The very last member of the IDeF-X ASIC family is presented: IDeF-X ECLAIRs is a 32-channel front end ASIC designed for the readout of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) ...Detectors. Thanks to its noise performance (Equivalent Noise Charge floor of 33 e - rms) and to its radiation hardened design (Single Event Latchup Linear Energy Transfer threshold of 56 MeV.cm 2 .mg -1 ), the chip is well suited for soft X-rays energy discrimination and high energy resolution, ldquospace proof,rdquo hard X-ray spectroscopy. We measured an energy low threshold of less than 4 keV with a 10 pF input capacitor and a minimal reachable sensitivity of the Equivalent Noise Charge (ENC) to input capacitance of less than 7 e - /pF obtained with a 6 mus peak time. IDeF-X ECLAIRs will be used for the readout of 6400 CdTe Schottky monopixel detectors of the 2D coded mask imaging telescope ECLAIRs aboard the SVOM satellite. IDeF-X ECLAIRs (or IDeF-X V2) has also been designed for the readout of a pixelated CdTe detector in the miniature spectro-imager prototype Caliste 256 that is currently foreseen for the high energy detector module of the Simbol-X mission.
Automatic and fast identification of gamma-ray-emitting radionuclides is a challenge in the field of nuclear safety, especially in case of emergency, since it requires complex calculations and often ...the knowledge of experts to interpret the data. We present a development of an automatic identification method based on convolutional neural networks (CNNs) as a new tool to analyze gamma-ray spectra in real time, which uses not only photoelectric peaks but also extracts all discriminant features in the spectrum, such as Compton structures, for instance. The original approach relies on the training of the CNN with a fully synthetic database, built by means of a Monte Carlo simulation with Geant4 combined with a detailed analytical detector response model. The algorithm and training method are evaluated to identify radionuclides in measurements of the mixtures of sources acquired with Caliste, a fine-pitch CdTe imaging spectrometer. The neural network is able to discriminate each element in an arbitrary mixture very quickly with high accuracy.
The CdTe gamma-ray camera IBIS/ISGRI, on board the INTEGRAL satellite launched in October 2002, is currently the largest spectro-imager of this type in the world. The development of this detector, ...for research in the field of astrophysics, has provided the opportunity to demonstrate the feasibility of massive integration of CdTe nuclear detectors, taking advantage of the CdTe good spectral performances and high modularity. Many other groups in the world work also to further develop detectors using this material in view of improving its spectral performances (crystal quality, electrode geometry and type, electronics and filtering, etc.), the spatial resolution (pixelization of monolithic crystals) and the detection efficiency at high energy (thickness). In this review, I will detail the main directions in which to strive in order to explore these fields in the upcoming years through examples of techniques or applications.
Compton imaging is the main method for locating radioactive hot spots emitting high-energy gamma-ray photons. In particular, this imaging method is crucial when the photon energy is too high for ...coded-mask aperture imaging methods to be effective or when a large field of view is required. Reconstruction of the photon source requires advanced Compton event processing algorithms to determine the exact position of the source. In this study, we introduce a novel method based on a Deep Learning algorithm with a Convolutional Neural Network (CNN) to perform Compton imaging. This algorithm is trained on simulated data and tested on real data acquired with Caliste, a single planar CdTe pixelated detector. We show that performance in terms of source location accuracy is equivalent to state-of-the-art algorithms, while computation time is significantly reduced and sensitivity is improved by a factor of ∼5 in the Caliste configuration.
NDIP20: 9th International Conference on New Developments in Photodetection Bougamont, E.; Carrel, F.; Chipaux, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
June 2023, 2023-Jun, 2023-06-00, 20230601, Letnik:
1051
Journal Article
We present the IDeF-X HDBD integrated circuit, our latest 32-channel application specified integrated circuit devoted to semiconductor photon counting X-ray detectors, designed to read charges ...ranging from −40 to 40 fC. The chip reaches an equivalent noise charge (ENC) floor of 17 electrons rms and is optimized for low input capacitance (< 10 pF). Each channel is based on an optimized charge sensitive amplifier (CSA) followed by a CR-RC 2 filter and a peak detector with a power consumption of <inline-formula> <tex-math notation="LaTeX">850 ~\mu \text{W} </tex-math></inline-formula>/channel. Gain and shaping times are tunable. This circuit has been designed with radiation mitigation techniques to meet space application requirements. This ASIC can read either cadmium telluride or silicon detectors for imaging-spectroscopy applications. An energy resolution of 230-eV FHWM at 6 keV and a low-level threshold of 1.2 keV were demonstrated with a single pixel silicon drift detector connected to one channel.
For the first time in the history of high energy astronomy, a large CdTe gamma-ray camera is operating in space. ISGRI is the low-energy camera of the IBIS telescope on board the INTEGRAL satellite. ...This paper details its design and its in-flight behavior and performances. Having a sensitive area of 2621 cm2 with a spatial resolution of 4.6 mm, a low threshold around 12 keV and an energy resolution of ~8% at 60 keV, ISGRI shows absolutely no signs of degradation after 9 months in orbit. All aspects of its in-flight behavior and scientific performance are fully nominal, and in particular the observed background level confirms the expected sensitivity of 1 milliCrab for a 106 s observation.
Compton imaging is one of the main methods to localize radioactive hotspots, which emit high-energy gamma-ray photons, above 200 keV. Most of the Compton imaging systems are composed by at least two ...detection layers or one 3D position sensitive detector. In this study, we demonstrate the application of a new miniature pixelated single plane detector to Compton imaging. In this configuration, we do not have the information on interaction depth but we successfully test its ability to perform Compton localization by means of comparing different Compton reconstruction algorithms applied to real data measured with our single plane detection system.
Diagnostics and monitoring of radiological scenes are critical to the field of nuclear safety and here, the localization of radioactive hotspots is mandatory and remains a critical challenge. In ...order to perform gamma-ray imaging, one main method relies on indirect imaging by means of coded mask aperture associated with a position sensitive gamma-ray detector and a dedicated deconvolution algorithm. However, the deconvolution problem is non-injective, which implies limitations of the reconstruction performance, especially for spatially extended radioactive sources with respect to the angular resolution. In this paper, we present and evaluate a new method based on a deep learning algorithm with a convolutional neural network to overcome this limitation, in comparison with a classical iterative algorithm. Our deep learning algorithm is trained on simulated data of extended sources that may imply an intrinsic regularization of the neural network. We test it on real data acquired with a gamma camera system based on Caliste, a CdTe detector for high-energy photons.
This paper describes a 16x16 pixels CdTe-based X-ray detector named dimension 2 revision 1 (D 2 R 1 ) with a pixel size of 300 μm x 300 μm. An application-specific integrated circuit (ASIC) is ...interconnected to a CdTe detector by means of an indium gold stud bonding process. This ASIC has a mean equivalent noise charge of 29 el.rms (at 0 pF). The combination of a low capacitance interconnection and low-dark-current detector (0.5 pA) with an optimized ASIC results in a spectral resolution of 584-eV full-width at half-maximum at 60 keV, an energy threshold of 2 keV with a dynamic range of 250 keV. A filtering stage made of a multicorrelated double sampling allows the system to measure X-ray photons at a frequency of 10 kcounts/s typically suited for low photon flux less than 3000 <inline-formula> <tex-math notation="LaTeX">\text {photons}\cdot \text {cm}^{-2}\cdot \text{s}^{-1} </tex-math></inline-formula>. The energy range, resolution, and timing capability of D 2 R 1 can suite a variety of different applications such as X-ray astrophysics, nuclear safety, or medical applications.
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