Diffractive Triggers

E

Andrew Brandt, U. Texas at Arlington

FPD WorkshopMarch 29, 2004UERJ, Brazil

A1U A2U

P2DP1D

P

Pbar

LMVC

Trigger Strategy I1) 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

Trigger Strategy II3) 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

Gap+Jet TriggersJT_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 highestinclusive 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 doublepomeron jet physics (Gaps and FPD). Needs more people lookingat data.

J/ +Gaps

J/ +Gap2MT1_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 goodCould be unprescaled at all lum, when low PT track match works

J/ +Gaps2MT1_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 steptowards validating diffractive Higgs models

No one has looked at this data yet!!!

FPD DAQ

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

TDC

TDC

TDC

VTX

8 68

‘1’ D‘2’ +V

FPD_LM

Includes 3 TDC boards for timing and one VTX board which sends infoto trigger manager, James will update status

Trigger Manager Inputs

FPD_LM1x96

3x96

1x96

FPD_DFE

TMLM

1) FPD_LM Information on which detectors are hit and halo2) 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 3) DFE information from scintillating fiber detectors, forseen to give , t now using segment information, multiplicity

In-time hits in AU-PD detectors, no early time hits, or LM or veto counter hits

A1U A2U

P2DP1D

P

Pbar Halo Early Hits

LMVC

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)

Special Run Trigger

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 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

New Trigger PlanInput 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 levelIssues:• 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

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

TM AlgorithmDFE 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 trackDIFFQ=any quadrupole spectrometer track (could be false if >1 or 2 on A or P side)DIFFD=dipole trackELAS=AU-PD or AD-PU or AI-PO or AO-PIDPOM=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)

FPD Trigger ListTentative L1 FPD trigger list. V13.x/V14 (April?)

1) elastic (diag opposite spectrometers) +GAPSN2) soft diffraction (single spectrometers)+GAPS or GAPN3) overconstrained track (pbar in quadrupole +dipole spectrometers)+GAPN4) double pom (up-up, dn-dn etc.)+GAPSN if needed5) CJT(2,3) + FPD Track (DIFFQ or DIFFD) +GAPS or GAPN if needed6) 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 specialruns. Also rates are unknown. If 4 (dpom) it is not low enough torun unprescaled we would need to repeat 5-8 with two FPD tracks.Possibly 1-3+any monitors are best done in a separate globalrun since they will not need general farm reconstruction.

Trigger WorkShort term trigger work:

DFE algorithms: Mario, WagnerData analysis inputs from special runs: Molina, Mike, James, Renata …DFE firmware: Ricardo, DanielCTS tests: DanielDFE 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