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Explore Sasha Milov's research on photoelectron statistics, momentum distribution, and entry number distribution in event analysis. Understand blob shape, ToF distribution, and future plans for simulation and improvement.
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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 • 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
Where electrons are coming from? s.s. beam pipe? “Direct” electrons Sasha Milov Sept, 25, 2002
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
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
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
Photoelectron statistics Sasha Milov Sept, 25, 2002
Momentum distributions Sasha Milov Sept, 25, 2002
Entry distributions Sasha Milov Sept, 25, 2002
ToF distribution of photoelectrons Cutting here looks very natural. That would require the time measurement in the electronic channels Sasha Milov Sept, 25, 2002
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