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The realization of pulsed-laser diffused, thin n + contacts on high purity germanium (HPGe) and their successful segmentation is described. The contacts have been obtained by a laser-induced diffusion of Sb atoms, deposited by sputtering on Ge surface, and then segmented by means of a photolithographic technique. Three small prototypes of gamma ray detectors have been implemented, using the same n + contact (laser diffused Sb) but with three different geometries and a B implanted p + contact. Electrical and detection properties of the prototypes have been characterized, showing low leakage currents and good spectroscopy data with different gamma-ray sources. The stability of the detector performance has also been tested subjecting one of the prototypes to a typical annealing treatment. [ABSTRACT FROM AUTHOR]

One of the goals of the MICADO Euratom project is to monitor the gamma-rays emitted by radioactive waste drums in storage sites on a medium to long term basis. For this purpose, 36 low-cost gamma-ray counters were designed and built to act as a demonstrator. These counters, named SciFi, are based on a scintillating fiber readout at each end by a silicon photomultiplier, assembled in a robust arrangement in the form of 80 cm long pipes. Several counters will be placed around radwaste packages in order to monitor the gamma dose-rate by collecting a continuous data stream. The 36 sensors were thoroughly tested with a 22Na and a 137Cs gamma-ray sources, and with an AmBe neutron and gamma-ray source, the results are quite satisfactory, and the next step will be the test in a real environment. [ABSTRACT FROM AUTHOR]

Initially intended as student-led projects at universities and research institutions, the CubeSats now represent a unique opportunity to access space quickly and in a cost-effective fashion. CubeSats are standard and miniaturized satellites consisting of multiple identical units with dimensions of about 10 × 10 × 10 cm 3 and very limited power consumption (usually less than a few W). To date, several hundreds of CubeSats have been already launched targeting scientific, educational, technological, and commercial needs. Compact and highly efficient particle detectors suitable for payloads of miniaturized space missions can be a game changer for astronomy and astroparticle physics. For example, the origin of catastrophic astronomical events can be pinpointed with unprecedented resolution by measuring the gamma-ray coincidence signals in CubeSats flying in formations, and possibly used as early warning system for multi messenger searches. In this paper, we will discuss and analyze the main features of a CubeSat mission targeting intense and short bursts of gamma-rays. [ABSTRACT FROM AUTHOR]

Fusion neutron activation experiments have been carried out to investigate the activation of metal materials in Experimental Advanced Superconducting Tokamak (EAST). Some cylindrical samples made of stainless steel 316L, carbon steel (A3), high purity cadmium (Cd), oxygen-free copper (Cu), and high purity aluminum (Al) were transported to Port G in the EAST hall for neutron irradiation. The characteristic gamma rays emitted by activated samples were measured with a spectrometer consisting of a digital multichannel analyzer (MCA) and a high purity germanium (HPGe) detector. Qualitative identification of the dominant radionuclides and quantitative measurement of the specific activity have been performed. The experimental results indicated that the high radioactive nuclides with short half-life were produced, such as 56Mn in 316L and A3, 28Al in Al, 66Cu in Cu, and 111m Cd in Cd. Moreover, the long half-life radionuclides were generated in 316L, A3, Cu and Cd samples, which will become the major factors on environment and personnel. In addition, the normalized dose rate at 10 cm in the air of 316L, A3, Al, Cd, and Cu was 1.53 × 10−23, 4.83 × 10−24, 5.57 × 10−23, 4.90 × 10−24 and 1.10 × 10−23 Sv/h/n, respectively. Finally, the comparison between the experimental neutron activation results and the predicted quantities calculated with FISPACT-2007 was discussed. [ABSTRACT FROM AUTHOR]

