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A spectral decomposition method has been implemented to identify and quantify isotopic source terms in high-resolution gamma-ray spectroscopy in static geometry and shielding scenarios. Monte Carlo simulations were used to build the response matrix of a shielded high-purity germanium detector monitoring an effluent stream with a Marinelli configuration. The decomposition technique was applied to a series of calibration spectra taken with the detector using a multi-nuclide standard. These results are compared with decay-corrected values from the calibration certificate. For most nuclei in the standard (241Am, 109Cd, 137Cs, and 60Co), the deviations from the certificate values were generally no more than 6% with a few outliers as high as 10%. For 57Co, the radionuclide with the lowest activity, the deviations from the standard reached as high as 25%, driven by the meager statistics in the calibration spectra. In addition, a complete treatment of error propagation for the technique is presented. [ABSTRACT FROM AUTHOR]

The measurement of uranium ore samples by high-resolution gamma-ray spectroscopy requires long measurement time and expensive high-purity germanium detectors. In this work, we present the possibility to measure uranium concentration by low-resolution gamma-ray spectrometry with an easy-to-operate and cost-effective NaI(Tl) detector. This method is based on the analysis of two energy bands of the NaI gamma spectrum, which allows estimating a possible “U/Rn” imbalance between the top (238U and its daughters up to 230Th) and the bottom (226Ra, 222Rn and their daughters) of the 238U decay chain in roll-front deposits. Indeed, in case of secular equilibrium, more than 95% of gamma rays emitted by uranium ores come from 214Pb and 214Bi isotopes, which are in the backend of the 238U chain. Consequently, a disequilibrium in the chain might produce an overestimation of uranium concentration if U/Rn < 1, or an underestimation if U/Rn > 1. Therefore, the estimation of the disequilibrium between the beginning and the end of the chain represents a crucial issue in uranium mining and exploitation. Finally, the uranium concentration is derived from the U/Rn activity ratio and from the “Rn” activity of the backend chain that is measured by conventional gamma-ray spectroscopy with the 609-keV peak of 214Bi. The total uncertainty is less than 30% within a few minutes of acquisition, and we observe a very good agreement with inductively coupled plasma mass spectrometry (ICP-MS) analyses performed on real samples. [ABSTRACT FROM AUTHOR]

This work presents a 3-D-integrated opto-electrical receiver (RX) analog front end (AFE) operating up to 50 Gb/s. The electronic integrated circuit (EIC) is fabricated in ST SiGe BiCMOS-55-nm technology and flipped and mounted on top of the ST photonic integrated circuits (PICs) die through copper pillars (Cu-Pi). In the RX chain, a low-power fully differential shunt-feedback trans-impedance amplifier (FD SF-TIA) is exploited to reduce the input-referred noise. Following the TIA, a postamplifier (PA) based on a novel active feedback circuit topology extends the bandwidth (BW) and a buffer delivers the output electrical signal to the 100- $\Omega $ differential off-chip load. An automatic offset cancellation loop is included to protect the RX from any offset source at the input. The RX AFE consumes 56 mW from 1.8-V supply voltage and provides a trans-impedance (TI) gain of $78.7~\Omega $ with 27-GHz BW. By exploiting the FD SF-TIA with low parasitic capacitance of the germanium photodiodes (Ge-PD) in the photonic die as well as BW recovery by the PA, the RX achieves the sensitivity of −7.5-dBm OMA at Ge-PD and −2.3-dBm OMA at the single-mode fiber (SMF) optical output with bit error rate (BER) of <10−12 and PRBS-7. To the author’s best knowledge, among published state-of-the-art 50-Gb/s TIAs and RX exploiting SiGe BiCMOS technologies, this work proves the best energy efficiency ((pJ/bit)) and figure of merit (FoM) ($({\text {Gbps}}/{\mu \text {A.mW}})$) in terms of sensitivity and power consumption. [ABSTRACT FROM AUTHOR]

