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The detection efficiency of a gamma ray detector should be calibrated prior to the measurement of activity in samples. The aim of this research is to develop a simple experimental technique to calibrate the efficiency of detectors for geometrical sources by replicating their responses from virtually equivalent sources (VES) constructed from a collection of Standard Point Source (SPS) measurements. Experiments were performed to replicate the response of a disk source of 5.2 cm radius by equivalent disk sources (EDS) reconstructed from a collection of 19, 91 and 169 SPS measurements to optimize the number of measurements, response of detector for radially symmetric SPS locations was verified through Absolute Peak Efficiency (APE) calculations. APE was calculated experimentally for the actual disk source and EDS as well as using EGS5 simulations. The difference between experimentally measured and simulated APE for 5.2 cm EDS was observed to be about 7.8 %, 5.2 % and 5.4 % for 137Cs and about -1.3 %, 1.3 % and 2.7 % for 22Na for the EDS constructed from 19, 91- and 169 SPS measurements respectively

LHAASO is planning to enhance its sensitivity at energies around 100 GeV by utilize MCP staffed 20” PMT in the Water Cherekove Detector Array. The effective area for gamma ray detection will reach to 1800 m2 and differential sensitivity to 0.2 CU at 50 GeV. It will be the very useful survey detection for transient phenomena at 50 GeV in the northern sky. LHAASO is expected to play an important role in the multimessenger observation with the upgrading.

A simple scintillator kit developed by Ian Bearden [1] was used to prepare a learning experience on gamma ray detection for secondary students. The goal is to offer an opportunity to collect gamma spectra, analyse data and understand how coincidence measurements are useful in space physics and in many other applications.

Glenn Knoll was one of the leaders in the field of radiation detection and measurements and shaped this field through his outstanding scientific and technical contributions, as a teacher, his personality, and his textbook. His Radiation Detection and Measurement book guided me in my studies and is now the textbook in my classes in the Department of Nuclear Engineering at UC Berkeley. In the spirit of Glenn, I will provide an overview of our activities at the Berkeley Applied Nuclear Physics program reflecting some of the breadth of radiation detection technologies and their applications ranging from fundamental studies in physics to biomedical imaging and to nuclear security. I will conclude with a discussion of our Berkeley Radwatch and Resilient Communities activities as a result of the events at the Dai-ichi nuclear power plant in Fukushima, Japan more than 4 years ago.

As one of the important targets of the DArk Matter Particle Explorer (DAMPE), the GeV gamma- ray observations of DAMPE with good angular resolution, high energy resolution and high back- ground rejection facilitate the search of fine structures in the spectra of gamma-ray sources. In this work we summarize the performance of DAMPE for gamma-ray detection using simulation data, including the effective area, angular resolution and energy resolution.

In this paper, we propose the fast and efficient detection method using the continuous measurement technique for the gamma-ray signal acquisition. This method is improved than the conventional method for the getting information of the radiation distribution. First, we implement the stereo radiation detection system using gamma-ray sensors and the motion controller. We apply continuous measurement technique to the gamma-ray detector and conduct gamma-ray irradiation test for the comparison of detection techniques. The results show that the continuous measurement technique has the high efficient performance than the conventional method.Key Words : Fast gamma detector, Scintillation detector, Gamma-ray detection, Gamma Imager†Corresponding Author : Dept. of Nuclear convergence Techcnology Development, Korea Atomic Energy Research Institute, Korea.E-mail: yghwang@kaeri.re.kr*Dept. of Nuclear convergence Techcnology Development, Korea Atomic Energy Research Institute, Korea.Received : July 31, 2014; Accepted : August 26, 2014

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.

