Intrinsic Germanium Detector Research Articles

Работы по ядерной спектроскопий выполненные с участием Монгольских Сотрудников в ЛЯП

Decay schemes of 150-157Er and 148-161Ho have been studied. β-, γ-, X-rays and conversion electrons were investigated and ten new isotopes and isomeric states were identified at the first time. Endpoint energies of β*-spectrum were measured using an intrinsic germanium detector, and Qec values have been obtained. A group of proton emitters of Au, Ir, Re and Ta have been identified, and the proton drip line was determined. Anisotropics of the gamma rays in well deformed Yb isotopes have been measured from the decay of radioactive Lu oriented at at low temperature. Multipole mixing ratio of the hundreds transitions have been deduced, about 170 of them uniquely and unambiguous spin assignments were made for 30 levels. External perturbations of two 171Yb levels have been observed.
 Study of the decay for 112-118In isotopes were the first nuclear physics experimental work in Mongolia. Mini-orange β*-spectrometer was constracted in Dubna for the inner conversion electrons measurements for neutron deficit nuclides. Measured conversion coclTicicnts were used for determination the transition mullipolaritics. A specific method for efficiency calibration of mini-orange spectrometer was applied using the continuous β* -spectrum of 90Sr in energy range from 500 to 2200 keV.

Techniques employed for detection of hot particles in the marine environment

During the decommissioning of the Maine Yankee nuclear plant, several methods weredeveloped and employed to survey for hot particles in the marine environmentsurrounding the site. The methods used and the sensitivities achieved in the search forenvironmentally dispersed particles during the various decommissioning activitiesperformed are described in detail. Surveys were performed on dry soil, exposed marinesediment and submerged marine sediment. Survey techniques ranged from the use ofthe basic NaI detector coupled to a count rate meter to an intrinsic germaniumdetector deployed in a submarine housing coupled to a multi-channel analyser.The initial surveys consisted of collecting samples of marine sediment, spreading them out over a1 m2 surface in a thin layer, and scanning the deposited sediment by hand using a 5 cm by 5 cmNaI detector coupled to a standard count rate meter. This technique was later replaced bywalkover scans with the 5 cm by 5 cm NaI detector moved in a serpentine pattern overthe sediment surface. By coupling the detector to a ‘smart meter’, an alarm setpoint could be used to alert the surveyor to the presence of a particle within theinstrument’s field of view. A similar technique, with the detector mounted in awatertight housing secured to the end of a pole, was also employed to scan underwaterlocations. The most sensitive method developed for performing underwater surveyswas the use of the intrinsic germanium detector placed in a submarine housing.Detailed descriptions of the methods employed and the results obtained are presented. Thiswork demonstrates that there are several approaches to surveying for discreteparticles in the marine environment and the relative merits of each are considered.

The Majorana project

The objective of the Majorana experiment is to study neutrinoless double beta decay ββ(0ν) with an effective Majorana-neutrino mass sensitivity near 100 meV in order to characterize theMajorana nature of the neutrino, the Majorana mass spectrum, and the absolute mass scale. An experimental study of the neutrino mass scale implied by neutrino oscillation results is now technically within our grasp. This exciting physics goal is best pursued using the well-established technique of searching for ββ(0ν) of 76Ge, augmented with recent advances in signal processing and detector design. The Majorana experiment will consist of a large mass of 76Ge in the form of high-resolution intrinsic germanium detectors located deep underground within a low-background shielding environment. Observation of a sharp peak at the ββ endpoint will quantify the ββ(0ν) half-life and thus the effective Majorana mass of the electron neutrino.

Bioturbation in near-surface sediments from the COMRA Polymetallic Nodule Area: Evidence from excess210Pb measurements

In order to evaluate bioturbation in sediments from the COMRA Polymetallic Nodule Area in the northeast tropical Pacific, excess210Pb profiles in sediments cores collected with multiple corers during R/V DAYANGYIHAO Environmental Program Cruise in 1998 were measured by direct gamma assay using Ortec HPGe GWL series well-type coaxial low background intrinsic germanium detectors. A steady-state diffusion model of excess210Pb profiles suggests that bioturbation mixing depths and biodiffusion coefficients are 16 cm and 2.75 cm2/a in East Zone, and 6 cm and 0.26 cm2/a in West Zone, respectively. Furthermore, the observations of macrofauna and measurements of total organic carbon (TOC) content in sediments suggest that bioturbation is directly controlled by species and abundance of benthic fauna, such aspolychaete, and the bioturbation mixing depth and intensity are positively correlated with the organic matter content.

