fpd triggering

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Hard Diffractive Candidtate. FPD Triggering. Hard Double Pomeron Candidate. Data Taking and Trigger Strategy. No special conditions required Read out Roman Pot detectors for all events (can’t miss ) Some dedicated global triggers for diffractive - PowerPoint PPT Presentation


  • FPD Triggering Hard Diffractive CandidtateHard Double Pomeron Candidate

  • Data Taking and Trigger Strategy No special conditions required Read out Roman Pot detectors for all events (cant miss ) Some dedicated global triggers for diffractive jets, double pomeron, and elastic events Use CTT trigger system 1) Allows selection of x , |t| ranges at L1 (reduce background, keep rare high- |t| unprescaled) 2) readout D standard Reject fakes from multiple interactions (Ex. SD + dijet) using LM timing, silicon tracker, longitudinal momentum conservation, and scintillation timing Obtain large samples (for 1 fb-1): ~ 1K diffractive W bosons ~ 3K hard double pomeron ~500K diffractive dijets with minimal impact on standard D physics program

  • FPD L1 TriggerModelled after CTT trigger but with fiber detectors read out by multi-anode PMTs instead of VLPCs

    Requires a transition board to shape signals and discard excess charge for use with AFEs(undergoing final tests at AFE test stand to determine capacitor values)

    DFE tracking firmware to divide tracks in momentum and angle bins undergoing tests

    LM TDC boards to process trigger scintillators

    FPD timing and LM information will feed intoFPD trigger manager along with DFE information to form FPD AND/OR terms


  • FPD Triggers16 AND-OR terms allocated to implement allFPD triggers (13 currently in use) The FPD Trigger Manager allows cuts on =1-p/p and t, and also incorporates information from the trigger scintillator via the LM boards. A track is defined as two detector hits in any spectrometer with a valid x and t, a trigger scint. confirm, and no halo veto set.

    AND-OR term definitions:

    RTK = track in any spectrometer, (D= veto on halo) RPT = proton track RAT = anti-proton trackRTK(1) x > 0.99, all tRTK(2) 0.99 > x > 0.9 all tRTK(3) x > 0.9 all t, no halo vetoRTK(4) x > 0.9, |t|>1 GeV2RTK(5) x > 0.9, all tREL = Elastic (diagonally opposite p and )ROV = Overconstrained track (D+Q proton tracks) REL(1) = x > 0.99, all t REL(2) = x > 0.99, |t | > 1 GeV2ROV(1) = x > 0.90, all t ROV(2) = x > 0.90, |t | > 1 GeV2)

    LMO = no hits in LM; LMI(1) = Single Interaction;LMD=N+Sbar .OR. S+Nbar

  • FPD Trigger List (V 2.5.1)Can include a diffractive Heavy Flavor Triggerto reduce(avoid) prescaling.

  • Hard Double Pomeron (jets) with FPD Tag proton and anti-proton with Require two 2 GeV trigger towers Estimate 2,500 events/fb-1

    Also have version of this trigger with one track PT > 1.5 GeV, rates probably ok, needs study

  • Semi-hard Double Pomeron with FPD Tag proton and anti-proton with Estimate 6,000 events/fb-1

  • Inclusive Double Pomeron with FPD Tag proton and anti-proton with

    Demand non-diagonal spectrometers to remove elastic background. Large background from multiple SD events, requires study (can isolate double pom by measuring as function of luminosity).

    Same, but require number of hits above threshold in fiber tracker.

  • Double Pomeron with gap + track Use single gap + jet trigger (demand gap in Level 1 using luminosity monitior) and look for events with track on other side

    Use single diffractive trigger (both with and without jets) to look for events with gap on the other side

  • Double Pomeron with two gaps Demand two gaps in luminosity monitor along with:

    1) jets

    2) EM cluster 3) track

  • FPD_LMTDCTDCTDCVTX886APDVAllowed 80 bits from each side to vertex boardFor each TDC give in-time bit 0 or 1; 14 (8) bitsFor each TDC give halo bit 0 or 1; 14 (8) bitsIf two times on and consistent give average time of spectrometer (8 bits)dont pass veto time; 40 (32) bits TOTAL 68 (48) bits

    Can pass 96 bits to TM 9 in-time spec bits18 halo bits63 7-bit spectrometer times (for up to 9 tracks)OR 56 8-bit times for first 7 trackswhat about header?How to calculate singles rates???(LM has 6x8 TDCs) DV=2 dipole+4 veto

  • Trigger Manager InputsFPD_LM1x963x961x96FPD_DFETMLM1) FPD_LM 9 in-time bits, 18 halo bits, 7-9 spec times, header?2) LM TL 8 bits (50 psec) TR 8 bits Fast Z ? Bits #N counters 5 bits #S counters 5 bits 16 and/or bits header?3) 16 bits/track with p, t, spectrometer allow multiple tracks/spec? Header?

  • Trigger Manager Logic1) For each track, check coincidence in timing should be 100%2) If both opposite halo bits set, reject track (possibility of using only one halo bit)3) For valid tracks use fast-z to calculate new ,t If no fast-z calculate z with TL+p time or TR+pbar time and adjust track Else use z=0 (default ,t)4) Compare ,t with trigger list and set and/or terms5) Also could use TL,TR, track time to calculate if valid event time (pass if any valid track)

  • Real Steps to TriggeringDont trigger, just readout all eventsAnd/or terms from SCR:Diff_x (x=PU, 5 in all) Diff_any, Elas_x (2), Elas (1), DPOM ( up_up, dn_dn, dipole_up, dipole_dn,any): bypass TMAdd DFE to TM (with no LM or FPD_LM). First use multiplicity cut to reject halo sprays. Estimated rejection? Expect at least 10.Add trigger equations, this will rule out invalid combinations, allow selection of high-t. Reduce MI background. Estimated rejection? 5) Add L2 Gap tool, L3 tools6) If LM TDC boards are ready, but no vertex board, can we send signals to TM? Replace functionality of vertex board in TM? 7) Once vertex board works, can apply single interaction algorithm.8) Add in FPD_LM information and disable SCR and/or terms

  • Conclusions

    We have gap data and stand-alonedata that can (must) be used to reviseour triggering strategy taking into accountrealities in resolution, multiplicites, halo,pot locations, hardware etc.

    This effort must begin in earnest now!


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