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Purpose: Over the last decade, wireless capsule endoscope has been the tool of choice for noninvasive inspection of the gastrointestinal tract, especially in the small intestine. However, the latest clinical products have not been equipped with a sufficiently accurate localization system which makes it difficult to determine the location of intestinal abnormalities, and to apply follow-up interventions such as biopsy or drug delivery. In this paper, the authors present a novel localization method based on tracking three positron emission markers embedded inside an endoscopic capsule. Methods: Three spherical 22Na markers with diameters of less than 1 mm are embedded in the cover of the capsule. Gamma ray detectors are arranged around a patient body to detect coincidence gamma rays emitted from the three markers. The position of each marker can then be estimated using the collected data by the authors' tracking algorithm which consists of four consecutive steps: a method to remove corrupted data, an initialization method, a clustering method based on the Fuzzy C-means clustering algorithm, and a failure prediction method. Results: The tracking algorithm has been implemented in MATLAB utilizing simulation data generated from the Geant4 Application for Emission Tomography toolkit. The results show that this localization method can achieve real-time tracking with an average position error of less than 0.4 mm and an average orientation error of less than 2°. Conclusions: The authors conclude that this study has proven the feasibility and potential of the proposed technique in effectively determining the position and orientation of a robotic endoscopic capsule. [ABSTRACT FROM AUTHOR]

We investigated MOVPE growth conditions to grow large-area and thick single crystal CdTe layers with uniform material properties directly on (211) Si substrates to develop nuclear radiation detectors. We found that group VI/II precursor flow-ratio as well as rapid thermal annealing performed by interrupting the growth at the initial stage has marked influence on the crystal quality. By using a VI/II precursor ratio of 3.0, and a 900 °C anneal performed in flowing hydrogen, we were able to achieve 1-sq inch sized thick single crystal CdTe that showed uniform material properties and high crystal quality throughout the wafer. We further demonstrated that the grown crystals were suitable for fabricating nuclear radiation detector. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: The light output response and the neutron and gamma-ray detection efficiency are determined for liquid scintillator EJ-309. The light output function is compared to those of previous studies. Experimental efficiency results are compared to predictions from GEANT4, MCNPX and PENELOPE Monte Carlo simulations. The differences associated with the use of different light output functions are discussed. [Copyright &y& Elsevier]

CdZnTe (CZT) is a promising medium for room-temperature gamma-ray detectors. However, the low production yield of acceptable quality crystals hampers the use of CZT detectors for gammaray spectroscopy. Significant efforts have been directed towards improving quality of CZT crystals to make them generally available for radiation detectors. Another way to address this problem is to implement detector designs that would allow for more accurate and predictable correction of the charge loss associated with crystal defects. In this work, we demonstrate that high-granularity position-sensitive detectors can significantly improve the performance of CZT detectors fabricated from CZT crystals with wider acceptance boundaries, leading to an increase of their availability and expected decrease in cost. [ABSTRACT FROM AUTHOR]

A new approach was developed for the design of front-end circuits for semiconductor radiation detectors. The readout scheme is a charge sensitive amplifier, split between a very front-end stage (input transistor, feedback resistor and capacitor) located close to the detector and a remote second stage located far from the detector. The element of novelty, with respect to similar configurations, is the fact that the connecting links between the very front-end and the second stage are made with transmission lines. As a result, wide bandwidth and closed-loop stability are maintained even if the distance between the very front-end and the second stage is much larger than usual, up to tens of meters. The circuit was named GeFRO for Germanium front-end, and was tested with a BEGe detector from Canberra. Timing resolutions of 20 ns (open loop) and 185 ns (closed loop with 60^ \circ phase margin) were obtained with 10 m long cables between the very front-end and the second stage. The noise of the circuit after a 10~\mu\s Gaussian shaping was close to 160 ~\e^ - RMS with an input capacitance of 26 pF. [ABSTRACT FROM AUTHOR]

