Stefano Del Sordo - Academia.edu (original) (raw)

Papers by Stefano Del Sordo

Cornell University - arXiv, Jan 15, 1999

The BeppoSAX Narrow Field Instruments observed the galactic source GS 1826-238 in October 1997, f... more The BeppoSAX Narrow Field Instruments observed the galactic source GS 1826-238 in October 1997, following a hard X-ray burst with a peak flux of about 100 mCrab detected by BATSE. Two short X-ray bursts (∼150 seconds) were detected up to 60 keV, with larger amplitude and duration at lower energies (up to a factor 20 times the persistent emission). This confirms the proposed identification of the source as a weakly magnetized neutron star in a LMXRB system. For both persistent and burst states, the spectrum in the 0.4-100 keV energy range is well fitted by an absorbed black body, plus a flat power-law (Γ ∼ 1.7) with an exponential cutoff at 50 keV.

Semiconductor Radiation Detectors, 2017

IAUC 6659 available at Central Bureau for Astronomical Telegrams.

Optics for EUV, X-Ray, and Gamma-Ray Astronomy VI, 2013

ABSTRACT The development of wide band Laue lens imaging technology is challenging, but has import... more ABSTRACT The development of wide band Laue lens imaging technology is challenging, but has important potential applications in hard X- and γ-ray space instrumentation for the coming decades. The Italian Space Agency has funded a project dedicated to the development of a reliable technology to assemble a wide band Laue lens for use in space. The ground support equipment (GSE) for this project was fundamental to its eventual success... The GSE was implemented in a hard X-ray beam line built at the University of Ferrara and had the main purpose of controlling the assembly of crystals onto the Laue lens petal and to verify its final performance. The GSE incorporates the management and control of all the movements of the beam line mechanical subsystems and of the precision positioner (based on a Hexapod tool) of crystals on the petal, as well as the acquisition, storing and analysis of data obtained from the focal plane detectors (an HPGe spectrometer and an X-ray flat panel imager). The GSE is based on two PC's connected through a local network: one, placed inside the beam line, to which all the movement subsystems and the detector I/O interface and on which all the management and acquisition S/W runs, the other in the control room allows the remote control and implements the offline analysis S/W of the data obtained from the detectors. Herein we report on the GSE structure with its interface with the beam line mechanical system, with the fine crystal positioner and with the focal plane detector. Furthermore we describe the SW developed for the handling of the mechanical movement subsystems and for the analysis of the detector data with the procedure adopted for the correct orientation of the crystals before their bonding on the lens petal support.

Sensors, 2009

Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap ... more Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors.

Science, 2000

We report the discovery of a transient equivalent hydrogen column density with an absorption edge... more We report the discovery of a transient equivalent hydrogen column density with an absorption edge at ∼3.8 kiloelectron volts in the spectrum of the prompt x-ray emission of gamma-ray burst (GRB) 990705. This feature can be satisfactorily modeled with a photoelectric absorption by a medium located at a redshift of ∼0.86 and with an iron abundance of ∼75 times the solar one. The transient behavior is attributed to the strong ionization produced in the circumburst medium by the GRB photons. The high iron abundance points to the existence of a burst environment enriched by a supernova along the line of sight. The supernova explosion is estimated to have occurred about 10 years before the burst. Our results agree with models in which GRBs originate from the collapse of very massive stars and are preceded by a supernova event.

2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2019

We report on the development and of a complete X/γ rays detection system (10-1000 keV) based on C... more We report on the development and of a complete X/γ rays detection system (10-1000 keV) based on CZT spectrometers with spatial resolution in three dimensions (3D) and a digital electronics acquisition chain. The prototype is made by packing four linear modules, each composed of one 3D CZT sensors. Each sensors is realized using a single spectroscopic graded CZT crystal of about 20×20×5 mm3. An electrode structure consisting of 12 collecting anodes with a pitch of 1.6 mm and 3 drift strips between each pair of anodes for 48 strips (0.15 mm wide) on the anodic side was adopted. The cathode is made of 10 strips with a pitch of 2 mm and orthogonal to anode side strips. Since the reading of the drift strips will carried out by putting in parallel all the strips that occupy the same place with respect to a collecting anode, the channels number for each sensors is only 25. The detector readout front-is based on custom designed low noise charge sensitive pre-amplifiers (CSP) implemented in ...

