Ring finding efficiencies and RICH event display Semeon Lebedev GSI, Darmstadt and LIT JINR, Dubna Gennady Ososkov LIT JINR, Dubna X CBM collaboration meeting Dresden, 27 September 2007

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Contents Systematic studies of RICH Ring finding efficiencies –Improvements: Hough transform ring finder was rewritten and optimized for Hamamatsu PMT. Selection routine was tuned for this PMT. –Simulation parameters –Efficiency with Hamamatsu PMT –Efficiency and beam energy –Efficiency vs number of noise hits –Efficiency and magnetic field –Compact RICH Event Display –Introduction, requirements –Screenshots

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Simulation parameters 5000 central Au-Au collisions at 25, 15 and 35 GeV and 5e+ and 5e- in each event Cbmroot august 2007 Muon and Active B-field L1 STS track finder and KF extrapolation Standard RICH geometry: - N 2 radiator - Hamamatsu H flat panel MAPMT TAU radius fit and ring radius correction for geometrical distortions Ring-track assign by closest distance approach Hough Transform ring finder Ring quality selection cut using ANN > -0.5

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency definition, hit density Efficiency will be shown in Efficiency will be shown in dependence on radial position, so keep in mind that hit density strongly depend on radial position. Mean size of the single Mean size of the single channel is 0.6x0.6 cm 2.

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency standard RICH layout Efficiency, % Matching eff., % Fakes per event 0.75 Clones per event 0.12

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency and beam energy[1] Beam energy, GeV Efficiency, % Matching eff., % Fakes per event Clones per event

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency and beam energy[2] Decrease of efficiency with energy due to increased hit and track density in the center of PMT plane.

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency vs. number of noise hits[1] Hamamatsu H flat panel MAPMT: Dark current 0.1 nA/channelDark current 0.1 nA/channel Gain 1.5*10 6Gain 1.5* ns time window for one event10 ns time window for one event Negligible number of hits from thermal noise (~10 -5 per channel) Other background sources will dominate

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency vs. number of noise hits[2] Number of noise hits per event % of # of PMTs Efficiency, % Matching eff., % Fakes per event Clones per event

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency and magnetic field[1] Active B-field Muon B-field ActiveMuon Bx integral, Tm 0.17* By integral, Tm 0.7* *10 -2 Magnetic field shown in range of RICH detector.

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency and magnetic field[2]FieldActiveMuon Efficiency, % Matching eff., % Fakes per event Clones per event

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Efficiency and magnetic field[3] ActiveMuon Mean, cm Sigma, cm 0.26 (4%) 0.33 (5%) Slight loss of ring radius resolution for Muon field due to larger field integral in RICH.

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Compact RICH Nof fakes = 10 per eventNof fakes = 10 per event RICH event is shown in the figure.RICH event is shown in the figure. Many RICH rings look like ellipses, especially in theMany RICH rings look like ellipses, especially in the outer part of the PMT. outer part of the PMT. Will be improved with optimized position of PMT plane.Will be improved with optimized position of PMT plane. With improved geometry and ring/ellipse fitting same performance expected as for standard RICH.With improved geometry and ring/ellipse fitting same performance expected as for standard RICH.

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Event display, introduction and requirements 3D view of the detectors3D view of the detectors Tracks visualizationTracks visualization Points, hits visualizationPoints, hits visualization Rotation, zoomingRotation, zooming 2D view of the tracking detectors stations and RICH PMT2D view of the tracking detectors stations and RICH PMT GUI interfaceGUI interface Other requirements will come during the event display developmentOther requirements will come during the event display development QT4 for GUI + ROOT and CbmRoot libraries for reading data filesQT4 for GUI + ROOT and CbmRoot libraries for reading data files

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Event display, screenshot

RICH Ring Recognition X CBM Collaboration meeting, Dresden, 27 September 2007 S. Lebedev and G.Ososkov Summary Hough Transform ring finder and selection algorithm were optimized and tested and showed good results. Efficiency is roughly 90% and fake rate is about 0.7 ring per event. Efficiency and number of fakes strongly depend on hit density. For a noise hit level < 1% of the number of channels negligible effect on efficiency observed. Due to larger hit density with increasing beam energy efficiency slightly drops and fake rate and mismatches increase. The difference in efficiency between Active and Muon field is negligible. Compact RICH geometry needs to be tuned, may be need for ellipse fit algorithm, after optimization the same performance is expected as for standard RICH. First Qt4 version of RICH event display is ready.