Due to its exceptional properties, 3He proportional counters are the golden standard for neutron detection, particularly in homeland security applications where large area detectors are deployed. However, in recent years 3He has become severely scarce, which led to a tremendous price increase and acquisition restrictions of this material. Motivated by this, the development of 3He-free solutions became a priority. In a previous work, we have established a novel concept for neutron detection: a proportional counter with boron carbide (B 4 C) fine powder suspended in the proportional gas, forming a neutron sensitive aerosol that relies on the 10B neutron capture reaction. Computer simulations and prototype exposure to a cold neutron beam yielded favorable results, validating the detection concept, which may also be applied to hard x-ray and gamma ray detection by using fine particles made of a heavy element, such as Bi or Au. In this work we study the effect of the presence of B 4 C microparticles in the charge gain and energy resolution of a proportional counter filled with Ar-CH4 (90%–10%), by irradiation with x-rays from a 55Fe source. For the same applied voltage, an average gain loss by a factor of 36% and energy resolution (FWHM) increase by 15% (absolute value) was observed with the inclusion of B 4 C microparticles. Intrinsic energy resolution was calculated, obtaining 15% for pure P10 operation and 32% in the presence of the microparticles. While the gain drop is recoverable by increasing anode voltage, energy resolution degradation may be a drawback in low energy applications, were energy resolution is favored over detection efficiency.

Characterization of the electrical response of HPGe segmented detectors as a function of the interaction position is one of the current goals for the Nuclear Physics community in order to perform γ-ray tracking or even imaging with these detectors. For this purpose, scanning devices must be developed to achieve the signal-position association with the highest precision. With this aim, SALSA, a γ-camera-based scanning system, is under development at our laboratory. In this work, the optimization study aimed to obtain the best spatial resolution in the position-sensitive detectors employed as γ camera is described.

We describe experiments for the undergraduate laboratory that use a high-resolution gamma detector to measure radiation in environmental samples. The experiments are designed to instruct the students in the quantitative analysis of gamma spectra and secular equilibrium. Experiments include the radioactive dating of Brazil nuts, determining radioisotope concentrations in natural samples, and measurement of the 235U abundance in uranium rich rocks.

In gamma-ray spectroscopy and imaging, the natural gamma-ray background can significantly reduce detection sensitivity, especially when the source is weak and the background varies substantially. This project aims to systematically measure and characterize the spatial and temporal variations of the background in order to assess their impact on detection sensitivity and specificity for homeland security applications. An extensive survey of typical backgrounds found in the San Francisco bay area was performed, and initial measurement results are presented here.

LiCaAlF6 scintillators are one of the attractive scintillators for neutron detection. To reduce the effect on gamma-rays, the Ce doped LiCaAlF6 scintillators can discriminate the neutron and gamma-ray events based on the pulse shape discrimination technique. To apply the scintillators for the oil logging, the high temperature characteristics must be investigated. In this paper, the temperature dependence of the neutron-gamma discrimination based on pulse shape discrimination technique in the Ce:LiCaAlF6 scintillator is investigated as one of the high temperature characteristics. The property of pulse shape discrimination in the Ce:LiCaAlF6 has small temperature dependence ranging from 25°C to 150°C. We concluded that the Ce:LiCaAlF6 scintillators can discriminate neutron and gamma-ray events under high temperature condition up to 150°C .

This work reports on the characterization of TlBr detectors for use in nuclear medicine. Several different detectors have been used to assess the potential performance of the material. A 12 mm thick detector with a Frisch collar has been used to achieve an energy resolution of 3.5% at 511 keV and 2.3% at 662 keV. A 0.4 mm thick detector biased at 200 V has been operated in coincidence with an LSO crystal coupled to a PMT and a timing resolution of 24 ns FWHM has been obtained by gating the energy of the events. A strip TlBr detector with 0.4 mm width strips and 0.1 mm inter-strip separation has been used to measure the intrinsic spatial resolution to the level of 1 mm (a result limited by the setup geometry). The results show promising results of TlBr detectors for nuclear medicine applications.

We describe a setup we developed for the measurement of scintillation properties of crystals, from room temperature down to 3 K, under α and γ particle irradiation which resolves lines from both types of excitations. This setup is described here and we report some results obtained with this setup on BGO (Bi4Ge3O12) and ZnWO4 crystals.

