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Systematic studies of RICH ring finding

Systematic studies of RICH ring finding. Semen Lebedev GSI, Darmstadt, Germany and LIT JINR, Dubna, Russia Claudia Höhne GSI, Darmstadt Gennady Ososkov LIT JINR, Dubna, Russia. Many innovations were done for ring finder.

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Systematic studies of RICH ring finding

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  1. Systematic studies of RICH ring finding Semen Lebedev GSI, Darmstadt, Germany and LIT JINR, Dubna, Russia Claudia Höhne GSI, Darmstadt Gennady Ososkov LIT JINR, Dubna, Russia

  2. Many innovations were done for ring finder. Ring finder was optimized in terms of calculation time and fake ring rate. Robustness of HT was investigated. Introduction

  3. Ring finding efficiency for embedded electrons 5e- and 5e+ were embedded in each event to enhance statistics Au-Au 25AGev central Au-Au 25AGev mbias Nof fakes / event = 3.5 Nof clones / event = 0.9 scalar version – 5 ms / event parallel version –3 ms / event Nof fakes / event = 0.3 Nof clones / event = 0.2 scalar version – 1 ms / event parallel version –0.6 ms / event 2 x Intel Xeon X5550 at 2.67GHz (8 cores)

  4. Collection efficiency of the photodetector (I) Due to the photodetector H8500 construction, collection efficiency can be up to 70% 21 13 Au-Au 25AGev central plus 5e+ and 5e- average nof hits/electron ring Ring finding efficiency for embedded electrons

  5. Efficiency vs. additional error to hit • Mirror resolution • WLS coverage Xhit = Xhit + Gauss(0, sigma) Yhit = Yhit + Gauss(0, sigma) Expectation for CBM mirror • Compact RICH, • NO WLS, • 100% collection efficiency for σ = 0.6 cm, efficiency = 85%, nof fakes = 7.3/event

  6. Efficiency vs. nof rings per event (I) electrons with parametersθ = (2.5, 25), ϕ = (0, 360), pt=(0,3) Part of event with 150 rings: test of ring finder

  7. Efficiency vs. nof rings per event (II) electrons with parametersθ = (2.5, 25), ϕ = (0, 360), pt=(0,3) Ring finding efficiency for embedded electrons

  8. Efficiency vs. nof of noise hits per event Noise hits were added with uniform distribution expected value Ring finding efficiency for embedded electrons

  9. Event parallelism

  10. Event parallelism Hough Transform Au-Au 25AGev central Thread1 – Thread2 -> Core1 …. Thread15 – Thread16 -> Core8 2 x Intel Xeon X5550 at 2.67GHz (8 cores)

  11. Event parallelism, Hough Transform Au-Au 25AGev mbias Thread1 – Thread2 -> Core1 …. Thread15 – Thread16 -> Core8 2 x Intel Xeon X5550 at 2.67GHz (8 cores)

  12. Hough Transform ring finder has shown very good robustness to different RICH layout parameters If required it can be tuned for a specific RICH layout parameters set Event parallelism for ring finder was investigated Hough Transform throughput for CENTR: 1 thread = 200, for 16 threads = 1885, gain factor = 9.4 (8 cores) MBIAS: 1 thread = 950, for 16 threads = 7650, gain factor = 8.2 (8 cores) Summary

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