This paper discusses the multi-wavelength scanning Raman lidar being built at Lidar Division, CEILAP (CITEDEF-CONICET) in the frame of the Argentinean CTA (Cherenkov Telescope Array) collaboration. CTA is an initiative to build the next generation of ground-based instruments to collect very high energy gamma-ray radiation (greater than a few tens of GeV). The atmospheric conditions are of major interest to CTA, and lidars are requested to acquire atmospheric profiles fast, accurately and in the line of sight of the event. Due to the expected low aerosol optical depth of the future site, the short observation period as well as the extension of the observation, an enhanced collection area is required. Based on this constraints, and energy laser pulse, a backscatter lidar signal simulation was performed to estimate the main characteristics of the system. To derive these features, a SNR (signal-to-noise ratio) was also simulated to derive the total number of mirrors to achieve a good quality signal over the whole tropopause. Raman capabilities were added in the UV and VIS wavelengths to retrieve the spectral characteristics of the aerosol extinction and the water vapor profile. The results of the simulation, and the main characteristics derived are shown. [ABSTRACT FROM AUTHOR]

We have developed a 4-layer depth-of-interaction (DOI) detector which consists of four layers of scintillation crystal arrays and a position sensitive photomultiplier tube (PS-PMT). To control the behavior of scintillation light in each DOI crystal array, some reflectors between crystals are removed so that all crystal responses in the four layers are expressed in one two-dimensional (2D) position histogram by implementing an Anger-type calculation of the PS-PMT signals. Since the method utilizes spread of scintillation light through the boundary of the crystals with no reflectors, positioning performance in the 2D position histogram depends on the crystal dimensions, the crystal surface finish, and gap materials. In this work, we propose an adjustment method for crystal identification performance of the 4-layer DOI detector by selecting the optimal refractive index for the gap materials between the crystals in which the reflectors are removed. We fabricated single-layer detectors and 4-layer detectors using LYSO scintillators and evaluated the crystal identification performance, while varying the refractive index of the gap materials (by using different optical cements). As a result, we found the 2D position histogram changes as a function of the refractive index of the optical cement between crystals and the optimal refractive indices can be determined for the detector using the LYSO crystals. We concluded that the crystal response of the 2D position histograms can be adjusted and crystal identification performance can be optimized by changing the refractive index of the gap materials. [ABSTRACT FROM AUTHOR]

Comprehensive measurements of the excitation energy and spin-parity assignments for states in 31S are presented, from the first excited state, up to energies relevant for the 30P(p,γ)31S reaction in ONe novae. This reaction rate strongly influences heavy element abundances in novae ejecta. States in 31S are paired with their 31P analogues using y rays detected with the Gammasphere detector array following the 28Si(4He, n) fusion-evaporation reaction. The evolution of mirror energy differences is explored and the results are compared with new shell-model calculations. The excellent agreement observed in this work between experimental data and shell-model calculations provides confidence in using computed estimates in situations where experimental data are unavailable. [ABSTRACT FROM AUTHOR]

Abstract: The High Altitude Water Cherenkov (HAWC) observatory is a TeV gamma-ray and cosmic-ray detector currently under construction at an altitude of 4100m close to volcano Sierra Negra in the state of Puebla, Mexico. The HAWC [1] observatory is an extensive air-shower array composed of 300 optically isolated water Cherenkov detectors (WCDs). Each WCD contains ~200,000l of filtered water and four upward-facing photomultiplier tubes. In Fall 2014, when the HAWC observatory will reach an area of 22,000m2, the sensitivity will be 15 times higher than its predecessor Milagro [2]. Since September 2012, more than 30 WCDs have been instrumented and taking data. This first commissioning phase has been crucial for the verification of the data acquisition and event reconstruction algorithms. Moreover, with the increasing number of instrumented WCDs, it is important to verify the data taken with different configuration geometries. In this work we present a comparison between Monte Carlo simulation and data recorded by the experiment during 24h of live time between 14 and 15 April of 2013 when 29 WCDs were active. [Copyright &y& Elsevier]

Abstract: VERITAS is an array of four imaging atmospheric Cherenkov telescopes near Tucson, Arizona and is one of the world's most sensitive detectors of very high energy (VHE: ) gamma rays. The scientific reach of VERITAS covers the study of both extragalactic and Galactic objects as well as the search for astrophysical dark matter. In these proceedings we will discuss the status of VERITAS operations and upgrades and present a selection of recent results. [Copyright &y& Elsevier]

