Search

Europium-doped TlSr2I5 (TSI), a new high light yield scintillator for gamma-ray detection, has been grown by the vertical Bridgman method. A 12mm and 16mm diameter boules of TSI is grown in a two-zone vertical furnaces. Samples extracted from the grown boule have been characterized for their scintillation properties. Energy resolution of < 3% (FWHM) at 662 keV and a gamma-ray light yield of approximately 54,000 Ph/MeV have been obtained. Decay times of 395 ns (89%) and 2.0 microseconds (11%) have been measured.

In article number 2001882, Pavao Andričević, László Forró, and co‐workers introduce the ‘oriented crystal‒crystal intergrowth’ method, yielding solution‐grown MAPbBr(3) crystals with volume and mass of over 1000 cm(3) and 3 kg. Its increased size, equipped with carbon electrodes, is utilized for sensitive gamma ray detection of a (60)Co source at the dose rate up to 2.3 Gy h(−1) at ambient conditions. [Image: see text]

Inorganic scintillators of CsI(Tl), LYSO and BGO crystals were characterized using photomultiplier tube R1306 PMT readout for gamma ray detection. The photoelectron yield, light yield and photofraction were measured at gamma energies in range 59.5 keV to 1332 keV. It is found that the photoelectron yield of LYSO is much better than that of CsI(Tl) and BGO crystals. CsI(Tl) crystal showed the high light yield of 63855.25 ph/MeV in this energy range, which is better than that of LYSO and BGO crystals. The photofraction for all crystals was determined and compared with the cross-section ratio for the photoelectric effect to the total one which calculated by WinXCom program.

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.

A quaternary iodide KCa0.8Sr0.2I3:Eu2+ scintillator with 2.5% energy resolution at 662 keV in a 5 mm3 sample shows great potential for use in gamma-ray spectroscopy applications. In this work, we report the state-of-the-art growth of high quality 25, 38, and 50 mm diameter KCa0.8Sr0.2I3:Eu2+ single crystals by the vertical self-seeding Bridgman method. KCa0.8Sr0.2I3:Eu2+ with a size of ∅25 mm × 25 mm can achieve excellent energy resolutions of 3.15% at 662 keV and 6.8% at 122 keV irradiation, which are superior to that of a commercial NaI:Tl+ of the same size. The nonuniformity of light collection and production in ∅25 mm × 25 mm and ∅38 mm × 38 mm KCa0.8Sr0.2I3:Eu2+ crystals was evaluated by using a technique based on a collimated 137Cs source and coupling the crystal to a photomultiplier tube (PMT) in different directions. The performances of the packaged crystals for practical use were also measured.

The development of autonomous measuring systems for radioactivity in the ma- rine environment is today of important scientific priority for the marine sciences and especially for the Operational Oceanography. This paper concentrates on the improvement and application of an existing Nal-based gamma ray detection system for radioactivity measurements in seawater. The set up of the system will be described together with the appropriate calibrations in the laboratory. The operation of the system in the Aegean Sea provides the monitoring efficiency at 1461 keV by intercalibration with an appropriate salinity sensor mounted close to the Nal-detector. The gross counting rate was found constant within the statistical uncertainty of the measurements, during dry periods. The artificial radioactivity (137Cs) in the North Aegean Sea was increased, however, up to seven times after strong rainfall, compared to the mean radiation level as given in literature. This increment remains only for a short period of time (~2 days), due to strong advection processes of the water masses during strong rainfall.

Directional detection plays an important role in the search for rogue or illicit radioactive sources but is often complicated by Poisson statistics, large distances, and various sources of noise. A currently used directional detection method involves extracting the angular information of a source’s location from a cluster of detectors in a set geometry. Traditional algorithms designed to process detected data typically involve performing a least squares assessment against a database prepopulated with detector responses of known source locations. These algorithms perform best when the standoff distance is like that available in the prepopulated database; they lose accuracy when distances and environments of measurements are not well represented in the database. Analysis of highly variable and noisy data can often benefit from the robustness of machine learning, which has been implemented in applications such as isotope identification and radium mapping. This work aims to investigate the utility of machine learning algorithms capable of analyzing data with large amounts of statistical variability to improve directional location capabilities for large area source searches. Preliminary results with a fully connected residual neural network include the successful source location for simulated search scenarios to within 1 degree in 24% of trials. The same simulated data analyzed using traditional methods resulted in 1 degree location for 11% of trials. The traditional and neural network algorithms were compared in terms of error and accuracy as well performance as a function of distance for a simulated dataset of source searches. Results indicate that more robust algorithms, such as the implemented neural network, can improve system-inherent accuracy and over all directional capabilities.

