0000000000063997
AUTHOR
S. Del Sordo
showing 20 related works from this author
Evaluation of the Spectroscopic Performance of 3D CZT Drift Strip Detectors
2021
CdTe/CZT is an attractive and consolidated material with which to realize detectors with good efficiency and energy resolution, operating at room temperature and suitable for a large variety of applications such as medical imaging, nuclear security, and astrophysics. Right in this last field several spectro-imagers based on these CdTe/CZT detectors were mounted onboard space missions such as INTEGRAL, Swift, and NuSTAR for hard X and gamma-ray astrophysics. Much effort has been expended in the development of CZT spectroscopic imagers for obtaining sub-millimeter spatial resolution in three dimensions (3D) and high energy resolution up to 1 MeV. The motivations are mainly related to the poss…
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 …
Temporal Analysis of EXO 0531−66 in Outburst
1998
We report a timing analysis of the Be transient X-ray binary EXO 053109-6609.2 in outburst observed with BeppoSAX. The luminosity of the source is ~1.1 × 1037 ergs s-1, similar to that observed in the previous three outbursts. The source shows pulsations from 0.1 up to 60 keV. The pulsed fraction does not seem to decrease with the energy. The pulse profile is double peaked in the whole energy band. The barycentric pulse period is 13.67590 ± 0.00008 s at MJD 50,520.0. The average rate of period change during the ~2 days of BeppoSAX observation is (3.7 ± 0.5) × 10-9 s s-1. Comparison with ROSAT data allowed the determination of a secular spin-down sec ~(3.67 ± 0.05) × 10−11 s s-1, computed ov…
Performance of a digital CdTe X-ray spectrometer in low and high counting rate environment
2010
Abstract The high performances of CdTe detectors for X-ray and gamma ray spectroscopy are already well known. Among the traditional semiconductor spectrometers, CdTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact detection systems. In this work, we investigated the performance of a CdTe detector coupled with a custom digital pulse processing (DPP) system for X-ray spectroscopy. The DPP method, implemented on a PC platform, performs a pile-up inspection and a pulse height analysis of the preamplifier output pulses, digitized by a 14-bit, 100 MHz ADC. The spectroscopic results point out the excellent performanc…
Spectroscopic response of a CdZnTe multiple electrode detector
2007
Abstract The spectroscopic performances of a CdZnTe detector (crystal size: 5×5×0.9 mm 3 ) with five electrodes (cathode, anode and three steering electrodes) were studied. The anode layout, which consists of a circular electrode ( φ =80 μm) surrounded by two ring electrodes (gap=100 μm; radial width Δ r =100 μm) and by one electrode that extends to the edge of the crystal, is mostly sensitive to the electron carriers, overcoming the well known effect of the hole trapping in the measured spectra. We report on the spectroscopic response of the detector at different bias voltages of the electrodes and at various photon energies ( 109 Cd, 241 Am and 57 Co sources). The CdZnTe detector exhibits…
BeppoSAX observation of the transient X-ray pulsar GS 1843+009
1999
Abstract The transient X-ray pulsar GS 1843+009 was observed by BeppoSAX satellite on 1997 April 4, while it was at flux level of 50 mCrab in the 20–200 keV energy band. Using the MECS and LECS concentrators, the source position was measured with unprecedented accuracy of 30. In this poster we present results on both spectral and temporal analysis.