The Timepix3 hybrid-pixel readout chip consists of a matrix made of 256 × 256 square-shaped pixels with a 55-μm pitch, which can be hybridized to several semiconductors, such as silicon (Si) or cadmium telluride (CdTe) with thicknesses up to 5 mm. Working as an event-based readout chip, it simultaneously records the time-over-threshold (ToT) in each pixel, measuring the deposited energy, as well as the time-of-arrival (ToA), with a time resolution of 1.5 ns. In this article, we present the energy calibration of two Timepix3 chips: the first one was bump-bonded with a 300-μm-thick silicon sensor and the second one with a 1-mm-thick CdTe sensor. Both detectors were calibrated with per pixel calibration, using the monochromatic SOurce of Low-Energy X-rays [SOLEX from Henri Becquerel National Laboratory (LNHB) at CEA Saclay] and a set of calibration-grade sealed radioactive sources. Evaluations were carried out over the energy range 6-122 keV for Timepix3 Si and 20 keV- 1.332 MeV for Timepix3 CdTe. Based on this experimental procedure, an energy resolution of 2.6 keV (3.4%) at 59.5 keV was observed for Timepix3 Si. For Timepix3 CdTe, this parameter was 5.6 keV (9.4%) at 59.5 keV, 27.24 keV (4.1%) at 661.7 keV, and 47.4 keV (3.5%) at 1.332 MeV. It is the first time that CdTe bump-bonded Timepix3 spectral performances were evaluated for gamma rays above 1 MeV. The reconstruction of the full-energy peak for such high energies is possible due to the ToA information, which allows the identification of all interactions caused by a given gamma ray within the detector. [ABSTRACT FROM AUTHOR]

The NDeGRA project is researching the application of novel technologies in the development of position-sensitive detectors for gamma ray astronomy and medical imaging. The project's approach to simulation and some preliminary results on the upper limit of efficiency of a Compton camera design based on monolithic scintillator crystals are discussed. [ABSTRACT FROM AUTHOR]

Cadmium–zinc–telluride (CZT) pixel detectors represent a consolidated choice for the development of room‐temperature spectroscopic X‐ray imagers, finding important applications in medical imaging, often as detection modules of a variety of new SPECT and CT systems. Detectors with 3–5 mm thicknesses are able to efficiently detect X‐rays up to 140 keV giving reasonable room‐temperature energy resolution. In this work, the room‐temperature performance of 3 mm‐thick CZT pixel detectors, recently developed at IMEM/CNR of Parma (Italy), is presented. Sub‐millimetre detector arrays with pixel pitch less than 500 µm were fabricated. The detectors are characterized by good room‐temperature performance even at high bias voltage operation (6000 V cm−1), with energy resolutions (FWHM) of 3% (1.8 keV) and 1.6% (2 keV) at 59.5 keV and 122.1 keV, respectively. Charge‐sharing investigations were performed with both uncollimated and collimated synchrotron X‐ray beams with particular attention to recovering the charge losses at the inter‐pixel gap region. High rate measurements demonstrated the absence of high‐flux radiation‐induced polarization phenomena up to 25 × 106 photons mm−2 s−1. [ABSTRACT FROM AUTHOR]

Pile up and dead time are two important corrections in the analysis of X-ray and gamma ray spectra. The most important of these is pile up correction because these peaks do not really exist in the spectra; they only seem to exist. For this reason, these peaks affect both the qualitative and quantitative accuracy of the analysis. In addition, the pile up pulses forming the pile up peaks increase the background count in the spectrum. Companies that produce X-ray or gamma ray detector systems design pile up reject circuits and integrate them into detector systems to prevent these pulses. These circuits have time limitations because they are made up of electronic devices. For this reason, the pile up problem cannot be solved completely in these circuits. Therefore, mathematical models based on a statistical approach are needed. Such a model was developed in this study. A computer program based on this model was developed. This developed program has been applied to X-ray and gamma ray spectra. It has been shown that this model provides about 2% correction in the main peak regions and significantly reduces background counts. [ABSTRACT FROM AUTHOR]

The unfluctuating running of on-orbit spacecraft equipment has a decisive impact on the smooth implementation of space exploration mission. However, due to the adverse work conditions and complex running states, it is really a challenge for the online monitoring of aerospace equipment. In this paper, an improved growing neural gas method based on incremental learning is proposed, which is dedicated to solving the problem of online anomaly detection. The learning rate of the proposed method is adaptively adjusted according to the process of model training, ensuring the weights update quickly at the beginning of model construction and converge steady at the end of model training. The optimized insertion mechanisms of neurons ensure that the necessary new neurons are inserted at the right time and location dynamically, while the innovative deletion mechanisms of neurons ensure that the worthless neurons be deleted timely and at the same time guarantee the representation ability of model. The comparison results with the conventional methods on public datasets show that the proposed method achieves the better performance obviously, both in the aspects of detection accuracy and computational efficiency, respectively. At last, as a case study, the proposed method is used for online anomaly detection of a real aerospace device, i.e., a gamma ray detector, and the final F1 score of anomaly detection is as high as 98.78%. The results show that the proposed method can be applied to online detection of aerospace equipment health conditions effectively. [ABSTRACT FROM AUTHOR]