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.

SrF2 ve SrF2:xCe3+ (x=0.5 mol %, 0.6282 g -10 mol %, 12.5630 g) nanoparçacıklar kimyasal birlikte çöktürme yöntemiyle sentezlenmiştir. Katkısız ve seryum katkılı nanoparçacıkların yapısal ve optik özellikleri X-Işını Difraktometresi (XRD), Yüksek Çözünürlüklü Geçirimli Elektron Mikroskobu (HRTEM) ve Fotolüminesans Spektrofotometre (PL) ile karakterize edilmiştir. Sentezlenen nanoparçacıkların otalama parçacık boyutları, Debye-Scherer eşitliği kullanılarak, X-Işını kırınım desenlerindeki piklerin genişlemesinden belirlenmiştir. Hesaplanan ortalama parçacık boyutları 30 nm - 52 nm aralığında değişmektedir. Sentezlenen tüm nanoparçacıkların uyarma ve emisyon piklerinin dalga boyları sırasıyla 232 nm ve 464 nm’dir. Disk şekline sahip iri ve hacimli nanokompozit sintilatör malzemelerin üretiminde sentezlenen SrF2 and SrF2: %1 Ce3+ nanoparçacıklar fosfor dolgu malzemesi olarak, epoksi reçine ise matriks malzemesi olarak kullanılmıştır. Üretilen iri ve hacimli nanokompozit sintilatör malzemelerinin enerji spektrumları Am-241, Cs-137 ve Co-60 nokta kaynakları kullanılarak elde edilmiştir. Elde edilen spektrumlar incelendiğinde üretilen nanokompozit sintilatör malzemelerin, gama ışını dedeksiyonunun yanı sıra, gelen gama ışınının enerjisini ayırabilecek potansiyelde olduğunu göstermektedir. SrF2 and SrF2:xCe3+ (x=0.5%-10%) nanoparticles were synthesized using chemical co-precipitation method. Structural and optical properties of the undoped and cerium doped nanoparticles were characterized with X-Ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), and Photoluminescence (PL) measurements. Average sizes of the synthesized nanoparticles were determined from the broadening of X-Ray Diffraction peaks using Debye-Scherer equation. Estimated values were ranging between 30 nm-52 nm. All synthesized nanoparticles show photoluminescence characteristics with an excitation and emission peaks centered at 232 nm and 464 nm, respectively. Disc shaped bulk nanocomposite scintillators were also fabricated using synthesized SrF2 and SrF2:1% Ce3+ nanoparticles as phosphor fillers and epoxy resin as matrix material. Energy spectrums of bulk nanocomposite scintillators were collected using Am-241, Cs-137, and Co-60 point sources. Gamma ray energy responses of the fabricated scintillator materials revealed the fact that these nanocomposites have a potential for the detection of gamma rays and energy discrimination of the radioactive sources.

Quality and performance of a detection system are the crucial parameters in all nuclear physics experiments. This system serves as a source of all signals and noises to be processed. Better performance, higher amplification and lower noises occurrence simplify subsequent signal analysis. In the field of Mossbauer spectroscopy, the spectrum quality and Mossbauer effect are crucial parameters which are affected especially by the quality of the detection system. These parameters were evaluated for different types of a detection setup. Finally an improvement of the spectrum quality by 15% and Mossbauer effect by 7% has been achieved for the natural iron reference absorber measurement in comparison with previous version of the detection system. K e y w o r d s: gamma ray detection, signal processing, Mossbauer spectroscopy, Mossbauer spectrum

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.

We proposed a new method to determine the activity of each nuclide in a mixture of Cs-134, Cs-137 and Sr/Y-90. The point of this new measurement method is simultaneous counting between beta and gamma ray detection. We assembled a setup that employs plastic and NaI(Tl) scintillation detectors for beta- and gamma-ray detection, respectively. The obtained result shows that discrimination of Cs-134 and Cs-137 was successfully achieved. Radioactivity determined by measurement was in agreement with one prepared as a mixture. The results show that the method can be adapted to measure the radioactivity of samples contaminated by the accident at the Fukushima Daiichi Nuclear Power Plant.