Silicon photomultipliers (SiPMs) are expected to replace photomultiplier tubes (PMTs) in several applications that require scintillation detectors with excellent timing resolution, such as time-of-flight positron emission tomography (TOF-PET). However, the theory about the timing resolution of SiPM-based detectors is not yet fully understood. Here we propose a comprehensive statistical model to predict the timing resolution of SiPM-based scintillation detectors. It incorporates the relevant SiPM-related parameters (viz. the single cell electronic response, the single cell gain, the charge carrier transit time spread, and crosstalk) as well as the scintillation pulse rise and decay times, light yield, and energy resolution. It is shown that the proposed model reduces to the well-established Hyman model for timing with PMTs if the number of primary triggers (photoelectrons in case of a PMT) is Poisson distributed and crosstalk and electronic noise are negligible. The model predictions are validated by measurements of the coincidence resolving times (CRT) for 511 keV photons of two identical detectors as a function of SiPM bias voltage, for two different kinds of scintillators, namely LYSO:Ce and LaBr3:5%Ce. CRTs as low as 138 ps +/- 2 ps FWHM for LYSO:Ce and 95 ps +/- 3 ps FWHM for LaBr3:5%Ce were obtained, demonstrating the outstanding timing potential of SiPM-based scintillation detectors. These values were found to be in good agreement with the predicted CRTs of 140 ps FWHM and 95 ps FWHM, respectively. Utilizing the proposed model, it can be shown that the CRTs obtained in our experiments are mainly limited by photon statistics while crosstalk, electronic noise and signal bandwidth have relatively little influence.

The shortage of 3He has triggered the search for effective alternative neutron detection technologies for national security and safeguards applications. Any new detection technology must satisfy two basic criteria: (1) it must meet a neutron detection efficiency requirement, and (2) it must be insensitive to gamma-ray interference at a prescribed level, while still meeting the neutron detection requirement. It is the purpose of this paper to define measureable gamma ray sensitivity criteria for neutron detectors. Quantitative requirements are specified for: intrinsic gamma ray detection efficiency and gamma ray absolute rejection. The ratio GARRn is defined, and it is proposed that the requirement for neutron detection be 0.9 < GARRn < 1.1 at a 10 mR/h exposure rate. An example of results from a 3He based neutron detector are provided showing that this technology can meet the stated requirements. Results from tests of some alternative technologies are also reported.

This paper describes a study of background estimation in Modular X- and Gamma ray Sensor (MXGS) onboard ESA's Atmosphere-Space Interactions Monitor (ASIM) mission, using Geant4 simulations and Spenvis packages for particle flux generations.

This paper presents the CNES analysis of CCD dark current degradation in orbit. For the first time, data coming from several detectors in orbit have been collected and congregated to extract general trends about in-flight detector behaviours. The in-orbit degradation is therefore compared to the on-ground prediction for each detector. This work has been done in collaboration with the CNES detection subsystem office, the CNES image quality office and the CNES components & environment effects office.

This paper measures the sample to sample variation in the light yield proportionality of NaI(Tl), and so explores whether this is an invariant characteristic of the material or whether it depends on the chemical and physical properties of the tested samples. We report on the electron response of nine crystals of NaI(Tl), differing in shape, volume, age, manufacturer and quality. The proportionality has been measured at the SLYNCI facility in the energy range between 3.5 to 460 keV. We observe that while samples produced by the same manufacturer at approximately the same time have virtually identical electron response curves, there are significant sample to sample variations among crystals produced by different manufacturers or at different times. In an effort to correlate changes in the electron response with details of the scintillation mechanism, we characterized other scintillation properties, including the gamma response and the x-ray excited emission spectra and decay times, for the nine crystals. While sample to sample differences in these crystals were observed, we have been unable to identify the underlying fundamental mechanisms that are responsible for these differences.

The performance of hand-held radioisotope identification devices (RIDs) is still hampered by the performance of the NaI(Tl) detectors, which are commonly used in such instruments. In this paper, we continue the search for better detector options. One of the largest single elements ever made, a coplanar CdZnTe (CZT) detector (30times15times12.1 mm3 volume 5.45 cm3 designed by University of Michigan) is compared with a commercially available LaBr3(Ce) detector (ominus1''times1'' volume 12.9 cm3.) Parameters that are relevant to the performance of isotope identification devices, such as resolution and efficiency as function of the gamma-ray energy, temperature shift, linearity and others are measured and compared. According to measurement results, it seems that for this application LaBr3(Ce) detectors are a viable alternative to CZT detectors; even more so if one bears in mind that LaBr3(Ce) became commercially available only recently and detectors with larger volumes are likely to appear in the near future

Some examples of space-borne applications that require improvements in detector technology compared with conventional Si and Ge designs are described. Properties of compound semiconductors are noted, and a range of different detector developments are briefly reviewed. Material fabrication improvements for several compound semiconductors have resulted in near Fano-limited performance.

