FRONTIER DETECTORS FOR FRONTIER PHYSICS 24 30 May

FRONTIER DETECTORS FOR FRONTIER PHYSICS 24 -30 May 2009 An Innovative Approach to Compact Calorimetry in Space, NEUCAL S. Bottai, O. Adriani, L. Bonechi, M. Bongi, G. Castellini, R. D’Alessandro, P. Papini, S. Ricciarini, G. Sguazzoni, G. Sorichetti, P. Sona, P. Spillantini, E. Vannuccini. INFN (Florence) and University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy bottai@fi. infn. it Basic idea e -, g P calorimeter Electromagnetic shower q Electromagnetic/hadronic showers identification is a common requirement in High Energy Physics and in particular for space detectors devoted to Astroparticle Physics. 1 Te. V protons 400 Ge. V electrons hadronic shower neutrons Expected neutron yield neutrons q Space detectors make use of heavy and complex imaging calorimeters in order to achieve the necessary shower identification-rejection (ATIC, PAMELA, CALET…. ) q Different neutron yields are also expected from hadronic and electromagnetic showers. The use of an appropriate neutron detector can be used to rescale the calorimeter without loosing in identification power. Neutron detector CALET BGO CALORIMETER SIMULATED WITH FLUKA Neutrons are produced in both hadronic and electromagnetic showers (Giant. Resonance is responsible for neutron production in electromagnetic showers). The figures show the outgoing neutrons/event from showers produced by electrons and interacting protons ( with similar energy release in the calorimeter). A rejection factor for hadronic showers as high as 10 3 can be achieved considering the neutron counting alone. Neutron energy and timing 1 Te. V protons Peak of excited nucleus emission Direct neutrons emission in hadronic interactions plus moderation The bulk of neutrons comes from excitation and de-excitation of nucleus and exhibit a maximum in the M e V energy region. Many neutrons undergo moderation before escaping and their energy is consequently degraded down to the e. V energy region. Some neutrons can also be produced promptly in the hadronic Direct neutrons emission E<1 Me. V interactions along the shower core, with an energy that can reach that of the primary proton. The highest energy neutrons ( E>10 M e V ) arrive close in time with respect to the charged 60% component of the shower, while the low energy and more abundant component arrives in the neutron detector with a Arrival time of the charged particles delay of 10 -1000 ns and can be easily identified. The figure for Outgoing neutron energy Log (E(Ge. V)/1 Ge. V) electromagnetic showers is similar but with a reduced contribution in the prompt neutrons emission. Outgoing neutron energy Log (E(Ge. V)/1 Ge. V) . . NEUCAL : detection principle Neutron-proton elastic scattering in the plastic scintillators provide the active neutrons moderation. Scattered protons release their energy inside the scintillators and are detected. Scintillators layers (1 cm each) : an active moderator 3 He Tubes (1 cm diameter) : a neutrons counter Few ns resolution electronics to preserve the timing information NEUCAL : expected performance The energy released during the moderation process is detected by means of an active moderator composed of several plastic scintillator layers. Neutrons with energy in the Ke. V-Me. V region are detected with high efficiency. The moderated neutrons can be detected by means of nuclear capture followed by 0, 765 Me. V proton emission in the 3 He proportional counters. Thin layers of lead could enhance signals for very high energy neutrons Simulated response for a 12 scintillator layers detector. Neutrons with energy up to few Me. V are fully moderated and detected with high efficiency. At 10 Me. V 70% of neutrons gives detectable signals, while only 10% are fully moderated and detectable by the 3 He Tubes