Presentation on theme: "VELO Beamtest Trigger VELO meeting 08/12/2005 Jianchun (JC) Wang Syracuse University."— Presentation transcript:
VELO Beamtest Trigger VELO meeting 08/12/2005 Jianchun (JC) Wang Syracuse University
01/07/02Jianchun (JC) Wang2 Event Category The testbeam data will be used to align the telescope. The 450 GeV/c proton beam hits the detector sensor instead of the center of circle. We need interaction events, which benefit the alignment. p Beam p SignalBackground
01/07/02Jianchun (JC) Wang3 Scintillation Trigger ABC Trigger = A C B
01/07/02Jianchun (JC) Wang4 Simulation On Scintillation Trigger MC sample of 120 GeV/c beam at (30, 10) mm (by Tomas Lastovicka). Scintillation counter B (veto): size=20 20mm 2, at 2m downstream from first station. The beam is assumed to be perfect: 0 in size, no dispersion. The scintillation efficiency is 100%. The trigger efficiency is about 50%. With 450 GeV/c proton beam the efficiency will be less. The size of scintillation counter will be decided once we have more realistic beam condition. The rejection rate will be estimated then. The hardware will be provided by Syracuse group. Advantage: hardware, at L0 trigger. Disadvantage: very strict on beam condition.
01/07/02Jianchun (JC) Wang5 Alternative Trigger The number of hits can be used in L1 trigger. Example: Sum of maximum number of R hits per station and maximum number of hits per station is required to be > 20. Same MC sample used. The noise level is about 0.1%. All 21 stations are included. The efficiency is more than 50%. With 450 GeV/c proton beam the effect will be more significant. We can also use hits per sector, or total number of hits of all station and so on. Advantage: simple, not rely on alignment. Disadvantage: strict on common mode noise.
01/07/02Jianchun (JC) Wang6 Vertex Trigger Use vertex trigger, similar to that of official L1 trigger ( see Tomas’ presentation on 07/22/05). The pattern recognition is complicated due to that the tracks are not from the designed beam axis. R/ Z constant Tomas is working on the algorithm. I will implement the algorithm. Currently I am still on the learning curve of LHCb software. Advantage: more close to final trigger; The pattern recognition is needed anyway for analysis. Disadvantage: CPU time, … !!!