The Advanced GAmma Tracking Array (AGATA) multidetector spectrometer will provide precise information for the study of the properties of the exotic nuclear matter (very unbalanced proton (Z) and neutron (N) numbers) along proton- and neutron-drip lines and of super-heavy nuclei. This is done using the latest technology of particle accelerators. The AGATA spectrometer consists of 180 high-purity germanium detectors. Each detector is segmented into 38 segments. The very harsh project requirements are to measure gamma-ray energies with very high resolution ($ < 1\times 10^{-3}$) at a high detector counting rate (50 K events/s/crystal). This results in a very high data transfer rate per crystal (5–8 Gb/s). The 38 segments are sampled at 100 MHz with 14 bits of resolution. The samples are continuously transferred to the control and processing (CAP) module, which reduces the data rate from 64 to 5 Gb/s. The CAP module also adds continuous monitoring data, which results in total outgoing data rate of 10 Gb/s. The serial transfer acquisition and readout over Ethernet (STARE) module is designed to fit between the CAP module and the computer farm. It will package the data from the CAP module and transmit it to the server farm using a 10-Gb/s user datagram protocol (UDP) connection with a delivery insurance mechanism implemented to ensure that all data are transferred. [ABSTRACT FROM AUTHOR]

One of the major limitations of X-ray Absorption Spectroscopy (XAS) experiment at synchrotron facilities is the performance of the detectors. In order to be able to measure more challenging samples and to cope with the very high photon flux of the current and future (diffraction limited) sources, technological developments of detectors are necessary. This article reports on the construction and characterization of a monolithic 19-channel germanium detector demonstrator fitted with CMOS preamplifiers. The detector was characterized in the laboratory with radioactive sources and with the X-ray synchrotron beam. Characteristics such as energy resolution, linearity, counting rate capabilities, and stability of the detector were thoroughly evaluated. In addition, it was proved that by using an advanced pulse processor such as Xspress4, it was possible to improve the performance of the detector system by eliminating the crosstalk among channels and by suppressing the charge-shared events. This work could pave the way to enhanced germanium fluorescence detectors for high-throughput X-ray spectroscopy. [ABSTRACT FROM AUTHOR]

In China Fusion Engineering Testing Reactor research, the neutronics experiment is essential in validating the neutronics codes and tools used in a blanket. Reduction activation ferritic–martensitic steel is the main structural material of the water-cooled ceramic breeder blanket, of which the main composition is Fe. However, the activation reaction of 54Fe(n, p)54Mn will bring the long half-life product of 54Mn. Therefore, the reaction rate of the reaction channel 54Fe(n, p)54Mn was investigated with accuracy in this paper. In a fusion reactor, neutron is generated not only from deuterium tritium reaction but also from the deuterium deuterium (DD) reaction. The spontaneous neutron source, $3 \times 10^{8}$ n/s 252Cf, was used to simulate DD neutron field. After irradiated for about 5 days, the activated Fe foil was measured by a high-resolution gamma-ray spectrometer with a high-purity germanium detector. The neutron flux was calculated using a Monte Carlo transport code and Fusion Evaluated Neutron Data Library (FENDL) 3.0 Files. The neutron group cross section was processed by NJOY. The relative error between the calculated value and the experimental value is less than 7%. The error of the database EAF2010 is the smallest in this paper. The self-shielding factor has a greater impact on FENDL 3.0 database. [ABSTRACT FROM AUTHOR]

Recent progress on the development of very low noise high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a direct detection search for low mass, WIMP dark matter. This transaction reports the thermal characterization of the cryostat, specifications of the newly prepared 1.2 kg p-type point contact germanium detector, and the spectroscopic performance of the integrated system. The integrated detector and low background cryostat achieved full-width-at-half-maximum noise performance of 98 eV for an electronic pulse generator peak and 1.9 keV for the 1332-keV 60Co gamma ray. [ABSTRACT FROM AUTHOR]

