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AMS - ECAL Jan 7 th -8 th, 2003 Page 1 F. Pilo - Siena University/ INFN Pisa Update on stand alone ECAL trigger S. Di Falco, M. Incagli, F. Pilo, G. Venanzoni.

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Presentation on theme: "AMS - ECAL Jan 7 th -8 th, 2003 Page 1 F. Pilo - Siena University/ INFN Pisa Update on stand alone ECAL trigger S. Di Falco, M. Incagli, F. Pilo, G. Venanzoni."— Presentation transcript:

1 AMS - ECAL Jan 7 th -8 th, 2003 Page 1 F. Pilo - Siena University/ INFN Pisa Update on stand alone ECAL trigger S. Di Falco, M. Incagli, F. Pilo, G. Venanzoni

2 AMS - ECAL Jan 7 th -8 th, 2003 Page 2 F. Pilo - Siena University/ INFN Pisa 3Trigger algorithms 3Results on photon efficiency and trigger rate 3Trigger robustness (against gain fluctuation,...) 3First results on electrons OUTLINE

3 AMS - ECAL Jan 7 th -8 th, 2003 Page 3 F. Pilo - Siena University/ INFN Pisa In the previous presentation a trigger algorithm AND has been described. This will be called AND algorithm. Due to the possible problems related to the low threshold values and to the rigid AND logic, we decided to develope a different more flexible MIX algorithm which will be called MIX. Trigger algorithms

4 AMS - ECAL Jan 7 th -8 th, 2003 Page 4 F. Pilo - Siena University/ INFN Pisa The AND trigger algorithm 3thresholds on 6 superlayers: 3Low energy trigger: AND+ AND of four superlayers (2,3,4,5) + + X/Y directions cut + mean density cut. 3 High energy trigger: AND+ AND of four superlayers (4,5,6,7) + X/Y directions cut. 3Global trigger: OR low energy trigger OR high energy trigger SuperlayerThr(MeV)SuperlayerThr(MeV)

5 AMS - ECAL Jan 7 th -8 th, 2003 Page 5 F. Pilo - Siena University/ INFN Pisa p1.0% (47 Hz) E g (GeV)0 o -10 o 10 o -20 o 145%43% 283%82% 592%90% 1097%96% 2098% 5095%96% 10099%96% 30096%94% Results of the previous presentation

6 AMS - ECAL Jan 7 th -8 th, 2003 Page 6 F. Pilo - Siena University/ INFN Pisa 3New higher thresholds 3Thresholds on 6 Superlayers 3Thresholds logic: 3 AND 4 AND (2 OR 6) AND (5 OR 7) 3New X/Y directions cut: 3 No density cut, No high energy trigger < < 4 b MAX N hit 6+N hit 7 A new trigger algorithm: MIX logic Thr(MeV) Superlayer Thr(MeV)Superlayer

7 AMS - ECAL Jan 7 th -8 th, 2003 Page 7 F. Pilo - Siena University/ INFN Pisa New proton sample 3In the previous presentation the protons sample was generated ECAL focused. This was not completely correct mainly because of the secondary particles produced in detector interactions which were not taken into account (a 30% effect was estimated). A new sample of protons generated isotropically on the surface of the standard box (390 x 390 x 390 cm 3 ) surronding the detector was used. 3The rate is defined as: where N BOX is the number of protons generated on the box, A BOX is the acceptance of the standard box (286.7 sr m 2 ), is the flux and N TRG is the number of events which are selected by our stand alone trigger.

8 AMS - ECAL Jan 7 th -8 th, 2003 Page 8 F. Pilo - Siena University/ INFN Pisa Proton Flux The flux is taken from Choutkos note Over Cutoff Proton Flux… (May 2000) and it corresponds to the polar orbit. 1830

9 AMS - ECAL Jan 7 th -8 th, 2003 Page 9 F. Pilo - Siena University/ INFN Pisa E p KIN (GeV) Flux (Hz sr -1 m -2 ) BOX (10 -4 ) rate (Hz) E p KIN (GeV) Flux (Hz sr -1 m -2 ) BOX (10 -4 ) rate (Hz) > TOTAL57.8 Hz Thresholds only: 482 Hz Updated Results for the AND trigger algorithm

