MINUTES OF THE SLT-INTERNAL MEETING (APR 26 2000) ================================================= T E R E S A : 1) JPSI efficiency studies on MC-events Teresa+Vitaly have optimized the J/Psi->mu+mu- trigger efficiency using MC-DAQIF events. *The efficiency vs RoI-Size was studied, which lead to the following preferred RoI settings: X1_min: 24cm Y1_min: 3.9cm X2_min: 2cm Y2_min: 9.1cm *The minimum number of required Slicer hits was optimized to 15. *The J/Psi->mu+mu- efficiency using these settings is now 10% without including the SLT-tracking algos (SLT-MUON only), and 8% when Slicer/Refit are added. The efficiency has increased by a factor of 2.5 since last report (test performed by Brian) because a cut on the number of requested hits in the MUON-SLT code was loosened. It is still a factor 3 lower than the expected number from the geometrical acceptance (the MUON digitization could be an explanation). Clearly the background rate is also increased by loosening the request on the minimum number of hits in MUON-SLT. Note that the difference between SLT-MUON-ONLY and SLT-MUON+SLICER+REFIT is of about 20%, which is not too far from the expected efficiency-drop due to the ITR hole. So at first glance, the Slicer/Refit efficiencies are already high, without a deep optimization work. 2) Offline MUON-SLT BACKGROUND studies: *The measured background rejection on a MUON-PRE-TRIGGER run, combining SLT-MUON+SLICER+REFIT in SLP-emulation mode is ~150 (==0.67% efficiency) *The MUON-SLT code has now an additional cut on the minimum distance between hits (>1cm in X and Y), because of a probable Pre-Trigger bug which creates double-pad-singnals for a single hit. 3) ONLINE MUON-SLT studies: *The measured background rejections are Slicer: 5 RefitX: <2 RefitY: 8 *The number of J/Psi->mu+mu- candidates observed in the Invariant Mass region around the J/psi mass is discrepent (== inexistant!) compared to MC-expectations, by at least an order of magnitude. (Run 14907: 1h45, 4MHz, flat invariant mass plot near JPSI mass). This discrepancy could be explained via a problem in the Online Hit-request in the SLT, or maybe via an alignement problem (see next points) -------------------------------------------------------------------------- P E T E R : 1) check of SLT-hits: A run was taken ealier (14951) with the SLT-sections in transparant mode (== all SLT-MUON events accepted in the rest of SLT, and SLT-record in output flow). The SLT-hits from the first file of this run were compared to ARTE-hits in the same RoI. The agreement is >98% for 0-stereo view. The 2 missing % have to be analyzed, and the same analysis will be performed on the stereo-layer hits. 2) SLT-alignment *The l2geo file using OTR-alignment constants seems to be wrong what the Silicon is concerned. To be checked and re-produced. ------------------------------------------------------------------------- B R I A N : Brian has worked on the JPSI->mumu optimization as well (see points above). He will generate: - MC-DAQIF JSPI->mu+mu- file with mask included in the OTR-digitization, in order to get a realistic expectation from data. - Same for the JPSI->e+e- channel -------------------------------------------------------------------------- L A R S : *The DAQif tool now allows to include MC-truth information. All fields suggested by Reinhard Eckmann have been implemented, except for the parent-id information. Only the first mimp on each superlayer-hit is kept. *Lars will write functions to decode the MC-truth messages (to be used in a demon, or in the SLP-code. --------------------------------------------------------------------------- This week's plans in the SLT: ============================ => MU-Pre-Trig + MUON-SLT ONLINE with new code + Slicer/Refit; hope for a JPSI ! => if ECAL ready, go for JSPI->e+e- production in order to have a nice Jpsi for next week (PRIORITY !)