Abstract: The Large High Altitude Air Shower Observatory (LHAASO) is a multipurpose project with a complex detector array for high energy gamma ray and cosmic ray detection. The array of 1km2 is composed of five types of detectors to measure shower arrival direction, total number of secondary particles, muon content, Cherenkov image and high energy gamma rays near shower core, respectively. The main scientific goals are (1) searching for galactic cosmic ray origins by extensive spectroscopy investigations of gamma ray sources above 30TeV; (2) all sky survey for gamma ray sources at energies higher than 300GeV; (3) energy spectrum and composition measurements of cosmic rays over a wide range covering knees with fixed energy scale and known fluxes for all species at the low energy end. In this paper, the progress on relevant detector developments is reported, including constructions of prototype detectors at Tibet site and coincidence operation with the ARGO-YBJ resistive plat chamber full coverage array at 4300m a.s.l. The energy spectrum of cosmic ray hydrogen and Helium nuclei up to 0.8PeV is reported as the first piece of physics measurements by the LHAASO experiment. [Copyright &y& Elsevier]

The presence of gamma-ray background significantly reduces detection sensitivity when searching for radioactive sources in the field, particularly in mobile systems which must contend with a variable background that is not known a priori . An extensive survey of the background was performed in the San Francisco Bay Area using both sodium iodide and high-purity germanium detectors, covering a wide variety of environments that might be encountered in an operational scenario. This data was used as a basis for source injection in a moving detector scenario in order to assess the effects of the background on different detection approaches. Both imaging and spectroscopic algorithms were implemented for the sodium iodide array, and their performances are compared for a variety of source energies and stand-off distances in the presence of the measured background. [ABSTRACT FROM PUBLISHER]

The CaLIPSO project focuses on the development of an innovative energetic-photon detector. The detector uses a “heavy” organometallic liquid: the TriMethyl Bismuth (TMBi), 82% by weight of Bismuth. TMBi efficiently converts through the photo-electric effect photons of energies below 1 MeV. The ionisation signal and light produced in the liquid are both detected. Beyond the measurement of gamma photon energies, this detector will allow locating photon interactions in the detector in three dimensions down to 1~\mm^3 and a sub nanosecond timing accuracy. All these desirable properties can be obtained simultaneously with liquid TMBi detector. [ABSTRACT FROM PUBLISHER]

Performance of a new modification of xenon gamma-ray detector (XGD) is presented. This detector differs from the previous ones by virtue of improved energy resolution (1.7 ± 0.1) at 662 keV and the ability to function in the presence of external acoustic noise (up to 100 dB) with virtually no degradation of spectrometric characteristics. These results have been achieved by developing a digital method of processing every electric signal coming from the XGD. For this method, digital electronics based on field-programmable gate array has also been developed. [ABSTRACT FROM AUTHOR]

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) is an advanced new high-efficiency γ-ray spectrometer being developed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF’s Isotope Separator and Accelerator (ISAC-I) radioactive ion beam facility. GRIFFIN will be comprised of sixteen large-volume clover-type high-purity germanium (HPGe) γ-ray detectors coupled to custom digital signal processing electronics and used in conjunction with a suite of auxiliary detection systems. This article provides an overview of the GRIFFIN spectrometer and its expected performance characteristics. [ABSTRACT FROM AUTHOR]

The TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer is a high energy-resolution, high efficiency γ-ray detector array for radioactive beam experiments. It consists of high-purity germanium detectors with scintillator suppressors and waveform digitization. TIGRESS can operate in modes optimized for either maximum efficiency or for high peak-to-total, and can switch between these modes within a day. The digitized waveforms provide 6 mm FWHM position resolution for incident 137Cs γ rays. The array hosts a suite of auxilliary detectors for charged particles and neutrons. [ABSTRACT FROM AUTHOR]

