Status of the ALICE Project NIKHEF annual scientific meeting

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Status of the ALICE ProjectNIKHEF annual
scientific meeting
Thomas PeitzmannUniversiteit Utrecht
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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

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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 as small
• thermodynamical limit
• baryon. chem. potential mb 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)
• L polarisation (E. Schillings, see talk)
• small polarisation at mid-rapidity
• W production (P. de Rijke)
• understanding the systematic errors
• alignment, efficiencies,

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Hydrodynamical Model Fits To NA49 Data

• 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

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 AuAu collision at ?sNN200GeV in the
  STAR TPC

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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

• Detector

5mm

• FE module

50 cm
ADC racks outside magnet

• Endcap

25 m

• FEROM

200 m

• CF support
• Cooling

Alice Inner Tracking System

• DAQ

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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

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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