1 ALICE Status Orlando Villalobos Baillie University of Birmingham NuPECC Meeting Edinburgh 10 th October 2014

ALICE Physics  We collide lead ions (& p-p, p-Pb) to study QCD at extreme energy densities over large volumes and long time-scales. 2  Study the role of chiral symmetry in the generation of mass in hadrons (accounts for ~ 99% of mass of nuclear matter).  Study the nature of quark confinement.  Study the QCD phase transition from nuclear matter to a deconfined state of quarks and gluons - The Quark-Gluon Plasma.  Study the physics of the Quark-Gluon Plasma (QCD under extreme conditions).

QCD Phase Diagram 3 Early Universe ALICE colour Only gauge theory phase transition accessible to experiment

Heavy Ion Collisions 4 Colliders: AGS, SPS, RHIC, LHC Create QGP by colliding ultra-relativistic heavy ions  S NN (GeV) = (5500) Jets Open charm, beauty Probe properties of QGP by studying characteristics of all particles produced in collisions. Use p-p & p-Pb collisions as baseline.

ALICE Physics A lot of high-quality data to work with from the PbPb, pPb and pp runs The harvest of results continues –Over 60 journal publications so far –The impact of physics publications remains extremely high - after the 4 Higgs discovery papers the next three highest cited LHC physics papers come from ALICE. 5

Size: 16 x 26 metres Weight: 10,000 tonnes Detectors: 18 The ALICE Experiment Collaboration: > 1300 Members > 120 Institutes > 35 countries Birmingham-built Central Trigger Processor Electronic Brain of the detector.

Some Highlights of Run 1 We have measured many of the global features –Phase transition temperature - Agrees with theory T c ~ 164 MeV –Energy density - Over 10x critical energy density,  > 15 GeV/fm 3 (> 3X RHIC) –size & lifetime of system ~ 5000 fm 3,  ~ fm/c –Highest temperature ever measured (from low p T photon spectrum) –Very strong radial flow,  ≈

Thermal Models 8 Fit to extended set of particle species using an equilibrium model (SHARE).  2 /ndf ~ 2 One of the largest contributions to  2 comes from low yield of protons w.r.t. pions.

QGP is Perfect Liquid Elliptic Flow: Collective effects of data fit hydro- dynamical models  Most ideal liquid ever created 9 x z y Reaction Plane Viscosity/Entropy density,  /S  0.2 AdS/CFT prediction limit:  /S > 1/4  ≈  Study angular dependence of emitted particles

Flow – Ideal Liquid 10 V 2 = elliptic flow Collective effects of data fit hydro-dynamical models  Most ideal liquid ever created Evidence for flow from D- mesons suggests collective effects from charm.  More data needed (Run 2)

Jet Quenching 11 Large suppression of jets seen in central collisions 192 GeV 168 GeV 10-20% peripheral   47 GeV 102 GeV 0-10% central 

High p T Suppression (R AA ) High p T particles supressed by factor 7 in central Pb-Pb w.r.t. weighted p-p data No such suppression seen in p-Pb Direct photons, of course, not supressed in Pb-Pb. 12 < 1 : Medium effect = 1 : No medium effect

First measurement of R D AA /R  AA Probe QGP with different quark flavours: u, d, s, c (b only after upgrade) Theoretical expectation:  E light quark >  E massive quark First indication of mass effects ? High p T Suppression of charm

 p and  Pb at the LHC When b > (R 1 + R 2 ), hadronic interactions are very much suppressed, and photon processes become important. Photon flux  Z 2 Photons are quasi-real; virtuality limited by size of nuclei.  from p  Q 2 ~ (250 MeV) 2  from Pb  Q 2 ~ (35 MeV) 2 Photon energy determined by boost of emitting particle.  from p (4 TeV):  from Pb: 14

J/  photoproduction 15 Leading Order

p-Pb Measurements Our knowledge of the photon emitter allows us to solve for  (W  p ) using the measured d  /dy A power law fit (  (W)~W  ) to ALICE data points gives  =0.67  HERA Measurements H1  =0.67  0.03 ZEUS  =0.69 

ALICE Upgrade 17 Opens a new and unique window of discovery with rare charm and beauty physics

ALICE Upgrade Focus on rare probes, study their coupling with QGP medium and their (medium-modified) hadronisation process –precision studies of charm and beauty at low-p T –low mass lepton pairs and thermal photons –  -jet and jet-jet with particle identification from low momentum up to 30 GeV. –exotic nuclear states low-transverse momentum observables (complementary to the general purpose detectors ATLAS and CMS) –Many features not triggerable => need to examine full statistics. –Target: Pb-Pb recorded luminosity ≥ 10 nb -1  8 x events pp Tev) recorded luminosity ≥ 6 pb -1  1.4 x events Gain a factor 100 over the statistics of the approved programme Operate ALICE at high rate while preserving its uniqueness, superb tracking and PID, and enhance its vertexing capability and tracking at low-p T 18

Summary of Upgrades 19 Trigger electronics (CTP + LTUs) Muon Forward Tracker (MFT) Muon Arm Readout Data Acquisition (DAQ) High Level Trigger (HLT) MAPS Inner Tracking System (ITS)

UK Objectives To build upon and significantly enhance the UK’s current prominence & leadership in ALICE. Design, build & commission new trigger system for ALICE Upgrade –Build upon the Birmingham’s existing leadership & prominence within ALICE. (Responsible for the current trigger system. Represented on the ALICE Management, Technical, & Physics Boards) To make a major contribution to the Inner Tracking System (ITS) Upgrade. –The key sub-detector for the proposed enhanced physics programme post Long Shutdown 2 (LS2). –Utilise the strong international reputation of Liverpool & Daresbury in Si tracking systems. –Significantly strengthen the UK’s role in this important field and place us in an ideal position to fully exploit ALICE physics post LS2. 20

An exciting long-term Research Programme at the LHC Related STFC Roadmap questions: How did the universe begin and how is it evolving? What is the physics of the early universe? What are the fundamental constituents and fabric of the universe and how do they interact? What is the nature of nuclear and hadronic matter? Studying the phase diagram of strongly interacting matter New probes, properties of deconfined matter Thermodynamics of the Standard Model? A major opportunity for UK to play a leading role in: Construction of ALICE Upgrade (Trigger and Inner Tracking System) Summary