Nuclear structure of the 26Mg nucleus has been probed, for the first time, using heavy-ion-induced fusion-evaporation reaction and a large array of high-resolution γ-ray detectors (Clovers). The level structure of the nucleus reported in the earlier studies, using light-ion reactions, has been re-examined and new transitions have been identified. Existing spin-parity assignments have been confirmed and new assignments have been made from anisotropy and polarization measurements. Large basis shell-model calculations, involving cross-shell excitation-have been carried out, for the first time, in 26Mg as well as in the neighboring isotopes and the agreement with the experimental level energies is rather remarkable. [ABSTRACT FROM AUTHOR]

In recent years, a new generation of space missions has offered great opportunities for discovery in high-energy astrophysics. In this article we focus on the scientific operations of the Gamma-Ray Imaging Detector (GRID) on board the AGILE space mission. AGILE-GRID, sensitive in the energy range of 30 MeV-30 GeV, has detected many γ-ray transients of both galactic and extragalactic origin. This work presents the AGILE innovative approach to fast γ-ray transient detection, which is a challenging task and a crucial part of the AGILE scientific program. The goals are to describe (1) the AGILE Gamma-Ray Alert System, (2) a new algorithm for blind search identification of transients within a short processing time, (3) the AGILE procedure for γ-ray transient alert management, and (4) the likelihood of ratio tests that are necessary to evaluate the post-trial statistical significance of the results. Special algorithms and an optimized sequence of tasks are necessary to reach our goal. Data are automatically analyzed at every orbital downlink by an alert pipeline operating on different timescales. As proper flux thresholds are exceeded, alerts are automatically generated and sent as SMS messages to cellular telephones, via e-mail, and via push notifications from an application for smartphones and tablets. These alerts are crosschecked with the results of two pipelines, and a manual analysis is performed. Being a small scientific-class mission, AGILE is characterized by optimization of both scientific analysis and ground-segment resources. The system is capable of generating alerts within two to three hours of a data downlink, an unprecedented reaction time in γ-ray astrophysics. [ABSTRACT FROM AUTHOR]

ASTRO-H is the sixth X-ray observation satellite in Japan developed by Institute of Space and Astronautical Science (ISAS/JAXA). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution and broadband observations. In order to achieve the mission objectives, ASTRO-H will carry six scientific instruments (two telescopes, two imagers, a detector, and a spectrometer) covering very wide energy range from 0.3 to 600 keV. This paper describes thermal design for the Soft Gamma-ray Detector (SGD) and the Hard X-ray Imager (HXI) installed on the ASTRO-H satellite. These instruments consist of silicon and cadmium-telluride semiconductor-based cameras, BGO active shields with avalanche photo diodes, and electronics. In order to achieve highly-sensitive observations, the semiconductor cameras and BGO active shields are required to be maintained at low temperatures for their high signal-to-noise ratios. This paper shows some measures and efforts to keep these devices at low temperatures under varieties of external heat input conditions and high heat dissipations from the semiconductor cameras and electronics. Thermal analyses using thermal mathematical model and some development tests using thermal test model of these instruments are reported as well. [ABSTRACT FROM AUTHOR]

An important aspect of the ongoing upgrade at the Budapest PGAA-NIPS facility has been the design and installation of a second Compton-suppressed gamma spectrometer. The aim was to provide excellent spectroscopic conditions for future position sensitive and large sample prompt gamma activation analysis applications. The optimum geometry of the setup was determined by Monte Carlo calculations with the MCNP-CP code. The suppression factors for various layouts (co-axial, perpendicular), shapes (cylindrical, tapered), and thicknesses were compared at different gamma-ray energies. The optimum configuration, as a trade-off between performance and cost, was selected, purchased, and installed. Several characteristic features of a collimated, Compton-suppressed system could be revealed, which allowed us to achieve a better and cost-effective performance. The calculations were validated with a 14N(n,γ) 15N calibration source. [ABSTRACT FROM AUTHOR]

