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AGILE on-board BKG rejection

AGILE on-board BKG rejection. GLAST Italian meeting Francesco Longo & Carlotta Pittori Udine 11 marzo 2004 V. Cocco, A.Giuliani, P.Lipari, A. Pellizzoni, M.Prest, M.Tavani. E.Vallazza. DETECTOR DESCRIPTION. Top Anticoincidence Lateral Anticoincidences SuperAGILE Silicon Tracker

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AGILE on-board BKG rejection

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  1. AGILE on-board BKG rejection GLAST Italian meeting Francesco Longo & Carlotta Pittori Udine 11 marzo 2004 V. Cocco, A.Giuliani, P.Lipari, A. Pellizzoni, M.Prest, M.Tavani. E.Vallazza

  2. DETECTOR DESCRIPTION • Top Anticoincidence • Lateral Anticoincidences • SuperAGILE • Silicon Tracker • Mini-Calorimeter • Mechanical structure (not shown in the figure) 54 cm 15 cm 22 cm 5 cm 40 cm

  3. Expected particle/albedo-photon background for an Equatorial Orbit • Particle flux from SAS-2 and BeppoSAX data (~0.3 cm-2 s-1 for Ekin 1 MeV) • 3 main components:e+,e-, p • Spectral data from AMS and Marya • Assumptions: 1) isotropic distribution for e+,e-, and low energy protons 2) sky-incidence for high energy p (Ekin 7 GeV) • Albedo photons from the Earth (from SAS-2 data) [Thompson et al. 1981] Longo, Cocco & Tavani (2002)

  4. Albedo Photons [Thompson et al. 1981]

  5. Event Generation AGILE Payload • Particle/Albedo-photon Background • Astrophysical point sources • Particle/photon tracks originating on a spherical surface • Montecarlo methods for the generation of the distribution functions Longo, Cocco & Tavani (2002) AGILE Satellite

  6. Trigger Levels Level-1 Level-2 • Hardware Implementation • Information from Silicon Tracker and AC panels • Track topology at the ‘chip’ level • Software Implementation • Analog Information on the released charge in the Si-microstrips • Track topology at the ‘cluster’ level • 3D-reconstruction to reject albedo photons

  7. L1 - TRIGGER R trigger concept

  8. L1- TRIGGER

  9. Charge deposition Optimal spatial resolution: ~40 m for a broad range of incidence angles (0-50) 50 MeV gamma-ray,  ~50

  10. Monte Carlo Simulations: Simulated background proton event: Simulated Gamma-Ray (E=100 MeV, =30º) It can be rejected by the on-board trigger because of the crucial use of the analog signal from the Si-microstrips providing information on cluster charges.  direction from 3-D AGILE REconstruction Method (AREM)integrated with Kalman filter algorithms(Pittori-Tavani NIM 2002)

  11. On-board GRID Background Rejection: • Particle background rates : • e+/e-: reduced by a • factor ~ 100 • Protons: reduced by a • factor ~ 1000 • Earth albedo -ray flux : • reduced by a factor ~ 30 The GRID on-board background rejection is quite efficient, reducing the total charged-particle rate from ~ 2000 Hz to ~ 20 Hz. Cocco, Longo & Tavani (2002)

  12. SUMMARY OF ON-BOARD BACKGROUND REJECTION • Expected total rate of particle/albedo-photon entering into the Tracker volume 2-3 KHz • Level-1Trigger cut100 Hz • Level-2 processing cut20-30 Hz On-board Background Rejection :~10-2

  13. Effective Area Science with AGILE (2003)

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