Axel Drees, SUNY Stony Brook GSI, May January 15 th 2002 PHENIX Upgrade Plans for RHIC II Overview of baseline PHENIX detector Physics goals of RHIC II upgrades Upsilon spectroscopy Lepton pair continuum  Dalitz rejection Heavy Flavor  Silicon vertex tracking High pt phenomena  particle ID to 10 GeV Timeline for upgrades

Axel Drees The RHIC Accelerator Complex  s RHIC design luminosity (reached in Run 2) 200 GeV Au-Au L ~ 2 x cm -2 s -1 (peak ) 500 GeV p-p L ~ 1 x cm -2 s -1 (~ 1/10) PHOBOS STAR BRAHMS

Axel Drees PHENIX Physics Capabilities l 2 central arms: electrons, photons, hadrons charmonium J/ ,  ’  e  e  vector meson   e  e  high p T       l direct photons l open charm l hadron physics l 2 muon arms: muons “onium” J/ ,  ’,      vector meson      l open charm l combined central and muon arms: charm production DD  e  l global detectors forward energy and multiplicity l event characterization designed to measure rare probes: + high rate capability & granularity + good mass resolution and particle ID - limited acceptance Au-Au & p-p spin

Axel Drees l West Arm l tracking: DC,PC1, PC2, PC3 l electron ID: RICH, EMCal l photons: EMCal l East Arm l tracking: DC, PC1, TEC, PC3 l electron & hadron ID: RICH,TEC/TRD, TOF, EMC l photons: EMCal PHENIX Setup Completed in 2003 l South & North Arm l tracking: MuTr l muon ID: MuID l Other Detectors l Vertex & centrality: ZDC, BBC, MVD Run 1: Au-Au events Run 2: 2002/ Au-Au events Au-Au sampled ~ 10 8 p-p sampled

Axel Drees Beyond the PHENIX Baseline Program l Heavy Ion Physics shift of focus from establishing the existence of QGP and first studies of its properties to systematic study of QCD high T focus on key measurements not or only partially addressed by original PHENIX setup: upsilon spectroscopy, Y(1S), Y(2S), and Y(S3) lepton pair continuum: low mass to Drell Yan heavy flavor high p T phenomena for these measurements the PHENIX central and muon spectrometer are essential but not sufficient !

Axel Drees PHENIX Beyond the Baseline l Spin Physics l gluon spin structure over large x range l heavy flavor l W-Boson l transversity l p-A Physics l parton structure of nuclei l diffractive processes Expected luminosity upgrades at RHIC (RHIC-II) Au-Au L ~ 8 x cm -2 s -1 (x40) O-O L ~ 1.6 x cm -2 s -1 p-p L ~ 4 x cm -2 s -1 (possibly -> 4 x cm -2 s -1 ) Measurement focus on rare processes  requires high luminosity prompt photon cc->eX bb->e  X J/  GS95

Axel Drees Upsilon Spectroscopy l original PHENIX capability: l luminosity upgrade to cm -2 s -1 muon spectrometer: ~ Y central spectrometer:~ 1600 Y north muon arm:  m ~ 190 MeV south muon arm  m ~ 240 MeV 22 week of Au-Au at cm -2 s -1 total of ~ 400 Y decays (~ 1/10 in central arms)

Axel Drees PHENIX Detector Upgrades l central vertex spectrometer l flexible magnetic field l multi layer silicon vertex tracker l TPC/HBD l forward vertex tracking l multiple layer silicon l enhanced particle ID l TRD (east) l Aerogel/TOF (west) l enhanced muon trigger l forward hodoscopes l forward calorimeter l station 1 anode readout l pA trigger detectors l DAQ Vertex Spectrometer

Axel Drees  Luminosity 2 x cm -2 s -1  Interaction rate 1200 Hz  10 weeks run sec  RHIC and PHENIX efficiency 0.25  dN/dy (  o ) per min. bias event 100 m=     Y(e + e - ) per  o (p T > 200 MeV)  pair reconstruction efficiency 0.25  Total yield (10 weeks run)  without trigger Rate and Yield Estimates for Low Mass Dileptons DAQ bandwidth limitation: ~ 330 Hz  events Au-Au pair trigger useful p-ppair trigger mandatory Au-Au collisions at  s NN =200 GeV

Axel Drees Electron ID at low momentum RICH EMCAL E-p matching e/  ~ at lower pt include TOF (400 ps) Electron ID low momentum EMCAL RICH (TOF 500 ps) (C 2 H 6 ) CO 2 Electron ID in PHENIX central arms Acceptance: p t > MeV/c  = 2x  / <  < 0.35 MC simulation (<1997) Au-Au data 2001 E/P ratio all charged with RHIC hit 0.8 GeV <p< 0.9 GeV random background 150 electrons ~90% of background