Environmental scientific research requires a detector that has sensitivity low enough to reveal the radiological content for the presence of potential contaminants in the sample at a reasonable counting time. CANBERRA developed a germanium detector geometry called Small Anode Germanium (SAGe) Well detector. The SAGe Well detector is a new type of low capacitance device manufactured using small anode technology capable of advancing many environmental scientific research applications. The performance of this detector has been evaluated for a range of sample sizes and geometries counted inside the well, and on the end cap of the detector. The detector has energy resolution performance similar to semi-planar detectors, and offers significant improvement over the existing coaxial and Well detectors. Energy resolution performance of 750 eV Full Width at Half Maximum (FWHM) at 122 keV \gamma-ray energy and resolution of 2.0–2.3 keV FWHM at 1332 keV \gamma-ray energy are guaranteed for detector volumes up to 425 ~\cm^3. The SAGe Well detector offers an optional 28 mm well diameter with the same energy resolution performance as the standard 16 mm well. Such outstanding performance will benefit environmental applications in revealing the detailed radionuclide content of samples, particularly at low energy. The detector is compatible with electric coolers without any sacrifice in performance and supports the CANBERRA Mathematical efficiency calibration method (In situ Object Calibration Software or ISOCS, and Laboratory SOurceless Calibration Software or LabSOCS). In addition, the SAGe Well detector supports true coincidence summing available in the ISOCS/LabSOCS framework. The improved resolution performance of this new device greatly enhances its detection sensitivity for a range of sample sizes and geometries counted inside the well. This results in lower minimum detectable concentrations (MDC) compared to Traditional Well detectors. The SAGe Well detectors are compatible with Marinelli beakers and compete very well with semi-planar and coaxial detectors for large samples in many applications. [ABSTRACT FROM PUBLISHER]

In this work we present the architecture and results of a fully digital Front End Electronics (FEE) read out system developed for the GALILEO array. The FEE system, developed in collaboration with the Advanced Gamma Tracking Array (AGATA) collaboration, is composed of three main blocks: preamplifiers, digitizers and preprocessing electronics. The slow control system contains a custom Linux driver, a dynamic library and a server implementing network services. This work presents the first results of the digital FEE system coupled with a GALILEO germanium detector, which has demonstrated the capability to achieve an energy resolution of 1.53‰ at an energy of 1.33 MeV, similar to the one obtained with a conventional analog system. While keeping a good performance in terms of energy resolution, digital electronics will allow to instrument the full GALILEO array with a versatile system with high integration and low power consumption and costs. [ABSTRACT FROM AUTHOR]

We have constructed a pixelated germanium detector using a technique which has been shown to provide good isolation between adjacent pixels. In this work we present initial tests of the application of a low-noise CMOS ASIC to read out this detector. The detector has 64 pixels, each 0.5~\mm\times 5~\mm, arranged as a series of strips. It is connected by wire-bonds to two 32-channel application-specific integrated circuits (ASICs) which provide a complete photon-counting chain for every channel. Since the size of the pixel array is no longer restricted by the difficulties of instrumenting large channel-count conventional electronics, this development will open up the possibility of even larger arrays, similar to those offered by silicon detectors. [ABSTRACT FROM PUBLISHER]

A novel, multi-point contact high-purity germanium detector has been developed for applications in high-rate gamma environments. The planar detector was fabricated with seven point contacts, a high-voltage steering grid and bias electrode using amorphous germanium technology. We have characterized this detector and report herein on the depletion profile, leakage current, energy resolution, and charge-sharing behavior. [ABSTRACT FROM PUBLISHER]

