T.Peitzmann

Status of the ALICE Project

NIKHEF annual scientific meeting

Thomas PeitzmannUniversiteit Utrecht

T.Peitzmann

The Quark-Gluon-Plasma

l QCD ground state– color charge of quarks and gluons

is confined– chiral symmetry spontaneously

brokenl pressure or heat leads to overlap

of hadrons– intuitive in bag model

l new state of matter:– color charges can move between

hadrons– deconfinement:

quark-gluon-plasma– restoration of chiral symmetry

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The QCD Phase Diagram

l SPS– QGP probably reached– dominated by transition and

hadron gas– theoretically extremely difficult

l RHIC and LHC– dominated by QGP– theoretically simpler

» coupling as small» thermodynamical “limit”» baryon. chem. potential mb = 0

– new physical observables» heavy quarks» jets

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People (NIKHEF and Utrecht University)

l PhD– M. van Leeuwen NA49

» strangeness and charm yields– E. van der Pijll WA98

» direct photons– P. de Rijke NA57

» omega production– E. Schillings NA57

» lambda polarisation– A. Sokolov ALICE

» SSD module tests

l staff– M. Botje– N. van Eijndhoven– R. Kamermans– P. Kuijer– G.-J. Nooren– T. Peitzmann– R. Snellings

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SPS: Reaping The Harvest

l Example 1: WA98 (E. van der Pijll)– study of direct photon production

» signal of hot initial state in heavyion collisions

» very difficult: small signal with highbackground

– direct photon signal observed inWA98

– development of new analysismethod

– extension of analysis to lowertransverse momenta

» even more difficult!

l Example 2: NA57 (E. Schillings, P.de Rijke)– L polarisation (E. Schillings, see

talk)» small polarisation at mid-rapidity

– W production (P. de Rijke)» understanding the systematic

errorsl alignment, efficiencies, …

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l transverse mass spectra ofdifferent hadron species

l well described bythermalized source

l measures freeze-outconditions– hadronic interactions stop– similar temperatures for all

SPS energies– high average expansion

velocity

Hydrodynamical Model Fits To NA49 Data

M. van Leeuwen

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RHIC: Joining The -Party

l exciting data from first beam timesat RHIC

l the most important physics activityin present day heavy ion physicsis happening at RHIC

l STAR one of the major players– substantial contribution

to be built up!l see talk by R. Snellings

l central Au+Au collision at÷sNN=200GeV in the STAR TPC

STARSTAR

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LHC: Preparations for ALICE

l hardware contribution: silicon stripdetector– design and prototyping well under

wayl physics simulation

– efforts being started

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Hardware Contributions

••DetectorDetector

••FE moduleFE module

••EndcapEndcap

••FEROMFEROM

••DAQDAQAlice Inner

Tracking System

ADC racks

outside magnet

5mm

50 cm

25 m

200 m

••CF supportCF support

••CoolingCooling

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Status Of Technical Workl preseries of double sided strip

detectors– delivered (Canberra, SINTEF,

ITC)– tested (IRES, Trieste)

l ladder spaceframes– delivered (St. Petersburg)

l ASICs for endcap– design ready (NIKHEF/UU)

l readout chain using prototypeASICs– first test (NIKHEF/UU)

l testequipment for ASICs andhybrids– operational (NIKHEF/UU)

l ladder assembly robot– near to completion (NIKHEF/UU)

l first silicon strip detector module– NIKHEF/UU + IRES design– manufactured at IRES by Ukraine

people– to be tested at NIKHEF/UU

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Tests Of SSD With Infrared Laser

l laser wavelength chosen tooptimize penetration depth– close to band gap energy– 20-30% light absorbed– nearly uniform density of ionization

l properties adequate for detectortests– beam spot ≈ 30 µm

» larger than for particle, but smallcompared to strip pitch

– precision of positioning ≈ 1.5 µm

A. Sokolov

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2-Dimensional Map Of Collected Charge

l strip structure visible– aspect ratio distorted

» y-axis compressed byfactor 15

» true angle: 35 mradl setup used for

– dead strip search– relative calibration– measurement of charge

sharing

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Charge Sharing Around Dead Strip

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ALICE Physics Studies (Simulation)l work on the Physics Performance

Report for ALICEl pA physics

– important link pp - pA - AA– nuclear modifications– no thermalization/phase transition

l further simulation studies foreseen– prepare analysis framework for

future data taking (pp, pA and AA)l full tracking with ITS and TPC

l example: impact parameter vs.charged multiplicity– HIJING simulations

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Summary

l physics analysis from SPSexperiments– very fruitful!

l participation in STAR– major activity in heavy ion group

l gearing up for ALICE– hardware contribution well under

way– increase effort on physics

simulations