FPD Triggering

1. Hard Diffractive Candidtate FPD Triggering Hard Double Pomeron Candidate

2. 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 • 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 DØ 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 DØ physics program

4. FPD L1 Trigger • Modelled after CTT trigger but with fiber detectors read out by multi-anode PMT’s instead of VLPC’s • Requires a transition board to shape signals • and discard excess charge for use with AFE’s • (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 into • FPD trigger manager along with DFE information to form FPD AND/OR terms • NEXT SLIDES ASSUME FULL FUNCTIONALITY NEED TO REVISE, ADD REALISM

5. FPD Triggers • 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 track • RTK(1) x > 0.99, all t • RTK(2) 0.99 > x > 0.9 all t • RTK(3) x > 0.9 all t, no halo veto • RTK(4) x > 0.9, |t|>1 GeV2 • RTK(5) x > 0.9, all t • REL = 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 GeV2 • ROV(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 16 AND-OR terms allocated to implement all FPD triggers (13 currently in use)

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

7. 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

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

9. 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.

10. 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

11. Double Pomeron with two gaps • Demand two gaps in luminosity monitor • along with: • 1) jets • 2) EM cluster • 3) track

12. FPD_LM A DV P DV=2 dipole+4 veto T D C T D C V T X T D C (LM has 6x8 TDC’s) 8 8 6 • Allowed 80 bits from each side to vertex board • For each TDC give in-time bit 0 or 1; 14 (8) bits • For each TDC give halo bit 0 or 1; 14 (8) bits • If two times on and consistent give average • time of spectrometer (8 bits)—don’t pass • veto time; 40 (32) bits • TOTAL 68 (48) bits • Can pass 96 bits to TM • 9 in-time spec bits • 18 halo bits • 63 7-bit spectrometer times (for up to 9 tracks) • OR 56 8-bit times for first 7 tracks • what about header? • How to calculate singles rates???

13. Trigger Manager Inputs 1x96 FPD_LM T M 1x96 LM 3x96 FPD_DFE 1) 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?

14. Trigger Manager Logic 1) 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 terms 5) Also could use TL,TR, track time to calculate if valid event time (pass if any valid track)

15. Real Steps to Triggering • Don’t trigger, just readout all events • And/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 TM • Add 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 tools • 6) 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

16. Conclusions We have gap data and stand-alone data that can (must) be used to revise our triggering strategy taking into account realities in resolution, multiplicites, halo, pot locations, hardware etc. This effort must begin in earnest now!