STAR Future Physics and Upgrades Planning Working Group

1. STAR Future Physics and Upgrades Planning Working Group • Chairs: R. Majka (Yale), S. Vigdor (Indiana U.) • Initiated in Feb. 2003: • refine the upgrades plan and the physics case supporting it • back it up with relevant simulations • define the implications for physics-driven requirements on the upgraded subsystems • monitor progress on the upgrade designs to ensure they will satisfy these requirements • produce a white paper detailing STAR’s physics program and detector upgrades for the next ten years • coordinate simulations to verify the feasibility of the proposed physics • define the detector requirements • coordinate the detector R&D with the detector requirements. • First activity (Mar. – Sept. 3): Respond to the request from Tom Kirk to prepare a report on the collaboration's decade-scale physics goals and upgrade plans, to be submitted to the BNL HENP PAC R. Majka DOE Presentation 15-September-2003

2. Goal: Produce a STAR 10 year planning document 1. Start with the broad physics questions 2. Determine what measurements STAR can make to address those questions 3. Determine what detector and collider requirements are needed to make those measurements.

3. Physics Questions • Is partonic matter dominant in the early stages of A+A collisions? • Can hadronic mechanisms be ruled out as explanation for observed effects? • Can gluon saturation models be ruled out? • What are the gross properties of the partonic matter? • Is it equilibrated? (measure charm yields, scale dependant fluctuations) • Does it behave collectively? (W flow, charm flow) • What are its early temperature and pressure? (g-g HBT, J/, Upsilon yields) • What is its gluon density? ("tagged" jets of various kinds ) • Are symmetries restored/broken in the partonic matter? • CP violation (L spin correlation) • Chiral symmetry and UA(1) restoration (modification to di-lepton spectrum opposite moderate pT jets , hadron production ratios opposite moderate pT jets, resonance masses and widths, h vs. h' mass difference)

4. What are the properties of the hadronic medium after hadronization • Resonance studies • HBT • Non-identical particle correlation • Gluon densities in normal nuclear matter • Jets of various kinds in p(d)-A vs impact parameter • What are the contributions to the proton spin? • What is the nature of the quark-antiquark sea in the nucleon? (W production program in polarized pp collisions)

5. Measurements, Goals, Detector and Collider Requirements, Timeline, Issues STAR Decadal Plan – Table 1.

6. Proposed Upgrades and Time Line • Barrel MRPC TOF: Proposal is submitted • Pixel Micro-vertex Detector: Proposal underway • DAQ/FEE Upgrades – 10 x Increase in DAQ throughput • Inner Tracker – match TPC tracks into pixel detector and help with forward tracking • EndCap Tracker – better resolution in 1<|h|<2 for W sign • Compact, Fast TPC for RHIC II Luminosity

7. MRPC Barrel TOF One Tray (1/120th of full barrel) installed for d-Au run. Performed extremely well. Doubles momentum reach of PID (p+K – p separation to ~3 GeV/c) Also, TOF combined with TPC dE/dx  electron tag Proposal submitted for full system Joint US/ China project. electrons hadrons

8. Active Pixel Sensor (APS) micro-vertex detector APS uses conventional CMOS process – great advantages: readout can be on same chip as detector (eliminates millions of bonds); can be very thin (20mm or less) Aggressive development at LEPSI/IReS and LBNL/UC Irvine to produce fast devices. <20 mm resolution projected to primary vertex in STAR should be possible LBNL pursuing infrastructure development as well (support structure; thin, small radius beam pipe; cooling; cabling… ) to achieve the best resolution.

9. Intermediate Tracking + Forward Tracking GEM pad or strip chambers: Endcap – GEM pad or strip chambers to help resolve sign of efrom Wdecay – polarization of sea anti- u,d. Intermediate tracker (GEM plus Si to help match TPC tracks to pixel detector and, give intermediate point for forward tracking Cross section through STAR detector

10. High Rate Data Acquisition and Front End Electronics • Since initial operation, the STAR DAQ has been upgraded from a rate of 1 to ~30 Hz Hz central Au-Au events (DAQ100) • The system is now at hard limits throughout. • Propose an order of magnitude increase in throughput: • Replace TPC front end electronics • Replace SVT (silicon drift tracker – slow readout) • Implement DAQ100 cluster finding code in hardware • New interconnect and event builder hardware

11. For RHIC II, 40 X Luminosity upgrade, the space charge distortions in the STAR TPC will becom unacceptably large - Fast, compact TPC with GEM readout ~50 cm ~20 cm ~50 cm 16 identical modules with 35 pad-rows, double (triple) GEM readout with pad size: 0.2x1. cm². Maximum drift: 40-45 cm. “Working” gas: fast, low diffusion.

12. Continuing Activities of theSTAR Future Physics and Upgrades Planning Working Group • refine the upgrades plan and the physics case supporting it • back it up with relevant simulations • define the implications for physics-driven requirements on the upgraded subsystems • monitor progress on the upgrade designs to ensure they will satisfy these requirements • produce a white paper detailing STAR’s physics program and detector upgrades for the next ten years • coordinate simulations to verify the feasibility of the proposed physics • define the detector requirements • coordinate the detector R&D with the detector requirements. “To accomplish these upgrade goals on the timescale demanded by the urgency of the physics questions, a robust program of detector R&D needs to begin now. “