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Enhanced Algorithms for Particle Detection: Stability and Efficiency Improvements

This paper details advancements in algorithms for particle detection, focusing on improvements in angular resolution and background rejection. Key modifications include decoupling XY information, refining step cuts on Dbmax, and introducing new LOOSE and TIGHT algorithms for enhanced efficiency at high energies. The efficiency for photons has significantly improved, particularly with respect to proton rates during varying solar activity. Robustness against PMT failures is exemplified, maintaining effective rates and gains. Insights into background electron fluxes and the operational stability of the detection system are also discussed.

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Enhanced Algorithms for Particle Detection: Stability and Efficiency Improvements

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  1. PART Isimulation S. Di Falco, M. Incagli, F. Pilo, F. Spinella, G. Venanzoni

  2. Algorithms evolution… • The algorithm has been improved in these points: • XY informations decoupled; old: Dbmax(NhitX6+NhitY7). Not nice for hardware implementation. • angular resolution: all the combination treated with the same importance but the worst Db was never the one obtained from the farest superlayers (e.g. Db37=|b3-b7|/2) that has the best angular resolution. • step cut on Dbmax: really needed 3 steps? • ‘MIX’ logic:it was requesting at least 2/3 superlayer with at least 1 PMT above threshold for both Y and X view, but, to optimize background rejection, one of them had to beY3 (or X4): • More critic for PMT failures in that planes • Efficiency not 100% also at very high energies

  3. New algorithms: LOOSE and TIGHT • A more ‘LOOSE’ algorithm was studied to get more high and stable efficiencies: • pure 2/3 logic(no specific requests on superlayers Y3 and X4) • new thresholds: • new angular cut: • - angular resolution: • DbX= Db26 if applicable DbY= Db37 if applicable • max(Db24 ,Db46) otherwise max(Db35 ,Db57) otherwise • - 2 steps cut and XY decoupling : • DbX< 1.15 (NhitX4+NhitX6) < 5 DbY < 1.15 (NhitY5+NhitY7) < 6 • 2.15 otherwise 2.15 otherwise • The ‘MIX’ logic can still be useful, we called ‘TIGHT’ algorithm the old ‘MIX’ algorithm with the new angular cut.

  4. Efficiency for photons (table) TIGHT Proton Rate: 50 Hz (170 Hz) LOOSE Proton Rate: 70 Hz (250 Hz) FAST TRIGGER FAST TRIGGER

  5. Efficiency for photons (graph)

  6. Acceptance for protons (LOOSE) LOOSE

  7. Acceptance for protons (TIGHT) TIGHT

  8. Rate for protons (LOOSE) Using the downward proton flux measured by AMS01 Fast trigger Rate: 250 Hz LEV 1 Trigger Rate: 70 Hz (83% below 20 GeV)

  9. Rate for protons (TIGHT) Using the downward proton flux measured by AMS01 Fast trigger Rate: 170 Hz LEV 1 Trigger Rate: 50 Hz (80% below 20 GeV)

  10. AMS paper binning: acceptance for protons (LOOSE) LOOSE

  11. Effect of increased solar activity LOOSE 90 Hz 70 Hz

  12. Rate(q) and Rate(f) (LOOSE)

  13. Background rate from electrons Fluxes determination from AMS01: rough interpolation from bilog scale!! Polar downward electrons LOOSE (TIGHT) Fast trigger: 8 Hz (6 Hz) LEV 1: 3.5 Hz (3 Hz) Equatorial upward electrons (and the same for positrons) LOOSE (TIGHT) Fast trigger: 1.1 Hz (0.5 Hz) LEV 1: 0.8 Hz (0.3 Hz)

  14. Backsplash recovery

  15. Robustness and stability studies • Dead PMTs • Dead HV channels: gain  gain 10 • Global gain variation: ±30 % • Dynode energy resolution

  16. g efficiency with 10 PMTs dead (LOOSE) No problems for the rate: Worst fast trigger Rate: 245 Hz (instead of 250 Hz) Worst LEV 1 Trigger Rate: 67 Hz (instead of 70 Hz) 10 bad PMTs 0 º< q <20º

  17. g efficiency with 10 PMTs dead (TIGHT) Worst fast trigger Rate: 140 Hz (instead of 150 Hz) LEV 1 Trigger Rate: 40 Hz (instead of 50 Hz) 10 bad PMTs 0 º< q <20º

  18. eg with 10 PMTs dead: LOOSE vs TIGHT 0 º< q <20º

  19. g efficiency with 5 PMT dead (LOOSE) 5 bad PMTs 0 º< q <20º

  20. g efficiency with 1 PMT dead (LOOSE) 1 bad PMT 0 º< q <20º

  21. eg with PMT gains10 ( LOOSE) Proton rate remains practically unchanged 10 bad PMTs 0 º< q <20º

  22. eg with PMT gains10 ( LOOSE) 5 bad PMTs 0 º< q <20º

  23. eg with PMT gains10 ( LOOSE) 1 bad PMT 0 º< q <20º

  24. Proton rate with PMT gains10 ( LOOSE) FAST TRIGGER (250 Hz) LEV1 TRIGGER (70 Hz)

  25. Proton rate with PMT gains10 ( TIGHT) FAST TRIGGER (170 Hz) LEV1 TRIGGER (50 Hz)

  26. Global gain variation: g efficiency LOOSE TIGHT

  27. Global gain variation: proton rate FAST TRIGGER RATE (Hz) LOOSE algorithm LEV1 TRIGGER RATE (Hz)

  28. Dynode energy smearing* LOOSE TIGHT *from Sylvie

  29. Summary of part I • photon efficiency loose (tight) : 1 GeV : 31% (16%) 1.5 GeV : 73% (53%) 2 GeV : 90% (83%) >2GeV : >97% • proton rate : 70Hz(50Hz) ; becomes 90Hz during high solar activity • electron loss due to backsplash almost completely recovered by ECAL trigger • robust algorithm with respect to failures: • worst case is a coherent gain variation of ±30% (relevant only at low energies)

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