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that wil... more The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band.

Optics for EUV, X-Ray, and Gamma-Ray Astronomy IX

Journal of Synchrotron Radiation

In the last two decades, great efforts have been made in the development of 3D cadmium–zinc–tellu... more In the last two decades, great efforts have been made in the development of 3D cadmium–zinc–telluride (CZT) detectors operating at room temperature for gamma-ray spectroscopic imaging. This work presents the spectroscopic performance of new high-resolution CZT drift strip detectors, recently developed at IMEM-CNR of Parma (Italy) in collaboration with due2lab (Italy). The detectors (19.4 mm × 19.4 mm × 6 mm) are organized into collecting anode strips (pitch of 1.6 mm) and drift strips (pitch of 0.4 mm) which are negatively biased to optimize electron charge collection. The cathode is divided into strips orthogonal to the anode strips with a pitch of 2 mm. Dedicated pulse processing analysis was performed on a wide range of collected and induced charge pulse shapes using custom 32-channel digital readout electronics. Excellent room-temperature energy resolution (1.3% FWHM at 662 keV) was achieved using the detectors without any spectral corrections. Further improvements (0.8% FWHM at...

What can BeppoSAX do about the 2-10 keV cosmic background ? A progress report.

In the last decades, great efforts are being devoted to the development of CdTe detectors for hig... more 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 phenomena, typical of CdTe diode detectors, were investigated through electrical and spectroscopic approaches, pointing out the influence of the bias voltage, the temperature and the detector thickness. Good time stability, during a short-term operation of one hour, was observed for both detectors...

Filtration & Separation - FILTR SEP, 2004

We are working on the development of a balloon borne telescope based on multilayer optics for ene... more We are working on the development of a balloon borne telescope based on multilayer optics for energy from ∼10 keV up 80 keV. This hard X-ray telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. Currently the most appealing choice is offered by the development of CdTe/CZT detectors. Herein we present the characterization both in spectroscopic and spatial response of a small CZT detector (1 cm2) with 0.5 mm pixel size. The readout of the detector use an innovative low noise and low power dissipation ASICs developed within the collaboration. We present the results of tests with both collimated and non collimated radioactive sources using the RENA front-end electronics and a back-end electronics, that comprises a 64 independent channels system with coincidence logic.

Arxiv preprint astro-ph/ …, 1997

arXiv:astro-ph/9711295v1 25 Nov 1997 ... D. Dal Fiume1, M. Orlandini1, G. Cusumano2, S. Del Sordo... more arXiv:astro-ph/9711295v1 25 Nov 1997 ... D. Dal Fiume1, M. Orlandini1, G. Cusumano2, S. Del Sordo2, M. Feroci3, F. Frontera1,4, T. Oosterbroek5, E. Palazzi1, AN Parmar5, A. Santangelo2, and A. Segreto2 1 Istituto Tecnologie e Studio delle Radiazioni Extraterrestri (TeSRE ...

The Astrophysical …, 1998

... Boella, G., Butler, RC, Perola, GC, Piro, L., Scarsi, L., &amp; Blecker, J. 1997a, A&... more ... Boella, G., Butler, RC, Perola, GC, Piro, L., Scarsi, L., &amp; Blecker, J. 1997a, A&amp;AS, 122, 299 First citation in article | Abstract at Astrophysics Data System ... 263; Garching: MPE), 131 First citation in article | Abstract at Astrophysics Data System; Di Salvo, T. 1997, degree thesis, Univ. ...