Characterization of Al-Schottky CdTe detectors
2011
In the last decades, great efforts are being devoted to the development of CdTe detectors for high resolution X-ray and gamma ray spectroscopy. Recently, new rectifying contacts based on aluminum (Al) are very appealing in the development of CdTe detectors with low leakage currents and anode pixellization. In this work, we report on preliminary results of electrical and spectroscopic investigations on Schottky CdTe diode detectors (4.1 × 4.1 × 0.75 and 4.1 × 4.1 × 2 mm3) with Au/Ti/Al/CdTe/Pt electrode configuration. The detectors are characterized by very low leakage currents even at room temperature (26 pA at 25 °C under a bias voltage of −100 V for the 2 mm thick detector). Polarization …
A CZT 3D imaging spectrometer prototype with digital readout for high energy astronomy
2023
The scientific challenges still open in hard X-rays and γ-rays astronomy require the development of new instrumentation able to overcome the sensitivity limits of the present one. Among the technologies currently under study to cover the energy range between several tens of keV and one MeV, the development of telescopes equipped with broadband Laue lenses associated with focal planes with high spectroscopic and imaging performance represents an extremely promising solution. With this perspective, we report on the development and the first spectroscopic characterisation results of an X/γ rays detection system (10-1000 keV) based on CZT spectrometers with spatial resolution in three dimension…
Investigation on pixellated CZT detectors coupled with a low power readout ASIC
2008
In this work, we investigated on the spectroscopic performances of two pixellated CZT detectors coupled with a custom low noise and low power readout ASIC. The detectors (10 x 10 x 1 mm3 and 10 x 10 x 2 mm3 single crystals) consist of an array of 256 pixels with a geometric pitch of 0.5 mm. The ASIC, fabricated in 0.8 μm BiCMOS technology, is equipped with eight independent channels (preamplifier and shaper) characterized by a dynamic range from 10 keV to 100 keV, low power consumption (0.5 mW/channel) and low noise (150–500 electrons r.m.s.). The spectroscopic results point out the good energy resolution of both detectors at room temperature (5.8 % FWHM at 59.5 keV for the 1 mm thick detec…
Monte Carlo evaluation of a CZT 3D spectrometer suitable for a Hard X- and soft-γ rays polarimetry balloon borne experiment
2015
Today, the measurement of the polarization status of cosmic sources high-energy' emission, is recognized as a key observational parameter to understand the active production mechanism and its geometry. Therefore, a mandatory requirement for new instrumentations operating in this energ.-y range will be to provide high sensitivity for polarimetric measurements. In this framework, we have presented the concept of a small high-performance imaging spectrometer optimized for polarimetry between 100 and 600 keV suitable for a stratospheric balloon-borne payload and as a pathfinder for a future satellite mission. The detector with 3D spatial resolution is based on a CZT spectrometer in a highly seg…
High-rate x-ray spectroscopy in mammography with a CdTe detector: A digital pulse processing approach
2010
Purpose:Direct measurement of mammographic x-ray spectra under clinical conditions is a difficult task due to the high fluence rate of the x-ray beams as well as the limits in the development of high resolution detection systems in a high counting rate environment. In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate x-ray spectroscopy in mammography. Methods: The DPP system performs a digital pile-up inspection and a digital pulse height analysis of the detector signals, digitized through a 14-bit, 100 MHz digitizer, for x-ray spectroscopy even at high photon counting rates. We investigated on the respon…
Rejection Power of A Horizontal Rpc Telescope For Left and Right Coming Cosmic Muons
1993
Abstract The possibility of performing neutrino astronomy by means of a detector above the ground depends critically on the feasibility of a rejection power on the order of 10 11 required to discriminate the enormous background of cosmic downward going muons from the signal of upward going muons produced by neutrinos. In order to check whether and how this rejection is obtainable, we have built in the Physics Department of the University of Bari a horizontal cosmic muon telescope (MINI) instrumented with resistive plate counters. By performing time-of-flight measurements, we have estimated the rejection power of our telescope for left and right coming cosmic muons. The rejection dependence …
Spectroscopic response and charge transport properties of CdZnTe detectors grown by the vertical Bridgman technique
2015