Finding and tracking radioactive sources have numerous security applications in civilian energy installations, military facilities, and ports of entry. The price of radiological sensors varies proportionally to size and imaging characteristics such as angular resolution, and the cheapest devices are nearly isotropic–i.e., they integrate radiation from a sphere of directions centered at the sensor. While many radiation sensors have high aspect ratios or odd shapes, the sensors used here are right cylinders, with a near identical directional efficiency such that for analysis purposes, other aspects, such as counting statistics, would make nonisotropy of the sensor negligible. In this article, we propose a simple and robust way to integrate measurements from both isotropic radiological sensors and depth sensors, whose reliability and resolution benefit from recent advances in computer vision and imaging. Our key idea is to convert all sensor measurements into proximity signals based on radial distance variations over time. Based on this sensor fusion model, we show that for moving radiological sources even a simple Kalman filter can trade-off the complementary strength of high-resolution depth sensors and isotropic radiological sensors. We show novel results with a LIDAR sensor and a thermal stereo pair, and demonstrate applications such as tracking and rendering non-line-of-sight imagery behind obstacles and detecting multiple radiological sources in the same scene. [ABSTRACT FROM AUTHOR]

Metallic magnetic calorimeters (MMCs) combine the excellent energy resolution of cryogenic gamma ray detectors with a very small nonlinearity and a reproducible response, owing to their magnetization-based sensor and their metallic heat flow path. These attributes make MMCs well suited for photon and particle spectroscopy applications requiring the highest accuracy. We are developing high-resolution MMC gamma ray detectors with the goal of improving the quality of key nuclear decay data for nuclear safeguards and fundamental science. Our exploratory "integrated" (SQUIDs and sensors on the same chip) 14-pixel MMC designs recently demonstrated energy resolution of 37.5 eV at 60 keV. Here, we describe the design and optimization for a new generation of MMC detectors using both "integrated" and "split" designs (SQUIDs and sensors on separate chips). The new designs are expected to have an energy resolution < 25 eV (< 5 eV) for MMCs optimized for energies up to 100 keV (10 keV) and have up to 32 pixels. [ABSTRACT FROM AUTHOR]

Radiation rays, especially gamma rays, are produced during nuclear fusion plasma discharge. To obtain the gamma rays around the Experimental Advanced Superconducting Tokamak (EAST) during nuclear fusion plasma discharges, Ar-based gamma ray detectors have been adopted in this article, and to fully monitor the gamma ray dose rates inside the EAST hall, three gamma ray detectors have been set at three selected radiation monitoring sites. Due to the long distances between the monitoring personal computer (PC) and each radiation monitoring site, the monitoring system based on the RS-485 differential communication mode has been designed and set up. With each plasma discharge, the gamma ray radiation field undoubtedly appears as a pulsed radiation field in the EAST hall. Based on the gamma ray dose rates obtained by the monitoring system, the pulsed radiation field of gamma ray dose rates has been carefully studied during one lower hybrid current drive (LHCD)-based plasma discharge. Finally, the exponential function model of the gamma ray dose rates during one plasma discharge in the EAST hall was well obtained and presented. [ABSTRACT FROM AUTHOR]

The heavy element semiconductor compound Cs2Hg6S7 is of interest as a potential wide gap semiconductor for gamma ray detection. To determine electrically active defects and their energy levels, photoconductivity (PC) spectroscopy was carried out over the temperature range of 90-295 K. The low temperature spectrum exhibits photoconductive transitions at 1.495, 1.61, 1.66, and 1.68 eV. The optical transitions are tentatively attributed to defects with levels located at energies of 50, 70, 120, and 240 meV from the band edge. A superlinear dependence of photocurrent on illumination intensity is observed that is attributed to a two-center recombination process that involves shallow traps and recombination centers. Near band edge photoluminescence (PL) was observed over the temperature range of 24-80 K. The spectrum revealed three defect related emission bands located at 1.68, 1.66, and 1.62 eV, whose ionization energies are 57 meV, 78 meV, and 115 meV, respectively. From the temperature and excitation dependencies of the observed peak intensities and energies, the radiative recombination mechanisms of the bands were attributed to transitions involving excitons bound to neutral and ionized acceptors. Good agreement of the defect level energies determined by PL and PC were noted, indicating that they were of the same origin. The defects were tentatively attributed to metal vacancies that form shallow acceptor levels. [ABSTRACT FROM AUTHOR]

