Diffractive Triggers

1. LM A1U A2U VC Pbar P E P1D P2D f h Diffractive Triggers Andrew Brandt, U. Texas at Arlington FPD Workshop March 29, 2004 UERJ, Brazil

2. Trigger Strategy I • Write out FPD, LM for every DØ event (may need to strip LM info • from Raw data?) • -cross section determined using standard methods x fraction • that are diffractive corrected for acceptance+efficiency • 2) Trigger on events that would not get written otherwise • (Ex. single diffractive, elastic, double pomeron) • using FPD track AND/OR terms, sometimes combined • with gaps (veto on LM N or S) • -high rate processes, cross sections will be measured in special • run at some point (along with total cross section?) • -these triggers will be in global list (or 2nd global run) to measure  and t • distributions, also be used as monitors and for alignment, • calibration, and efficiency studies • -double pomeron lower rate, will require extra thought for cross • section, may be able to tie to elastics, or work backwards • from double pomeron + object triggers

3. Trigger Strategy II 3) Trigger on events that would otherwise be too heavily prescaled (Ex. Jets, J/, and then add gap(s) and/or track(s)) -cross sections determined using object trigger that does not have diffractive conditions and then bootstrapping

4. Gap+Jet Triggers JT_15TT_GAPN or S CJT(2,3)+GAP L3(1,15) Prescaled, currently .3-.4 Hz each L<40E30; <.1Hz at 40 E30 e80-l40-n30? JT_15TT_GAPSN CJT(2,3)+GAPS L3(1,15) Currently unprescaled 0.6 Hz at 40E30; prescaled (although natural prescale from double gap should take hold) JT_45TT_GAPN or S CJT(2,5)+GAP L3(1,45) Currently prescaled by 2 at 40E30 .08 Hz each would like to keep unprescaled at least to 60E30 (like highest inclusive ET trigger). Also will have natural SI prescale JT_45TT_GAPSN CJT(2,5)+GAPS L3(1,45) Unprescaled at all luminosity 0.03 at 40E30 *Also have 3 zero-bias+gap triggers These triggers are used for single diffractive and double pomeron jet physics (Gaps and FPD). Needs more people looking at data.

5. J/ +Gaps J/ +Gap 2MT1_2TRK_GAPN = 2MT1_C_2L2L_2TRK + ALMNorth[v] 2MT1_2TRK_GAPS = 2MT1_C_2L2L_2TRK + ALMSouth[v] Before Sep. shutdown prescale of 4 at 30E30, 200 at 40E30 (prescale now lowered) Unprescaled rate: .25 Hz @20E30 .5 Hz@40E30 e80-l60-n40 would be good Could be unprescaled at all lum, when low PT track match works J/ +Gaps 2MT1_2TRK_GAPSN = 2MT1_C_2L2L_2TRK + ALMSouth[v]ALMNorth[v} <.01 Hz at 20E30 <.04 at 80E30 should be unprescaled at all luminosity These triggers are being used to search for exclusive J/ and C , a key step towards validating diffractive Higgs models No one has looked at this data yet!!!

6. FPD DAQ

7. FPD L1 Trigger • Modelled after CTT (central fiber tracker trigger) but with fiber detectors read out by multi-anode phototubes (MAPMT’s) instead of VLPC’s • Requires a transition board (TPP) to shape signals and discard excess charge for use with AFE’s (Analog Front End boards) which receive signals, record analog values, and discriminate • DFE (Digital Front End boards) receive digital signals from AFE’s and apply tracking firmware to select potential good events and remove spray events • LM TDC boards used to perform timing from hits in scintillators from the Luminosity Monitor sub-detector as well as the FPD trigger scintillators • FPD timing and LM information will feed into FPD trigger manager (TM) • along with DFE information to form FPD AND/OR terms

8. ‘1’ ‘2’ D +V T D C T D C V T X T D C 6 8 8 FPD_LM Includes 3 TDC boards for timing and one VTX board which sends info to trigger manager, James will update status

9. 1x96 FPD_LM T M 1x96 LM 3x96 FPD_DFE Trigger Manager Inputs • FPD_LM • Information on which detectors are hit and halo • 2) LM pass through 16 LM and/or terms • includes GapN GapS GAPSN SI etc. • (is anyone in LM group doing this) mostly can get this info separately • DFE information from scintillating fiber detectors, • forseen to give , t now using segment information, multiplicity

