Publications (23)4.24 Total impact
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Article: UVSiPM: a light detector instrument based on a SiPM sensor working in single photon counting
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ABSTRACT: UVSiPM is a light detector designed to measure the intensity of electromagnetic radiation in the 320-900 nm wavelength range. It has been developed in the framework of the ASTRI project whose main goal is the design and construction of an end-to-end Small Size class Telescope prototype for the Cherenkov Telescope Array. The UVSiPM instrument is composed by a multipixel Silicon Photo-Multiplier detector unit coupled to an electronic chain working in single photon counting mode with 10 nanosecond double pulse resolution, and by a disk emulator interface card for computer connection. The detector unit of UVSiPM is of the same kind as the ones forming the camera at the focal plane of the ASTRI prototype. Eventually, the UVSiPM instrument can be equipped with a collimator to regulate its angular aperture. UVSiPM, with its peculiar characteristics, will permit to perform several measurements both in lab and on field, allowing the absolute calibration of the ASTRI prototype.05/2013; -
Article: The ASTRI Project: a mini-array of dual-mirror small Cherenkov telescopes for CTA
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ABSTRACT: ASTRI is a flagship project of the Italian Ministry of Education, University and Research, which aims to develop an end-to-end prototype of the CTA small-size telescope. The proposed design is characterized by a dual-mirror Schwarzschild-Couder configuration and a camera based on Silicon photo-multipliers, two challenging but innovative technological solutions which will be adopted for the first time on a Cherenkov telescope. Here we describe the current status of the project, the expected performance and the possibility to realize a mini-array composed by a few small-size telescopes, which shall be placed at the final CTA Southern Site.04/2013; -
Conference Proceeding: Investigation on pixellated CZT detectors coupled with a low power readout ASIC
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ABSTRACT: 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 mm<sup>3</sup> and 10 x 10 x 2 mm<sup>3</sup> 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 detector; 5.5 % FWHM at 59.5 keV for the 2 mm thick detector) and low tailing, confirming the single charge carrier sensing properties of the CZT detectors equipped with a pixellated anode layout. Temperature measurements show optimum performances of the system (detector and electronics) at T = 10 °C and performance degradations at lower temperatures. The detectors and the ASIC, designed by our collaboration, represent two small focal plane detector prototypes for hard X-ray telescopes operating in the 10–100 keV energy range.Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE; 11/2008 -
Article: Science with the new generation high energy gamma- ray experiments
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ABSTRACT: This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large Spatial Dimensions and Tests of Lorentz Invariance.01/2008; -
Article: GAW - An Imaging Atmospheric Cherenkov Telescope with Large Field of View
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ABSTRACT: GAW, acronym for Gamma Air Watch, is a Research and Development experiment in the TeV range, whose main goal is to explore the feasibility of large field of view Imaging Atmospheric Cherenkov Telescopes. GAW is an array of three relatively small telescopes (2.13 m diameter) which differs from the existing and presently planned projects in two main features: the adoption of a refractive optics system as light collector and the use of single photoelectron counting as detector working mode. The optics system allows to achieve a large field of view (24x24 squared degrees) suitable for surveys of large sky regions. The single photoelectron counting mode in comparison with the charge integration mode improves the sensitivity by permitting also the reconstruction of events with a small number of collected Cherenkov photons. GAW, which is a collaboration effort of Research Institutes in Italy, Portugal and Spain, will be erected in the Calar Alto Observatory (Sierra de Los Filabres - Andalucia, Spain), at 2150 m a.s.l.). The first telescope will be settled within Autumn 2007. This paper shows the main characteristics of the experiment and its expected performance.08/2007; -
Article: Gamma Air Watch (GAW): the electronics and trigger concept
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ABSTRACT: GAW proposes a new approach for the detection and measurement of the Cherenkov light produced by GeV/TeV gamma rays traversing the Earth atmosphere which imposes specific requirements on the electronics design. The focal surface of the GAW telescope consists of a matrix of multi-anode photomultipliers. The large number of active channels (of the order of 10^5) makes it basically a large UV sensitive digital camera with high resolution imaging capability. The limited amount of space available, due to the large number of channels, requires a compact design with minimal distance between the elements of the focal surface. The front-end electronics uses the single photoelectron counting technique to capture the Cherenkov light. The data acquisition is based on free-running data taking method. Self-triggering capability for each telescope is assured by detecting an excess of active pixels, in a 10ns time frame, inside overlapping trigger areas covering the whole focal surface. In this paper we describe the GAW electronics, as well as the trigger concept and implementation.08/2007; -