One of the essential requirements of the tagged neutron inspection system, which is the principle of the EURITRACK project, is an efficient and inexpensive gamma ray detector. For this purpose properties of cylindrical 3"times3" and 5"times5" BGO, and 3"times3", two different 5"times5", and a rectangular 5"times5"times10" NaI(Tl) scintillators were explored. In this communication we report on light yield, energy and time resolution of the investigated crystals at high energies of gamma-rays. Additionally, results of Monte Carlo simulations of the crystals' efficiencies are compared to peak-to-total ratios obtained experimentally for various combinations of PMTs and the scintillators

We discuss the silicon photomultiplier as a novel photon detector for the Major Atmospheric Gamma Imaging Cerenkov Telescope and the Extreme Universe Space Observatory. For these astroparticle experiments we pursue two different developments of the SiPM. One development is pursued at MEPhI, where prototypes are available. In the course of this paper we will describe some characteristics of these devices. The second development, which is using the back illumination principle is at present in its design phase.

The performance characteristics of Frisch-ring CdZnTe (CZT) detectors are described and compared with other types of CZT devices. The Frisch-ring detector is a bar-shaped CZT crystal with a geometrical aspect ratio of /spl sim/1:2. The side surfaces of the detector are coated with an insulating layer followed by a metal layer deposited directly upon the insulator. The simple design operates as a single-carrier device. Despite the simplicity of this approach, its performance depends on many factors that are still not fully understood. We describe results of testing several detectors fabricated from CZT material produced by different vendors and compare the results with numerical simulations of these devices.

A phoswich detector composed of a thin plate CsI(Tl) scintillator and a plastic scintillator (BC-400) has been designed and evaluated in order to improve the sensitivity in the low-energy region of a large-area plastic scintillation detector. This newly designed phoswich detector can be applied to both gross gamma measurement and energy spectrometry for low-energy gamma-ray emitters. Judging by estimations of minimum detectable activity, the lower measurable energy of a large-area plastic scintillation detector can be expanded down to a few tens of keV by adding a thin plate CsI(Tl) scintillator.

Countering clandestinely delivered nuclear and radiological threats requires a multielement, global, civil/military, system-of-systems approach. One important element is geographically layered, sensor-based detection of threat objects, including radiation detection systems. An effective defense against these threats should take advantage of the latest developments in radiation detection technology. This paper reviews the physics of nuclear detection, and points out areas where improvements can be anticipated, via case studies of technologies such as gamma-ray imaging, advanced radiography, large-area detectors, and active interrogation.

TlBr crystals, grown by hydrothermal and "Bridgman-Stockbarger" methods, were investigated as potential single and pixel detectors of X- and gamma radiation. Technology of detectors manufactured from TlBr crystals is reported. The spectra of the radionuclides Fe-55, Am-241, Cd-109, Co-57, and Cs-137, measured by single TlBr detectors are presented. Full-width at half-maximum (FWHM) energy resolutions of 500 eV at 5.9 keV; 518 eV at 9.87 keV; 670 eV at 13.92 keV; 777 eV at 22.1 keV; 2.7 keV at 59.5 keV; 3.7 keV at 88 keV; 4.4 keV At 122 keV, and 29 keV at 662 keV have been achieved. Small format (3/spl times/3) pixel detectors with pads 0.35/spl times/0.35 mm and gap 0.1 mm were also fabricated on single TlBr crystals of dimensions 2.7/spl times/2.7/spl times/1.0 mm/sup 3/. The interpixel resistivities measured at a bias of 50 V were 400-600 GOhm. The pixel leakage currents at a bias of 250 V were typically less than 0.5 nA. The best spectra were obtained at a temperature of -30/spl deg/C, a shaping time constant of 6 /spl mu/s and high voltage of 400 V. Energy resolutions of 2.2, 3.0, 3.7 and 29 keV were measured at input energies of 59.5, 88, 122, and 662 keV, respectively. Values of /spl mu//spl tau/ have been evaluated for two different ingots produced by the "Bridgman-Stockbarger" method. They are /spl mu//sub e//spl tau//sub e/=2.5/spl times/10/sup -4/ cm/sup 2/ V/sup -1/ and /spl mu//sub h//spl tau//sub h//spl sim/10/sup -6/ cm/sup 2/ V/sup -1/ for one ingot at -30/spl deg/C and /spl mu//sub e//spl tau//sub e/=7/spl times/10/sup -5/ cm/sup 2/ V/sup -1/, and /spl mu//sub h//spl tau//sub h/=1.5/spl times/10/sup -5/ cm/sup 2/ V/sup -1/ for the other ingot at -10/spl deg/C.