Natural radioactivity levels in river, stream and drinking water of the northwestern areas of Pakistan

Natural radioactivity in the aquatic media has been determined by collecting samples of river, stream and drinking water from the northwestern areas of Pakistan. The concentrations of 40K, 226Ra and 232Th have been measured using a low background gamma-spectrometer and a 10 cm3 planar intrinsic high purity germanium detector. The annual ingestion of these radionuclides, using local consumption rates (average over the whole population) of 0.9 l.d-1, were estimated to be 49.2, 6.2 and 1.1 Bq.y-1 for 40K, 226Ra and 232Th, respectively. A comparison of the annual intakes of these radionuclides, using annual consumption rates of NCRP, ICRP and FBSP shows that the contribution from natural radionuclides to annual intake is slightly greater for NCRP than for ICRP and FBSP consumption rates. However, the estimated values and weighted means of these radionuclides compare well with the world average. The annual effective dose equivalent from drinking water was found to be 3.6.10-6 mSv.y-1 (226Ra), 3.2.10-12 mSv.y-1 (232Th) and 2.1.10-6 mSv.y-1 (40K). These values are lower than those given by NCRP.

Uranium and plutonium solution assays by transmission-corrected x-ray fluorescence spectrometry

An x-ray fluorescence analysis technique was developed for uranium and plutonium solutions, which compensates for variations in the absorption of the exciting gamma rays and fluorescent x-rays. 57Co is used to excite efficiently the K lines of the elements, and a mixed 57Co plus 153Gd transmission source is used to correct for variations in absorption. The absorption correction is a unique feature of the technique which permits accurate calibration with a single solution standard and the measurement of a wide range of concentrations (up to 300 g l−1). Without this correction procedure, up to six solution standards are required to correct for non-linearity over this concentration range. In addition, other elements present in the specimens and not present in the standards would otherwise reduce the accuracy or even invalidate the analyses. Specially designed equipment incorporates a planar intrinsic germanium detector, excitation and transmission radioisotopes and specimen holder. The apparatus can be inserted into a rubber glove of a glove-box, keeping the apparatus outside and the solutions inside the glove-box, thereby protecting the user and the equipment from possible contamination. This technique will be tested at the Bochvar Institute of Inorganic Materials in Moscow for possible use in the Russian complex of nuclear facilities. This is part of a cooperative program between laboratories in the USA and Russia to strengthen systems of nuclear materials protection, control and accountability (MPC&A) in both countries. A part of this program is to measure accurately and track inventories of materials, hence the need for good non-destructive analytical techniques. Copyright © 1999 John Wiley & Sons, Ltd.

Uranium and plutonium solution assays by transmission‐corrected x‐ray fluorescence spectrometry

An x-ray fluorescence analysis technique was developed for uranium and plutonium solutions, which compensates for variations in the absorption of the exciting gamma rays and fluorescent x-rays. 57Co is used to excite efficiently the K lines of the elements, and a mixed 57Co plus 153Gd transmission source is used to correct for variations in absorption. The absorption correction is a unique feature of the technique which permits accurate calibration with a single solution standard and the measurement of a wide range of concentrations (up to 300 g l−1). Without this correction procedure, up to six solution standards are required to correct for non-linearity over this concentration range. In addition, other elements present in the specimens and not present in the standards would otherwise reduce the accuracy or even invalidate the analyses. Specially designed equipment incorporates a planar intrinsic germanium detector, excitation and transmission radioisotopes and specimen holder. The apparatus can be inserted into a rubber glove of a glove-box, keeping the apparatus outside and the solutions inside the glove-box, thereby protecting the user and the equipment from possible contamination. This technique will be tested at the Bochvar Institute of Inorganic Materials in Moscow for possible use in the Russian complex of nuclear facilities. This is part of a cooperative program between laboratories in the USA and Russia to strengthen systems of nuclear materials protection, control and accountability (MPC&A) in both countries. A part of this program is to measure accurately and track inventories of materials, hence the need for good non-destructive analytical techniques. Copyright © 1999 John Wiley & Sons, Ltd.