In pinhole single photon emission computed tomography (SPECT), multi-pinhole collimators can increase sensitivity but may lead to projection overlap, or multiplexing, which can cause image artifacts. In this work, we explore whether a stacked-detector configuration with a germanium and a silicon detector, used with ^123I (27–32, 159 keV), where little multiplexing occurs in the Si projections, can reduce image artifacts caused by highly-multiplexed Ge projections. Simulations are first used to determine a reconstruction method that combines the Si and Ge projections to maximize image quality. Next, simulations of different pinhole configurations (varying projection multiplexing) in conjunction with digital phantoms are used to examine whether additional Si projections mitigate artifacts from the multiplexing in the Ge projections. Reconstructed images using both Si and Ge data are compared to those using Ge data alone. Normalized mean-square error and normalized standard deviation provide a quantitative evaluation of reconstructed images' error and noise, respectively, and are used to evaluate the impact of the additional nonmultiplexed data on image quality. For a qualitative comparison, the differential point response function is used to examine multiplexing artifacts. Results show that in cases of highly-multiplexed Ge projections, the addition of low-multiplexed Si projections helps to reduce image artifacts both quantitatively and qualitatively. [ABSTRACT FROM AUTHOR]

This paper presents progress on the development of a cryostat intended to improve upon the low-energy threshold (below 0.5 keV) of p-type point contact germanium gamma-ray spectrometers. Ultra-low energy thresholds are important in the detection of low-energy nuclear recoils, an event class relevant to both dark matter direct detection and measurement of coherent neutrino-nucleus scattering. The cryostat design, including a thermal and electrical-field model, is given. A prototype cryostat has been assembled and data acquired to evaluate its vacuum and thermal performance. [ABSTRACT FROM PUBLISHER]

Non-proportionality of light yield and energy resolution of Compton electrons in three scintillators (LaBr3:Ce, LYSO:Ce and CsI:Tl) were studied in a wide energy range from 10 keV up to 1 MeV. The experimental setup was comprised of a High Purity Germanium detector and tested scintillators coupled to a photomultiplier. Probing the non-proportionality and energy resolution curves at different energies was obtained by changing the position of various radioactive sources with respect to both detectors. The distance between both detectors and source was kept small to make use of Wide Angle Compton Coincidence (WACC) technique, which allowed us to scan large range of scattering angles simultaneously and obtain relatively high coincidence rate of 100 cps using weak sources of about 10 \muCi activity. The results are compared with those obtained by direct irradiation of the tested scintillators with gamma-ray sources and fitting the full-energy peaks. [ABSTRACT FROM PUBLISHER]

We describe a physics simulation software framework, MaGe, that is based on the Geant4 simulation toolkit. MaGe is used to simulate the response of ultra-low radioactive background detectors to ionizing radiation, specifically the Majorana and Gerda neutrinoless double-beta decay experiments. Majorana and Gerda use high-purity germanium detectors to search for the neutrinoless double-beta decay of ^76 Ge and MaGe is jointly developed between these two collaborations. The MaGe framework contains the geometry models of common objects, prototypes, test stands and the actual experiments. It also implements customized event generators, Geant4 physics lists and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators and physics lists. [ABSTRACT FROM AUTHOR]

Cross-talk limits of monolithic highly-segmented semiconductor detectors for high-resolution X-gamma spectrometry are investigated. Cross-talk causes false signal components yielding amplitude losses and fold-dependent shifts of the spectral lines, which partially spoil the spectroscopic performance of the detector. Two complementary electrical models are developed, which describe quantitatively the inter-channel cross-talk of monolithic segmented detectors whose electrodes are read out by charge-sensitive preamplifiers. The first is here designated as Cross-Capacitance (CC) model, the second as Split-Charge (SC) model. The CC model builds around the parasitic capacitances Cij linking the preamplifier outputs and the neighbor channel inputs. The SC model builds around the finite-value of the decoupling capacitance C_C used to read out the high-voltage detector electrode. The key parameters of the models are individuated and ideas are shown to minimize their impact. Using a quasi-coaxial germanium segmented detector it is found that the SC cross-talk becomes negligible for decoupling capacitances larger than 1 nF, where instead the CC cross-talk tends to dominate. The residual cross-talk may be reduced by minimization of stray capacitances Cij, through a careful design of the layout of the Printed Circuit Board (PCB) where the input transistors are mounted. Cij can be made as low as \sim5 fF, but it is shown that even in such case the impact of the CC cross-talk on the detector performance is not negligible. Finally, an algorithm for cross-talk correction is presented and elaborated. [ABSTRACT FROM AUTHOR]