Article: Detection of the Cherenkov light diffused by Sea Water with the ULTRA Experiment
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ABSTRACT: The study of Ultra High Energy Cosmic Rays represents one of the most challenging topic in the Cosmic Rays and in the Astroparticle Physics fields. The interaction of primary particles with atmospheric nuclei produces a huge Extensive Air Shower together with isotropic emission of UV fluorescence light and highly directional Cherenkov photons, that are reflected/diffused isotropically by the impact on the Earth's surface or on high optical depth clouds. For space-based observations, detecting the reflected Cherenkov signal in a delayed coincidence with the fluorescence light improves the accuracy of the shower reconstruction in space and in particular the measurement of the shower maximum, giving a strong signature for discriminating hadrons and neutrinos, and helping to estimate the primary chemical composition. Since the Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission and Reflection in the Atmosphere)experiment has been designed to provide the diffusing properties of sea water, overcoming the lack of information in this specific field. A small EAS array, made up of 5 particle detectors, and an UV optical device, have been coupled to detect in coincidence both electromagnetic and UV components. The detector was in operation from May to December, 2005, in a small private harbor in Capo Granitola (Italy); the results of these measurements in terms of diffusion coefficient and threshold energy are presented here.08/2007; -
Article: Characteristics and Performance of the GAW Experiment for a Large Field of View Cerenkov Gamma-ray Telescope
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ABSTRACT: One of the intents of the ground-based gamma-ray astronomy is to obtain a sky survey in the TeV energy region, and nowadays this target can be reached with giant arrays of telescopes, which however need many pointings due to their small field of view. A different approach is on the basis of GAW, acronym for Gamma Air Watch, an array of three relatively small Cerenkov telescopes which differentiate from the existing and presently planned telescopes for two main features: the adoption of a refractive optics system as light collector with a large field of view capability, and the use of single photoelectron counting as detector working mode. During a first phase, the focal plane detector of the GAW telescopes will be implemented in a reduced configuration to test the sensitivity and to prove the feasibility of the method; then the focal plane will be enlarged to cover a field of view of 24°×24°; pointing along different North-South directions, GAW would reach a survey of 360°×60° region of the sky. In this paper, the GAW expected performance are reported as evaluated in the case of the Calar Alto site, Spain, 2150 m a.s.l., where GAW is planned to be located within 2007. GAW is a collaboration effort of Research Institutes in Italy, Portugal and Spain.Chinese Journal of Astronomy and Astrophysics 01/2007; 6(S1):369. · 0.89 Impact Factor -
Article: Characterization of a CZT focal plane small prototype for hard X-ray telescope
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ABSTRACT: 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 mm<sup>3</sup> and 10times10times2 mm<sup>3</sup> single crystals) with 0.45 mm pixel size. We present the results obtained using both standard commercial read-out electronics Readout Electronics for Nuclear Applications (RENA) and innovative low noise and low power dissipation ASICs developed within the collaborationIEEE Transactions on Nuclear Science 01/2006; · 1.45 Impact Factor -
Article: GAW, Gamma Air Watch - A Large Field of View Imaging Atmospheric Cherenkov
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ABSTRACT: GAW, acronym for Gamma Air Watch, is a path-finder experiment to test the feasibility of a new generation of imaging atmospheric Cherenkov telescopes that join high flux sensitivity with large field of view capability. GAW is conceived as an array of three identical imaging telescopes disposed at the vertexes of an equilateral triangle, about 80 m side. Two main features characterize GAW with respect to all the existing and presently planned ground-based Cherenkov telescopes. The first difference concerns the optics system: GAW uses a Fresnel refractive lens (2.13 m diameter) as light collector instead of classical reflective mirror. The second main difference is the detection working mode used: the detector at the focal surface operates in single photoelectron counting mode instead of the usual charge integration one. The GAW array is planned to be located at the Calar Alto Observatory site, Spain, 2150 m a.s.l. During its first phase, only 6x6 degrees of the focal plane detector will be implemented; moving it along the field of view, the sensitivity of the telescopes will be tested observing the Crab Nebula with on-axis and off-axis pointing up to 20 deg and with energy threshold of 300 GeV and energy peak of 700 GeV. As path-finder, GAW will also monitor the Very High Energy activity of some flaring Blazars as well as will follow-up GLAST detections at high energies. In a second phase, the focal plane will be enlarged to cover a field of view of 24 deg (full); pointing along different North-South directions, GAW would reach a survey of 360x60 degrees region of the sky. GAW is a collaboration effort of Research Institutes in Italy, Portugal and Spain.10/2005; -