We are developing a frequency-multiplexed readout for arrays of high-resolution Gamma detectors based on superconducting transition edge sensors (TESs). Each sensor is part of an LCR resonant circuit and is biased at an identifying carrier frequency. Several carrier signals are added and amplified with a single SQUID preamplifier at 4 K. Gamma absorption modulates the amplitude of the carrier, and demodulation at room temperature retrieves the initial temperature evolution of the sensor. This multiplexing system has originally been developed to read out large arrays of bolometers for cosmic microwave background studies. To accommodate the faster Gamma-ray signals, its demodulator bandwidth is being extended to 20 kHz to allow reading out up to eight TESs with a detector bandwidth of 10 kHz. Here we characterize the system noise performance and show how this multiplexing scheme can be adapted to read out arrays of superconducting Gamma-ray detectors.

[Display omitted] • Quality non-polar GaN films (which itself is believed to be challenging) are deposited on the polar substrates using PLD route. • These non-polar GaN films exposed to 60Co Gamma radiations varying dose values from 40 kGy to maximum value of 260 kGy under atmospheric conditions. • The critical investigations reported on the non-polar GaN films for the first time, clearly demonstrate the resistive nature of the films against expose to energetic gamma rays is highly impressive. • The result reported herewith demonstrate use of non-polar GaN films can be one of the options to fabricate next generation of gamma ray detectors. The GaN films/layers exposed to γ-radiations is known to harvest defects and vacancies in the crystals producing donor, acceptor and recombination centers within the bandgap. Therefore it is important to investigate and study the γ- ray irradiation effects on various physical and chemical properties of a material before any optoelectronic and/or electronic devices are being fabricated. To avoid Stark effect which is observed in most of the optoelectronic devices fabricated using GaN films grew along polar face, use of non-polar GaN films is suggested by researchers. To address such issues the article reports the investigations of physical and chemical properties of non-polar GaN films grown on polar substrate using pulsed laser deposition, which were exposed to the 60Co gamma rays varying dose values. Resistive nature against the impairment of the films caused by γ-rays observed herewith is highly encouraging, suggesting the use of non-polar GaN films as radiations harden material suitable for fabricating new generation γ-ray detectors. To our knowledge very limited information is available that report such investigations. [ABSTRACT FROM AUTHOR]

The electrical signals generated by radiation detectors are often subject to undesired effects that can affect the energy resolution of the detector. These effects may be caused by the measurement system itself or by the high rate of events. Traditional methods for shaping the signals and mitigating these effects often have limitations, such as requiring explicit information about the signals. In this paper, the authors propose a deconvolution method based on least square filtering and non-negative sparsity theory to address these limitations. The method is evaluated using simulated data representing a gamma ray detector with a NaI(Tl) crystal and a photomultiplier tube (PMT). The electrical pulses in this system are pre-processed using a CR coupling circuit and a RC integrator. The energy resolution obtained with the traditional method was 6.60%, while the proposed method resulted in an energy resolution of 5.65%. In addition to improving accuracy, the proposed method also reduces implementation complexity. [ABSTRACT FROM AUTHOR]

The speeding particles may in turn generate gamma rays, for example by colliding with photons and boosting their energy. With its improved resolution and ability to produce detailed spectra of gamma ray energies, CTAO's data should help refine theoretical models of the supernova particle accelerators, Araudo says. [Extracted from the article]

In order to obtain the relationship between energy and channel, the suitable radionuclides are chosen to calibrate. The result shows a goodness of fitting. The Monte Carlo simulation about the detection efficiency of the high purity germanium (HPGe) gamma-spectrometry system was performed. The distance between radioactive source and the end cap is set 15, 20, 25 and 50 cm, respectively. The maximum absolute efficiency locates at around 80 keV. It can be concluded that the absolute efficiency is declining accompany with the increasing of distance. In the end, at the distance of 25 cm, the authors changed thickness of the dead layer and the source distribution to calculate. The maximum absolute efficiency is 8.56E−03, and the relative deviation is 0.0011. Then it was compared with the experimental result provided with the manufacturer. The result of simulation shows a certain agreement with the experimental results. This work will be helpful for calculating the efficiency of HPGe gamma-spectrometry. [ABSTRACT FROM AUTHOR]

