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Direct Gamma Study in NCC

Explore gamma-jet problem, isolation cut challenges, gamma-pi0 separation, simulation accuracy, tracking optimization, hadron rejection. Collaboration insights and setup modifications discussed.

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Direct Gamma Study in NCC

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  1. Direct Gamma Study in NCC Strips distribution for single gamma in geant3 (schematic view) • Had some initial meetings with Itaru and Edouard • Was very constructive, but we’re all very busy so it would be helpful if we could maybe find a student • Recap: The problem with direct gamma A_LL and gamma-jet (with gamma in the NCC) is that the background was too high • The isolation cut didn’t seem to be as effective as the central arm. • Without a spectrometer in front and with a thin calorimeter, there is a fundamental limit to how well an isolation cut can work since charged hadrons often just punch through • At relatively low pt (5 GeV) the pi0’s merge and look like gammas – In central arm the partner gamma to the pi0 helps to veto pi0’s but not in the NCC • We will continue to explore the space of cuts, which is multi-dimensional. • More IMPORTANTLY, we want to help Edouard with solving the pi0/gamma separation using the strips. • Fluctuations are very large, up to 3-4 times the signal. • Is the simulation correct, or is there some issue in the implementation? • Is the reconstruction properly done? • If both correct, then it might be that there is a simple algorithm to separate pi0/gamma, but most likely we’ll have to go to a principle components analysis or neural network. x1 y1 x2 y2

  2. VTX, FVTX, NCC in PISA SVX • Was drawing pictures to make sure things were working when the disks went to hell last night • Have some vague idea how to do the tracking • Dave W. et al have been doing studies for optimizing the FVTX design, and have tracking with the mutoo Kalman filter going. • Still a bit rough, eg, they use smeared VTX positions from the pisa hits info. • Put in a GEM for a 50 um hit position in inner radius of NCC, want to extend the acceptance = NEW PHYSICS (should separate this out as a different project). Requires NO HAD section. • Want to study region of good sign determination using full simulation (measuring deflection on NCC is better than sagitta) • Actual background rejection using full simulation • Charged Hadrons • Pi0 dalitz, conversions, pi0+overlapping track • Time scale: hoping for 2-4 weeks

  3. Changes to Standard Pisa Here’s what I did to get PISA working with the VTX, FVTX, and NCC • Used the setup from run7, and taking files from simulation/pisa2000/wrk • Modified pisa.kumac • The CUTS line to have lower cutoffs for particles • Does this affect the reconstruction? • Removed the NOSE entry, changed the PIPE to PIPN • Using Sim3D++ • Enabled SVX and NCC only • Might have to smear vertex according to expected resolution? • Modified phnx.par • None so far… maybe need to change some parameters • sili_endcap_strip_on = 1 to make fvtxgeom.root for offline reco • sili_endcap_config =1 (1=new geom, 2 and up = old geom) • Anything else?

  4. Don’t underestimate the W • RIKEN originally joined RHIC to do the W measurement – paid for south muon arm • Recently, $6.6 million was spent to JUST do the W • $2.3 million for RPC in PHENIX • $2.3 million for Mutr FEE upgrade in PHENIX • $2.0 million for Forward Gem Tracker in STAR • NCC can do W plus MUCH MORE

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