Publications (9)0 Total impact
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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: Expected performance of the GAW Cherenkov Telescopes Array. Simulation and Analysis
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ABSTRACT: GAW 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 using Fresnel lens, stereoscopic observational approach, and single photon counting mode. GAW is an array of three telescopes that will be erected at the Calar Alto Observatory site (Spain, 2150 m a.s.l.). To evaluate the performance of GAW, a consistent data--set has been simulated, including a Crab-like source observation, and a proper image analysis code has been developed, as described in this contribution. The expected performance of GAW are also reported, mainly for what concerns effective area, angular resolution, Cherenkov flux as function of the core distance, ability in the gamma/proton separation, and sensitivity. The first telescope realization, foreseen within the end of this year, will allow to verify if the parameters used in the analysis are in agreement with the "real" performance of the GAW apparatus.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: 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; -
Article: EUSO Operations: Flight and Ground
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ABSTRACT: The EUSO operations concept is described. Both the on-board and onground systems play an important role on operations. Since no permanent contact with the payload is provided, a considerable autonomy of the on-board system is required. The fulfilment of the scientific goals of the mission and the safety of the instrument require the definition of different operational modes and procedures. On-board, scientific and housekeeping data are collected and sent to ground, and control of the instrument subsystems is performed, based on on-board autonomous procedures and on telecommands sent from ground. On ground, telemetry is received, processed, monitored and archived. Telecommands are prepared for uplink, according to a defined mission activity planning.06/2003; 2:1085. -
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: 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. -
Article: The ULTRA experiment : a supporting activity for the Euso project