Compact multi-channel radiation detectors rely on low noise front-end application specific integrated circuits (ASICs) to achieve high spectral resolution. Here, a new ASIC developed to readout virtual Frisch-grid cadmium zinc telluride (VFG CZT) detectors for gamma ray spectroscopy is presented. Corresponding to each ionizing event in the detector, the ASIC measures the amplitude and timing at the anode, the cathode and four pad sense electrodes associated with each sensor in a detector array. The ASIC is comprised of 52 channels of which there are 4 cathode channels and 48 channels which can be configured as either anode channels with a baseline of 250 mV or pad sense channels to process induced signals with a baseline of 1.2 V. With a static power dissipation of 3 mW, each channel performs low-noise charge amplification, high-order shaping, peak and timing detection along with analog storage and multiplexing. The overall channel linearity was better than ± 1% with timing resolution down to 700 ps for charges greater than 8 fC in the 3 MeV range. With a 4 × 4 array of 6 mm × 6 mm × 20 mm virtual Frisch-grid bar sensors connected and biased, an electronic resolution of ≈ 270 e−rms for charges up to 100 fC in the 3.2 MeV range was measured. Spectral measurements obtained with the 3D correction technique demonstrated resolutions of 1.8% FWHM at 238 keV and 0.9% FWHM at 662 keV. [ABSTRACT FROM AUTHOR]

Two high performance single crystal diamond (SCD) radiation detectors for neutrons and gamma ray have been fabricated. One was coated with a 5 μm 6LiF (95% enriched in 6Li) layer in order to detect the neutrons and the other one is without any conversion layer for comparison. The detectors are irradiated with the 241Am-Be and 252Cf neutron sources and 152Eu gamma source to test their performance. Under neutron sources, the neutron signal peak was clearly observed in the detector with the 6LiF conversion layer. Meanwhile, both detectors are responsive to the gamma rays at the low energy. The 152Eu gamma source was specially used to verify the gamma ray detection ability of the fabricated SCD detectors. The results show that the detector's count rate and the gamma peak center position in the PHS depend on the incident gamma spectra critically. Combined, these results demonstrate that the design and fabrication process of the detectors are feasible. [ABSTRACT FROM AUTHOR]

Abstract A Cerium doped Lutetium Yttrium Orthosilicate (LYSO) crystal based precision gamma detection system has been developed using a position sensitive photomultiplier tube, with minimal pulse processing requirements. The assembly's detailed characterization has been reported in this work. This kind of a setup with a precise spatial resolution can be very useful for scanning high purity germanium detectors that use pulse shape analysis algorithms for signal processing in gamma ray spectroscopy experiments. The highly pure LYSO crystal used here is custom-made and the overall setup including the multi anode readout photomultiplier tube is compact. The system has been tested for energy, timing and position information regarding gamma photons interacting within the crystal using a coincidence mechanism. Position sensitivity has been found to be in the anticipated range of a few millimeters. This kind of a detector can be used in various fields, vis-à-vis, medical imaging, radioactive waste management, nuclear proliferation control, and various applications that deal with precisely identifying and locating radioactivity. [ABSTRACT FROM AUTHOR]

Abstract The transient responses of the CMOS image sensor (CIS) detectors during radiation are one of the key issues to the detector design, reliability and applicability in space and nuclear environments. The transient radiation experiments of the CIS detectors irradiated by gamma rays and X rays were carried out to compare the difference and the similarity of the transient responses. The CISs have 4 Megapixels and pinned photodiode (PPD) pixel architecture with a standard 0.18 μ m CMOS technology. The white spots and lines of the dark images induced by gamma rays and X rays during radiation are analyzed to compare the difference and the similarity of transient response characteristics. The comparison of the DSNU fluctuation of the CIS detectors versus the continuous frames induced by gamma rays and X rays are also analyzed. The theoretical analysis of the difference is presented by radiation particle transportation simulation using GEANT4. The mechanisms of the transient responses in the CIS detectors are demonstrated by combining the experimental results and theoretical analysis. [ABSTRACT FROM AUTHOR]

Abstract Decay of 244Am m,g , produced by neutron irradiation of 243Am, has been studied by singles and coincidence measurements of decay γ rays. Two new γ rays of energy 940.54 ± 0.08 and 983.46 ± 0.08 keV have been observed in the decay of 244Am m which suggests a new level of 983.5 keV in 244Cm. This level has been assigned a tentative spin of (1 −). In the present studies, uncertainties in the γ -ray intensities of 244Am m,g have been significantly reduced by nearly an order of magnitude for most of the γ rays. The data of half-lives have also been improved. More precise half-lives for 244Am m (T 1∕2 = 26.13 ± 0.43 min) and 244Am g (T 1∕2 = 600.4 ± 1.8 min) have been obtained. [ABSTRACT FROM AUTHOR]

