Transcript Slide 1
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 [email protected] Basic idea e-, g P Expected neutron yield Electromagnetic/hadronic showers identification is a common requirement in High Energy Physics and in particular for space detectors devoted to Astroparticle Physics. 1 TeV protons calorimeter 400 GeV electrons Space detectors make use of heavy and complex imaging calorimeters in order to achieve the necessary shower identification-rejection (ATIC,PAMELA,CALET….) Electromagnetic shower hadronic shower neutrons neutrons 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 (GiantResonance 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 103 can be achieved considering the neutron counting alone. Neutron energy and timing Peak of excited nucleus emission 1 TeV protons 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 MeV energy region. Many neutrons undergo moderation before escaping and their energy is consequently degraded down to the eV energy region. Some neutrons can also be produced promptly in the hadronic interactions along the shower core, with an energy Direct neutrons emission E<1 MeV that can reach that of the primary proton. The highest energy neutrons ( E>10 MeV ) arrive close in time with respect to the 60% charged component of the shower, while the low energy and more abundant component arrives in the neutron detector with Arrival time of the charged particles a delay of 10-1000 ns and can be easily identified. The figure for Outgoing neutron energy Log (E(GeV)/1GeV) electromagnetic showers is similar but with a reduced contribution in the prompt neutrons emission. Outgoing neutron energy Log (E(GeV)/1GeV) . . 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 (1cm each) : an active moderator 3He 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 KeV-MeV region are detected with high efficiency. The moderated neutrons can be detected by means of nuclear capture followed by 0,765MeV proton emission in the 3He 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 MeV are fully moderated and detected with high efficiency. At 10 MeV 70% of neutrons gives detectable signals, while only 10% are fully moderated and detectable by the 3He Tubes