Ted Liu, July 5,00, idea on Ztrigger L1 Trigger Strategy L1 Trigger Requirements and Trigger Lines L1 Trigger performance Background Study Improving Performance: near-term strategy Future Prospect: long-term strategy summary Ted Liu, Lawrence Berkeley Lab (for the trigger group)

Ted Liu, July 5,00, idea on Ztrigger Trigger Line Definition/Convention DCT Objects: A: long track reaching SL10, Pt ~180 MeV B: short track reaching SL5, Pt ~120 MeV A’: high Pt track reaching SL10, Pt > 800 MeV EMT Objects: M: minimal ionizing cluster, E >100 MeV G: intermediate energy cluster, E >300 MeV E: high energy cluster, E >700 MeV Y: backward barrel cluster, E >1 GeV IFT Objects: 1U: 1 high P muon in backward endcap B*,M*...* means back-to-back objects(>120 ) D2 = 2B&1A, D2* = B*&1A D2*+ = B*&1A&1A’, A+ = A&A’ o

Ted Liu, July 5,00, idea on Ztrigger Trigger Lines for Hadronic Events B Physics Continuum Pure DCT Pure EMT DCT + EMT CP Channels: high eff. Non-CP channels: high + precise eff. Requirements: High & precise eff. for background sub. orthogonal lines redundant lines record all trigger DAQ data prescaled lines Strategy for eff. Measurements : run9304

Ted Liu, July 5,00, idea on Ztrigger Use orthogonal DCT-EMT lines to study eff. Total eff for hadron skim: (EMT OR DCT) > 99.3% From Su Dong

Ted Liu, July 5,00, idea on Ztrigger Trigger Lines for non-physics Events Luminosity, calibration: 2-prong ee,  High + precise eff. Pure DCT Pure EMT DCT + EMT Requirements: Calibration, beam monitor: 1-prong ee,  Background&Trigger studies Background monitoring  only run9304

Ted Liu, July 5,00, idea on Ztrigger Trigger Lines for  and 2  Events  Physics Pure DCT Pure EMT DCT + EMT Rare & Asy.: high eff. Branch Ratios: precise eff. Requirements: precise eff. All unprescaled lines have high Pt cut (800MeV) and with back-to-back requirement. No unprescaled orthogonal lines. All high eff. Lines have to be prescaled. Shortcomings : 2  Physics high background rate, will try to improve… add 2BM+1AM, lower Pt cut?

Ted Liu, July 5,00, idea on Ztrigger L1 Strategy to improve performance Better Combination of trigger lines: DCT+EMT phi matching Give up some orthogonal lines Improve trigger objects: Short-term: PTD ---> DOCAD Long-term: DOCAD --> DOCAZD? Need good understanding of background --> next...

Ted Liu, July 5,00, idea on Ztrigger HERLER Single beam L1 pass thr. events Z distribution LER HER From S. Petrak

Ted Liu, July 5,00, idea on Ztrigger HER LER Single beam L1 pass thr. events x-z view Many tracks from beampipe: off Z --> off IP in x-y LER HER

Ted Liu, July 5,00, idea on Ztrigger Trigger data Fine position data for segments found for axial SLs Drift Chamber Track Segment Finder (x24) DOCAD 24 Gbits/s Coarse data for all supercell hits Binary Track Linker (BLT x1) PT Discriminator PTD (x8) GLT A, B A’ 16 DCT Trigger Hardware New idea (only firmware change)

Ted Liu, July 5,00, idea on Ztrigger Drift Chamber Trigger ( DCT ) The heart of DCT is the Track Segment Finder TSF continuously live image processor A novel method: using both occupancy and drift-time information, to find track segments continuously with: time resolution of ~ 100 ns, event-time jitter window ~ 100 ns spatial resolution ~ 1 mm used for track Pt Discrimination Use 24 TSF modules (2) send segment patterns to the DAQ system for use in Level 3... (1) send segment patterns downstream for L1 trigger decision making Upon a L1 accept: Track Segment Finder