Abstract: Neutron resonance densitometry (NRD) has been proposed to quantify nuclear materials in melted fuel (MF) that will be removed from the Fukushima Daiichi nuclear power plant. The problem is complex due to the expected presence of strong neutron absorbing impurities such as 10B and high radiation field that is mainly caused by 137Cs. To identify the impurities under the high radiation field, NRD is based on a combination of neutron resonance transmission analysis (NRTA) and neutron resonance capture analysis (NRCA). We investigated with Geant4 the performance of a gamma-ray detector for NRCA in NRD. The gamma-ray detector has a well shape, consisting of cylindrical and tube type LaBr3 scintillators. We show how it measures 478keV gamma rays derived from 10B(n, ) reaction in MF under a high 137Cs-radiation environment. It was found that the gamma-ray detector was able to well suppress the Compton edge of 662-keV gamma rays of 137Cs and had a high peak-to-Compton continuum ratio, by using the tube type scintillator as a back-catcher detector. Then, we demonstrate that with this ability, detection of 478-keV gamma rays from 10B is accomplished in realistic measuring time. [Copyright &y& Elsevier]

One of the goals of the Lomonosov satellite designed by scientists of Moscow State University is to study the prompt emission of cosmic gamma-ray bursts. This paper describes the gamma-ray burst monitor in the gamma-ray range (the BDRG instrument) and the wide-field optical cameras (the SHOK instrument) for detecting both the gamma-ray burst prompt emission and its precursors. [ABSTRACT FROM AUTHOR]

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These data provide additional compositional evidence that Vesta is the parent body to HED meteorites. A subset of fast neutron data having lower statistical precision show spatial variations that are consistent with a 400 ppm variability in hydrogen concentrations across Vesta and supports the idea that Vesta's hydrogen is due to long-term delivery of carbonaceous chondrite material. [ABSTRACT FROM AUTHOR]

Internal dosimetry of 210Pb in the cranium deals with the determination of the amount of energy deposited in tissue by 210Pb radiations within the cranium. 210Pb in the human cranium was monitored by in vivo counting in a low background facility 640 m (2100 ft) underground with a germanium (Ge) gamma-ray detector having a beryllium window. The minimum detectable activity (MDA) was established with this system to be 0.2 Bq (5 pCi) in 25-h counting time with a 15-mm diameter and 7-mm thick Ge detector, having a beryllium window of thickness of 0.08 mm, in contact with the cranium just above the ear adjacent to the temple region. To establish an MDA of 0.004 Bq (0.1 pCi) with this system, the limitation arising from the ambient radon level at 10 Bq m−3 was investigated. [ABSTRACT FROM AUTHOR]

Context. AGILE is a γ-ray astrophysics mission which has been in orbit since 23 April 2007 and continues to operate reliably. The γ-ray detector, AGILE-GRID, has observed Galactic and extragalactic sources, many of which were collected in the first AGILE Catalog. Aims. We present the calibration of the AGILE-GRID using in-flight data and Monte Carlo simulations, producing instrument response functions (IRFs) for the effective area (Aeff), energy dispersion probability (EDP), and point spread function (PSF), each as a function of incident direction in instrument coordinates and energy. Methods. We performed Monte Carlo simulations at different γ-ray energies and incident angles, including background rejection filters and Kalman filter-based γ-ray reconstruction. Long integrations of in-flight observations of the Vela, Crab and Geminga sources in broad and narrow energy bands were used to validate and improve the accuracy of the instrument response functions. Results. The weighted average PSFs as a function of spectra correspond well to the data for all sources and energy bands. Conclusions. Changes in the interpolation of the PSF from Monte Carlo data and in the procedure for construction of the energy-weighted effective areas have improved the correspondence between predicted and observed fluxes and spectra of celestial calibration sources, reducing false positives and obviating the need for post-hoc energy-dependent scaling factors. The new IRFs have been publicly available from the AGILE Science Data Center since November 25, 2011, while the changes in the analysis software will be distributed in an upcoming release. [ABSTRACT FROM AUTHOR]

Abstract: Thallium bromide (TlBr) is a promising compound semiconductor for fabrication of gamma-ray detectors. The attractive physical properties of TlBr lie in its high photon stopping power, high resistivity and good charge transport properties. Gamma-ray detectors fabricated from TlBr crystals have exhibited excellent spectroscopic performance. In this paper, advances in TlBr radiation detector development are reviewed with emphasis on crystal growth, detector fabrication, physical properties and detector performance. [Copyright &y& Elsevier]