Instrumentation of the ESRF medical imaging facility

At the European Synchrotron Radiation Facility (ESRF) a beamport has been instrumented for medical research programs. Two facilities have been constructed for alternative operation. The first one is devoted to medical imaging and is focused on intravenous coronary angiography and computed tomography (CT). The second facility is dedicated to pre-clinical microbeam radiotherapy (MRT). This paper describes the instrumentation for the imaging facility. Two monochromators have been designed, both are based on bent silicon crystals in the Laue geometry. A versatile scanning device has been built for pre-alignment and scanning of the patient through the X-ray beam in radiography or CT modes. An intrinsic germanium detector is used together with large dynamic range electronics (16 bits) to acquire the data. The beamline is now at the end of its commissioning phase; intravenous coronary angiography is intended to start in 1999 with patients and the CT pre-clinical program is underway on small animals. The first in vivo images obtained on animals in angiography and CT modes are presented to illustrate the performances of these devices.

Methodology for the U.S. Food and Drug Administration's radionuclides in foods program

The U.S. Food and Drug Administration (FDA) is responsible for the wholesomeness of the nation's food supply. The FDA modified its food monitoring program in January, 1973, to include radioactive isotopes. The methodology used to perform, analyses on these food products are taken from the standerd setting societies such as the AOAC International, American Society for Testing Materials and American Public Health Association Standard Methods. In addition, methods not tested by these societies are taken from the literature or from Department of Energy manuals such as the Health and Safety Laboratory and also from Environmental Protection Agency, Public Health Service, and Food and Agricultural Organization manuals. These include the methods for long-lived radionuclides such as tritium, strontium-90, cesium-137 and plutonium. Also, the short-lived radionuclides such as iodine-131, radiocesium, radiocerium and radioruthenium. In addition, they include the natural occurring radionuclides such as radium and uranium isotopes. The activity concentrations of gamma-emitters such as radiocesium, iodine-131 and radioruthenium are determined by gamma-ray spectrometry. This is done using intrinsic germanium detectors with the appropriate hardware and software. The alpha and “pure” beta-emitters are determined by various radiochemical methods and techniques. The radiochemical methodology and equipment used in analyzing these radionuclides are described and discussed. Also, the methodology and equipment for the gamma-emitters are described in more detail in this paper. In addition, the limits of detection for the methods used will be discussed.

Validation of induced radioactivity calculations for candidate fusion materials through measurements in a graphite-centered assembly

Abstract Induced radioactivity measurements were carried out jointly by the USA and Japan in a graphite-centered assembly, in the framework of ITER Task T-218 entitled ‘Shielding Blanket Neutronics Experiments’. An intense, accelerator-based D-T rotating target neutron source at JAERI, with a nominal intensity of 5 × 1012 s–1, was used. Two locations, providing different neutron energy spectra, were chosen for irradiating samples of a range of materials of interest to ITER. Three independent experimental campaigns were conducted so as to accommodate a large number of samples, on one hand, and as many short and long half-life products as possible, on the other. The total neutron fluence ranged from 4.7 × 1011 to 1.5 × 1014 ncm–2. Altogether, samples of Mg, Al, SiO2, Ti, V, Cr, Mn, Fe, Co, Ni, FH82 steel, SS316LN steel (ITER grade), Cu, Zn, KCl, Zr, Nb, Mo, Ag, In, Sn, Dy, Ta, Hf, Re, Au, Ir, and Pb were irradiated. The irradiated samples were cooled for variable periods ranging from 30 s to 250 days before their decay gamma-ray spectra were counted on high purity intrinsic germanium detectors. The half lives of the observed radioisotopes have ranged from 18.7 s (46mSc from Ti) to 5.3 years (60Co from Ni). The neutron energy spectra for the two locations were calculated using Monte Carlo code MCNP with FENDL-1 and ENDF/B-VI data libraries. The analysis of isotopic activities, expressed in Bq cc–1, of the irradiated materials has been carried out using REAC-3 radioactivity code, with FENDL-2A and FENDL-1A activation cross-section and decay data libraries. Typically, C/E lies in a band of 0.5–1.5 for the results being reported.