10 AMS - ECAL Jan 7 th -8 th, 2003 Page 10 F. Pilo - Siena University/ INFN Pisa E p KIN (GeV) Flux (Hz sr -1 m -2 ) BOX (10 -4 ) rate (Hz) <0.01< E p KIN (GeV) Flux (Hz sr -1 m -2 ) BOX (10 -4 ) rate (Hz) > TOTAL31.8 Hz Results for the MIX trigger algorithm: rejection Thresholds only: 188 Hz

11 AMS - ECAL Jan 7 th -8 th, 2003 Page 11 F. Pilo - Siena University/ INFN Pisa AND vs MIX trigger algorithm: rejection

12 AMS - ECAL Jan 7 th -8 th, 2003 Page 12 F. Pilo - Siena University/ INFN Pisa 3In the previous presentation trigger efficiency was calculated by requiring photon trajectory intersection with the TOFs and the 5 th ECAL superlayer. In the present study the photons intersecting the external ECAL columns have not been considered (common definition with Sapinski). New photon selection

13 AMS - ECAL Jan 7 th -8 th, 2003 Page 13 F. Pilo - Siena University/ INFN Pisa E (GeV)0 o -10 o 10 o -20 o 116%14% 283%81% 394% 4 595%94% 1095% 2097%96% 5097%96% 10098%97% 30097%95% E (GeV)0 o -10 o 10 o -20 o 145%43% 283% 390%89% 490%89 % 593%90% 1097% 2098% 5095%97% 10099%95% 30096%94% OLDNEW AND vs MIX trigger algorithm: efficiency

14 AMS - ECAL Jan 7 th -8 th, 2003 Page 14 F. Pilo - Siena University/ INFN Pisa AND vs MIX trigger algorithm: efficiency (II)

15 AMS - ECAL Jan 7 th -8 th, 2003 Page 15 F. Pilo - Siena University/ INFN Pisa MIX trigger algorithm robustness: gain fluctuation Proton rate changes from 31.8 (no smearing) to 30.8 Hz (sigma = 20%) Gain fluctuation was simulated by MC, applying a gaussian spread to all the PMT outputs, with sigma chosen between 2% and 20%. fluctuation changes event by event same fluctuation for all the events

16 AMS - ECAL Jan 7 th -8 th, 2003 Page 16 F. Pilo - Siena University/ INFN Pisa MIX trigger algorithm robustness: gain shift Proton rate changes from 31.8 (no gain shift) to 18.9 Hz (gain shift= -30%), to 50.1 Hz (gain shift +30%) The effect of a systematic gain shift between +30 and –30% was studied negative gain shift positive gain shift

17 AMS - ECAL Jan 7 th -8 th, 2003 Page 17 F. Pilo - Siena University/ INFN Pisa Proton rate changes from 31.8 (no broken PMTs) to 29.1 Hz in the worse case. No broken PMT  1 broken PMT Effect of broken PMTs: efficiency is the average of 20 different configurations of broken PMTs. No broken PMT 5 broken PMTs No broken PMT 10 broken PMTs MIX trigger algorithm robustness: broken PMTs

18 AMS - ECAL Jan 7 th -8 th, 2003 Page 18 F. Pilo - Siena University/ INFN Pisa Proton rate changes from 31.8 (no broken PMTs) to 29.6 Hz in the worse case. No broken PMT  1 broken PMT Effect of broken PMTs in the superlayer 3 and 4: efficiency is the average of 20 different configurations of broken PMTs. No broken PMT 5 broken PMTs No broken PMT 10 broken PMTs MIX trigger algorithm robustness: broken PMTs (II)

19 AMS - ECAL Jan 7 th -8 th, 2003 Page 19 F. Pilo - Siena University/ INFN Pisa Proton rate changes from 31.8 (no broken PMTs) to 37.0 Hz in the worse case. No broken HV ch.  1 broken HV ch. HV failure was simulated by increasing the output of some PMTs by a factor of 10: efficiency is the average of 20 different configurations. No broken HV ch. 5 broken HV ch.s No broken ch. 10 broken ch.s MIX trigger algorithm robustness: HV failures