In this study, albedo parameters are experimentally measured to determine radiation scattering features of some thermoluminescent dosimetry materials (TLD 100, TLD 100h, TLD 200 and TLD 400). In experimental setup, it was used scattering angle of 168°, 59.54 keV gamma rays and HPGe detector. The effective atomic numbers of the investigated materials were determined from the coherent to Compton scattering intensity ratio. Also, the mass attenuation coefficient, the mass energy absorption coefficient and kerma relative to air and ICRU tissue were calculated for the TLD materials. It was observed that TLD 100h is the best tissue equivalent material among other TLD materials and best reflects 59.54 keV gamma rays. • The effective atomic numbers of some thermoluminescent dosimetry materials were obtained from scattering ratios. • The effective atomic number and albedo parameters are obtained for 59.54 keV photon energy. • TLD 100h is the material that best reflects 59.54 keV gamma rays. [ABSTRACT FROM AUTHOR]

We report on the indigenous design and development of laboratory scale travelling heater method (THM) system to grow detector grade Cd 0.9 Zn 0.1 Te (CdZnTe) single crystals. THM system mainly consists of two-zone furnace with a tuneable temperature gradient (30–80 °C/cm), high precision translation (1–25 mm/day) and rotation (1–50 rpm) assemblies to meet the stringent conditions that are essential to grow detector grade CdZnTe single crystals. Further, a load cell in the THM system enables continuous monitoring of the growth. Systematic growth experiments were performed to optimize the various growth parameters in order to achieve large grain single crystals. Herein, the effect of temperature gradient and growth rate on the increase in grain size is discussed in detail. Each successful growth experiment yields a minimum of four detector grade elements of dimensions 10 × 10 × 5 mm3 from a starting charge of 100 g of CdZnTe. The crystalline nature and quality of the detector elements were evaluated using Laue, NIR transmission spectroscopy and I–V characteristics. Crystals with resistivity greater than ∼109 - 1010 Ω-cm were identified for testing gamma ray detection. The photo peak of 137Cs was resolved with an energy resolution of 4.2% at 662 keV and its measured electron mobility lifetime product is found to be ∼3.3 × 10−3 cm2/V. The demonstration of the gamma ray detection with a relatively high μτ product is the testimony to the successful growth of detector grade CdZnTe single crystals by an indigenously developed THM system. [Display omitted] • Detector grade CdZnTe crystals are grown using indigeniously developed THM system. • Temperature gradient and growth rate are optimized for high quality crystals. • Atleast 4 detector elements of 10 × 10 × 5 mm3 obtained from 100 g of initial charge. • Indigenous developed CdZnTe detectors display energy resolution of 4.2 % at 662 keV. [ABSTRACT FROM AUTHOR]

Abstract The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) , composed of two small satellites, is a new mission to monitor the Gamma-Ray Bursts (GRBs) coincident with Gravitational Wave (GW) events with a FOV of 100% all-sky. Each GECAM satellite detects and localizes GRBs using 25 compact and novel Gamma-Ray Detectors (GRDs) in 6 keV–5 MeV. Each GRD module is comprised of LaBr 3 :Ce scintillator, SiPM array and preamplifier. A large dynamic range of GRD is achieved by the high gain and low gain channels of the preamplifier. The energy response of GRD prototype was evaluated using radioactive sources in the range of 5.9–1332.5 keV. A energy resolution of 5.3% at 662 keV was determined from the 137Cs pulse height spectra, which meets the GECAM requirement (< 8% at 662 keV). Energy to channel conversion was evaluated and a nonlinearity correction was performed to reduce the residuals (< 1.5%). Also, a Geant4-based simulated in-flight background and a measured GRD LaBr 3 :Ce intrinsic activity were used to evaluate the capability of in-flight calibration. These results demonstrate the design of GRD. [ABSTRACT FROM AUTHOR]

