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ALICE UPGRADES

ALICE UPGRADES. BUDAPEST March 2012. Long- t erm goals of the HI program. Understanding QCD as a multi-particle theory detailed characterization of the Quark-Gluon-Plasma critical temperature, degrees of freedom, speed of sound, transport coefficients

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ALICE UPGRADES

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  1. ALICEUPGRADES BUDAPEST March 2012

  2. Long-term goals of the HI program • Understanding QCD as a multi-particle theory • detailed characterization of the Quark-Gluon-Plasma • critical temperature, degrees of freedom, speed of sound, transport coefficients • precision measurements to address deconfinement and chiral symmetry restoration • A lot has been achieved owing to the spectacular performance of the LHC with ions

  3. What does it take? • Progress on the nature of the QGP is made by studying multi-differential observables: • centrality • transverse momentum • event plane • flavour, … •  This requires high statistics (luminosity) • In order to understand the dynamics of the condensed phase of QCD access to very rare physics channels is needed: • Charm and beauty from low to high pt • Quarkonia • Jets and energy loss • Low mass lepton pairs • This requires high precision measurements and statistics

  4. ALICE Upgrades: RRB 2011 • approved detector upgrades • EMCal (jet-quenching, completed), • TRD (electron ID, mostly installed, to be completed by 2012-13), • DCAL (di-jets, to be completed in 2013) • upgrade of rate capabilities (≥ 2012) • TPC (faster gas, readout), DAQ/trigger/HLT (increase bandwidth) • phase 1 upgrades (to be installed in LS 2017/18): • ITS: improve sec. vertex resolution, topological trigger • MFT: sec. vertex for muon arm • VHMPID: hadron PID to ≈20 GeV/c • FoCal: large rapidity/small x physics (Phase 1) • diffraction, PHOS, more calorimeters (to be defined?)

  5. Heavy-ion program Originally approvedprogram:1 nb-1 Scenarios, with large uncertainties goal:10 nb-1 an aside: Pb-p at high luminosity provides an unprecedented brilliant photon source Presentation in Chamonix 2012

  6. Status now • In fall, Upgrade Strategy Task Force set up to define an overall strategy and provide a framework for the future of ALICE beyond the approved program • A document has been prepared defining the physics goals and the experimental approach for a run of 10 nb-1 with PbPb • The PbPb run would be complemented by pPb and pp running • The Strategy document has been approved by the Collaboration Board in January for submission to LHCC • Still a draft, but contains the essential elements for a discussion • Contextually, approved the CDR for the ITS upgrade which is an integral part of the General Strategy • Requires also a new, smaller radius beam pipe • For the other new detectors, VHMPID, FOCAL and MFT, the timeline for approval or not has been defined: by September • In the meantime, a vigorous R&D program continues for the different proposed upgrades, and the negotiations with the Funding Agencies to defines the resource boundaries have been launched • Strong interest from all groups in ALICE, even several new groups joining

  7. Upgrade Strategy for ALICE @ High Rate • Physics Scope • Heavy flavors and quarkonia at low-pT • Low mass leptons • Jet studies and the medium of the fireball • Exotica, antimatter • Experimental Strategy • Access to low-pT observables => inspection of large number of events • Trigger and Data Acquisition Issues • Detector Issues • Performance improvement => new/upgraded detectors

  8. Scientific Goals • focus on precision studies of primary charm and charmonia as function of • Centrality • rapidity and transverse momentum • Reaction plane • low mass lepton pairs and thermal photons as messengers of fireball's history • measure thermalization of jets in the hot medium via gamma-jet and jet-jet studies with particle identification (pi/n_charged) to > 30 GeV. • search for exotic states of (anti)-matter

  9. An example of the unique ALICE physics coverage Electrons from the decay of heavy flavor hadrons

  10. Heavy flavors – open charm • detailed measurements of phase space distributions for charm hadrons at low pt need 10 nb-1 integrated luminosity • needs tracking and PID from the TPC • measurements down to low pt for all charmed hadrons and with enough statistics to address • energy loss of charm quarks • thermalization and hydrodynamic flow • hadronization and recombination

  11. HQ Energy Loss • Current detectors • ALICE uniqueness: PID ( charm); low pt (low material and field); • ALICE limits: B/D separation difficult, especially at lot pt (electron PID + vertexing); indirect B measurement via electrons; charm difficult for pt0 (background is too large); • CMS limits: no PID  no charm?; minimum pt at about 6 GeV/c; Need:  Smaller systematics on D (requires high precision and statistics)  B measurement at lower pt

  12. Heavy flavors – charmonia • Goal: measure J/y, y', and c_c with enough precision to get for 0 < pt < 10 GeV • Spectra • polarization • hydrodynamic flow • RAA

  13. detailed chi_c and psi' measurements cannot be performed with 1 nb-1

  14. What NEEDS to be done? Detector upgrades • Rates: • No upgrade: 2 x 108 events/yr min bias • Upgrade: > 2 x 109 events/year min bias • High rate capability achieved via pipelined readout of major ALICE detectors • New readout and event selection scheme with online tracking and calibration • Upgrade of the central detectors (ITS, TPC, TRD, TOF, EMCal (Dcal, PHOS)) • New DAQ/HLT • Builds on unique ALICE strengths at high multiplicities: • Tracking from low to very high pt • Particle identification (pi/n_charged) to > 30 GeV in ITS, TPC, TRD, TOF, EMCal

  15. ITS Upgrade, design goals • 1. Improve impact parameter resolution by a factor of ~3 • Get closer to IP • Reduce material budget • Reduce pixel size • 2. High standalone tracking efficiency and pt resolution • Increase granularity • Increase radial extension • 3. Fast readout • readout of Pb-Pb interactions at > 50 kHz and pp interactions at > 2MHz • 4. Fast insertion/removal for yearly maintenance • possibility to replace non functioning detector modules during yearly winter shutdown