A miniature radiation monitor (MRM) device has been developed, which utilizes a charge-coupled device (CCD) as its sensitive element. Its shielding configuration has been designed to mitigate the displacement damage threat in space environments, while also introducing a good degree of directional sensitivity.

The gamma ray detection efficiency of two HPGe detectors for off-center points was measured both on the detector's cap and outside the detector's cap. It was found that similar to measurements on the detector symmetry axis, for off-center measurements including those outside the detector cap also, the detector could be treated as an effective point detector. The virtual point detector was found to be almost at the same position for vertical and horizontal source displacements.

This paper studies the effect of lead wrapping on the response of the plastic scintillators as gamma detectors. Experimental tests and Geant4 simulations showed that lead wrapping cannot increase the gamma absorption efficiency of the detector but, as a reflector, it can improve the optical properties of the detector. The reflectivity of the lead foil as an optical reflector was determined equal to 66% using an experimental-simulation combined method. Based on the obtained results, the optical collection efficiency of the detector was also increased about 4% after employing the lead reflector.

Currently we are investigating the inclusion of organotin compounds in new polystyrene scintillator materials to improve full gamma-ray energy sensitivity. Accurate calibration of the relative light yield from the newly developed scintillators is crucial to assess merits of compounds and chemical processes used in the scintillators' development. The full energy gamma-ray peak in a measured gamma-ray spectrum is commonly used in calibrating the relative light yield. However, the Compton continuum in the newly developed plastic scintillators is measured with much better efficiency and statistics and is found to be the best spectral feature that can be exploited for expeditious calibration of the relative light yield. In this study, we present a spectral gain matching of measured and simulated spectra, using a spectrum rebinning technique, to determine the Compton edge in a measured Compton continuum for accurate relative light yield calibration. The Compton edges determined using this technique were found to be within 1.2% of their theoretical estimates.

One of the main ingredients of nuclear astrophysics is the knowledge of the thermonu-clear reactions responsible for the stellar luminosity and for the synthesis of the chemical elements. Deep underground in the Gran Sasso Laboratory the cross section of the key reactions of the proton-proton chain and of the Carbon-Nitrogen-Oxygen (CNO) cycle have been measured right down to the energies of astrophysical interest. The main results obtained in the past 20 years are reviewed and their influence on our understanding of the properties of the neutrino and the Sun is discussed.

Observations of strong flux of low-energy neutrons were made by $^{3}\mathrm{He}$ counters during thunderstorms [Gurevich et al (Phys. Rev. Lett. 108, 125001, 2012)]. How the unprecedented enhancements were produced remains elusive. To better elucidate the mechanism, a simulation study of surrounding material impacts on measurement by $^{3}\mathrm{He}$ counters was performed with GEANT4. It was found that unlike previously thought, a $^3\mathrm{He}$ counter had a small sensitivity to high-energy gamma rays because of inelastic interaction with its cathode-tube materials (Al or stainless steel). A $^{3}\mathrm{He}$ counter with the intrinsic small sensitivity, if surrounded by thick materials, would largely detect thunderstorm-related gamma rays rather than those neutrons produced via photonuclear reaction in the atmosphere. On the other hand, the counter, if surrounded by thin materials and located away from a gamma-ray source, would observe neutron signals with little gamma-ray contamination. Compared with the Gurevich measurement, the present work allows us to deduce that the enhancements are attributable to gamma rays, if their observatory was very close to or inside a gamma-ray emitting region in thunderclouds., Comment: Accepted for publication in Astroparticle Physics.29 Pages, 9 figures

The solution to the scatter problem remains a major technical challenge in gamma ray imaging. This paper presents a modelization of apparent images formed by scattered photons at various energies. It may be used either to generate a series of realistic multi-energy images or be included in an image enhancement procedure. The application to SPECT is discussed.