Abstract The main aim of this work is to provide a method to retrieve the intrinsic spatial resolution of a gamma-ray detector block based on monolithic crystals within an assembled scanner. This method consists on a discrimination of the data using a software collimation process. The results are compared with an alternative method of separating two detector blocks far enough to produce a "virtual" source collimation due to the geometric constraints on the allowed coincidence event angles. A theoretical model has been deduced to fit the measured light distribution profiles, allowing estimating the detector intrinsic spatial resolution. The detector intrinsic spatial resolution is expected to follow a Gaussian distribution and the positron-emitter source shape, given the small size of a 22Na source with 0.25 mm in diameter, can be assumed to follow a Lorentzian profile. However, the collimation of the data modifies the source shape that is no longer a pure Lorentzian distribution. Therefore, the model is based on the convolution of a Gaussian shaped distribution (contribution of the detector) and a modified Lorentzian distribution (contribution of the collimated source profile) that takes into account the collimation effect. Three LYSO crystals geometries have been studied in the present work, namely a 10 mm thick trapezoidal monolithic block, and two rectangular monolithic blocks with thicknesses of 15 mm and 20 mm, respectively. All the blocks have size dimensions of 50 mm × 50 mm. The experimental results yielded an intrinsic detector spatial resolution of 0.64 ± 0.02 mm, 0.82 ± 0.02 and 1.07 ± 0.03 mm, for the 10 mm, 15 mm and 20 mm thick blocks, respectively, when the source was placed at the center of the detector. The detector intrinsic spatial resolution was moreover evaluated across one of the axis of each crystal. These values worsen to an average value of 0.68 ± 0.04 mm, 0.90 ± 0.14 and 1.29 ± 0.19 mm, respectively, when the whole crystal size is considered, as expected. These tests show an accurate method to determine the intrinsic spatial resolution of monolithic-based detector blocks, once assembled in the PET system. Highlights • Software collimation based on LOR discrimination. • Gamma ray detectors based on monolithic scintillators and arrays of photosensors. • Method providing the intrinsic spatial resolution in PET detectors based on monolithic crystals. • Intrinsic resolution of 0.64 ± 0.02, 0.82 ± 0.02 and 1.07 ± 0.03 mm, for 10, 15 and 20 mm crystals. [ABSTRACT FROM AUTHOR]

Abstract The DArk Matter Particle Explorer (DAMPE), a satellite-based cosmic ray and gamma-ray detector, was launched on December 17, 2015, and began its on-orbit operation on December 24, 2015. In this work we document the on-orbit calibration procedures used by DAMPE and report the calibration results of the Plastic Scintillator strip Detector (PSD), the Silicon-Tungsten tracKer-converter (STK), the BGO imaging calorimeter (BGO), and the Neutron Detector (NUD). The results are obtained using Galactic cosmic rays, bright known GeV gamma-ray sources, and charge injection into the front-end electronics of each sub-detector. The determination of the boundary of the South Atlantic Anomaly (SAA), the measurement of the live time, and the alignments of the detectors are also introduced. The calibration results demonstrate the stability of the detectors in almost two years of the on-orbit operation. [ABSTRACT FROM AUTHOR]

Abstract Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new high-efficiency γ -ray spectrometer designed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF's Isotope Separator and Accelerator (ISAC-I) facility. GRIFFIN is composed of sixteen Compton-suppressed large-volume clover-type high-purity germanium (HPGe) γ -ray detectors combined with a suite of ancillary detection systems and coupled to a custom digital data acquisition system. The infrastructure and detectors of the spectrometer as well as the performance characteristics and the analysis techniques applied to the experimental data are described. [ABSTRACT FROM AUTHOR]

The inverse beta decay is the most important reaction for registration of an electronic antineutrino.v˜e+p=e+n↗n+p→d+γ(2.2MeV)↘n+157GD+γ(8MeV)The detector of electronic antineutrinos consists of a target and a gamma-ray detector. Sorbent C100 with the applied gadolinium is supposed to be used as a target for the detector to register the products of reaction ṽe + p= e+ + n. According to the Boyd model [1], the sorption on ion-exchange resins is a complicated and multistage process that includes mechanisms of external (film) diffusion and internal (gel) diffusion. The mechanism of chemical reaction also influences the sorption process. Diffusion mechanisms are sequential stages of the sorption process, so that the slowest of them is the limiting stage of the process. The sorption kinetics was examined by the finite volume method. The main purpose was to reveal the limiting stage in each phase of the sorption process [2] in system Gd3+-C100 in H+ form. It was necessary to find out how the acid concentration and temperature influence the sorbent sorption properties. [ABSTRACT FROM AUTHOR]