10. LM VC Halo Early Hits A1U A2U Pbar P P2D P1D Special Run Trigger In-time hits in AU-PD detectors, no early time hits, or LM or veto counter hits Current NIM logic allows us to form several elastic and diffractive triggers for special runs using trigger scintillators (in parallel information from scintillators is sent to TDC’s for commissioning FPD_LM system, and CAMAC scalars), veto counters, and LM. Can trivially switch from elastic to double pomeron (Aup-Pup for example)

11. Previous Plan for 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 (13 used of 16 allowed): • 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

12. New Trigger Plan • Input information: • Currently no global run trigger capability • Vertex board is delayed • DFE boards work and TM ready to be commissioned • Main background not from pileup (multiple interactions) but from halo spray • New strategy: • Instead of calculating bin of  and t, use fiber hit patterns to demand 2 or 3 out • of 3 planes of each detector are hit. Replaces trigger scintillator, simpler algo • Use multiplicity cut to reject halo spray, code several multiplicity levels • NOTE fiber ADC threshold must be high enough to avoid noise, low enough • to retain efficiency and allow vetoing of halo • One advantage is pot positions not needed at trigger level • Issues: • Setting ADC threshold, need special run (and analysis) • Dealing with noisy channels, variable means, could initially set threshold high, • later load in mean pattern, known hot channels • Need to settle on bit pattern to proceed with TM logic • Measure efficiency with jet triggers, scint triggers from special runs • Little experience with DFE, none with TM • Exposure groups, triggers in global run or separate global run

13. Exposure Groups • For normalization purposes each trigger is assigned an exposure group • and live time is measured for that group—different beam conditions require • different groups • Only 8 exposure groups (7 used), we have more combos so must • operate outside exposure groups—new value NOLUM • If this is not changed we cannot run in global run • Another issue is dynamic dowloading, which allows multiple global runs • This would allow us to take elastic or other monitoring data in separate • global run, so as to avoid general reco; streaming and other issues with this • Once TM is ready we are restricted to dedicated special runs until these • other issues are resolved

14. TM Algorithm DFE will pass word for each spectrometer (Mario’s talk) indicating coincidence of two detectors (loose track and tight track, for example) At TM we would form terms DIFF=any spectrometer track DIFFQ=any quadrupole spectrometer track (could be false if >1 or 2 on A or P side) DIFFD=dipole track ELAS=AU-PD or AD-PU or AI-PO or AO-PI DPOM=AU-(PU or PI or PO) or AD-(PD or PI or PO) or AI-(PU or PI or PD) or AO-(PU or PD or PO) OVER=AU-DI or AD-DI or AO-DI or AI-DI (over-constrained track for alignment)

15. FPD Trigger List Tentative L1 FPD trigger list. V13.x/V14 (April?) 1) elastic (diag opposite spectrometers) +GAPSN 2) soft diffraction (single spectrometers)+GAPS or GAPN 3) overconstrained track (pbar in quadrupole +dipole spectrometers)+GAPN 4) double pom (up-up, dn-dn etc.)+GAPSN if needed 5) CJT(2,3) + FPD Track (DIFFQ or DIFFD) +GAPS or GAPN if needed 6) CEM(1,3)? +FPD track +GAP? 7) TTK(1,?) +FPD track +GAP? 8) MU(1,x) +FPD track +GAP? Monitors may be necessary, will need to study with special runs. Also rates are unknown. If 4 (dpom) it is not low enough to run unprescaled we would need to repeat 5-8 with two FPD tracks. Possibly 1-3+any monitors are best done in a separate global run since they will not need general farm reconstruction.

16. Trigger Work Short term trigger work: DFE algorithms: Mario, Wagner Data analysis inputs from special runs: Molina, Mike, James, Renata … DFE firmware: Ricardo, Daniel CTS tests: Daniel DFE examine? TM: Daniel, Mario… MC:? Trigsim: Wagner + Trigger database:? L2 Gap: ? L3 SI, Gap, PLtot, FPDreco:? With detectors in readout, next key is maximizing useful data sample: getting L1 trigger online is vital to FPD physics success