Ted Liu, July 5,00, idea on Ztrigger

x x A10 seed IP SL7 SL4 SL1 Pt threshold (800MeV) Current PTD algorithm x x SL7 SL4 SL1 IP New DOCAD algorithm Tracks (above threshold) coming from IP should leave all the hits in one of the slices Tracks not coming from IP will most likely leave hits in different slices 4 hits on one track with  ~1mm, should be able to tell whether the track is from IP (baseline design: simple algo.) 800MeV 850MeV 900MeV 1 GeV

Ted Liu, July 5,00, idea on Ztrigger Apply DOCAD algorithm to TSF data Hadron skim: signal LER single beam run: background PTD on DOCAD on PTD on DOCAD on Background rejection: 40% Effect on Signal: Effect on Background: Use hadron skim (~10% bkg) ~ 4% loss at turn on Use single beam run L1 pass thr events 40% rejection on A’ line with simple algorithm Max Pt in the event The goal here is not to find the best algorithm possible, but one which is easy to be implemented and with good performance

Ted Liu, July 5,00, idea on Ztrigger DOCAD algorithm: possible improvement Require3/3 in ALL slices 70% bkg rejection! But 20% signal loss Due to cell ineff. TSF can determine segment location with 1 mm resolution only for 4/4 patterns The resolution is degraded for 3/4 patterns: = x x x x x x x x x x x 3/44/4  11 22  1 <  <  2 calibrating 3/4 patterns should help Currently 3/4 pattern LUT is derived from 4/4 patterns + using the  information should help (baseline design ignored  )

Ted Liu, July 5,00, idea on Ztrigger The Drift Chamber ( DCH ) 10 superlayers of 4 layers each Axial and stereo alternate Cell size: 1.2 cm x 1.8 cm L1 Long term strategy: cut in Z using TSF fine position info from stereo superlayers?

Ted Liu, July 5,00, idea on Ztrigger L1 long-term strategy: Can we cut in Z using TSF position info from stereo SLs? Stereo SLs --> Z Axial SLs --> DOCA DOCAZD Cosmic ray events Close to IP in z Off IP in z In other words: move some L3 DCH algorithm upstream to L1 (cut in doca&z) Tough but possible ! What to expect? The answer is in the TSF data we already have

Ted Liu, July 5,00, idea on Ztrigger B1 Track z distribution for L1 passthrough events LER HER Lost particle interact with beampipe flange due to a step in the synchrotron mask real collision

Ted Liu, July 5,00, idea on Ztrigger 40~50 or so slices in theta ~ 2 cm in z for SL2 TSF phi resolution ~ 1 mm Z resolution ~ 2 cm Off Z track Basic idea (~16 new DOCAZ boards in phi)

Ted Liu, July 5,00, idea on Ztrigger L1 long-term strategy: Can we cut in Z using TSF position info from stereo SLs? Stereo SLs --> Z Axial SLs --> DOCA DOCAZD What to expect? The answer is in the TSF data we already have! Current “trigger volume” Possible improved “trigger volume”??

Ted Liu, July 5,00, idea on Ztrigger Trigger data DAQ Fine position info for segments found for all superlayers Drift Chamber DAQ Level 3 Filter Track Segment Finder (x24) Upon a L1 Accept... Using segments found by TSFs as seeds, fast algorithm applied to DCH data to further reject background... reduce the rate from 2 kHz to 100 hz. Currently TSF provides fine position info for all SuperLayers to L3, only axial SLs info passed to PTD. 24 Gbits/s

Ted Liu, July 5,00, idea on Ztrigger Trigger data DAQ All track segments found Drift Chamber DAQ Level 3 Filter Track Segment Finder (x24) 24 Gbits/s DOCAZD ?? GLT A,B DZ? Fine phi info for all(?) SLs Supercell hits One possible scenario

Ted Liu, July 5,00, idea on Ztrigger HER LER

Ted Liu, July 5,00, idea on Ztrigger

The Drift Chamber ( DCH ) 10 superlayers of 4 layers each Axial and stereo alternate