Conference Proceeding: Characterization of a CdTe microstrip detector as a hard X ray focal plane prototype
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ABSTRACT: Our collaboration is developing a hard X-ray telescope operating in the 10-100 keV energy range and based on focusing multi-layers coupled to a CdTe/CZT focal plane detector. Two classes of detectors can comply with the focal plane requirements: pixel detectors, where an electrode is segmented as a bi-dimensional array and micro-strip detectors. In the last ones each of the opposite crystal surfaces contains a set of orthogonal micro-strips. This geometry reduces noticeably the number of readout independent channels even if it requires the coincidence among at least two opposite strips to determine the position. In the current work we present the characterization of the spectroscopic and spatial response of CdTe prototype (1 cm<sup>2</sup>) equipped with two orthogonal micro-strip electrodes with 0.5 mm pitch and mounted on an alumina substrate using both collimated and un-collimated radioactive sources. The 16 anode strips use, as front-end analogical electronics, an innovative low noise and low power dissipation (<1 mW/ch) ASIC, whereas the cathode strips pulses are readout by 16 charge sensitive preamplifiers. The handling and acquisition electronics implements a gamma camera logic, where the equivalent of 256 channels are acquired and converted via 4 ADC and afterwards sent to a 32 bit parallel interface. This system calculates a weighted average of the signals from the irradiated strips to determine the mean position and the energy of the interaction. The comparison between these results and those obtained with an equivalent pixel detector should allow to decide the definitive design of the hard X ray focal plane detectorNuclear Science Symposium Conference Record, 2004 IEEE; 11/2004 -
Conference Proceeding: Characterisation of a CZT focal plane small prototype for hard X-ray telescope
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ABSTRACT: 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 cm<sup>2</sup>) 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.Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004 -
Article: Spectroscopic performances of 16 × 16 pixel CZT imaging hard--X-ray detectors
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ABSTRACT: Cadmium zinc telluride (CZT) pixel detectors show very good spectral and spatial resolution and are suitable for use in compact hard-X-ray sensors operated without cryogenics. One of the most appealing astrophysical applications is their use as focal-plane detectors for multilayer hard-X-ray telescopes operating in the (10-80) keV energy band. This paper reports experimental results obtained from two 16×16 pixellated CZT detectors ( 10×10×1 mm3 and 10×10×2 mm3 single crystals) with 450 μm pixel operated at room temperature using standard commercial read-out electronics. We have investigated about energy resolution and material properties of both detectors. Both arrays gave similar results showing an energy resolution less than 5% at 59.5 keV and a good material uniformity. The good energy resolution of both detectors demonstrates as the pixellated anode structure reduces (small pixel effect) the incomplete charge collection due to severe hole trapping typically present in CZT crystals. A calibration curve, obtained using three different energies, shows a linear response of the detectors.Il Nuovo Cimento B 02/2004; 119:257. -
Article: Measurements of the UV Nocturnal Atmospheric Background in the 300-400 nm Wavelength Band with the Experiment BaBy during a Transmediterranean Balloon Flight
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ABSTRACT: We present new results of U V no cturnal atmospheric background measured with the balloon borne experiment BaBy that performed a trans-Mediterranean flight on July 11 2002. The experiment looked downwards from about 40 km of altitude the dark no cturnal atmosphere over the sea in a moonless night. It is composed of 8 filtered and collimated fast PMTs detecting the U V light in the 300-400 nm wavelength band and in the 3 narrow bands centered at the emission lines of the atmospheric Nitrogen molecules. Both single photon counting and charge integration methods are used in pairs of PMTs with the same filter. The background measured over the sea is about 300 photons m-2 sr-1 ns-1 in the 300-400 nm wavelength band. Introduction The Backround Bypass, BaBy, experiment is a scientific support activity to the evaluation of the sensitivity of EUSO [3], devoted to the observation of the Extreme Energy Cosmic Rays from space by detecting U V fluorescence light. One of the fundamental information in EUSO design is the U V no cturnal atmospheric background level whose main sources are: light pollution from cities, planes and ships, naturally occurring bioluminescence, lightning flashes, reflected moonlight and starlight, auroral flashes, low energy cosmic ray air showers and atmospheric chemical reactions. Since 1998, no cturnal atmospheric U V background measurements, in the wavelength interval (300-400 nm) relevant for EUSO, have been performed by06/2003; 2:849. -
Article: GAW (Gamma Air Watch): a novel imaging Cherenkov telescope
