ALICEUPGRADES

BUDAPESTMarch 2012

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

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

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?)

Heavy-ion program2013-14 Long shutdown LS1, increase E

2015-16 Pb-Pb Design luminosity, ~ 250 µb-1/year, Luminosity levelling?

2017 p-Pb or Pb-Pb

P-Pb to enhance 2015-16 data. Energy?Pb-Pb if µb-1 still needed

2018 LS 2 ? install DS collimators to protect magnets ALICE upgrade for 6 × design luminosity

2019 Pb-Pb Beyond design luminosity … as far as we can. Reduce bunch spacing?

2020 p-Pb

2021 Ar-Ar Intensity, to be seen from injector commissioning for SPS fixed target.

2022 LS3, upgrades ?? Stochastic cooling ??

>2022 Pb-Pb PbPb luminosity production, pA, other ions (U??)

adapted from J.M. Jowett

Originallyapprovedprogram:1 nb-1

goal:10 nb-1

an aside: Pb-p at high luminosity provides an unprecedented brilliant photon sourcePresentation in Chamonix 2012

Scenarios, w

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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

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

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

An example of the unique ALICE physics coverage

Electrons from the decay of heavy flavor hadrons

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

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 pt0 (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

Heavy flavors – charmonia

• Goal: measure J/, ', and _c with enough precision to get for 0 < pt < 10 GeV– Spectra

– polarization

– hydrodynamic flow

– RAA

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

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

ITS Upgrade, design goals1. 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

I) Get closer to the IP• radius of innermost pixel layer is constrained by central beam pipe

Present beam pipe: ROUT = 29.8 mm, R = 0.8 mm New reduced beam pipe: ROUT = 19.8 mm, R = 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 50m x 425m

monolithic pixels O(20m x 20m),

hybrid pixels O(30m x 30m), state-of-the-art O(50m x 50m)

Impact parameter resolution

Higher granularity

• increase number of layers in the outer region (seeding) and inner region (high occ.)

o present detector: 6 layers, optimized for track matching with TPC

o new detector: 7 layers (assuming 95% efficiency)

• increase granularity of central and outer layers

o pixels 20m x 20m

o Combination of pixels (20m, 20m) and strips (90m, 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

Improve tracking performance

Two design options are being studied

A.7 layers of pixel detectors• better standalone tracking efficiency and pt resolution• worse PID (or no PID)

B.3 innermost layers of pixel detectors and 4 outermost layers of strip detectors • worse standalone tracking efficiency and momentum resolution• better PID

7 layers of pixels

Option A

3 layers of pixels

4 layers of stripsOption B

Pixels: O( 20 µm x 20 µm )

Pixels: O( 20x20µm2 – 50 x 50µm2)Strips: 95 µm x 2 cm, double sided

685 krad/ 1013 neq per year

Implementation Options

Layout 1: “All New” – Pixels (7 pixel layers)

•Resolutions: r = 4 m, z = 4 m 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: r = 4 m, z = 4 m for pixels r = 20 m, z = 830 m for strips

•Material budget: X/X0 = 0.3% for pixels X/X0 = 0.83% for strips

radial positions (cm): 2.2, 2.8, 3.6, 20, 22, 41, 43

Same for both layouts

Simulations for two upgrade layouts

MAPS Case

Impact parameter resolution

Layout 1 (all pixel layers)

•Resolutions: r = 4 m, z = 4 m for all layers

•Material budget: X/X0 = 0.3% for all layers

Layout 2 (3 layers of pixels + 4 layers of strips)

•Resolutions: r = 4 m, z = 4 m for pixels r = 20 m, z = 830 m for strips

•Material budget: X/X0 = 0.3% for pixels X/X0 = 0.83% for strips

radial positions (cm): 2.2, 2.8, 3.6, 20, 22, 41, 43

Same for both layoutsSimulations for two upgrade layouts

MAPS Case

Tracking performance

Online Systems

• Major change of mode of operation and strategy

• Extensive redesign

• => PVV’s talk!

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!

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

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!

spare

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 b-1)– 2011: int L 140 b-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, but

Increase int. Luminosity by an order of magnitude (to ~ 10nb-1 )Address rare probes (statistics limited: for ex., with 1nb-1 :J/: excellent, ’:

marginal, Y: ok (14000) , Y’: low (4000), Y’’: very low (2000))