Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop1 Level 1 Trigger: Introduction L1 trigger objects and strategy Implementation features L1 composition and rate projection Su Dong

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop2 Trigger Requirements and General Strategy The basic requirement of the trigger system is to select Interesting physics events with high, stable and well understood efficiency. Some implementation features: Trigger lines mostly defined by generic topology (2,3,4 particles etc.), not by specific physics source. Deploy orthogonal triggers using pure DCH or pure EMC triggers with high efficiency for affordable topologies. stability and efficiency measurability. Built in tolerance for detector inefficiencies: –Accept 3 out of 4 hits for track segment finding in a superlayer –Allow missing segments in L1 and L3 track triggers –Allow at least one signal particle is allowed to miss DCH or EMC trigger, whenever possible.

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop3 L1 Trigger System

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop4 L1 Trigger Primitives (I) DCT primitives: BLT coarse r  tracks with no Z/tan /P t info –A 16 : long track reaching SL10 (P t >180MeV) –B 16 : short track reaching SL5 (P t >120MeV) ZPD 3D tracks with Z/tan /P t info reaching SL7 –Z 16 : standard Z track (|Z| 200 MeV) –Zt 8 : tight Z cut track (|Z| 200 MeV) –Z’ 8 : high P t track (|Z| 800 MeV) –Zk 4 : moderate P t cut (|Z| 350 MeV)

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop5 L1 Trigger Primitives (II) EMT primitives: –M 20 :  strip energy sum MIP (>120MeV) –G 20 :  strip energy sum medium E (>300MeV) –E 20 :  strip energy sum high E (>800MeV) –Y 10 : Backward barrel high E (>1 GeV) IFT primitive: –U 3 : coded pattern number for various 2 muon and 1 muon barrel/endcap hit topologies

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop6 L1 Trigger Features (I) PEP-II beam essentially continuous so that L1 trigger also operates in `DC’ mode in conjunction with fully pipelined subdetector frontend electronics. There is no fast trigger detector element such as TOF but still get L1 time resolution of ~50ns. Subsystem readout work on raw waveform to calculate pulse height => decouple trigger timing from pulse heights. However, there are pathological effects in frontend electronics input to trigger or vulnerable trigger settings which can introduce gross timing shifts. Careful testing is required for changes with timing consequences.

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop7 Ghost retriggering events (from 2000) Due to EMC electronics glitch during a ramping down pulse

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop8 L1 Trigger Features (II) Low multiplicity triggers such as 1B can sometimes saturate at high background conditions so that e.g. 2B is on, but 1B may appear to be off due to lack of off->on transition. GLT trigger lines are currently optimized for best mean time alignment between lines. If we were to deliberately delay L1 as late as possible to minimize SVT ‘background hit poisoning’, we may need to try optimizing for best late edge alignment.

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop9 L1 Trigger Line Naming Conventions 3B&2A means B>3 and A>2 M* means 2 M hits back to back EM* means M and E hits back to back A+ means A>1 & A’>1 D2 means B>2 & A>1 (short hand 2 trk trg) BM means B matched by M in same  location For counting distinct objects from the  maps: Normal objects (B,A,M,E etc.) are separated by more than 1 f bin: 22.5 o for DCT tracks, 18 o for EMT hits. Back to back angles cuts for B*,M*,EM* ~120 o. DCT/EMT match objects BM ~90 o apart.

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop10 This configuration is used throughout runs. The ‘Beam/beam’ contribution can also be due to low angle Bhabha debris. Feb/02

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop11 L1 Trigger Efficiency old DCT configuration: Pure DCT Pure EMT All L1 lines BB generic 99.1% 99.8% >99.9% B->     + B->X 79.7% 99.2% 99.8% B->  + B->X 92.2% 95.5% 99.7% cc 95.3% 98.8% 99.9% uds 90.6% 95.6% 98.2% Bhabha 98.9% 99.2% >99.9%  99.1% %  80.6% 77.6% 94.5% ( Hadronic final states: all events Leptonic final states: fiducial events)

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop12 L1 Rate Projection Feb/02 Background run result suggest Possible model: L1 Rate (Hz) = 125 (cosmic) + 50*I LER (A) + 190*I HER (A) + 180*I 2 HER (A) + 70* L / *I LER *I HER at good conditions

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop13 Checking L1 Rate Projection Derived background L1 rate compared to prediction: >2*backgr 24% >3*backgr 4.6% >4*backgr 2.2% Use prediction with caution !

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop14 L1 Rate Extrapolations (Jan/04)

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop15 L1 Rate Extrapolations (Jan/04) Model-2: + 100*I her *I 2 ler + 100*L

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop16 Can we get more reduction out of DCZ ?

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop17 Backup Slides

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop18 L1 Trigger Rate Growth vs Trigger Types

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop19 New L1 Rate Extrapolations (II) Model-1: + 50*I her *I ler + 120*I her *I 2 ler + 70*L

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop20 HER background characteristics

Dec/02/04 Su DongCaltech Trigger/DAQ/Online workshop21 Lumi vs beam current