Nucleon Structure and QuarkGluonPlasma HERMES and ALICESTAR Thomas

Nucleon Structure and Quark-Gluon-Plasma: HERMES and ALICE/STAR Thomas Peitzmann Utrecht University/NIKHEF T. Peitzmann, NUPECC Groningen, Nov. 18,

Outline • HERMES – fragmentation in nuclei • STAR – elliptic flow – jet physics • ALICE – silicon strip detector – analysis preparations T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

~16 M€ per annum excluding investments ATLAS & D 0 GRID R&D Theory Antares ALICE & STAR LHCb & Babar T. Peitzmann, NUPECC Groningen, Nov. 18, 2005 NIKHEF Research programs Outreach HERA LEP 2005

HERMES • HERA/DESY • investigate spin structure of the nucleon – DIS with polarized leptons on polarized hydrogen target hardware contribution from NIKHEF: Lambda wheels • fragmentation in the nucleus – lepto-production of hadrons off nuclei T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

spin decomposition HERMES Analysis highlights: • N spin decomposition • hyperon production • transversity Ph. Ds: • 10 completed • 7 now @ institutes abroad • +5 in preparation Publications: • expect ~100 by 2007 T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Absorption/Energy Loss in Nuclei? • production of hadrons in nuclei vs deuterium • significant suppression of large z hadrons in heavy nuclei – absorption? – energy loss? T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Fragmentation in the Nucleus? • ratio of di-hadron to single hadron for different nuclei • very little dependence on mass of nucleus • important reference measurement for heavy ion collisions T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

ALICE/STAR • part of one FOM programme • ALICE at LHC/CERN – hardware contribution: silicon strip detector – data taking from 2007 • STAR at RHIC/BNL – joined in 2002 – data taking and analysis • 7 Ph. D – 4 STAR, 3 ALICE • 45 publications – STAR from 2002 up to now • group will shift completely to ALICE in the near future T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

QCD phase diagram • QCD predicts transition from hadronic phase to a quark-gluon-plasma – Tc ≈ 160 -170 Me. V – order of transition unknown (but much larger number of d. o. f. ) – deconfinement and chiral symmetry restoration • studied in high-energy heavy ion collisions T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

The focus of our group • The properties of the QCD Equation of State above Tc – dp/d calculable in lattice QCD – observables: collective motion of low transverse momentum particles as function of mass • The color density of hot and dense QCD matter – induced soft gluon radiation by partons traversing the medium – observables: medium modifications of jets and heavy particle production T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

The STAR Detector Magnet Barrel EM Cal (BEMC) Coils Silicon Vertex Tracker (SVT) Silicon Strip Detector (SSD) Central Trigger Barrel (CTB) PMD ZCal FTPC Endcap EM Cal FPD Time Projection Chamber (TPC) TOFp, TOFr FPD Year 2000 Year 2001+ T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Elliptic flow T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Collective motion: velocity of sound P. F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/0305084 • buildup of collective flow depends on the magnitude of the velocity of sound and the relative time spend in various phases • sensitive to difference in equation of state (Eo. S) T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Self-quenching of elliptic flow P. F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/0305084 • the driving force of elliptic flow (anisotropy of pressure gradient) dominates at “early” times • elliptic flow “monitors” early collective (i. e. equilibrated) behaviour T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Measurement of elliptic flow • asymmetry of number distribution of particles with respect to the reaction plane • Fourier-decomposition: strong 2. order (v 2) ideal hydrodynamics STAR charged hadrons • early result from STAR: strength of elliptic flow reaches predictions of ideal hydrodynamics at RHIC

Identified particle flow • hierarchy of momentum dependent flow for different hadrons parallel talk by Bai Yuting – onset of v 2 shifts to larger p. T for heavier particles – consistent with ideal hydrodynamics – magnitude of difference not consistent with hadron gas, but with QGP T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Jets and jet quenching T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Parton energy loss: current understanding • collisional energy loss – original idea by Bjorken – very small effect • more important: induced gluon radiation • interference leads to non-linearity • dominant feature: – energy loss determined by density of color charges • parameterized by transport coefficient T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Measuring jets in AA? how to find this p+p dijet+X two observables: (STAR@RHIC) in here? Au+Au ? ? ? - high p. T single hadron distribution - dihadron distributions T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Inclusive Hadron Suppression Eskola et al. , hep-ph/0406319 • nuclear modification factor • suppression requires initial density 30 x larger than cold nuclear matter – compare to HERMES results • very close to maximum suppression – provides only lower bound on density T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Surface emission Eskola et al. , hep-ph/0406319 ? • large energy loss: opaque core – emissions from surface • inclusive measurements insensitive above certain density – more information from correlation measurements? T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Dihadrons in heavy ion collisions • near-side correlation unchanged • away-side peak suppressed in central Au+Au – consistent with surface emission • distributions in d+Au similar to p+p – suppression is final state effect • more intuitive hint for “jet” suppression, but quantitatively much more difficult T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Emergence of away-side peak Equivalent to year 2 analysis STAR Preliminary Au+Au, 0 -5% p. T(trig) p. T(assoc) > 2 Ge. V/c High statistics year 4 dataset allows increase in Q 2 Emergence of the away side peak with increased trigger p. T T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

