1. L1 Trigger for ACDC Jianchun (JC) Wang Syracuse University VELO ACDC Software Meeting 01/20/2006

2. 01/20/06Jianchun (JC) Wang2  L0 scintillation counter (prime trigger):  Can be used either on straight through track (by moving counters) or on interaction.  Rates can be varied by changing either hole size (2 available) or moving along beam.  L1 software trigger: 1)Number of hits trigger:  No requirements on alignment information.  Requires stability and low noise. 2)Vertex (backup to number of hits trigger):  No strong requirement on beam condition, less dependent on noise performance.  Require alignment information, may bias the alignment study. Signal: interaction Bkg: straight-through Trigger for ACDC

3. 01/20/06Jianchun (JC) Wang3 L0 Scintillation Trigger Trigger 1 = A 0  (A 1  A 2 )  (B 1  B 2 ) efficiency~90% Trigger 2 = A 0  ((A 1  B 2 )  (A 2  B 1 )) efficiency~60% B1B1 A2A2 A1A1 B2B2 A0A0  The scintillation counters are being constructed at Syracuse.  Two pairs of B type with different sizes of hole (5  5cm 2 and 3  3cm 2 ) are made to incorporate beam size.

4. 01/20/06Jianchun (JC) Wang4 Number of Hit Trigger (I)  Requires that the sum of maximum number of R hits per station and maximum number of  hits per station be at least 20.  The noise level is about 0.1%. Only first 10 half stations are used. The selection efficiency is ~50%. Essentially no bkg is selected.  It favors events with more tracks, which is consistent with our goal.  It also keeps events with interaction happened at the last stations. signal bkg Signal selected Signal rejected

5. 01/20/06Jianchun (JC) Wang5 Number of Hit Trigger (II)  Requires that total number of hits of all 10 stations be at least 100.  The noise level is about 0.1%. Only first 10 half stations are used. The selection efficiency is ~67%. No bkg is selected.  It favors events with more tracks, and interactions happened at the beginning of the telescope. signal bkg Signal selected Signal rejected

6. 01/20/06Jianchun (JC) Wang6 II. Total number of hits I. Nhit(R) max +Nhit() max More on Number of Hit Trigger  The two triggers are correlated, although not fully. Both favor more tracks in the event.  Currently I keep both in the trigger: 51%  67% = 71%.  Noise simulation in MC might be too ideal. Different stations have different noise performance. A calibrated noise level will be subtracted.  If the noise level is much higher than 0.1% we can use hits with higher pulse height for trigger only.

7. 01/20/06Jianchun (JC) Wang7 Status  Code runs under DaVinci as a normal analysis program.  Need to modify the code to have trigger interface.  The CPU time will be measured. More MC data may be needed.