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The J/ Y and f Trigger

The J/ Y and f Trigger. Takashi Matsumoto ( CNS ) Kenta Shigaki ( KEK ) at PHENIX Heavy/Light PWG meeting on June 8, 2000. Outline. Recent EMCal trigger threshold issue Efficiency and rejection power of various trigger schemes RICH only (double)

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The J/ Y and f Trigger

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  1. The J/Y and f Trigger Takashi Matsumoto (CNS) Kenta Shigaki (KEK) at PHENIX Heavy/Light PWG meeting on June 8, 2000 T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  2. Outline • Recent EMCal trigger threshold issue • Efficiency and rejection power of various trigger schemes • RICH only (double) • RICH + EMCal with overlapping 4x4 tile (single) • RICH + EMCal with non-overlapping 2x2 tile (single) • Comparison of look-up schemes • Conclusions T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  3. Recent EMCal Trigger Threshold Issue • Problem with overlapping 4x4 sum • Hardware lower limit is > 5 % of full scale (ref. P.Stankus) • > 1 GeV in A+A and 200 GeV p+p • Too high even for J/Y trigger • Other options • RICH only (if possible…) • Non-overlapping 2x2 sum T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  4. Simulation Conditions • VRDC data set • 60 K single J/ Y →e+ eー events • 54 K single f → e+ eーevents • 200 K minimum bias p+p events • RICH trigger threshold is tuned • Both 2x2 and 4x4 EMCal trigger tiles are studied • Look-up methods • 16 bits (RICH) +16 bits (EMCal) • simple half sector coincidence between RICH and EMCal • 256 bits (RICH) + 172 bits (EMCal) table by D.Galanakis and W.Xie • tuned for > 0.2 GeV/c particles T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  5. Possibility of RICH Only Trigger ? • Threshold • Set at 3 photo-electrons in a 4x5 trigger tile • Efficiency • Nearly flat • Single ~ 99 % • Double ~ 90 % • Rejection Power against min. bias p+p • Single : 25 • Double : 80 1.0 Trigger Efficiency J/Y f 0.5 0 0 4 8 T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  6. Threshold Requirement of RICH +EMCal Trigger for J/Y and f (4x4 Sum , 2x2 Sum) 1.0 • 16 bits + 16 bits matching • Single electron trigger • Plots • Trigger efficiency as a function of pt of J/Y and f • Dotted line shows 90% efficiency • Threshold requirements 0.6 GeV 0.9 GeV 1.2 GeV J/Y : 4x4 J/Y : 2x2 0.5 8 8 1.0 0.15 GeV 0.3 GeV 0.45 GeV f : 2x2 f : 4x4 0.5 0 4 0 4 pt [GeV/c] T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  7. Rejection Power against p+p Minimum-Bias Events • 16 bits +16 bits matching • Single electron trigger • RICH + EMCal 4x4 sum • Rejection ~ 103 at0.7 GeV • RICH + EMCal 2x2 sum • Rejection ~ 103 at0.5 GeV • To trigger on J/Y • Both scheme are okay • To trigger on f • Marginal rejection power • Some pre-scaling may be needed Blue : 2x2 Red : 4x4 Black : RICH only (Double) T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  8. Comparison of Look-Up Schemes • Compared look-up tables • 16 bits + 16 bits (half sector) matching • 256 bits + 172 bits look-up by D.Galanakis and W.Xie • Single electron trigger • EMCal 4x4 and 2x2 trigger tiles T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  9. T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  10. Comparison of Look-Up Tables (4x4 Sum) 1.0 Blue 16bits +16 bits Red 256bits +172 bits 0.6 GeV Rejection Power Trigger Efficiency 0.9 GeV 1.2 GeV 16 bits+16 bits 256 bits+172 bits 0.5 8 0 8 0 J/Y pt [GeV/c] T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  11. Comparison of Look-Up Tables (2x2 Sum) x10 1.0 Blue 16bits +16 bits Red 256bits +172 bits 0.6 GeV Rejection Power Trigger Efficiency 0.9 GeV 1.2 GeV 16 bits+16 bits 256 bits+172 bits 0.5 0 8 0 8 J/Y pt [GeV/c] T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

  12. Conclusions • RICH only trigger does not provide sufficient rejection, even when 2 “rings” are required • EMCal 4x4 sum cannot be used to trigger on J/Y or f with the present hardware • EMCal 2x2 sum is a promising alternative • 16 bits +16 bits half sector matching works just as well as 256 bits +172 bits full look-up T.Matsuoto and K.Shigaki at PHENIX Heavy/Light PWG meeting

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