Search results for "Detectors"
showing 10 items of 2229 documents
Analysis of multipactor RF breakdown in a waveguide containing a transversely magnetized ferrite
2016
In this paper, the multipactor RF breakdown in a parallel-plate waveguide partially filled with a ferrite slab magnetized normal to the metallic plates is studied. An external magnetic field is applied along the vertical direction between the plates in order to magnetize the ferrite. Numerical simulations using an in-house 3-D code are carried out to obtain the multipactor RF voltage threshold in this kind of structures. The presented results show that the multipactor RF voltage threshold at certain frequencies becomes considerably lower than for the corresponding classical metallic parallel-plate waveguide with the same vacuum gap
Growth kinetics of colloidal Ge nanocrystals for light harvesters
2016
Colloidal Ge nanocrystals (NCs) are gaining increased interest because of their potential application in low-cost optoelectronic and light harvesting devices. However, reliable control of colloidal NC synthesis is often an issue and a deeper understanding of the key-role parameters governing NC growth is highly required. Here we report an extended investigation on the growth of colloidal Ge NCs synthesized from a one-pot solution based approach. A systematic study of the effects of synthesis time, temperature and precursor concentration is elucidated in detail. X-ray diffraction (XRD) analysis reveals the presence of crystalline Ge NCs with a mean size (from 5 to 35 nm) decreasing with the …
Heavy-ion induced single event effects and latent damages in SiC power MOSFETs
2022
The advantages of silicon carbide (SiC) power MOSFETs make this technology attractive for space, avionics and high-energy accelerator applications. However, the current commercial technologies are still susceptible to Single Event Effects (SEEs) and latent damages induced by the radiation environment. Two types of latent damage were experimentally observed in commercial SiC power MOSFETs exposed to heavy-ions. One is observed at bias voltages just below the degradation onset and it involves the gate oxide. The other damage type is observed at bias voltages below the Single Event Burnout (SEB) limit, and it is attributed to alterations of the SiC crystal-lattice. Focused ion beam (FIB) and s…
Study of silica-based intrinsically emitting nanoparticles produced by an excimer laser
2019
International audience; We report an experimental study demonstrating the feasibility to produce both pure and Ge-doped silica nanoparticles (size ranging from tens up to hundreds of nanometers) using nanosecond pulsed KrF laser ablation of bulk glass. In particular, pure silica nanoparticles were produced using a laser pulse energy of 400 mJ on pure silica, whereas Ge-doped nanoparticles were obtained using 33 and 165 mJ per pulse on germanosilicate glass. The difference in the required energy is attributed to the Ge doping, which modifies the optical properties of the silica by facilitating energy absorption processes such as multiphoton absorption or by introducing absorbing point defect…
Characterization of SiPM properties at liquid nitrogen temperature
2016
SiPM operation at cryogenic temperatures fails for many common devices. A particular type with deep channels in the silicon substrate instead of quenching resistors was thoroughly characterized from room temperature down to liquid nitrogen temperature by illuminating it with low light levels. The devices were mounted in vacuum with the temperature stabilized to allow long-term operation. SiPM signals from a LED pulser were acquired with single-pixel resolution. Generalized fits to the charge collection spectra were used to extract properties like single-pixel gain, inter-pixel variation, breakdown voltage, and photon detection efficiency. With these measurements a deeper investigation of th…
High Resolution X-Ray Spectroscopy with Compound Semiconductor Detectors and Digital Pulse Processing Systems
2012
The advent of semiconductor detectors has revolutionized the broad field of X-ray spectroscopy. Semiconductor detectors, originally developed for particle physics, are now widely used for X-ray spectroscopy in a large variety of fields, as X-ray fluorescence analysis, X-ray astronomy and diagnostic medicine. The success of semiconductor detectors is due to several unique properties that are not available with other types of detectors: the excellent energy resolution, the high detection efficiency and the possibility of development of compact detection systems. Among the semiconductors, silicon (Si) detectors are the key detectors in the soft X-ray band (15 keV) and will continue to be the c…
Hard X-Ray Response of Pixellated CdZnTe Detectors
2009
In recent years, the development of cadmium zinc telluride (CdZnTe) detectors for x-ray and gamma ray spectrometry has grown rapidly. The good room temperature performance and the high spatial resolution of pixellated CdZnTe detectors make them very attractive in space-borne x-ray astronomy, mainly as focal plane detectors for the new generation of hard x-ray focusing telescopes. In this work, we investigated on the spectroscopic performance of two pixellated CdZnTe detectors coupled with a custom low noise and low power readout application specific integrated circuit (ASIC). The detectors (10x10x1 and 10x10x2 mm3 single crystals) have an anode layout based on an array of 256 pixels with a …
Transmission Efficiency of the SAGE Spectrometer Using GEANT4
2013
The new SAGE spectrometer allows simultaneous electron and γ-ray in-beam studies of heavy nuclei. A comprehensive GEANT4 simulation suite has been created for the SAGE spectrometer. This includes both the silicon detectors for electron detection and the germanium detectors for γ-ray detection. The simulation can be used for a wide variety of tests with the aim of better understanding the behaviour of SAGE. A number of aspects of electron transmission are presented here.
New Results on High-Resolution 3-D CZT Drift Strip Detectors
2020
Intense research activities have been carry out in the development of room temperature gamma ray spectroscopic imagers, aiming to compete with the excellent energy resolution of high-purity germanium (HPGe) detectors (0.3 % FWHM at 662 keV) obtained after cryogenic cooling. Cadmium-zinc-telluride (CZT) detectors equipped with pixel, strip and virtual Frisch-grid electrode structures represented an appealing solution for room temperature measurements. In this work, we present the performance of new high-resolution CZT drift strip detectors (19.4 x 19.4 x 6 mm3), recently fabricated at IMEM-CNR of Parma (Italy) in collaboration with due2lab company (Reggio Emilia, Italy). The detectors, worki…
Fibre break processes in unidirectional composites
2014
International audience; A model to predict the effects of the accumulation of fibre breakages in unidirectional carbon fibre composites has been developed that takes into account several physical phenomena controlling fibre failure, including the stochastic nature of fibre strength, stress transfer between fibres due to the shear of the matrix, interfacial debonding and viscosity of the matrix. The damage processes leading up to failure are discussed and quantified, first in terms of fibre breaks for the case of monotonically increasing tensile loading, then for sustained loading and finally the implications for more complex loads and structures are discussed. It is clearly shown that the f…