We have developed a digital signal processing module (APV7109) for a germanium semiconductor detector. The benchmark test of this module has shown good energy resolution and high throughput compared with conventional analog modules. By adding an extension module, the APV7109 can perform more advanced on-line calculations using the pulse shapes delivered by the on-board programmable logic. Therefore, user defined algorithms for pulse shape analysis can be used to adapt this module to various applications. Tests have demonstrated the feasibility of this extensible design. [ABSTRACT FROM AUTHOR]

Cryogenic low-noise charge sensitive preamplifiers have been developed and realized for the GERmanium Detector Array (GERDA). An integrated JFET-CMOS preamplifier, which is fully functional at cryogenic temperatures, has been tested in conjunction with an unsegmented p-type HPGe detector. Both the crystal and the preamplifier were operated inside a liquid nitrogen dewar at 77 K. The detector capacitance was ~60 pF. An optimum resolution of 1.6 keV FWHM has been obtained for the pulser line at 6 μs shaping time. A resolution of 2.1 keV FWHM has been achieved for the 1.332 MeV line from a 60Co source. A wide bandwidth (rise time of ~ 16 ns) permits use of pulse-shape analysis techniques to localize the position of the photon interactions inside the crystal. A low power consumption ( ~23 mW) makes the preamplifier suitable for a multi-channel array of germanium detectors. [ABSTRACT FROM AUTHOR]

An AGATA symmetric, coaxial, high-purity germanium (HPGe) detector has been scanned in coincidence mode. Charge pulse shapes from the 36-fold segmented outer contacts and center contact were stored for events at more than 2000 precisely determined 3-D interaction positions spread over ten depths (z). A database (basis) of the 37 average experimental pulse shapes at each position was generated. The electric field simulation code Multi Geometry Simulation (MGS) was used to generate the pulse shapes for the geometry on a 1.0-mm cubic grid. A minimization between the experimental pulse shapes at each position and the MGS basis yielded mean displacements of between 1.5 and 3.0 mm in the x-y plane. The vectors of these displacements were biased in the direction of the center of the detector. This effect is attributed to cross-talk. The maximum level of derivative cross-talk was measured and shown to be 534%ns. However due to the lack of a global clock in the acquisition system, it could not be accounted for throughout the basis. [ABSTRACT FROM AUTHOR]

Wide-range energy measurements have been carried out with an encapsulated 36-fold segmented germanium detector of AGATA (Advanced GAmma-ray Tracking Array). An unprecedented equivalent energy range of 5 keY to 180 MeV, or ∼90 dB, has been obtained using a single acquisition chain, while maintaining a high energy resolution in the whole spectrum. For energies larger than 3 MeV the pulse-height is obtained with a Time-over-Threshold (ToT) technique. The measured resolution in all the tested range from 3 to 50 MeV is of <0.4%. The ToT technique has beendemonstrated using a 241Am + Be source with Ni target generating high-energy gamma photons by neutron capture reactions. A remarkable resolution of 0.21% has been obtained on the Ni spectrum line at the energy of 8.998 MeV. [ABSTRACT FROM AUTHOR]

An Advanced GAmma Tracking Array (AGATA) symmetric prototype high purity Germanium (HPGe) detector has been tested. The detector was illuminated with a 1 mm collimated, beam of 137Cs (662 keV) gamma rays. The beam was raster scanned across the front and sides of the detector and the charge sensitive preamplifier output pulse shapes from all 37 channels (36 segments plus the centre contact) were digitised and stored for off-line analysis. Rise time and image charge asymmetry magnitudes were measured as a function of interaction position to study the charge transport properties through the crystal volume. These parameters were then utilised as a calibrated look up table with which in-beam data was analysed and Doppler corrected. An average position resolution of approximately 9 mm (FWHM) was achieved with a crude analysis. [ABSTRACT FROM AUTHOR]

