1. K. Barish UC Riverside 7 Oct. 2000 Spin PHYSICS at PHENIX with a Central Arm Trigger Kenneth N. Barish For the PHENIX Collaboration UC Riverside DNP’2000, Oct 2000

2. K. Barish UC Riverside 7 Oct. 2000 PHENIX Spin Physics Channels Physics Process Trigger Direct Photon asymmetries O. Heavy flavor W-production asymmetries EMC, h.T. EMC*RICH, l.T. EMC, h.T. EMC, l.T., Mul. asymmetries EMC, l.T. Mul. Trigger bias EMC, RICH pre-scaled Physics Process Trigger Heavy flavor W-production Mu-Id based Trigger bias Mu-Id pre-scaled Central Arms Muon Arms

3. K. Barish UC Riverside 7 Oct. 2000 Heavy Flavor Spin Physics Tag as: single e, e-mu, e-D coincidence Most Events Below 2 GeV! Heavy Flavor Production: Fraction of Events above Threshold 10% 50% Electron Momentum [GeV] 2 GeV

4. K. Barish UC Riverside 7 Oct. 2000 Heavy Flavor Spin Physics A LL Stat. Error 0.031 0.014 0.012 0.014 0.017 GS-A GS-C GS-B Simulations performed by W. Xie and H. Sato Single e ee

5. K. Barish UC Riverside 7 Oct. 2000 Charged Pion Asymmetries Trigger Requirements: Jets with high z pions: o High EMC Multiplicities at low threshold o RICH hit Simulations performed by Y. Goto

6. K. Barish UC Riverside 7 Oct. 2000 Transversity Measurement Trigger Requirements: Jets with high z pions: o High EMC Multiplicities at low threshold o RICH hit Projected Asymmetry Statistical errors only Talk by M. Grosse Perdekamp K. Barish UC Riverside 7 Oct. 2000

7. K. Barish UC Riverside 7 Oct. 2000 The PHENIX trigger was designed for Heavy Ions: »For Heavy-Ion, data reduction done in Level-2 »But in proton-proton interaction rate will be high »Expected Level-1 DAQ Bandwidth is 12kHz »Need to be shared among 10 different physics channels –A rejection factor of 10,000 is needed in Level-1 to fully utilize beam Triggering Needs

8. K. Barish UC Riverside 7 Oct. 2000 EMCal/RICH Trigger EMCal and RICH detectors can be used to form a powerful central arm electron and hadron trigger

9. K. Barish UC Riverside 7 Oct. 2000 Electron Trigger Rejection Powers 2x2 Tiles: Different Granularity RICH alone EMC alone Simulations performed by D. Galanakis (see his poster) and W. Xie

10. K. Barish UC Riverside 7 Oct. 2000 Multiplicities Rejection Power Efficiencies Bias in z Triggering on Hadrons Simulations performed by B. Lillie (see his poster) and W. Xie

11. K. Barish UC Riverside 7 Oct. 2000 Summary A Central Arm Trigger is Needed for Spin Physics »EMCal trigger makes possible: –Gluon Polarizations measurements in direct  and  0 production (Yuji Goto’s talk) –Flavor Decomposition from W decay (Naohito Sato’s talk) »EMCal combined with RICH via FPGA adds: –Gluon Polarizations measurements in open heavy flavor – single e, e , and eD (Wei Xie’s talk) and charged pion production (Yugi Goto’s talk) –Transversity (Matthias Grosse Perdekamp’s talk)