Mobile radiation sensing techniques for surge deployment and wide area search are important for nuclear security applications. Radiation sensors were developed for the use with robotic platforms of unmanned aerial systems (UAS). Ambient temperature neutron and gamma CLYC sensor and high resolution CZT gamma sensor were integrated into the UAS as plug-and-play interchangeable components allowing easy attachment to a robot in field conditions. The time and position data were added via Robot Operating System to measured intensities of photon peaks and neutron rates enabling the input for the UAS flight control. The contour mapping of a radiation area by multiple UAS was simulated. [ABSTRACT FROM AUTHOR]

Abstract Laser induced transient current technique (LI-TCT) was proven to be a successful tool for measuring at the same time carrier lifetime, carrier mobility, and electric field distribution in X- and gamma ray detectors with plain contacts on opposite surfaces. Unfortunately, the most performing detectors exploit more complicated contact geometries that, hindering hole contribution to signal formation, allow a much better spectroscopy. In this paper, a LI-TCT based method is presented, for the determination of transport parameters as well as electric field distribution directly in single carrier devices. The method's validity is demonstrated in twin CdZnTe detectors having similar material properties, but different weighting potentials. [ABSTRACT FROM AUTHOR]

Abstract A new method for measuring the time integral of thermal neutron flux of a nuclear reactor is proposed. This method utilizes two consecutive (n, γ) reactions on the 58Ni isotope of a natural nickel sample placed near the core of a reactor, 58Ni(n, γ) → 59 Ni(n, γ) → 60 Ni(n, γ). Natural nickel contains 68% 58Ni producing an intense 8.999 MeV γ -line leading to the 59Ni ground state via the 58Ni(n, γ) reaction. The 59Ni isotope produced in this manner undergoes another (n, γ) reaction, emitting a γ -line at 11.388 MeV leading to the 60Ni ground state. By measuring the intensity ratio of the two γ -lines at 8.999 and 11.388 MeV using a HPGe detector, it is possible to deduce the integral over time of the neutron flux necessary for producing the 59Ni isotope. Good accuracy can be obtained with this method due to the low gamma background at such high energies. [ABSTRACT FROM AUTHOR]

Radiation Portal Monitors (RPM) acquire sequential measurements of gamma activity that can be modeled as a sequence of Poisson distributed random numbers. These series can be analyzed with Statistical Process Control (SPC) methods to trigger alarms when the statistical distribution of the ambient dose during a transit changes. Some usual SPC methods have been compared and modified to narrow the time required to bound an alarm. Both the probabilities of detection and the Average Run Length (ARL) are used and fitted to curves to benchmark the SPC methods, which are ranked as: SR, EWMA, CUSUM, SPRT, FLR, and Shewhart. [ABSTRACT FROM AUTHOR]

Highlights • Monitoring the size of liposomes designed for alpha-therapy by AF4-MALS. • New Coupling of a gamma detector on an AF4-MALS to analyze radioactive tracers. • Monitoring the encapsulation of highly energetic alpha emitter in liposomes. Abstract Alpha-particle-emitting radionuclides have been the subject of considerable investigation as cancer therapeutics, since they have the advantages of high potency and specificity. Among α-emitting radionuclides that are medically relevant and currently available, the lead-212/bismuth-212 radionuclide pair could constitute an in vivo generator. Considering its short half-life (T 1/2 = 60.6 min), 212Bi can only be delivered using labelled carrier molecules that would rapidly accumulate in the target tumor. To expand the range of applications, an interesting method is to use its longer half-life parent 212Pb (T 1/2 = 10.6 h) that decays to 212Bi. The challenge consists in keeping 212Bi bound to the vector after the 212Pb decay. Preclinical and clinical studies have shown that a variety of vectors may be used to target alpha-emitting radionuclides to cancer cells. Nanoparticles, notably liposomes, allow combined targeting options, achieving high specific activities, easier combination of imaging and therapy and development of multimodality therapeutic agents (e.g., radionuclide therapy plus chemotherapy). The aim of this work consists in assessing the in vitro stability of 212Pb/212Bi encapsulation in the liposomes. Indeed, the release of the radionuclide from the carrier molecules might causes toxicity to normal tissues. To reach this goal, Asymmetrical Flow Field-Flow Fractionation (AF4) coupled with a Multi-Angle Light Scattering detector (MALS) was used and coupling with a gamma (γ) ray detector was developed. AF4-MALS-γ was shown to be a powerful tool for monitoring the liposome size together with the incorporation of the high energy alpha emitter. This was successfully extended to assess the stability of 212Bi-radiolabelled liposomes in serum showing that more than 85% of 212Pb/212Bi is retained after 24 h of incubation at 37 °C. [ABSTRACT FROM AUTHOR]