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The Future of RHIC: a view from PHENIX. European Study Group Town Meeting CERN June 29, 2012. Barbara Jacak For the PHENIX Collaboration. Open questions drive the future at RHIC. How perfect is the near-perfect liquid? How do initial state fluctuations help to quantify this?
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The Future of RHIC: a view from PHENIX European Study Group Town Meeting CERN June 29, 2012 Barbara Jacak For the PHENIX Collaboration
Open questions drive the future at RHIC • How perfect is the near-perfect liquid? • How do initial state fluctuations help to quantify this? • How does the strongly coupled plasma emerge? • At what scales is coupling strong? • What is the mechanism for parton-plasma interactions? • What novel symmetry properties does the QGP have? • Are there quasiparticles in the medium? What are they? • Is there evidence for the onset of deconfinement and/or • the QCD critical point? • Is there a characteristic color screening length? What is it? • What are the properties of cold nuclear matter? • Is there evidence for saturation of the gluon density? • What is the spin structure of the nucleon?
What lurks in the heart of the plasma? T g How do QGP properties vary with length scale? probe Q2length scale probe virtuality
How does the strongly coupled plasma emerge? At what scales is coupling strong? • parton-plasma interaction • thermalization mechanism For weakly coupled systems: < Measure q and h/s independently Jets, di-jets and g-jet probe q RHIC: near Tc, longer distance scales < A. Majumder, B. Mueller, X.N. Wang PRL99, 192301 (2007)
T dependence is key! We’ll have h/s in next 5 years check q near Tc & compare to h/s RHIC + LHC together range in both T & Q2 Also need different T with same Q2 probe <
Measuring qhat, coupling RAA Jets extend pT range at RHIC Di-jets, g-jet give better sensitivity to q & coupling <
RHIC+LHC to tease out T dependence B. Mueller, Nuc.Phys.A855, 74 (2011) Key overlap for LHC+RHIC: 40-60 GeVjets
STAR Quasiparticles in the medium? Next 5 years! c vs. bcollisional energy loss, dileptons from qq annihilation Thereafter: jets, di-jets, g-jet to pin down theory
Is there a characteristic color screening length? LHC RHIC STAR projection with MTD sPHENIX projection
RHIC + LHC both! √s dependence is key to sorting it out! Shadowing in CNM Measure along with other hard probes in d/p+A J/y yield Cold matter effective absorption √s √s √s Final state recombination Screening in QGP LHC: important effect the goal! J/y yield J/y yield
PHENIX in next 5 years VTX & FVTX in place MPC-EX in 2014 Si/W preshower/ tracker before MPC gdir -> gluon nPDF d/p+Au
Then: an optimized jet detector at RHIC sPHENIX Compact calorimetric detector 2T 70cm inner radius first stage proposed to DOE 7/12; decision ~1/13
Magnet Solenoid 2 Tesla, Rinner = 70 cm VTX inner tracker Accordion Tungsten-Fiber EMCal SBIR with Tungsten Heavy Powder Prototype being constructed; EIC R&D 10 cm thick; 14%/sqrt(E) resolution Full GEANT-4 simulation results Silicon Photomultiplier (SiPM) readout Fe-ScintillatorHCal Acts as flux return for magnetic field Prototype being constructed 1 meter total thickness 75%/sqrt(E) resolution Full GEANT-4 simulation results Common SiPM/electronics with EMCal
How well will we do? g-jet well reconstructed for 20<pT<40 GeV/cg Good jet efficiency pT>20 GeV/c
sPHENIX evolution • Begin with jet, di-jet and g-jet physics • Additional tracking layers (RIKEN) • high-z fragmentation fn. • Add pre-shower to EMCAL • p0RAA to 40 GeV/c • eID for ϒ states; tag c,b jets • Forward upgrade for spin & cold nuclear matter • (NSF, RIKEN)
Evolve into ePHENIX for eIC physics • Goal: physics with initial electron beams from 5-10 GeV • Add to sPHENIX: hadron ID in barrel & forward • backward EMCAL for scattered electron • Measure: nuclear PDF’s, 3-d nucleon structure via g & qhelicity & transverse distributions
Future programs at both RHIC + LHC essential! Control T, Q2, l RHIC + LHC together vary knobs selectively
Possible bullet for Town Meeting • The complementarity of LHC and RHIC is an essential resource in efforts to quantify properties of the Quark-Gluon Plasma and features of the QCD phase diagram. While the LHC significantly extends the temperature and kinematic ranges of QGP studies, measurements at both facilities are needed to constrain the temperature dependence of QGP transport coefficients, such as viscosity and parton energy loss parameters. RHIC’s flexibility in collision energy and beam species adds important scope to QCD matter research, from the search for a unique QCD Critical Point and the onset of the deconfinement transition in heavy-ion collisions, to studying the partonic origin of nucleon spin with unique polarized proton collisions.
