 40K is estimated in terms of different hazard assessment indices and dose quantities. The high values of 232Th content in soil samples indicate the presence of thorium mineralization in the vicinity of study area. The methodology adopted and results obtained are discussed in details.

Study of primordial radionuclides and radon/thoron exhalation rates in Bageshwar region of Kumaun Himalaya, India

Abstract Inorganic scintillators play a major role in ionizing radiation detection due to their high versatility to detect multiple radiation sources such as X-rays, gamma-rays, alpha, beta, and neutron particles, and their fast and high light yield, making them especially convenient for imaging, spectroscopy, and timing applications. Scintillators-based detection systems are found, among various applications, in medical imaging, homeland security, high-energy physics, industrial control, oil drilling explorations, and energy management. This Review discusses advances and prospects of perovskite scintillators, particularly low-dimensional hybrid organic-inorganic perovskite crystals and all-inorganic perovskite nanocrystals. We highlight the promise of two-dimensional lithium-doped (PEA) 2 PbBr 4 crystals and CsPbBr 3 nanocrystals as scintillators with high light yields, exceeding 20 photons/keV, and fast decay times of less than 15 ns. Such a combination may result in fast-spectral X-ray imaging, an output count rate exceeding 30 Mcps/pixel in photon-counting computed tomography, and coincidence timing resolution of less than 100 ps in positron emission tomography. We review recent strategies to further improve light yield, decay time, and coincidence timing resolution through light-matter interactions such as extraction efficiency enhancement and Purcell-enhanced scintillators. These advancements in light yields and decay times of perovskite scintillators will be particularly useful in the medical and security applications. 

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Development and challenges in perovskite scintillators for high-resolution imaging and timing applications

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.

Radiological impact assessment of soil and groundwater of Himalayan regions in Uttarakhand, India

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.

Characterization of a Sr co-doped LaBr3:(Ce) detector for γ-ray spectroscopy

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 $1^{\prime \prime }\times 1^{\prime \prime } \text {CeBr}_{3}$ 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 $\delta $ -ray component is a major contributor to the intrinsic resolution of CeBr3.

Intrinsic Resolution of Compton Electrons in CeBr 3 Scintillator Using Compact CCT

NaI(Tl) is one of the oldest and most widely used scintillator due to its high detection efficiency, availability of large size crystal and reasonably good energy resolution. Various studies have been done to study the components contributing to the energy resolution of NaI(Tl) for gamma rays. Apart from components such as statistical contribution of PMT and transfer component, one component is inherent in the scintillator called intrinsic energy resolution. Intrinsic energy resolution presents a fundamental limit to the improvement of energy resolution. In the present work, intrinsic energy resolution of a 2"$\times2$" NaI(Tl) has been measured using advanced data acquisition system PIXIE-4 [3], which is digital pulse processing system and possesses internal amplification. This makes the experimental setup very compact. The measurements were done using $^{\mathbf{137}} {\mathbf{Cs}, } ^{\mathbf{22}}$\textbf{Na and}$^{\mathbf{60}}$ Co gamma ray sources and compared with values reported in literature.

V. Ranga

Papers

Radiological impact assessment of soil and groundwater of Himalayan regions in Uttarakhand, India

Characterization of a Sr co-doped LaBr3:(Ce) detector for γ-ray spectroscopy

Intrinsic Resolution of Compton Electrons in CeBr 3 Scintillator Using Compact CCT

Intrinsic resolution of NaI(Tl) using PIXIE-4 data acquisition system

Energy response and pulse shape discrimination studies of a 3- inch liquid scintillator