20 AMS - ECAL Jan 7 th -8 th, 2003 Page 20 F. Pilo - Siena University/ INFN Pisa e e sample selection: 43 out of 4 TOF planes 4extrapolated trajectory: - do not intersect ACC - crosses 5th SL (not at edges) ECAL fast trigger (thresh. only) to recover vetoed e ECAL fast trigger (thresh. only) to recover vetoed e TOF: TOF: 3 out of 4 TOF planesTOF+ANTI: 3 out of 4 TOF planes AND N ACC =0TOF+ANTI+ECfast: 3 out of 4 TOF planes AND (N ACC =0 OR ECthresholds OK) backsplash effect

21 AMS - ECAL Jan 7 th -8 th, 2003 Page 21 F. Pilo - Siena University/ INFN Pisa Summary and Outlook 3Two different algorithms were studied for the stand alone trigger: 3AND: good low energy gamma efficiency also to 1 GeV, but low threshold and rigid AND logic 3MIX: good efficiency E2 GeV, higher thresholds (~100 MeV), robusteness. 3 For MIX algorithm the proton rate is 30 Hz for the AMS01 proton flux in the worst latitude condition. 3 Study against gain fluctuations, shifts, broken PMTs,..., shows sensible differences in efficiency only for energy below 5 GeV (30% in the worse case). 3 Backsplash problem is well fixed.

22 AMS - ECAL Jan 7 th -8 th, 2003 Page 22 F. Pilo - Siena University/ INFN Pisa Trigger analog circuit simulation: Jitter Study 3Simulated circuit: follower + (10x) amplifier + comparator 3Two tested amplifier: LMH6643, OPA690, no SQ but in the AMS list 3The OPA690 amplifier requires more power (+2 mA). The overall trigger power consumption is increased by ~1 Watt. 3Using OPA690 the response delay for a small input signal is reduced (from 60 to 25 ns)

23 AMS - ECAL Jan 7 th -8 th, 2003 Page 23 F. Pilo - Siena University/ INFN Pisa Jitter Study: LMH6643 Input signal: 2mV Delay: ~60 ns Input signal: 2mV Delay: ~10 ns

24 AMS - ECAL Jan 7 th -8 th, 2003 Page 24 F. Pilo - Siena University/ INFN Pisa Jitter Study: OPA690 Input signal: 2mV Delay: ~25 ns Input signal: 2mV Delay: ~5 ns

25 AMS - ECAL Jan 7 th -8 th, 2003 Page 25 F. Pilo - Siena University/ INFN Pisa 3Minimum total energy threshold of 220 MeV: good efficiency at low energy but trigger rate sensitive to low energy proton flux 3 Minimum PMT threshold of 20 MeV MIP signal (~16 MeV): could it increase fast trigger Jitter? 3 AND logic rigidity could reduce trigger robustness (efficiency dependence on PMT gains and PMT failures) Open Problems for the AND trigger algorithm

26 AMS - ECAL Jan 7 th -8 th, 2003 Page 26 F. Pilo - Siena University/ INFN Pisa Accettanza dellECAL 3 Calcolo geometrico. Ogni faccia conta p (flusso solo entrante): 2p (0.648 x 0.648) + 4p (0.648 x )= 4 sr m 2 3 Verifica empirica. Flusso isotropo su una sfera di raggio 1 m: 3 Acettanza dinamica. Generando isotropicamente 10 5 fotoni da 2 GeV sulla scatola standard (3.9x3.9x3.9 m 3 ) e guardando gli eventi con E TOT >120 MeV sullECAL si trova: A ECAL (dallalto) = sr m 2 (Corinne gives 2.2 sr m 2 ) A ECAL (dal basso) = sr m 2

27 AMS - ECAL Jan 7 th -8 th, 2003 Page 27 F. Pilo - Siena University/ INFN Pisa Calcolo del rate di protoni 3 Per tenerne correttamente conto dei secondari si considerera lefficienza non rispetto agli eventi nellntupla ma rispetto a quelli chiesti al Montecarlo (TRIG card) usando come rate quello ottenuto moltiplicando il flusso per laccettanza della scatola standard (A BOX = sr m 2 ): 3 Il fattore 2 dovuto al fatto che si considerano solo particelle dallalto e incluso in N TRIG (il Montecarlo genera comunque anche le particelle dal basso ma non le scrive nellntupla)

28 AMS - ECAL Jan 7 th -8 th, 2003 Page 28 F. Pilo - Siena University/ INFN Pisa Effetto dei secondari 3 Generando isotropicamente 10 6 protoni con spettro energetico cosmico con 0.5


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