While the original Compton coincidence technique provided accurate measurements of electron response in scintillators, the data rate was low and measurements took weeks. We present the conceptual design for a high throughput version that is predicted to collect data at 65 cps, reducing measurement times from weeks to hours. In this design, a collimated 1 mCi 137Cs source will illuminate the scintillator sample from a distance of 18 cm and 5 high-purity germanium (HPGe) detectors placed 10 cm from the scintillator will measure the energy of the scattered gamma ray. The source can be placed in either of two positions spaced 15deg apart, allowing relatively uniform scattering angle coverage from 0deg to 146deg, corresponding to electron energies in the scintillator from 0 to 466 keV. The scintillator will be coupled to a hybrid photodetector (HPD), which has extremely linear response, and the HPD's ability to resolve single photoelectrons provides a built-in calibration mechanism. The output of each HPGe detector and the HPD will be digitized with a free-running 12-bit, 200 MHz ADC, providing accurate measurement of the signal amplitudes and the ability to measure the electron response for different temporal components of the scintillator signals. The facility will be located at Lawrence Livermore National Laboratory (LLNL) and is intended to be made available to the community at large. The goals are to facilitate scintillator development and to understand the nature of the light-yield non-proportionality and its effect on the energy resolution. [ABSTRACT FROM PUBLISHER]

Internal dose assessment can be derived from the measurement of retained activity in the whole body or in an organ at a given time. In radiation protection, this assessment, so-called in vivo measurement, is performed by an external measurement of the subject with germanium detectors (in most cases). Calibration of these detectors is ensured by anthropomorphic phantoms which, for technical reasons, can only provide rough representations of human. It is especially the case for the chest phantoms used in lung counting, subject of this paper. This leads to substantial corrections on calibration factors that are particularly crucial and delicate in low-energy in vivo measurements, resulting in important systematic errors. In order to improve calibration, former work based on numerical phantoms associated with Monte Carlo computing techniques has already proven its benefits. To go further, a Graphical User Interface called "OEDIPE", a French acronym for "tool for internal personalized dose assessment", has been developing at the IRSN internal dose assessment laboratory, simulating real measurements using person-specific computational phantoms in association with MCNP calculation code. The study presented here is dedicated to the implementation and validation of a real in vivo monitoring system (AREVA/COGEMA Marcoule, France) equipped with 4 high purity germanium (HPGe) detectors. After modeling the facility and measurement geometry using OEDIPE (design and positioning of the detectors…), validation with different configurations was carried out in two steps: first with point sources (different nuclides, different source-detector distances) and then with the Livermore calibration phantom (different overlay plates, lungs contaminated with 241Am and a mixture of actinides). The final goal is to approach a personalized numerical calibration of the facilities in order to improve dose assessment, as the use of physical phantoms for calibration induces large uncertainties. Such application could be an opening door on a better activity assessment in nuclear medicine, especially in personalized dosimetry in radioimmunotherapy. [ABSTRACT FROM AUTHOR]

The established technique for producing position-sensitive structures by means of photolithography and subsequent plasma etching of grooves through detector contacts was applied for amorphous germanium contacts (a-Ge contacts). A simple 50-strip structure with a pitch of 615 μm was produced. Charge sharing between two adjacent strips (33 mm length) was investigated with the aid of 60-keV photons and 5.8-MeY α-particles. No charge losses were detected when irradiating the structured α-Ge contact of the 16-mm-thick detector with 60-keV photons. The same was concluded for n-particles hitting the unstructured p+-contact made by boron implantation. Moreover, excellent position information for α-particles, with an accuracy of about 30 μm, could be extracted in this case. Surprising results were obtained for α-particles impinging on the structured a-Ge contact. No coincident signals from the two adjacent strips caused by α-particles were observed. But a normally positive signal from one of the strips occasionally coincided with a negative signal from the other strip and vice versa. Using a cooled FET assembly mounted near a strip, an energy resolution of 0.78 keV [FWHM] for 60-keV photons was achieved and a slightly better resolution for lower energies. Even better energy resolutions will probably be possible, because the measuring setup was far from being optimized. [ABSTRACT FROM AUTHOR]