EDS from then Till Now—A Chronology of Innovation

Abstract Since its introduction in 1968 on both the EPMA and SEM, the energy-dispersive spectrometer has become widely used from research laboratories to production testing. It has become the mainstay for microanalysis in many scientific disciplines. A discussion of energy-dispersive spectrometry (EDS) logically divides into two lines of development: X-ray detector/hardware and X-ray analyzer/software. Of the several types of EDS detectors, only Si(Li) and intrinsic germanium detectors (IG) will be covered in this review, as they are the most common on electron microscopes. The 1960s— The use of a solid state EDS detector on an EPMA was first described by Fitzgerald, et al. in 1968.1 They realized at the time that the high collection efficiency of about 80% permitted analysis at lower beam current for the same counting statistics and electron dose on the specimen. The first installation of a Si(Li) detector on an SEM came later the same year.

Using pulse shape discrimination to sort individual energy deposition events in a germanium crystal

A fast digital oscilloscope based pulse shape discrimination (PSD) system has been tested with intrinsic germanium detectors large enough to allow ionizing events which generate localized electron-hole pairs at a single site to be segregated from those depositing energy at several different sites in the crystal. Drift velocities of the electrons and holes result in pulses several hundred nanoseconds long. Since the electric field varies by almost a factor of 10 between the outer and inner surfaces, collection of electrons and holes can frequently be dinstinguished, and pulses due to multi-site events can be distinguished from single site events.

Use of large gamma-ray detector to measure 131I in milk and water at low levels.

A lower limit of detection of 0.04 Bq L-1 for measuring 131I in milk or water with a gamma-ray spectrometer was achieved with a large 118% intrinsic germanium detector. Three-liter samples with 131I tracer in a reentrant beaker were counted within a lead shield for 12,000 to 55,000 s to demonstrate detection at this concentration. Samples of milk collected at dairies and counted for 28,000 s showed no 131I at this level (as expected), but 137Cs from fallout was detected in some samples near its detection limit of 0.03 Bq L-1.

Nuclear Data Sheets for A = 194

Abstract:Experimental data pertaining to all nuclei with mass A = 194 were evaluated. Level schemes from both radioactive decay and reaction studies are presented, along with associated tables of experimental data and adopted properties for levels and γ rays. The literature cutoff date for this revision is September 30, 1996. This revision replaces 89SiO1. Extensive high-spin experiments using large gamma-detector arrays have revealed superdeformed structures in 194Hg (three SD bands: Yrast and pair of excited signature partners), 194Tl (six SD bands: Three pairs of signature partners), and 194Pb (three SD bands: Yrast and pair of excited signature partners). For yrast bands (SD-1) in 194Hg and 194Pb, connecting transitions between the SD band and normal bands have recently (96Kh04, 96Lo12,96Br07) been reported. Several dipole (oblate) bands in 194Pb, some based on high-K (oblate) states have been reported from similar in-beam γ-ray experiments. New γγ coincidence measurements (93Ko59, 94KoZQ) using the 193Ir(n,γ) reaction helped to place several transitions in the level scheme and established the 31.85-ms 194Ir isomer at 147.078 KeV 5. Results from the first study of the 193Ir(d,p) reaction (94Ga30) agree with those from (n,γ). Unpublished (95TeZZ) γγ coincidence results (using HERA, an array of 20 intrinsic germanium detectors) revealed a new level in 194Pt at 1737.4 KeV. It also provided correct placement in the decay scheme for many γ rays from 194Au ϵ decay. Recent measurements (92Hu04) of the α-decay chain 202Fr– 196At– 194Bi confirm the existence of 194Bi isomers, and show population to previously unknown levels at 218 and 396 KeV in 194Bi. Cutoff Date:All data received by September 30, 1996 were evaluated. General Policies and Organization of Material:See the January issue of Nuclear Data Sheets. Acknowledgments:Evaluators wish to thank R.R.P. Teixeira (95TeZZ) for making available their unpublished data on 194Au ϵ decay. General Comments:The analysis of γ-ray data is described in detail in 86BrZQ. The γ-ray energies given by various authors were fit to a level scheme for each data set through a weighted least-squares analysis. The scales for the corresponding intensities, which were assumed to be linearly related, were adjusted using the methods of Tepel (80TeZW) and Lederer (92LeZJ). Uncertainties of absolute γ-ray intensities were determined using the method of Browne (86Br21).

