1. Extending the PHENIX physics reach Physics beyond the baseline accessible at RHIC II Capabilities needed to address the new physics Detector upgrades to acquire these capabilities S. Aronson, BNL October 28, 2000 PHENIX Upgrade Plans

2. 10/28/00S. Aronson RHIC Planning Workshop 2 Disclaimers No discussion of completion of the “baseline,” including the full Muon System (covered in W. Zajc’s talk yesterday) No discussion of bandwidth and trigger enhancements* needed to keep up with beyond-the-blue-book luminosity, or of potential “performance upgrades.” No discussion of specific designs, costs and schedules* important  These are important, but for later.

3. 10/28/00S. Aronson RHIC Planning Workshop 3 Physics with baseline++ Low-mass dileptons from   Dalitz to J/  –Enhanced production (or medium modifications) 200 < m ee < 600 MeV/c 2 –Thermal radiation of pairs,1 < m ee < 3 GeV/c 2 Issue is combinatorial background –Dalitz and conversion electrons

4. 10/28/00S. Aronson RHIC Planning Workshop 4 Physics with baseline++ Heavy flavors –Enhanced charm production –B, W production Issues –tracking performance coverage, vertexing extend capabilities beyond single lepton spectra and e-  –high p T electron ID e/   10 -3 RICH sees  ’s at p > ~5 GeV/c h/  overlaps

5. 10/28/00S. Aronson RHIC Planning Workshop 5 Physics with baseline++ Enhanced photon capabilities – inclusive and single  spectra down to p T < 1 GeV/c –  /  0 separation at p T > 20 GeV/c Issues –conversion and background  ’s –shower shape Preliminary study of conversion photons with current PHENIX data

6. 10/28/00S. Aronson RHIC Planning Workshop 6 Physics with baseline++ Jets –  + jet,  0 + jet, jet + jet – Spin and H.I. programs both benefit from better jet acceptance Issue is tracking coverage in  pA physics at small x –D-Y and J/  vs. A down to x 2 ~ 10 -3 more on pA for the next 1.5 days Issue is acceptance at small angles for tagging

7. 10/28/00S. Aronson RHIC Planning Workshop 7 Summary of needed upgrade capabilities To go beyond the (broad and unique) PHENIX baseline program we need: –better combinatorial background rejection, especially for electrons and  ’s –better ( ,  ) acceptance for tracking –additional electron ID redundancy above the RICH  threshold –better  /  0 separation at the highest p T –forward tagging for better x-coverage Detector implementations do not necessarily map 1:1 onto these needs:

8. 10/28/00S. Aronson RHIC Planning Workshop 8 Detectors to address these needs Inner tracking/Dalitz rejecter –“hadron blind” (or purblind?) –significant R&D done by PHENIX (USB) a few years ago workshop next March –full-azimuth, bigger  Uses an additional inner coil in the Central Magnet that was foreseen in the original design. RICH DCH HBD Inner Coil

9. 10/28/00S. Aronson RHIC Planning Workshop 9 Detectors to address these needs EMCal pre-shower –augmented pixelation, vectoring –will also improve high p T momentum resolution outside TEC aperture (I.e., west arm) Forward tagging –ZDC (neutrons) –Roman pots (charged) –will get more discussion at pA Workshop (next)

10. 10/28/00S. Aronson RHIC Planning Workshop 10 Detectors to address these needs TRD upgrade to the Time Expansion Chamber –provided for in the TEC design –well-studied in test beam prototypes –also improves eID for 0.25<p T <2.0 GeV/c via enhanced dE/dx   (%) pp

11. 10/28/00S. Aronson RHIC Planning Workshop 11 Summary, outlook (and RHIC)The physics addressed is a qualitative addition to the PHENIX (and RHIC) program –low mass e-pairs enhanced production or medium effects, m ee < m  thermal radiation, m   <  m ee < m J/  –open charm, B, W production high p T leptons, precision vertexing –extended direct photon, jet capability single  spectra down to p T < 1 GeV/c ,  0 (  /jet) up to p T >> 20 GeV/c increased charged particle tracking acceptance –low-x coverage for QCD in pA

12. 10/28/00S. Aronson RHIC Planning Workshop 12 Summary, outlook These are known physics topics of interest; they merely require more detector performance, more luminosity or both. Some detector choices could provide enhanced capability of more than one kind (e.g., inner tracker)  design optimization Some technologies need further development (e.g., HBD)  R&D program (starting soon) The open geometry of PHENIX makes these and other upgrade paths possible.