Abstract: Transparent polycrystalline ceramic scintillators based on the composition Gd1.49Y1.49Ce0.02Ga2.2Al2.8O12 are being developed for gamma spectroscopy detectors. Scintillator light yield and energy resolution depend on the details of various processing steps, including powder calcination, green body formation, and sintering atmosphere. We have found that gallium sublimation during vacuum sintering creates compositional gradients in the ceramic and can degrade the energy resolution. While sintering in oxygen produces ceramics with uniform composition and little afterglow, light yields are reduced, compared to vacuum sintering. By controlling the atmosphere during the various process steps, we were able to minimize the gallium sublimation, resulting in a more homogeneous composition and improved gamma spectroscopy performance. [Copyright &y& Elsevier]

Abstract: Cs2LiYCl6 (CLYC) is one of the most interesting new scintillators developed during the last fifteen years. Its use as a thermal neutron scintillator was discovered in 1999 at the Delft University of Technology in Netherlands. In 2003, CLYC was selected by Radiation Monitoring Devices (RMD) for further studies and ultimately resulted in a commercial product. RMD's investigation of CLYC showed that it is a very good gamma ray detector with excellent 4% or better energy resolution, making it an ideal choice for dual mode detectors. Recently, Bubble Technology Industries of Canada discovered the possibility of fast neutron detection with CLYC, increasing its versatility even further. In this paper, we present the progress of CLYC’s development since its inception, with a focus on the work conducted at RMD. Our initial results with small crystals are presented, followed by data collected with samples of consecutively larger volumes and quality. We discuss the improvements in the energy resolution from 7% to 3.6%, as well as volume from 1cm3 to 100cm3. In addition, we address basic properties, gamma ray and neutron detection, pulse shape discrimination, and recently discovered fast neutron detection. [Copyright &y& Elsevier]

Abstract: Material homogeneity is critical in achieving high-performance in all types of radiation detectors. This requirement is not inevitably satisfied in today's commercial detector-grade CdZnTe (CZT) material because it contains high concentrations of extended defects, in particular, Te inclusions, dislocation networks, and twin- and subgrain-boundaries that affect the energy resolution and the efficiency of the devices. Defects, such as grain boundaries and cracks that completely block charge-carrier transport are impermissible in CZT radiation-detectors at concentrations exceeding certain threshold values. Our group in Brookhaven National Laboratory (BNL) conducts systematic studies, detailing the roles of crystal defects in CZT detectors and the mechanisms underlying their formation and effects. We employ infrared transmission microscopy, white beam X-ray diffraction topography, and high-spatial-resolution X-ray response mapping to identify particular types of defects and reveal their relationship with the devices' performances. In this article, we summarize some of the most important results that our group obtained over the past 5 years. [Copyright &y& Elsevier]

Cadmium Magnesium Telluride (Cd1−x Mg x Te/CMgT) offers several pronounced potential advantages over the well-studied CdZnTe and CdMnTe, possibly making it a good alternative for room-temperature X- and gamma-ray detectors. It possesses high crystallinity due to the near-similar lattice structure of CdTe (6.48Å) and MgTe (6.42Å). Its displays good homogeneity as the Mg segregation coefficient in CdTe is nearly 1. Furthermore, inhomogeneities in the crystal due to alloying effects can be minimized, because the optimal energy band-gap can be achieved using less Mg in CdMgTe compared to Zn and Mn needed in CdZnTe and CdMnTe. We recently grew an undoped- and a doped-ingot of CdMgTe, characterized its material properties, and tested its detection performance. We obtained some exciting results that demonstrated some of its potential advantages over the other materials. The band-gap was measured as 1.61eV at room temperature and 1.73eV at 4K. The yield was predominantly single crystals with about two orders-of-magnitude fewer Te inclusions and other growth defects compared to CdZnTe and CdMnTe crystals. The measured resistivity of the undoped annealed crystal was about ∼107 Ω-cm; after doping in a second growth trial, it increased by 2–3 orders-of-magnitude (109–1010 Ω-cm). We examined the doped as-grown crystal as a radiation detector and acquired reasonably good spectral response to an Am-241 source. The estimated mu-tau value was as high as 7×10−4 cm2/V, which is an extraordinarily high value for such an early-phase investigation. We also analyzed point and extended defects using various techniques that will be discussed in this manuscript. [ABSTRACT FROM AUTHOR]

