Evaluation of the Spectroscopic Performance of 3D CZT Drift Strip Detectors

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…

HERMIA - GENERAL DESCRIPTION

Charge loss correction in CZT pixel detectors at low and high fluxes: analysis of positive and negative pulses

Charge losses are typical drawbacks in cadmium–zinc–telluride (CZT) pixel detectors. The effects of these phenomena are strongly related to the interaction point of the photons and are more severe for photon interactions at the inter-pixel gap and near the pixelated anode. In this work, we present some original techniques able to correct charge losses in pixelated CZT detectors at both low and high fluxes. The height, the shape and the arrival time of collected- and induced-charge pulses with both positive and negative polarities are analysed to recover charge losses after the application of charge sharing addition (CSA). Sub-millimetre CZT pixel detectors, fabricated by different manufactu…

Transmediterranean flights, in the edge of two centuries

Abstract Transmediterranean flights take place at 40 km altitude and approximately 38°N latitude. Sixty six successful trans-mediterranean crossings have been performed in the period 1977–2002. A summary of system requirements, that would assure state-of-the-art stratospheric balloon flights is presented. Details of the 2002 campaign, along with a historical review of the flights corresponding to the Nineties, 2000 and 2001, are presented.

Portable CdTe detection system for mammographic X-ray spectroscopy

This paper describes a portable apparatus to be utilized in mammographic X-ray spectroscopy under clinical conditions. The system, based on a CdTe solid-state detector, is able to directly measure mammographic X-ray tube spectra. Good system response to monoenergetic photons was measured using X-ray and γ-ray calibration sources (109Cd and 241Am). The measured molybdenum X-ray spectra, in agreement with simulated spectra, show the good spectral capability of the system also at high photon fluence rates, as typical of clinical mammography. Low tailing, no secondary X-ray escape and low pile-up distortions in the measured spectra indicate that this portable system is suitable for mammographic…

DAISY: a distributed architecture for intelligent SYstem

Distributed perceptual systems are endowed with different kind of sensors, from which information flows to suitable modules to perform useful elaborations for decisions making. In this paper a new distributed architecture, named 'Distributed Architecture for Intelligent SYstem' (DAISY), is proposed. It is based on the concept of co-operating behavioral agents supervised by a 'Central Engagement Module'. This module integrates the processing of data coming from the behavioral agents with a symbolic level of representation, by the introduction of a 'conceptual space' intermediate analogue representation. The DAISY project is under development; experiments on navigation and exploration for an …

Steady shocks around black holes produced by sub-keplerian flows with negative energy

We discuss a special case of formation of axisymmetric shocks in the accretion flow of ideal gas onto a Schwarzschild black hole: when the total energy of the flow is negative. The result of our analysis enlarges the parameter space for which these steady shocks are exhibited in the accretion of gas rotating around relativistic stellar objects. Since keplerian disks have negative total energy, we guess that, in this energy range, the production of the shock phenomenon might be easier than in the case of positive energy. So our outcome reinforces the view that sub-keplerian flows of matter may significantly affect the physics of the high energy radiation emission from black hole candidates. …

High-Resolution 3-D CZT Drift Strip Detectors for Prompt Gamma Ray and Neutron Detection in BNCT

Spectroscopic imagers based on high-Z and wide-bandgap compound semiconductor detectors are widely proposed for the detection of prompt gamma rays in boron neutron capture therapy (BNCT). BNCT is a therapy based on the neutron capture reaction 10B (n,α)7Li. To perform a real-time monitoring of the spatial distribution of 10B during the treatments, the detection of the prompt gamma rays (478 keV), produced by the 7Li recoil nuclei, can be helpful. In this work, we presented the potentialities of new high-resolution CZT drift strip detectors, recently developed by our group, for BNCT measurements. The detectors, exploiting the analysis of the collected-induced charge pulses from anodes, catho…