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 have developed a gamma-ray detector based on a single-crystal diamond in order to improve the heat and radiation resistances of gamma-ray monitors. We fabricated prototypes with two types of diamond grown by a chemical vapor deposition method. The count rates with temperature and accumulated dose were obtained using a 137Cs gamma-ray source, then the errors at full scale (%FS) were evaluated using a method to reduce the dark count. The prototype-A worked to 643 K within 2.9%FS and to 3.1 MGy within 4.9%FS; on the other hand, the prototype-B worked to 545 K within 3.4%FS and to 5.0 MGy within 0.47%FS. This study demonstrates that the diamond semiconductor was promising for monitoring with enhanced heat and radiation resistances.

CsSrI3:Eu2+ was previously reported by our group as a highly efficient scintillator, and we now report the advantages of partial replacement of Sr by Ba. Scintillation and physical properties of CsSr1−xBaxI3:Eu2+ crystals are presented for 0≤x≤0.24. We found that the hygroscopicity decreased with increasing Ba concentration while density and effective atomic number increased, thus enhancing the X-ray and gamma ray detection efficiency. The scintillation light yield ranged from 22,000 to 28,000 photons per MeV for Ba concentrations between 3% and 24%. The principle scintillation decay time ranged from 1.8 to 2.1 μs.

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.

As safety and security systems of shipping logistics are reinforced all over the world, ubiquitous technology-based core technology for safety and security is developing to build the system of logistics security. It is feared that the logistics security system of Korea has a possibility to technically depend on developed countries in the futures. Because the essential skills and equipment to retain security of logistics are not developed. It is urgent to introduce a logistics security system that fully integrates the entire logistics segment in the future. Thus, the necessity of developing the portable radiation detector which can detect gamma-ray nuclide is increasing for reinforcing safety and security systems. In this paper, a research suggests the implementation of portable radiation detector platform using Cortex-A8.

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.

The first Polaris system was built in September 2010 and has gone through significant testing at multiple DOD and DOE facilities as well as at the University of Michigan. It has been biased almost continuously for the 18 months of its current lifespan without any replacement of its detectors. The second Polaris system was built in June 2011 and has also been almost continuously biased during its lifespan. The continuous operation of both devices has provided the best opportunity to study the long-term stability of pixelated CdZnTe detectors. Spectroscopic performance has been monitored throughout each system's lifespan to study their performance over time and the impact on long term operation of these devices. It is shown that the charge transport properties and spectroscopic performance of these CdZnTe detectors are stable over time and devoid of fabrication or assembly issues. It is expected that future detectors will exhibit excellent stability.

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 .

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.

A transportable and robust gamma ray detection system (GISPI) was employed to determine the concentrations of naturally occurring radionuclides on various beaches in and around Saldanha Bay, located on the West Coast of South Africa. Several mathematical techniques were applied to obtain GIS overlay that could be used to investigate various geophysical phenomenon. The results demonstrated direct relationships between radionuclide concentrations, grain size of beach sediment and the intensity of wave action. The element concentrations were used to make deductions on the origin of some of the beach sand. The article finally draws conclusions on coastal and beach formation processes, based on the results of the distribution of various radionuclides.

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.

We report the scintillation properties of both KPb 2 Cl 5 and K 2 CeCl 5 grown by vertical Bridgman method from synthesized and zone refined material. Both crystals exhibit minimal hygroscopic properties, which is desirable in applications where hermitization is not feasible. The KPb 2 Cl 5 crystal, doped with 2.5 mol% of EuCl 2 , appeared yellow in color and did not scintillate, while the self activated transparent K 2 CeCl 5 did. The energy resolution and decay time at 662 keV were measured to be 6.1% and 78 ns respectively, with a light yield of 31,000 photons/MeV.

The possibility has been investigated of determining, using graydar (Gamma RAY Detection And Ranging)approach, the in-depth partial-density profile of some substance absorbed in a dense medium. Analyticalalgorithms have been derived for retrieving the in-depth profile of the partial density of the absorbed substanceon the basis of the conjecturally known in-depth profile of the extinction of the absorbing medium and theexperimentallydeterminablegraydarprofile. TheretrievalerrorunderthePoissonnoiseconditionshasalsobeenestimated analytically. The simulations performed of the Poisson-noise effect concern the case of soil moisture.The results obtained confirm the validity of the derived retrieval algorithms and error estimates and show thatthesoilmoistureprofilemaybeaccuratelydeterminedtodepthsof50cm,dependingonthedry-soilbulkdensity,thesensingphotonflux,andthemeasurementtime.PACSnumbers:07.85.

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.