8 < p. T(trig) < 15 Ge. V/c Emergence of dijets p. T(assoc)>6 Ge. V STAR Preliminary increase associated p. T threshold also: clear jet-like peaks seen on near and away side in central Au+Au collisions! yields info on upper and lower limit of density! T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Where does the energy go? mean p. T of away-side associated hadrons = remaining jet fragments? Leading hadrons Medium significant softening of associated hadrons! T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

The perfect fluid at RHIC, the w. QGP at the LHC? w. QGP = weaklyinteracting plasma less flow at higher energies? beware: remember the predictions for RHIC! T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Elliptic flow at LHC energies from ideal hydrodynamics From Heinz, Kolb, Sollfrank • Whatever the outcome will be, elliptic flow is a day-one measurement at the LHC with very likely similar impact as at RHIC T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Solenoid magnet 0. 5 T Cosmic rays trigger ALICE: the dedicated Forward detectors: • PMD • FMD, T 0, V 0, ZDC Specialized detectors: • HMPID • PHOS Central tracking system: • ITS • TPC • TRD • TOF HI experiment MUON Spectrometer: • absorbers • tracking stations • trigger chambers • dipole T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

The Alice ITS • Strong contribution to outer layers (SSD) • project leader SSD (6 labs) • Main vertex 15 µm in central Pb. Pb • Vertex charm, strange decays 50 µm • Δp/p (p. T>1 Ge. V, with TPC) 14%->3% • Particle ID (d. E/dx) • FE module • Support and cooling • Endcap • FEROM SSD T. Peitzmann, NUPECC Groningen, Nov. 18, 2005 • DAQ

SSD: the first real ladder! T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

NIKHEF/UU ALICE hardware activities (SSD) • • • Design of SSD support (with Turin) Design ladder frames (with St. Petersburg) Design of SSD cooling system (with CERN) Design of front-end modules (with Kharkov and Strasbourg) Design ladder cabling (with Kharkov) • • Design SSD cabling (industrial production) Design and production of front-end module test equipment Design and production of End. Cap electronics Design and production of read-out modules • • Ladder assembly (with Nantes) Final SSD assembly • Bottom line: ITS project on schedule and NIKHEF SSD contribution will finish on time (2006) T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

ALICE group: current manpower • • Utrecht and NIKHEF Amsterdam manpower: – Staff physicist: 3 – Ph. D students: 2 • Utrecht manpower: – – • Staff physicist: 4 Post-doc: 1 Ph. D students: 5 Students: 2 Amsterdam infrastructure: – Mechanical and electronics workshop – Ladder assembly room • Utrecht infrastructure: – Faculty mechanical and electronics workshop – Mechanical and electronic workshop of the SAP department (4 fte) – Assembly room T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

ALICE group: current physics activities • Have strong role in STAR EMC analysis – 1 fte staff, 1 post-doc, 3 Ph. D's (until 2009) and 2 students • Had a leading role in correlation analysis with the reaction plane in STAR – Effort is scaled down to 1 Ph. D (until 2007) and 0. 2 fte staff • Have a coordinating role in correlation analysis with the reaction plane in ALICE (Physics Performance Report) – Effort 4 fte staff and 2 Ph. D – Will increase further with 3 Ph. D’s and 1 post-doc T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

Summary • important nuclear physics contributions from NIKHEF – HERMES with nuclear physics program in parallel to spin – ALICE/STAR nuclear physics at the highest energies • rich physics harvest from STAR – elliptic flow – jet quenching • ALICE well under way for data taking in 2007 – strong Dutch contribution to SSD – prepare physics analysis • elliptic flow as day-one topic T. Peitzmann, NUPECC Groningen, Nov. 18, 2005