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PART I simulation. S. Di Falco, M. Incagli, F. Pilo, F. Spinella, G. Venanzoni. Algorithms evolution…. The algorithm has been improved in these points: XY informations decoupled; old: D bmax(NhitX6+NhitY7). Not nice for hardware implementation.
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PART Isimulation S. Di Falco, M. Incagli, F. Pilo, F. Spinella, G. Venanzoni
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
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.
Efficiency for photons (table) TIGHT Proton Rate: 50 Hz (170 Hz) LOOSE Proton Rate: 70 Hz (250 Hz) FAST TRIGGER FAST TRIGGER
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)
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)
Effect of increased solar activity LOOSE 90 Hz 70 Hz
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)
Robustness and stability studies • Dead PMTs • Dead HV channels: gain gain 10 • Global gain variation: ±30 % • Dynode energy resolution
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
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
eg with 10 PMTs dead: LOOSE vs TIGHT 0 º< q <20º
g efficiency with 5 PMT dead (LOOSE) 5 bad PMTs 0 º< q <20º
g efficiency with 1 PMT dead (LOOSE) 1 bad PMT 0 º< q <20º
eg with PMT gains10 ( LOOSE) Proton rate remains practically unchanged 10 bad PMTs 0 º< q <20º
eg with PMT gains10 ( LOOSE) 5 bad PMTs 0 º< q <20º
eg with PMT gains10 ( LOOSE) 1 bad PMT 0 º< q <20º
Proton rate with PMT gains10 ( LOOSE) FAST TRIGGER (250 Hz) LEV1 TRIGGER (70 Hz)
Proton rate with PMT gains10 ( TIGHT) FAST TRIGGER (170 Hz) LEV1 TRIGGER (50 Hz)
Global gain variation: g efficiency LOOSE TIGHT
Global gain variation: proton rate FAST TRIGGER RATE (Hz) LOOSE algorithm LEV1 TRIGGER RATE (Hz)
Dynode energy smearing* LOOSE TIGHT *from Sylvie
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)