Download - FPD Triggering
DDFPD Triggering
Hard Diffractive Candidtate
Hard Double Pomeron Candidate
DDData 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 , |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
ttppp
with minimal impact on standard DØ physics program
DD
DDFPD 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 intoFPD trigger manager along with DFE information to form FPD AND/OR terms
NEXT SLIDES ASSUME FULL FUNCTIONALITY NEED TO REVISE, ADD REALISM
DDFPD Triggers
16 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 GeV2
RTK(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 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
p
DDFPD Trigger List (V 2.5.1)
Can include a diffractive Heavy Flavor Triggerto reduce(avoid) prescaling.
DDHard Double Pomeron (jets) with FPD
• Tag proton and anti-proton with Require two 2 GeV trigger towers
01.0
Estimate 2,500 events/fb-1
• Also have version of this trigger with one track PT > 1.5 GeV, rates probably ok, needs study
DD Semi-hard Double Pomeron with FPD
• Tag proton and anti-proton with 004.0
Estimate 6,000 events/fb-1
DDInclusive 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.
01.0
DD 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
DD Double Pomeron with two gaps
• Demand two gaps in luminosity monitor along with:
1) jets
2) EM cluster 3) track
DDFPD_LM
TDC
TDC
TDC
VTX
8 86
A PDV
•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 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 TDC’s)
DV=2 dipole+4 veto
DDTrigger Manager Inputs
FPD_LM1x96
3x96
1x96
FPD_DFE
TMLM
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?
DDTrigger 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 terms5) Also could use TL,TR, track time to calculate if valid event time (pass if any valid track)
DDReal Steps to Triggering
1) Don’t trigger, just readout all events2) 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 TM3) Add DFE to TM (with no LM or FPD_LM). First
use multiplicity cut to reject halo sprays. Estimated rejection? Expect at least 10.
4) 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
DD 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!