Check of Lambda Simulations in TOF-West Charlie Maguire 7/21/09 Group Meeting

Goals, Plans, and Methods for Lambda Simulations Check for strange backgrounds using HYDJET events Centrality dependence of backgrounds (next slide for real data anomaly example) Search for any cut improvements using simulated combinatoric backgrounds Plans Generate 100K central HYDJET events (0 – 5%) Embed Lambda events into the HYDJET input stream in order to have a sufficient number simulated Lambda at high transverse momentum Evaluate the Lambda reconstruction using the same cuts in simulation as were used in the real analysis Methods (all software tools do exist except CONDOR production macros) Use latest (July 25) version of HYDJET which has fixed the “repeat” bug Filter HYJDET generated events according to psuedo-rapidity cut from -0.6 to +0.6 and then add Lambda events producing output OSCAR files (event size TBD) PISAEvent files analysis uses anctfw2.root NTUPLE (pisaRootRead correlations) simDST.root files analysis uses simDSTCheck.root and simDSTCheckPairs.root Produced by the simDSTCheck.so library which uses the real data analysis cuts 7/21/09 Group Meeting

Goals, Plans, and Methods for Lambda Simulations Anomalous Peak at Low Mass in Most Central Bin Dillon’s Result from Taxi 143 for 7-9 GeV/c pT Bin Reported to Group on March 19 7/21/09 Group Meeting

pisaRootRead Analysis To Determine Acceptance Efficiency for Lambda Embedding Lambda generation 1) pT 0 to 10 GeV/c 2) -0.4 to + 0.4 eta 3) -15o to +35o in f Require detection of proton in TOF-W Sister p- must be seen somewhere 1) At least DC/PC1 2) Perhaps PC2? Maximum efficiency = 1515/33000 = 4.5 % Sets requirement on the embedding multiplicity 7/21/09 Group Meeting

Is there a slight drop in simDSTCheck Single Particle Analysis Evaluate correctness of TOF-West reconstruction Use time and path-length corrections from Shengli 20K proton events Same vertex kinematics as 33K L events 33K L events Kinematics on slide 4 Single particle detection only No sister particle cut Maximum pion momentum < 3 GeV/c for this set of L Is there a slight drop in proton mass towards higher momentum? 7/21/09 Group Meeting

simDSTCheck Single Particle Analysis Evaluate correctness of TOF-West reconstruction Use time and path-length corrections from Shengli 33K L events Kinematics on slide 4 40K pion events Same vertex kinematics as 33K L events Single particle detection only No sister particle cut Maximum pion momentum < 3 GeV/c for this set of L 7/21/09 Group Meeting

simDSTCheck Single Particle Analysis Evaluate correctness of TOF-West reconstruction Use time and path-length corrections from Shengli 200 central HYJDET++ events Events had weak-decay off New PISA particles (no geantinos) Eta from -0.6 t0 +0.6 Repeated particles removed Can clearly see the three mass bands Some background between kaon and proton bands Pion band appears to have some extra shoulder? The simDSTCheck.root has “MC truth” information which we can use to diagnose these extra features 7/21/09 Group Meeting

“Pion” is any negative in the West Arm simDSTCheck Reconstructed Pair Analysis Evaluate correctness of TOF-West pair reconstruction Use time and path-length corrections from Shengli Reconstructed pairs from 33K L events Proton is 0.6 to 1.2 in TOF-West m2 “Pion” is any negative in the West Arm with DC quality as 31 or 63 Same cuts as for 33K L events The green blip are the 16 true L determined from the MC “truth” data 7/21/09 Group Meeting

Next Steps To be added 7/21/09 Group Meeting