Diffractive Triggers

E

Andrew Brandt, U. Texas at Arlington

Trigger IntegrationNovember 18, 2003

A1U A2U

P2DP1D

P

Pbar

LMVC

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 expect a prescaleat higher luminosity unless can improve trigger (or naturalprescale from double gap takes 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 (note s80-u60 in prescale file!)

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)

J/ +Gaps

J/ +Gap2MT1_2TRK_GAPN = 2MT1_C_2L2L_2TRK + ALMNorth[v]2MT1_2TRK_GAPS = 2MT1_C_2L2L_2TRK + ALMSouth[v]

Before 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

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 perform hit multiplicity cut (veto events with excessive multiplicity), divide tracks in momentum and angle bins

•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

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. (who in LM group is doing this? ) mostly can get this info separately 3) DFE information from scintillating fiber detectors, , t, multiplicity

FPD Trigger StatusAll 18 FPD detectors are in readout, trigger scintillators in readout soon.(!)

•Currently can only trigger using special runs (NIM to generate AND/OR terms).

•Need LM vertex board (<6 months, according to Brendan) combined with Trigger Manager (commissioning starting in next few weeks) for scintillator based triggers.

•Could have DFE-based triggers through TM earlier

•Will need some resources, bandwidth, exposure groups, trigger bits

Proposed strategery: add high rate monitor and calibration triggers (elastic, inclusive diffractive) in separate global run not to be recoed.Use TM to define an FPD exposure group (gaps 3->1 or 2). A few global run triggers for double pomeron, J/, and dijets. Other diffractive physics symbiotically.

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

TDC

TDC

TDC

VTX

8 68

‘1’ D‘2’ +V

TDC Details:Step I TDC in readout• 3 TDC boards for FPD compared to 6 LM boards• ‘1’ board consists of Px1, and Ax1 where x=Up,Down, In, Out pots (first quadrupole castle on either side of IP)• ‘2’ board consists of Px2, and Ax2 (second quadrupole castle)• 2 dipoles + 4 veto counter signals

Step II Pass info to vertex board and add scalar info• Allowed 80 bits from each side to vertex board• Each board should set bits at two times, corresponding to in-time hits (time of flight from IP) and to early-time hits from halo (time of flight from IP earlier than interaction) Dipole 1 halo bit (T-D2<T-D1), VC none?• For each TDC give in-time bit 0 or 1; 16 (6) bits• For each TDC give halo bit 0 or 1; 16 (1) bits• TOTAL 32 (7) bits

FPD_LM

1 board should send 8 in-time and 8 halo bits to 2 boardwhich should receive these bits and send 16 in-time bits and 16halo bits to vertex board

D+V board should send 6 in-time and 1 halo bit to Vertex boardNote: cable lengths have been fixed such that 1 in-time/halo signals arriveat 1 board at a fixed time (594 nsec/438), and all 2 signals arrive at 2 boardat a different fixed time (625/407) , and D+V signals arrive at a 3rd

fixed time (825).

Manchester group on the job, plan to have TDC’s operational soonSteps to operational FPD TDC boards?Scalar on TDC board or vertex boards?Vertex Schedule?Update next week.

More TDC Details

Vertex board should receive 22 in-time bits and 17 halo bits from TDC boards. It could form 4 bit words for each of the 8 non-dipole spectrometers 0=no coincidence of 1+2 pots for that spectrometer1=coincidence of 1+2 pots for that spectrometer2=coincidence but either one of diagonally opposite spectrometer pots has halo bit set3=coincidence but both of diag opposite pots has halo bit set

Examples: PU1.and.PU2 no early time hits in AD1 or AD2 =1 PI1.and.PI2 with early time hits in AO1 and AO2 =3

OR it could just pass the info to TM, depending on Firmware space on Vertex or TMOR BOTH:Vertex board passes information to TMCan pass up to 96 bits to TM in 16 bit bursts (separated by 18 nsec) ,74 bits if send processed and raw info1) Spec 1-8 4bit words (32 bits)2) Spec 9 3 bit word, 2 in-time bits from spec. 9, 1 halo bit from spec. 9 (note for dipole halo bits are formed from order of dipole times D1>D2 ->halo) (3 bits)3) 4 veto counter in-time, 4 VC halo bits? Like lm halo? (4 bits) 4) 18 in-time bits from spec 1-9 (18 bits)5) 17 halo bits from spec 1-9 (17 bits)

Vertex Board Details

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 algo2) Use multiplicity cut to reject halo spray, code several multiplicity levels3) NOTE fiber ADC threshold must be high enough to avoid noise, low enough to retain efficiency and allow vetoing of halo4) 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 channels3) Need to settle on bit pattern to proceed with TM logic4) Measure efficiency with jet triggers, scint triggers from special runs 5) Little experience with DFE, none with TM

TM AlgorithmDFE will pass one word for each spectrometer indicating coincidence of two detectorsand multiplicity level, use this to define a track (could have different multiplicity level in different spectrometers).

At TM we would form terms DIFFQ=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 AD-PD or AI-PI or AO-POOVER=AU-DI or AD-DI or AO-DI or AI-DI (over-constrained track for alignment)

FPD Trigger ListTentative L1 FPD trigger list. V13 (mid-January) possible?

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 DIFFS) +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.We think triggers 1-3+any monitors are best done in a separate globalrun since they will not need general farm reconstruction.

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

Different Exposure TermsFPD track(s)0 with no vetos on halo, multiplicity, veto counter, or LM-standard exposure group? Monitor (halo veto requires vertex board)FPD track(s)1 (includes FPD halo vetos+multiplicity cuts) (probably only use in special run)FPD track(s)2 (FPD track1+ a veto counter) [VCNbar or VCSbar]5.2<<5.9 (standard inclusive SD term) [2 separate groups] (VC requires vertex board)FPD track(s)3 (FPD track1+ a veto counter+LM gap on same side) (standard inclusive SD term, gap may be necessary to control rate) [2 groups]FPD tracks4 (2 FPD tracks3)(elastic or double pomeron term)GAPN, GAPS, GAPSN

Global list:FPD track0, FPD track2 or 3 (and also + object), FPD tracks4 (and also +object),LM gap +object, LM gaps+object

Currently have 3 Gap exposure groups in global list out of 8 maximum. I assume 3 is limit for diffraction. Propose a single LM gap term and an FPD term.

I count 10 different diffractive exposure groups, 7 needed in global list!

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:?Trigger databaseL2 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