The energy released in a spontaneous decay process of natural radionuclides is the main source of the total radiation dose to human beings. Natural radionuclides are widely distributed in soil, rocks, air, and groundwater. In present investigation, the analysis of terrestrial radionuclides such as Ra, Th, and K in soil and sand of Chattarpur area of southeastern coast of Odisha has been carried out using NaI(Tl) gamma ray detector. The higher activity concentrations of naturally occurring radionuclides have been reported from the study area. The gamma radiationdose originating from the terrestrial radionuclides was found to vary from 95 to 1813 nGy/h with an average of 700 nGy/h. This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details. [ABSTRACT FROM AUTHOR]

The Compton camera is a relevant imaging device for the detection of prompt photons produced by nuclear fragmentation in hadrontherapy. It may allow an improvement in detection efficiency compared to a standard gamma-camera but requires more sophisticated image reconstruction techniques. In this work, we simulate low statistics acquisitions from a point source having a broad energy spectrum compatible with hadrontherapy. We then reconstruct the image of the source with a recently developed filtered backprojection algorithm, a line-cone approach and an iterative List Mode Maximum Likelihood Expectation Maximization algorithm. Simulated data come from a Compton camera prototype designed for hadrontherapy online monitoring. Results indicate that the achievable resolution in directions parallel to the detector, that may include the beam direction, is compatible with the quality control requirements. With the prototype under study, the reconstructed image is elongated in the direction orthogonal to the detector. However this direction is of less interest in hadrontherapy where the first requirement is to determine the penetration depth of the beam in the patient. Additionally, the resolution may be recovered using a second camera. [ABSTRACT FROM AUTHOR]

We report the first observation of 3-30 MeV prolonged gamma-ray emission that was abruptly terminated by lightning. The gamma-ray detection was made during winter thunderstorms on December 30, 2010, by the Gamma-Ray Observation of Winter Thunderclouds experiment carried out in a coastal area along the Sea of Japan. The gamma-ray flux lasted for less than 3 min, continuously hardening closer to the lightning occurrence. The hardening at energies of 3-10 MeV energies was most prominent. The gamma-ray flux abruptly ceased less than 800 ms before the lightning flash that occurred over 5 km away from the experimental site. In addition, we observed a clear difference in the duration of the 3-10 MeV gamma rays and those >10 MeV, suggesting that the area of >10 MeV gamma-ray emission is considerably smaller than that of the lower-energy gamma rays. This work may give a manifestation that a local region emitting prolonged gamma rays connects with a distant region to initiate lightning. [ABSTRACT FROM AUTHOR]

Schottky barrier diode (SBD) radiation detectors have been fabricated on n-type 4H-SiC epitaxial layers and evaluated for low energy x- and \gamma-rays detection. The detectors were found to be highly sensitive to soft x-rays in the 50 eV to few keV range and showed 2.1 % energy resolution for 59.6 keV gamma rays. The response to soft x-rays for these detectors was significantly higher than that of commercial off-the-shelf (COTS) SiC UV photodiodes. The devices have been characterized by current-voltage (I–V) measurements in the 94–700 K range, thermally stimulated current (TSC) spectroscopy, x-ray diffraction (XRD) rocking curve measurements, and defect delineating chemical etching. I-V characteristics of the detectors at 500 K showed low leakage current (<2 nA at 200 V) revealing a possibility of high temperature operation. The XRD rocking curve measurements revealed high quality of the epitaxial layer exhibiting a full width at half maximum (FWHM) of the rocking curve \sim3.6 arc sec. TSC studies in a wide range of temperature (94–550 K) revealed presence of relatively shallow levels (\sim0.25 eV) in the epi bulk with a density \sim 7\times 10^13 cm^-3 related to Al and B impurities and deeper levels located near the metal-semiconductor interface. [ABSTRACT FROM PUBLISHER]