u/u W Spin studies at RHIC (next 5 years) • 500 GeVp+p: p0 ALL • constrain Dg (0.01<x<0.3) • central/forward correlations • tag kinematics • W AL at forward, backward, mid rapidity for Du, Du,Dd,Dd valence/sea combine Curves => sea uncertainty d/d
Jets at RHIC to date • Both STAR and PHENIX have preliminary results • Publications in preparation – these jets are tricky Jet-h energy balance (vs. p+p) Jet Rcp < 1 in d+Au
Additional Tracking (RIKEN funded on same time scale) Preshower for e-ID and g/p0
Jet probes of QGP quasiparticles Radiative + Collisional E-loss ±10% changes in coupling strength Radiative E-loss only Heavy quarks in next few years! then Jets, di-jets, g-jet to pin down the theorists
T dependence of both h/s and qhat dial T and Q2 knobs, check q near Tc & vsh/s RHIC + LHC together range in both T & Q2 Also need different T with same Q2 probe
PHENIX near-term upgrades • VTX (2011) • FVTX (2012) • W trigger (’11 & ’12) • RPC’s & MuTR FEE • HBD (2009 & 2010) • DAQ2010 • MPC-EX (2014) With DAQ2010, PHENIX maintains high DAQ rate w/VTX & FVTX! ~5kHz (AuAu), ~7kHz(p+p)
VTX working in Run-11 Au+Au and in Run-12 P>2 GeV P>1 GeV Blue: e Red: charged (0.6x 10-3) Matched central arm-VTX tracks • DCA distributions of electrons are broader than those of all charged • Broadened by heavy flavor decays • Large DCA tail - b-signal? • MC study of other decays in DCA shape underway Blue: e Red: charged ( 10-3 ) P>3 GeV Blue: e Red: charged (0.6x 10-3)
First W -> m result • Run-11 • first use of RPC3 • sampled 25 pb-1 • polarization ~ 50% • Proof of principle • Clearly needs more statistics • Statistics also = • systematics
u/u Run-13 top priority: finish W measurement! inclusive high pT leptons ∫Ldt=300pb-1 in 30cm, P≥0.55 Need 250pb-1 in Run-13 valence/sea combine Curves => sea uncertainty d/d Requires ∫Ldt=900pb-1 Combined Run-11,12,13
Non photonic electrons 0, Heavy quark energy loss: a wakeup call PRC 84, 044905 (2011) ► more energy loss than gluon radiation can explain! ► charmquarks flow along with the liquid Mix of radiation + collisions (diffusion) but collisions with what? Drag force of strongly coupled plasma on moving quark? Test with b quarks…
D vs. B meson decays via DCA in FVTX goal Run-14
VTX expected performance Run-14
In 2015: Direct photons in MPC-EX in CNM • Anticipated performance with direct g in MPC-EX 49 pb-1 of p+p and 0.35 pb-1 of d+Au (full vertex) ~ 12 weeks of d+Au and p+p. Start in Run-14 • May require p+Au instead, due to dilution from isospin effect on q+g -> q+g. If so, will request dedicated p+Au run in 2015 Issue is being investigated…
Cold Nuclear Matter (CNM) and Low-x Partons in Nuclei other probes of shadowing & gluon saturation – forward hadrons Dilute parton system (deuteron) PT is balanced by many gluons Dense gluon field (Au) Mono-jets in the gluon saturation (CGC) picture give suppression of pairs per trigger and some broadening of correlation Kharzeev, NPA 748, 727 (2005)
p u unpol. p G not large: sea quarks polarized? d vs. u? Probe Dq-Dq via W production 100% Parity-violating: Start: 2009(tests)/2010(trigger) with 500 GeV p+p
strip layers pixel layers beam pipe Barrel VTX Detector • Specifications: • Large acceptance (Df ~ 2 p and |h| < 1.2) • Displaced vertex measurement s < 40 mm • Charged particle tracking sp/p ~ 5% p at high pT • Detector must work for both HI and pp collisions. • Technology Choice • Hybrid pixel detectors developed at CERN for ALICE • Strip detectors, sensors developed at BNL with FNAL’s SVX4 readout chip Hybrid Pixel Detectors (50 mm x 425 mm) at R ~ 2.5 & 5 cm Strip Detectors (80 mm x 3 cm) at R ~ 10 & 14 cm |h|<1.2 • ~ 2p z~ ± 10 cm
Forward Silicon Vertex Detector - FVTX FVTX Specifications: • 2 endcaps • 4 pixelpad layers/endcap • ~550k channels/endcap • Electronics a mod of BTeV readout chip • Fully integrated mech design w/ VTX • 2p coverage in azimuth and 1.2 < | h | < 2.4 • Better than 100 mm displaced vertex resolution