The clinically oriented NEMA NU-2 2000+ performance standards have been performed on an ADAC molecular coincidence detection dual-head camera. At 1 cm radius, the transverse resolution full-width at half-maximum was measured to be 5.2 (10.0) mm and the axial was 5.0 (10.6) mm. At 10 cm radius, the transverse radial resolution was 4.7 (7.4) mm and the transverse tangential was 8.5 (20.9) mm. The axial resolution was 14.0 (41.1) mm. The peak true count rate was 4370 counts/s at a concentration of 4.3 kBq/ml. The peak noise equivalent count rate (NECR) was 1620 counts/s at 2.9 kBq/ml. The system scatter fraction was 48%, The maximum relative count rate error observed at the NECR peak was -42%. The sensitivity was 1010 counts/sm/rSq in the center and 870 counts/s/MBq at an offset of 10 cm. The contrast for the hot spheres ranged from 18.5 (11.6)% to 11.6 (7.9)% for a contrast ratio of 8:1 (4:1). For the cold spheres, it ranged from 41% to 25% with an overall background variability of 7%. The residual error in scatter and attenuation correction was approximately 50%. All measurements were performed at the maximum allowed crystal-to-crystal distance of 810 mm.

The ionizing radiation response of pMOSFETs used as dosimeters (RADFETs) is compared for Co-60 gammas and high-energy protons. For comparable Co-60 and proton doses, RADFET response for high-energy protons (60-200 MeV) was found to be only 65-85% of their Co-60 response. This difference is not fully understood but is shown to be partially a result of increased columnar recombination in SiO/sub 2/ for high-energy proton irradiation.

The purpose of this work is to determine very precisely the relative detection efficiency curve for high purity germanium γ-ray detector. We used the method that Hawari and Fleming reported in Nucl. Instrum. Methods (A353, 106 (1994)). Measurement was carried out at a source-to-detector distance of 40 cm for 24Na, 46Sc, 48Sc, 60Co, 88Y, 94Nb and 108Ag sources. The relative detection efficiencies were fitted by a third-order polynomial function with the expected variance of about 0.2% from 430 to 2,750 keV.

A multiwire ionisation chamber filled with liquid xenon as a position sensitive detector for Positron Emission Tomography is studied. Both xenon scintillation, which provides a fast trigger, and ionisation charge for position and energy measurements are read. The detection efficiency of the detector is assessed in separate measurements of the probability of detection of the scintillation light and the charge signals due to 511 keV gamma-rays. These were measured to be about 1 and 0.82, respectively.

The NaI:Tl scintillation response has been studied for over four decades. Two of the significant conclusions that have been made from these studies (with respect to using NaI(Tl) to detect gamma rays and X-rays) are: (1) the NaI(Tl) scintillation response is nearly linear (especially over limited energy ranges) and (2) the NaI(Tl) scintillation response has significant nonproportionalities; while these conclusions may at first appear to be inconsistent with each other, upon further consideration these conclusions are not mutually exclusive. In fact, these conclusions are fully consistent with each other. Published results typically confirm only one of these conclusions (as it was likely the intention to study either linearity or proportionality, but not both) and are not always presented such that direct comparisons can be made with other results. Consequently, it is critical that both the intent of the study and the means with which the results are presented be appropriately considered. Otherwise, it is possible to make inaccurate conclusions about both linearity and proportionality. To facilitate accurate conclusions and meaningful comparisons, this study defines a fully consistent nomenclature, examines some of the subtleties which must be considered when comparing scintillation response results, and uses a review of the literature to demonstrate both the definitions and the subtleties.

Several articles have been reviewed on the scintillation response of NaI(Tl). Those publications which report results obtained with radioactive sources either dispersed throughout the NaI(Tl)-lattice or located inside the wells of NaI(Tl)-crystals match within a /spl plusmn/0.9% standard deviation of a linear scintillation response between 3 MeV and 3 keV. Several authors who plated their sources outside the crystals measured nonlinear responses of NaT(TI) with up to /spl plusmn/7% of standard deviations between 700 and 4.5 keV. The presented analysis suggests that the observed nonlinearity is not an intrinsic effect of NaI(TI) but could be caused, at least partly, by effects occurring at the radiation entrance surfaces of the crystals.

