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Rate of Protons and Antiprotons Nicolo’ Masi, Andrea Tiseni TOF Group Bologna

Analyzing rates of protons and antiprotons using various methods for dark matter searches, including selection criteria and unfolding procedures.

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Rate of Protons and Antiprotons Nicolo’ Masi, Andrea Tiseni TOF Group Bologna

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  1. Rate of Protons and Antiprotons Nicolo’ Masi, Andrea TiseniTOF Group Bologna N. Masi, A. Tiseni, Rate of Protons and Antiprotons Apr 2012

  2. Summary Dark Matter Antiproton Searches: • Selection of Protons and Antiprotons and live time • Rate of Protons and Antiprotons with TRD+ECAL+FULL TRACKER • Rate of Protons and Antiprotons with TRD+FULL TRACKER • AntiProton to Proton Ratio Steps: • MonteCarlo Efficiencies studies • Fluxes Analysis and acceptance • Unfolding procedure • Goals: We’re reconstructing the Protons and Antiprotons spectra, using different methods (TRD+ECAL+full tracker, TRD + full tracker). By now, we have analyzed the rates for all B550 pass 2 AMS Data = 15000 rootfiles

  3. Selection of Proton and Electrons: Selection of protons and Electrons with a program developed by ECAL and TRD group with the contribution of TOF and Tracker people. Preselection: Downgoing particle with: 0.6< β < 1.2 South Atlantic and Pole Exclusion Z=1 ± 0.3 TOF, TRD, Tracker, ECAL common cuts (only in TRD+ECAL+full tracker method) N. Masi, A. Tiseni, Rate of Protons and Antiprotons Apr 2012

  4. Proton and Electron Selection Antiproton: Likelihood Electron/Proton > 0.8 Likelihood Helium/Electron > 1.9 EBDT < -0.8 Cut on the ratio Energy Reconstructed over Rigidity: EnergyE/Rigidity < 0.1 Momentum < 0 Proton: Likelihood Electron/Proton > 0.8 Likelihood Helium/Proton > 1.9 EBDT < -0.8 Cut on the ratio Energy Reconstructed over Rigidity: EnergyE/Rigidity < 0.1 Momentum > 0 N.B: EBDT is used only in TRD+ECAL+Full Tracker METHOD N. Masi, A. Tiseni, Rate of Protons and Antiprotons Apr 2012

  5. Livetime

  6. Proton Rate (TRD+ECAL+Full Tracker Method) Protons/(sec*GeV)

  7. Proton Rate (TRD+Full Tracker Method) Protons/(sec*GeV)

  8. AntiProton Rate (TRD+Full Tracker Method) AntiProtons/(sec*GeV)

  9. AntiProton Rate (TRD+ECAL+Full Tracker Method) AntiProtons/(sec*GeV)

  10. AntiProton Fraction No operative Likelihood & spillover Correct PAMELA Ratio

  11. MC Preliminary Efficiency From few antiprotons rootfiles B550 v5 in the low energy range (T < 10 GeV) : total events analyzed: 233296 clean events: 7221 (3.1% of total) Clean Events = Minimum BIAS = Trigger && TrkRigAsim Cut && Beta && Track matches SAA: 233296 No effect on MC trd golden: 5291 (2.3% of total, 73% of clean events) ecal golden: 5737 (2.5% of total, 79% of clean events) golden di cuts: 4218 (1.8% of total, 58% of clean events) total: p 2 total: antip 4162 (1.8% of total, 58% of clean events) TRD & ECAL selectors (Likelihood and EBDT) : zero statistics

  12. Fluxes Data: No Brand News in these 90 days of 2012 From PAMELA and FERMI Electron + positron electron

  13. Fluxes Data: No Brand News in these 90 days of 2012 Positronfraction

  14. Fluxes Data: No Brand News in these 90 days of 2012 proton helium

  15. Fluxes Data: No Brand News in these 90 days of 2012 Antiproton/proton Antiproton

  16. Fluxes Analysis Without acceptance factor : 0.03 , 0.04 for TRD+Full Tracker and TRD+ECAL+Full Tracker Without ECAL, without acceptance factor

  17. Number of particlemeasured by AMS with a 10^-2 acceptance& efficiencyfactorin 1 year 10000 100 10^-2 ÷ 1 10 1 100 Higherthanantiprotonsone 10 positrons 10

  18. Unfolding FlatMultidimennsionalStepFunction Plus ExponentialSmoothing Multinomial or PoissonianFunctions

  19. Ifwedefine the efficiency: we can compute the truespectrum with the unfolded data for each bin: Data Posterior/Inverse probabilitycalculated with previousBayesTheorem Smearing/migrationeffect

  20. Conclusions • Background Studies: • contamination of electrons for antiproton signal, especially for the HE range (T > 100 GeV); • eventual contamination of positrons in proton signal at High Energy; • contamination of protons and positrons in antiproton signal for all energies. • Unfolding software to produce the true spectra

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