Photomultiplier transit time variation due to different high-voltage settings is a significant problem that degrades the performance of the systems that try to recognize fast image patterns in arrays of this type of photosensors. This effect is especially harmful for the performance of the trigger system of Cherenkov telescope cameras. With the aim of overcoming this effect, an electronic system has been designed, manufactured, and tested. This system can reduce the delay differences by introducing the appropriate variable delay for each photomultiplier (PMT), which is calculated by making use of a delay meter specially designed for this application. The specifications of the system have been defined by means of simulations and the measurements fulfill the requirements. The circuits used in this delay compensation system, as well as the simulations and measurements of the prototypes, are presented in this paper. [ABSTRACT FROM PUBLISHER]

Schottky diode X-/\gamma-ray detectors based on semi-insulating Cl-doped CdTe crystals have been developed and investigated. Both the Schottky and Ohmic contacts were formed by vacuum deposition of Ni electrodes on the opposite faces of (111) oriented CdTe crystals pretreated by Ar ion bombardment with different conditions. Record-low leakage current in the fabricated Ni/CdTe/Ni structure at high voltages ( \sim \5 nA at 300 K for the area of 10 \mm^2 at bias voltage of 1500 V) was achieved. The charge transport mechanisms in the detectors are interpreted on the basis of known theoretical models. The developed detectors have shown the record-high energy resolution in the measured spectra of ^137\Cs (0.42% FWHM). From a comparison of the spectra taken with the detector irradiated from the Schottky contact side and from the opposite side with an Ohmic contact, the concentration of uncompensated impurities (defects) in the CdTe crystals has been determined. The obtained value has been found to be close to the optimal one determined from the calculation results. [ABSTRACT FROM PUBLISHER]

VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-triggered pixel which will be connected to a global time-to-digital converter (TDC) with 1 ns resolution will provide the event's time stamp. The analog part of the readout chain and the ADC have been fabricated with TSMC 0.25 \mum mixed-signal CMOS technology and characterized with an external test pulse. The power consumption of these parts is 200 \muW from a 2.5 V supply. It offers 4 switchable gains from \pm 10 mV/fC to \pm 40 mV/fC and an input charge dynamic range of up to \pm 70 fC for the minimum gain for both polarities. Based on noise measurements, the expected equivalent noise charge (ENC) is 65 e^- RMS at room temperature. [ABSTRACT FROM PUBLISHER]

Abstract: Isomeric ratios have been measured for high-spin states in , , , , , and following the projectile fragmentation of a 1 A GeV 238U beam by a 9Be target at GSI Helmholtzzentrum für Schwerionenforschung. The fragments were separated in the fragment separator (FRS) and identified by means of energy loss and time-of-flight techniques. They were brought to rest at the centre of the RISING gamma-ray detector array and intensities of gamma rays emitted in the decay of isomeric states with half-lives between 100 ns and 40 μs and spin values up to were used to obtain the corresponding isomeric ratios. The data are compared to theoretical isomeric ratios calculated in the framework of the abrasion–ablation model. Large experimental enhancements are obtained for high-spin isomers in comparison to expected values. [Copyright &y& Elsevier]

We have developed a proof-of-concept prototype, rapid-deployment, gamma-ray portal monitor that can uniquely link the radiation signatures and visible-light images of vehicles in the system's field of view from the side of a multilane roadway. The instrument uses both visible-light and gamma-ray imaging to accomplish this. Vehicles entering the field of view of the visible-light imaging system are identified and tracked by an automated target acquisition and tracking software engine. The vehicle locations provided by this code are reported to the gamma-ray imager which uses them to locate the vehicles in the gamma-ray images and to collect the vehicle-specific radiation signatures from those images. Using this technique the gamma-ray data is integrated over the entire residence time of the vehicle in the gamma-ray imager field of view. The complete instrument comprises \sim 1-m^2CsI(Na) detector area split between two units. The system has been designed to handle up to five-lanes of traffic at highway speeds, with one unit located on either side of the roadway. Because no equipment is required in the roadway, the instrument can be deployed without impacting the flow of traffic. The results of a test and evaluation campaign indicates that the system meets its design goal of detecting 37 MBq-class sources in any of five-lanes of traffic at up to 113 km/h. [ABSTRACT FROM PUBLISHER]