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ABSTRACT: GAW (Gamma Air Watch) is a new imaging Cherenkov telescope designed for observation of very high-energy gamma-ray sources. GAW will be equipped with a 3 meter diameter Fresnel lens as light collector and with an array of 300 multi-anode photomultipliers at the focal plane. The pixel size will be 4 arcmin wide for a total field of view of 10.5 degrees. Whith respect to the planned imaging Cherenkov telescopes (CANGAROO III, HESS, MAGIC, VERITAS) GAW follows a different approach for what concerns both the optical system and the detection working mode: the Cherenkov light collector is a single acrylic flat Fresnel lens (instead of mirrors) that allows to achieve wide field of view; the photomultipliers operate in single photoelectron counting mode (instead of charge integration). The single photoelectron counting mode allows to reach a low energy threshold of ~200 GeV, in spite of the relatively small dimension of the GAW optic system.11/2001; -
Article: GAW: Gamma Air Watch
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ABSTRACT: The Cherenkov imaging technique is the most effective tool to detect and observe gamma-ray cosmic emission above 100 GeV. We propose an imaging Cherenkov telescope, GAW (Gamma Air Watch), designed for observations of very high-energy gamma-ray sources. GAW will be equipped with a 3 meter Fresnel lens light collector and an f/# ˜1.9, and with an array of about 300 multi-anode photomultipliers at the focal plane. The pixel size will be ˜2 arcmin wide, for a total field of view of ˜5.2°. GAW respect to the next planned imaging Cherenkov telescopes (CANGAROO III, HESS, MAGIC, VERITAS) follows a different technique approach being different for what concerns both the optical system and the smaller pixel size. Thanks to the smaller pixel size, the photomultipliers will operate in single photoelectron count mode (instead of charge integration) lowering the photoelectron threshold needed for the cosmic-ray background rejection technique: this consequently allows a low energy threshold in spite of the relatively small dimension of the GAW optics system.07/2001; 7:2824. -
Article: FIGARO IV: Large-area balloon-borne telescope to study rapid time variabilities in the gamma-ray sources at energies above 50 MeV
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ABSTRACT: We present a new γ-ray telescope based on the Limited Streamer Tube technology, used as tracking chambers to detect photons above 100 MeV. This technique allows to obtain very large sensitive areas (16 m2 in our experiment), together with a good angular resolution for payloads embarcable in high-altitude balloon flights. The capability to collect a large signal in a short exposure time makes the telescope particularly suitable and competitive with respect to satellite-based detectors for studying both periodic and random time variabilities on galactic and extragalactic γ-ray sources.Nuovo Cimento- Societa Italiana di Fisica Sezione C 10/1993; 16(6):715-720. · 0.35 Impact Factor -
Article: Figaro IV: 16 square meter balloon borne telescope to study rapid variabilities and transient phenomena at energies above 50 MeV
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ABSTRACT: We present the design of a balloon borne experiment based on the Limited Streamer Tube technology as a tracking telescope to detect gamma rays above 50 MeV. This technique allows one to obtain very large sensitive areas (16 m2 in our experiment). Because of the capability to collect a large signal in a short time and of its good angular resolution (about 2° above 200 MeV), the telescope is highly competitive to study both periodic and random rapid variabilities of gamma‐ray sources as well as to detect high energy gamma‐ray bursts.AIP Conference Proceedings. 07/1993; 280(1):1161-1165. -
Article: The high-pressure gas scintillation propertional counter on board the Italian X-ray astronomy satellite SAX
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ABSTRACT: A description of one of the experiments on board the Italian X-ray Astronomy Satellite SAX is presented. The principle of operation and the technological problems are discussed in some detail. Uno degli esperimenti a bordo del satellite italiano per Astronomia in raggi X è descritto. Vengono dati alcuni dettagli sul principio di funzionamento e sui problemi tecnologici affrontati. В статье описывается один из экспериментов на борту итальянского спутника SAX, предназначенного для рентгеновской астрономии. Подробно обсуждаются принципы действия и технологические проблемы.Nuovo Cimento- Societa Italiana di Fisica Sezione C 02/1990; 13(2):421-429. · 0.35 Impact Factor -
Article: Results from the ULTRA experiment in the framework of the EUSO project
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ABSTRACT: The detection of Cerenkov light from EAS in a delayed coincidence with fluorescence light gives a strong signature to discriminate protons and neutrinos in cosmic rays. For this purpose, the ULTRA experiment has been designed with 2 detectors: a small EAS array (ETscope) and an UV optical device including wide field (Belenos) and narrow field (UVscope) Cerenkov light detectors. The array measures the shower size and the arrival direction of the incoming EAS, while the UV devices, pointing both to zenith and nadir, are used to determine the amount of direct and diffused coincident Cerenkov light. This information, provided for different diffusing surfaces, will be used to verify the possibility of detecting from Space the Cerenkov light produced by UHECRs with the EUSO experiment, on board the ISS.
Top co-authors
Top Journals
Institutions
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2007
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INAF-Istituto Nazionale di Astrofisica
- Institute of Space Astrophysics and Cosmic Physics IASF - Rome
Roma, Latium, Italy
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2001
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National Research Council
Roma, Latium, Italy
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