T.Peitzmann

Status of the ALICE Project

NIKHEF annual scientific meeting

Thomas PeitzmannUniversiteit Utrecht

T.Peitzmann

The Quark-Gluon-Plasma

QCD ground state– color charge of quarks and gluons

is confined

– chiral symmetry spontaneously broken

pressure or heat leads to overlap of hadrons– intuitive in bag model

new state of matter:– color charges can move between

hadrons

– deconfinement: quark-gluon-plasma

– restoration of chiral symmetry

T.Peitzmann

The QCD Phase Diagram

SPS– QGP probably reached

– dominated by transition and hadron gas

– theoretically extremely difficult

RHIC and LHC– dominated by QGP

– theoretically simpler» coupling s small

» thermodynamical “limit”

» baryon. chem. potential b = 0

– new physical observables» heavy quarks» jets

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People (NIKHEF and Utrecht University)

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

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

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

» signal of hot initial state in heavy ion collisions

» very difficult: small signal with high background

– direct photon signal observed in WA98

– development of new analysis method

– extension of analysis to lower transverse momenta

» even more difficult!

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

talk)» small polarisation at mid-rapidity

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

errors alignment, efficiencies, …

T.Peitzmann

transverse mass spectra of different hadron species

well described by thermalized source

measures freeze-out conditions– 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

exciting data from first beam times at RHIC

the most important physics activity in present day heavy ion physics is happening at RHIC

STAR one of the major players– substantial contribution

to be built up! see talk by R. Snellings

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

STARSTAR

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LHC: Preparations for ALICE

hardware contribution: silicon strip detector– design and prototyping well under

way 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 Work

preseries of double sided strip detectors – delivered (Canberra, SINTEF,

ITC)– tested (IRES, Trieste)

ladder spaceframes– delivered (St. Petersburg)

ASICs for endcap– design ready (NIKHEF/UU)

readout chain using prototype ASICs– first test (NIKHEF/UU)

testequipment for ASICs and hybrids– operational (NIKHEF/UU)

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

first silicon strip detector module– NIKHEF/UU + IRES design

– manufactured at IRES by Ukraine people

– to be tested at NIKHEF/UU

T.Peitzmann

Tests Of SSD With Infrared Laser

laser wavelength chosen to optimize penetration depth– close to band gap energy

– 20-30% light absorbed

– nearly uniform density of ionization

properties adequate for detector tests– beam spot ≈ 30 µm

» larger than for particle, but small compared to strip pitch

– precision of positioning ≈ 1.5 µm

A. Sokolov

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2-Dimensional Map Of Collected Charge

strip structure visible– aspect ratio distorted

» y-axis compressed by factor 15

» true angle: 35 mrad

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) work on the Physics Performance

Report for ALICE pA physics

– important link pp - pA - AA

– nuclear modifications

– no thermalization/phase transition

further simulation studies foreseen– prepare analysis framework for

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

example: impact parameter vs. charged multiplicity– HIJING simulations

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Summary

physics analysis from SPS experiments– very fruitful!

participation in STAR– major activity in heavy ion group

gearing up for ALICE– hardware contribution well under

way

– increase effort on physics simulations