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HBD update (general p.e. statistics)

HBD update (general p.e. statistics). Sasha Milov Sept, 25, 2002. Outline. Procedure What does the event look like Blob shape Photoelectron statistics Momentum distribution Entry number distribution ToF distribution What’s next?. Sasha Milov Sept, 25, 2002. Procedure.

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HBD update (general p.e. statistics)

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  1. HBD update (general p.e. statistics) Sasha Milov Sept, 25, 2002

  2. Outline • Procedure • What does the event look like • Blob shape • Photoelectron statistics • Momentum distribution • Entry number distribution • ToF distribution • What’s next? Sasha Milov Sept, 25, 2002

  3. Procedure • HIJING central event (no acceptance cuts) • Using PISA with • HBD in • New Si detector in • Nose cones in • Compensated magnetic field • Existing PHENIX out • Using pisaRootRead • Using “unfolding” of the electron tracks: • Particle tracks is broken into entries to HBD • Photoelectrons are assigned to a particular entry based of ToF. • Remaining problems: • Mylar membranes • ~1% of p.e. are lost in this procedure due to ambiguities entry 2 entry 1 entry 3 entry 4 Sasha Milov Sept, 25, 2002

  4. Where electrons are coming from? s.s. beam pipe? “Direct” electrons Sasha Milov Sept, 25, 2002

  5. What does an event look like? 200 GeV Au-Au central event “unfolded” detector only electrons shown Grey - all electrons Blue - electrons from the vertex Red - first entry Sasha Milov Sept, 25, 2002

  6. Blob shape Red e+Blue e- (0,0) is the particle hit position on HBD Z – unchanged Y – pT dependent No strong hit position dependence Sasha Milov Sept, 25, 2002

  7. Blob shape Blob shape is pT dependent, however, most of particles are localized within 2-2.5cm from the center of the blob Sasha Milov Sept, 25, 2002

  8. Photoelectron statistics Sasha Milov Sept, 25, 2002

  9. Momentum distributions Sasha Milov Sept, 25, 2002

  10. Entry distributions Sasha Milov Sept, 25, 2002

  11. ToF distribution of photoelectrons Cutting here looks very natural. That would require the time measurement in the electronic channels Sasha Milov Sept, 25, 2002

  12. Conclusions & immediate plans • Simulation chain HIJING  PISA  pRR  private code is working and can be further improved: • Tune and use EXODUS instead of HIJING • Verify HBD description in PISA • Get rid of pRR. • Next step is “slow simulator” code. • Segment HBD in pads • Add noise, scintillation, charge particle response • Use some reasonable electronics response function • Relate electronics signals to the initial particles from PISA. • Questions to be answered: • Pad size and shape? • Magnetic field optimization? • What background suppression / signal efficiency can we achieve? • What do we do with less number of photoelectrons? Sasha Milov Sept, 25, 2002

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