Shielding and background reduction

The background spectrum in a Low Background intrinsic germanium detector was analysed. Different possible sources of background and the influence of the materials used as well as the thickness of shielding was studied. Lead, copper, nylon, delrin and teflon of different thicknessewere used. Too much shielding material could induce some gamma rays from neutron production in the shielding due to cosmic muons. The influence of cosmic muons by going underground was also analysed by using data from the underground LABAC laboratory in Calatayud (Zaragoza).

Measurement of the K X-ray absorption jump ratio of erbium by attenuation of a compton peak

The X-ray absorption jump ratio of erbium was measured with a high resolution intrinsic germanium detector by attenuation, with an erbium foil, of a Compton peak produced by the scattering of the 60 keV americium 241 X-rays. Data analysis consists of a deconvolution to find the true Compton peak shape and an integration of a parameterized expression of the attenuation coefficient adjusted by least squares. Our result has an error of 1.5% and compared with calculated data shows a difference of less than 5%.

Influence of photon beam aperture on Compton line profiles

Abstract A procedure to correct Compton profiles for geometrical effects, related to the solid angles subtended for an X-ray source and detector, has been obtained. The geometrical response function for a given experimental set up is found by a Monte Carlo simulation program and is meant to be used as a histogram for convolution purposes. The main features of this function show that it is not peaked at the angle between collimator axes because the maximum is shifted towards greater values and also increasingly broadens as this angle decreases. This procedure corrects the profile shape as a whole, not only its width as was done in previous methods. We have tested this correction with data taken from an experiment in which 60 keV photons from a 241Am radioactive source were scattered in a triple-distilled water sample and detected with an intrinsic germanium detector. A Compton profile, measured at an angle of 135°, was compared with a tabulated one convoluted with the distribution function, and thus the re...

Photon spectral characteristics of a new double-walled iodine-125 source.

The photon spectral characteristics of a recently designed Iodine-125 source have been measured. The source has a physical length of 5 mm and a diameter of 0.8 mm. A thin tungsten filament coated with radioactive Iodine-125 is used as a radiographic marker and is encapsulated in a double wall titanium shell of uniform thickness all around. The photon spectral characteristics, measured with an intrinsic germanium (Ge) detector coupled to a multichannel analyzer, reveal that the seed emits the 27.4-keV K alpha and 31.4-keV K beta x rays and 35.5-keV gamma photons from the decay of Iodine-125. Because of their low energy, the tungsten x rays are not observed in the spectrum. The anisotropy of the radiation fluence for each of the above-mentioned photon energies was measured in planes containing the seed short and long axes. The 4 pi-averaged anisotropy factor for the total radiation fluence, i.e., sum of the above three photon energies is 0.92. The photon intensity radiated along the seed long axis is approximately equal to the intensity in the seed transverse direction due to the absence of end welds. The new Iodine-125 source is characterized by good radiographic visualization, greater structural strength due to double wall encapsulation design, and emission of more isotropic Iodine-125 photon spectrum.

Preliminary characterization of an intrinsic germanium detector on a 400‐keV microscope

SUMMARYAn evaluation was made of an intrinsic germanium X‐ray detector fitted to a 400‐keV electron microscope. Its characteristics as a function of accelerating voltage, pulse processor settings and count rate were investigated. Comparisons are drawn between intrinsic Ge and Si(Li) detectors at both an experimental and theoretical level. The software requirements for the successful collection of spectra are discussed.

A Commentary on Recent Developments in X-RAY Detectors and Ancillary Instrumentation and Data Extraction Algorithms

When a lithium-drifted silicon, Si(Li), energy dispersive X-ray detector is attached to a scanning electron microscope or a scanning transmission electron microscope, it becomes possible to perform an assay of the elemental composition of a localized region of a specimen. This capability has existed now for almost 20 years. During this time, the quality of the analytical results has slowly improved with the availability of better instrumentation and increased understanding of the physical basis of measurement and matrix effects. During the last few years, the pace in both instrumental development and theoretical understanding has picked up dramatically. What seemed like a maturing and ever more mundane field has now been reinvigorated. We will catalog here and comment on several of the developments which have occurred in x-ray detectors and in the hardware and software used to process the resulting x-ray signals into quantitative information.Although the Si(Li) x-ray spectrometer has dominated the field of x-ray microanalysis for many years, recent developments in intrinsic germanium (IG) detectors have produced spectrometers which, in several important characteristics, rival or exceed those of the Si(Li) spectrometer.