As the yields of inertial confinement fusion (ICF) experiments increase to National Ignition Facility levels new diagnostic techniques for studying details of fusion burn behavior will become feasible. The new techniques will provide improved measurements of fusion burn temperature and history. Improved temperature measurements might be achieved with magnetic spectroscopy of fusion neutrons. High-bandwidth fusion reaction history will be measured with fusion-specific γ-ray diagnostics. Additional energy-resolved γ-ray diagnostics might be able to study a selection of specific behaviors during fusion burn. Present ICF yields greater that 1013 neutrons are sufficient to demonstrate the basic methods that underlie the new techniques. As ICF yields increase, the diagnostics designs can be adjusted accordingly in order to provide clear and specific data on fusion burn performance.

A bright, narrow band MeV γ-ray source-ray source based on Thomson scattering using a laser-driven electron accelerator has been developed. We discuss the application of this source for selective activation in regions of high particle (neutron or gamma) production, with minimal absorption in intervening materials.

It was found that IR illumination of a properly chosen wavelength and intensity can significantly improve spectrometric characteristics of CdZnTe quasi-hemispherical detectors [1]. Improving of the spectrometric characteristics is due to improvement of uniformity of charge collection by the detector volume. For operation at room temperature the optimal wavelength of IR illumination is about 940 nm, but for operation at lower temperature of -20 °C the optimal wavelengths of IR illumination is about 1050 nm. Infrared illumination can be performed using conventional low-power IR LEDs. Application of SMD LEDs allows produce miniature detection probes with IR illuminated CdZnTe detectors. We have fabricated and tested a variety of detection probes with CdZnTe quasi-hemispherical detectors from the smallest with volumes of 1-5 mm3 to larger with volumes of 1.5 cm3 and 4.0 cm3. The use of IR illumination significantly improves spectrometric characteristics of the probes operating at room temperature, especially probes with detectors of large volumes. The probe with the detector of 4 cm3 without IR illumination had energy resolution of 24.2 keV at 662 keV and of 12.5 keV with IR illumination.

International audience; Prompt secondary radiations such as gamma rays and protons can be used for ion-range monitoring during ion therapy either on an energy-slice basis or on a pencil-beam basis. We present a review of the ongoing activities in terms of detector developments, imaging, experimental and theoretical physics issues concerning the correlation between the physical dose and hadronic processes

Summary form only given. A hybrid coded imaging and detection system developed at the U.S. Naval Research Laboratory (NRL) was used for active interrogation measurements with pulsed bremsstrahlung at the Hermes-III facility at Sandia National Laboratories. This work follows previous experiments performed in 2011 and explores different targets and system conditions to the previous work. Unique detection and imaging of fissionable compared to nonfissionable material will be discussed.

The location of objects hidden in dense matter and the analysis of metallic surfaces using gamma backscattering are two possible applications strongly suggested here with experiments, highlevel Monte Carlo simulations, and some supporting basic theory.

We have constructed an endcap photon detector with undoped cesium iodide (CsI) crystals for K/sup +//spl rarr//spl pi//sup +//spl nu//spl nu. >

We investigated the feasibility of long-drift-time CdZnTe (CZT) gamma-ray detectors, fabricated from CZT material produced by Redlen Technologies. CZT crystals with cross-section areas of 5 5 mm2 and 6 6 mm2 and thicknesses of 20-, 30-, 40-, and 50-mm were configured as 3D position-sensitive drift detectors and were read out using a front-end ASIC. By correcting the electron charge losses caused by defects in the crystals, we demonstrated high performance for relatively thick detectors fabricated from unselected CZT material. VC 2016 AIP Publishing LLC.

We have recently evaluated the quality of γ -ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ -rays have been detected using the CsI(Tl) detectors of the spherical part of the CHIMERA array. Very clean γ -rays angular distributions were extracted in reactions induced by different stable beams impinging on 12 C thin targets. The results evidenced an effect of projectile spin flip on the γ -rays angular distributions. γ -particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.