I recently had a cardiac stress test. It was my fourth. Its purpose was to determine whether my heart is pumping an adequate quantity of blood during exercise. Additionally, is there a partial arterial blockage or damaged heart muscle? The test involves the patient receiving an injection of Cardiolite®, a substance containing a molecule to which Technetium-99m (Tc-99m)1 is attached, and then lying under a camera that detects gamma rays emanating from the interior heart wall and forms an image indicative of blood flow in the resting heart. This is followed by treadmill exercise, another injection of Cardiolite® during peak exercise, and then another image obtained with the camera indicating maximum blood flow. After the test, I decided to determine the biological half-life of Cardiolite®.

A new radionuclide quantification method is proposed on the basis of multiple gamma-ray detection, which is two or higher fold gamma-ray coincidence method. The coincidence method has so far been used for nuclear structure study. We apply this method for quantification of radioactive nuclei. The advantage of this method consists of high energy resolution and high sensitivity. It is successfully applied to nuclear waste analysis, neutron activation analysis and prompt gamma-ray analysis. The principle of the multiple gamma-ray detection method and future perspectives for an innovative pulsed neutron source and a new detector system will be presented.

We developed Lu0.4Gd1.6SiO5 (LGSO) crystal as a new scintillator for medical imaging applications. The size of the LGSO ingot obtained for this investigation was approximately 60 mm in diameter and 170 mm in length. The as-grown crystal was yellow in color. To eliminate the tint, the crystal was annealed in pure N2 atmosphere after the growth. As a result, the LGSO became colorless with uniform and large light output which is about 2.0 times that of GSO

Recycled steel products demands a new technique for determining tramp elements in steel. In this paper, As and Sb in iron certified reference materials were determined by neutron activation analysis with the multiple gamma-ray detection method. The determined values are in good agreement with certified and reference values. The lower determination limits (LDL) for As and Sb in high purity iron are 0.012 and 0.0025 ppm, respectively. As the demanded LDL for As and Sb is 0.1 ppm, the method described in this work is suitable for determining As and Sb in recycled steel.

In the present research the quality of 18F-FDG (fluorodeoxyglucose) is maintained to reduce hazards of the patients and produce good quality of image that helps interpret the image with proper diagnosis. The quality of produced 18F-FDG in the United Hospital, Bangladesh is checked in the quality control laboratory and compared with the guideline criteria of the International Atomic Energy Agency. This 18F-FDG has been injected into 2500 patients and found no immediate or afterward hazards to any patients till now. Radionuclide purity, radiochemical purity, chemical purity, pH are assessed to have the quality assurance of 18F-FDG studied. Radionuclide purity is validated by half-life measurement and gamma ray detection. The calculated average half-life (110.26 min) and halflife 18F (109.7 min) are found in good agreement. The peak from TLC result sheet gives only the peak of unhydrolyzed FDG which implies more than 99% 18F-FDG is evident in this experiment. Chromatographic spectrum of residual solvents like Acetonitrile and Ethanol are analyzed to access the chemical purity with respect to permissible concentration. The pH of 18F-FDG is found within 4.5 to 6.5.

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

The detection of high-energy γ-ray sources is vitally important to national security for numerous reasons, particularly nuclear materials smuggling interdiction and threat detection. This article presents two methods of detecting and locating a concealed nuclear γ-ray source by analyzing detector data of emissions that have been modulated with a coded mask. The advantages of each method, derived from a simulation study and experimental data, are discussed. Energetic γ-rays readily penetrate moderate amounts of shielding material and can be detected at distances of many meters. Coded masks are spatial configurations of shielding material (e.g., small squares formed from plates of lead or tungsten) placed in front of a detector array to modulate the radiation distribution. A coded mask system provides improved detection through an increased signal-to-noise ratio. In a search scenario it is impossible to obtain a comparison background run without the presence of a potential concealed source. The developed an...

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.

A prototype gamma radiation monitoring system based on In/sub 2/O/sub 3//SiO thick-film sensors array was designed. Four sensors had an identical pn-heterojunction structure with different material compositions. These sensors were subjected to gamma radiation emitted by /sup 137/Cs source with an activity of 370 kBq. Changes in their current-voltage characteristics were recorded and compared. The performance parameters of the devices, such as sensitivity to /spl gamma/ radiation exposure and working dose region, were found to be highly dependent on the composition of the materials used. To cover a wider range of radiation and improve the overall sensitivity, an approach of using sensor arrays was utilized. A dynamic selection of the multiple sensors of various sensitivities and working dose ranges was implemented by applying a pattern recognition analysis.

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.