In this work, we present the results of spectroscopic investigations on CdZnTe (CZT) detectors grown by the boron oxide encapsulated vertical Bridgman technique (1MEM-CNR, Parma, Italy). The detectors, with different thicknesses (1 and 2.5 mm), are characterized by the same electrode layout (gold electroless contacts): the anode is a central electrode (2 x 2 mm(2)) surrounded by a guard-ring electrode, while the cathode is a planar electrode covering the detector surface (4.1 x 4.1 mm(2)). The results of electrical investigations point out the low leakage currents of these detectors even at high bias voltages: 38 nA/cm(2) (T = 25 degrees C) at 10000 V/cm. The time stability and the spectros…
Charge Transport Properties in CZT Detectors Grown by the Vertical Bridgman Technique
2010
Great efforts are being presently devoted to the development of CdTe and CdZnTe detectors for a large variety of applications, such as medical, industrial, and space research. We present the spectroscopic properties of some CZT crystals grown by the standard vertical Bridgman method and by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR (Parma, Italy). By this technique the crystal is grown in an open quartz crucible fully encapsulated by a thin layer of liquid boron oxide. This method prevents contact between the crystal and the crucible thereby allowing larger single grains with a lower dislocation density to be obtained. Several mono…
Measurements with a hybrid detector prototype composed of a MOS CCD and a CZT spectrometer
2008
The scientific objectives of the future X-ray astronomy instruments require new type of focusing telescopes able to extend the observational range starting from 0.1 keV at least up to 100 keV to solve crucial question concerning the nature of the high energy emission. A challenging technology to extend the classical grazing incidence range to higher energy is today offered by the development of multilayer optics that are effective as X-ray concentrators between few keV up to 100 keV. A useful arrangement for this type of mission concept can foresee the soft (e.g. 0.1-10 keV) X-ray optics nested and coaxial with the hard-X mirrors. The focal plane of the telescope shall operate on a very wid…
Angular resolution of an array of tracking-chamber detectors for use in high-energy gamma-ray astronomy
1992
We describe a method of analysis for the reconstruction of the arrival direction of a high-energy photon impacting on the top of the atmosphere by using the directions of the particles on the shower front as measured by a ground-based array of tracking chambers uniformly distributed on a square surface; as an example, an array with enclosed surface of (120×120) m2 has been considered. Estimates on the accuracy of reconstruction are given, after application of the method to computer-simulated shower directions as a function of the number of «smapling» detectors and of their accuracy in the measurement of the «local» shower direction.
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…
Characterization of a CZT focal plane small prototype for hard X-ray telescope
2005
The promise of good energy and spatial resolution coupled with high efficiency and room temperature operation has fuelled a large international effort to develop cadmium zinc telluride (CZT) for hard X-ray applications. We are involved on the development of a hard X-ray telescope based on multilayer optics and focal plane detector operative in the 10-80 keV energy range. This telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. This paper reports preliminary results on the characterization both in spectroscopic and spatial response of two small pixellated CZT detectors (10times10times1 mm3 and 10times10tim…
Experimental results from Al/p-CdTe/Pt X-ray detectors
2013
Abstract Recently, Al/CdTe/Pt detectors have been proposed for the development of high resolution X-ray spectrometers. Due to the low leakage currents, these detectors allow high electric fields and the pixellization of anodes with the possibility to realize single charge carrier sensing detectors. In this work, we report on the results of electrical and spectroscopic investigations on CdTe diode detectors with Al/CdTe/Pt electrode configuration (4.1×4.1×0.75 and 4.1×4.1×2 mm 3 ). The detectors are characterized by very low leakage currents in the reverse bias operation: 0.3 nA at 25 °C and 2.4 pA at −25 °C under a bias voltage of −1000 V. The spectroscopic performance of the detectors at b…
Recent trends in the development of CdTe and CdZnTe semiconductor detectors for astrophysical applications
2010
Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) offer great promise as x-ray and gamma ray detectors. Due to the high detection efficiency, the good room temperature performance and the recent improvements on crystal growth technology, CdTe and CdZnTe detectors have obtained an increasing interest in the field of hard x-ray and gamma ray astronomy. In this paper, we report on the R&D activities on CdTe and CdZnTe detectors for high energy space instrumentation. Our group has been involved in the design of new multilayer hard x and soft gamma ray Laue lens telescopes and, in particular on the development of focal plane detectors based on CdTe and CdZnTe. Here we present the acti…