The Payload for Antimatter-Matter Exploration and Light Nuclei Astrophysics (PAMELA), primarily designed to directly measure antiparticles (antiprotons; and positrons) in the cosmic radiation, was launched successfully on June 15(th), 2006, and, since then, it is in continuous data taking. The calorimeter of the PAMELA apparatus has been designed to identify antiprotons from an electron background and positrons from a background of protons with high efficiency and rejection power. It is a sampling silicon-tungsten imaging calorimeter, which comprises 44 single-sided silicon sensor planes (380 mu m thick) interleaved with 22 plates of tungsten absorber (0.74 X(0) each). It is the first silicon-tungsten calorimeter to be launched in space. In this work we present the in-orbit performance of the calorimeter, including the measured identification capabilities. The calorimeter provides a proton rejection factor of similar to 10(5) while keeping a high efficiency in selecting electrons and positrons, thus fulfilling the identification power needed to reach the primary scientific objectives of PAMELA. We show also that, after almost two years of operation in space, the calorimeter is still performing nominally.
Performance of the PAMELA Si-W imaging calorimeter in space / V Bonvicini;M Boezio;E Mocchiutti;A Vacchi;G Zampa;N Zampa;R Bellotti;A Bruno;F Cafagna;O Adriani;L Bonechi;M Bongi;S Bottai;D Fedele;P Papini;S Ricciarini;P Spillantini;E Taddei;E Vannuccini;G Castellini;M Ricci;G A Basilevskaja;A N Kvashnin;Y I Stozhkov;A M Galper;L Grishantseva;S V Koldashov;A Leonov;V V Mikhailov;S A Voronov;Y T Yurkin;V G Zverev;G Barbarino;G De Rosa;G Osteria;D Campana;M Casolino;M P De Pascale;V Malvezzi;L Marcelli;M Minori;P Picozza;R Sparvoli;E A Bogomolov;S Y Krutkov;G Vasilyev;W Menn;M Simon;P Carlson;P Hofverberg;S Orsi;M Pearce. - In: JOURNAL OF PHYSICS. CONFERENCE SERIES. - ISSN 1742-6596. - STAMPA. - 160:(2009), pp. 012039-1-012039-9. [10.1088/1742-6596/160/1/012039]
Performance of the PAMELA Si-W imaging calorimeter in space
ADRIANI, OSCAR;BONECHI, LORENZO;BONGI, MASSIMO;
2009
Abstract
The Payload for Antimatter-Matter Exploration and Light Nuclei Astrophysics (PAMELA), primarily designed to directly measure antiparticles (antiprotons; and positrons) in the cosmic radiation, was launched successfully on June 15(th), 2006, and, since then, it is in continuous data taking. The calorimeter of the PAMELA apparatus has been designed to identify antiprotons from an electron background and positrons from a background of protons with high efficiency and rejection power. It is a sampling silicon-tungsten imaging calorimeter, which comprises 44 single-sided silicon sensor planes (380 mu m thick) interleaved with 22 plates of tungsten absorber (0.74 X(0) each). It is the first silicon-tungsten calorimeter to be launched in space. In this work we present the in-orbit performance of the calorimeter, including the measured identification capabilities. The calorimeter provides a proton rejection factor of similar to 10(5) while keeping a high efficiency in selecting electrons and positrons, thus fulfilling the identification power needed to reach the primary scientific objectives of PAMELA. We show also that, after almost two years of operation in space, the calorimeter is still performing nominally.
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