  16. Impact parameter resolution • I) Get closer to the IP • radius of innermost pixel layer is constrained by central beam pipe • Present beam pipe: ROUT = 29.8 mm, DR = 0.8 mm •  • New reduced beam pipe: ROUT = 19.8 mm, DR = 0.8 mm • II) Reduce material budget (especially innermost layers) • present ITS: X/X0 ~1.14% per layer •  • target value for new ITS: X/X0 ~0.3 – 0.5% per layer (STAR HFT 0.37% per layer) •  reduce mass of silicon, electrical bus (power and signals), cooling, mechanics • III) Reduce pixel size • currently 50mm x 425mm • monolithic pixels  O(20mm x 20mm), • hybrid pixels  O(30mm x 30mm), state-of-the-art O(50mm x 50mm)

  17. Improve tracking performance • Higher granularity • increase number of layers in the outer region (seeding) and inner region (high occ.) • present detector: 6 layers, optimized for track matching with TPC • new detector: 7 layers (assuming 95% efficiency) • increase granularity of central and outer layers • pixels 20mm x 20mm • Combination of pixels (20mm, 20mm) and strips (90mm, 20mm) • Increase radial extension • present detector: 39mm – 430mm • new detector: 22mm – 430mm(*) (CDR value) • (*) increasing outer radius to 500mm results in a 10% improvement in pt resolution

  18. Implementation Options • Two design options are being studied • 7 layers of pixel detectors • better standalone tracking efficiency and pt resolution • worse PID (or no PID) • 3 innermost layers of pixel detectors and 4 outermost layers of strip detectors • worse standalone tracking efficiency and momentum resolution • better PID 4 layers of strips Option B Option A 7 layers of pixels 3 layers of pixels  685 krad/ 1013neq per year Pixels: O( 20 µm x 20 µm ) Pixels: O( 20x20µm2 – 50 x 50µm2) Strips: 95 µm x 2 cm, double sided

  19. Impact parameter resolution MAPS Case Simulations for two upgrade layouts radial positions (cm): 2.2, 2.8, 3.6, 20, 22, 41, 43 Same for both layouts • Layout 1: “All New” – Pixels (7 pixel layers) • Resolutions: srf = 4 mm, sz = 4 mm for all layers • Material budget: X/X0 = 0.3% for all layers • Layout 2: “All New” Pixel/Strips (3 layers of pixels + 4 layers of strips) • Resolutions: srf = 4 mm, sz = 4 mm for pixels srf = 20 mm, sz = 830 mm for strips • Material budget: X/X0 = 0.3% for pixels X/X0 = 0.83% for strips

  20. Tracking performance MAPS Case radial positions (cm): 2.2, 2.8, 3.6, 20, 22, 41, 43 Same for both layouts Simulations for two upgrade layouts • Layout 1 (all pixel layers) • Resolutions: srf = 4 mm, sz = 4 mm for all layers • Material budget: X/X0 = 0.3% for all layers • Layout 2 (3 layers of pixels + 4 layers of strips) • Resolutions: srf = 4 mm, sz = 4 mm for pixels srf = 20 mm, sz = 830 mm for strips • Material budget: X/X0 = 0.3% for pixels X/X0 = 0.83% for strips

  21. Online Systems • Major change of mode of operation and strategy • Extensive redesign • => PVV’s talk!

  22. Further Detector Upgrades • enhancing the existing strengths of ALICE heavy flavour, quarkonia, low-mass vector mesons hadron identification up to high pT making use of opportunities for new observables • high rapidity, small x-physics • projects not ready to ask for endorsement yet • approval procedure in ALICE ongoing • significant progress is being made!

  23. Status Of Upgrade Projects • VHMPID • internal LoI very advanced, some modifications suggested, • physics gain is being quantified • MFT • LoI in preparation, performance studies ongoing • FoCal • draft of LoI being prepared, • physics sensitivity is being clarified • Final Decision in September 2012

  24. Summary: ALICE future • A very rich Physics program for a future well into the next decade • A unique experimental approach • Strategy orthogonal to ATLAS and CMS • Crucial low-pt reach and PID • Possibly to be further extended with new detectors • A bright future ahead of us!

  25. spare

  26. ALICE Program • Baseline Program as in the original, approved ALICE proposal: • initial Pb-Pb run in 2010 (< 1/20th design L, i.e. ~ 3 x 1025 , int L 15 mb-1) • 2011: int L 140 mb-1 , rate of nuclear collisions ~ 5 kHz • 2012 p A run (measure cold nuclear matter effects, e.g. shadowing) • 2013-2014 Long Shutdown 1 (install DCAL, complete TRD) • 2015, 2016, 2017: • 2-3 Pb-Pb runs (medium -> design Lum. L ~ 1027, 5.5 TeV ) integrate at least ~ 1nb-1 at the higher energy • possibly one more p A run at higher luminosity (depending on results of first run) • 1-2 low mass ion run (energy density & volume dependence) typ. ArAr • running with pp (comp. data, genuine pp physics) => Baseline Program more than fills the “HI runs” to ~ 2020 • Following or included: • lower energies (energy dependence, thresholds, RHIC) • additional AA & pA combinations • NEXT (after long shutdown at the end of the decade): • details of program and priorities to be decided based on results, butIncrease int. Luminosity by an order of magnitude (to ~ 10nb-1 ) Address rare probes (statistics limited: for ex., with 1nb-1 :J/Y: excellent, Y’: marginal, Y: ok (14000) , Y’: low (4000), Y’’: very low (2000))

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