Axel Drees Experimental Challenge l huge combinatorial pair background due to copiously produced photon conversion and Dalitz decays : need rejection of > 90% of  e + e - and    e + e - l active recognition and rejection of background pairs photon conversion  e + e - Dalitz decays    e + e - false “combinatorial pair” In PHENIX: combinatorial background factor > 250 larger than signal Note:  and  can be measured due to excellent mass resolution charm contribution is significant

Axel Drees e+e+ e-e- TPC/HBD e-e- e+e+    Strategy for Low Mass Pair Measurement l Low inner B field to preserve opening angle with rough momentum measurement l Identify signal electrons (p t > 200 MeV) in outer PHENIX detectors l Identify low momentum electrons (pt < 200 MeV) using Cherenkov light in Hadron Blind Detector (HBD) and/or dE/dx from TPC Measure momentum with TPC (few %  p/p) Use cuts on opening angle (or  < 350 mrad) and on invariant mass (m < 140 MeV) to reject background need rejection of > 90% of  e + e - and    e + e - l active recognition and rejection of background pairs Opening angle not so small at collider need e-ID to use opening angle background pairs have low mass and small opening angle 

Axel Drees Without Dalitz rejection S/B ~ 1/7 Assume for inner detector perfect electron ID (  e = 100%) perfect  rejection perfect double hit resolution S/B ~ 10 Effect of increased acceptance “veto region” : |  |< 0.40  < 100 o S/B ~ 30 Include: double hit resolution open charm contribution S/B ~ 1-3 Opening angle cut Principle Monte Carlo Simulation Efficiency - background rejection in  mass range (20 MeV bin) + additional rejection from mass cut

Axel Drees Drift regions HV plane (~ -30kV) TPC Readout Plane ~50000 channels Readout Pads  R ~ 1 cm r  ~ 2 mm CsI Readout Plane channels GEM TPC/HBD Strawman Design CF 4 or CH 4 drift gas radiator gas detector gas High rate capability: drift-time ~ 4  s Need to develop integrated electronics

Axel Drees Monte Carlo Simulation of Hadron Blind Detector 100 MeV electron ~ 20 photo electrons 4 cm Central Au-Au collision dN/d  ~ layers of silicon vertex detector N e ~ 25 for one arm ~ 130 charged particle single hits not shown 2/3 of one arm single 100 MeV electronxs

Axel Drees GEM Performance Studies R&D effort at BNL/Weizmann: Study GEM performance design TPC readout plane develop readout electronics develop CsI photo-cathode design HBD readout plane develop readout electronics B.Yu, UWG, 4/16/02 excellent spatial resolution Ar C0 2 70/30 E d ~200 V/cm E i ~4 kV/cm E t ~4 kV/cm  V G1 ~ 260 V  V G1 ~ 440 V

Axel Drees open charm production from inclusive electrons A high precision vertex detector will allow a clean separation of charm and bottom decays m c   eX GeV  m % D  6.75 D ±  17.2 B  5.3 B ±  5.2 Need secondary vertex resolution ~  m Charm and B Decays

Axel Drees Pixel barrels (50  m x 425  m) Strip barrels (80  m x 3 cm) Pixel disks (50  m x 200  m) e dca D eX primary vertex c  0 = 125  m c  ± = 317  m 1.0% X 0 per layer 500 mm Be Beam Pipe 1.2<|  |< 2.4 |  |< 1.2 Proposed Silicon Tracker in PHENIX

Axel Drees GEANT Without cuts on displaced vertex l S/B ~ 1 for high-pt l S/B ~ 0.1 p T = 0.5 GeV/c S/B improves to > 10 for p T > 1 GeV/c with DCA cut ~ 100  m Signal/Background with DCA cut

Axel Drees Technology Choices for Silicon Vertex Tracker l Silicon Strips l Prototype development at BNL l readout electronic options ABCD chip (ATLAS) SVX4 chip (Fermilab) AP6 (CMS) …. l Hybrid Silicon Pixel l adapt ALICE (NA60) readout chip l R&D collaboration with NA60/ALICE (two postdoc’s at CERN) l sensors for NA60 being developed at BNL l Monolithic active pixels l Lepsi, LBL (STAR), Iowa State l longer time scale target date for silicon barrel:

Axel Drees Silicon Strip Sensor Development l Prototype development at BNL 80  m x 3 cm strips l 2x 375 strips l stereoscopic projections 80  m x 1 mm effective strip size l readout on both sides l 1500 channels l Tests this summer/fall

Axel Drees Completion of Baseline Detector Install North Muon Spectrometer Upgrade TEC to TRD Silicon strip detectors Prototype silicon pixel detector Prototype HBD (upgradable to TPC) Prototype aerogel detector Complete silicon pixel detectors Complete TPC/HBD Complete aerogel detector R&D presently supported by various institutional funds (LDRDs,RIKEN) requires ~ 3-4 $M over 3-4 yrs needs DOE funding to continue Construction Staged approach, with detectors requiring less R&D to be implemented first Rough estimate of detector construction costs ~ $10-15M NSAC plan shows $80M in RHIC II detector upgrades over 7 years starting in FY05 Time Scale and Cost