Transcript Status of the ALICE Project NIKHEF annual scientific meeting Thomas Peitzmann Universiteit Utrecht

Status of the ALICE Project
NIKHEF annual scientific meeting
Thomas Peitzmann
Universiteit 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 as small
» thermodynamical “limit”
» baryon. chem. potential mb = 0
– new physical observables
» heavy quarks
» jets
T.Peitzmann
People (NIKHEF and Utrecht University)

PhD

– M. van Leeuwen
NA49
» strangeness and charm yields
– E. van der Pijll
WA98
» direct photons
– P. de RijkeNA57
» omega production
– E. Schillings
NA57
» lambda polarisation
– A. Sokolov
staff
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–
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–
–
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M. Botje
N. van Eijndhoven
R. Kamermans
P. Kuijer
G.-J. Nooren
T. Peitzmann
R. Snellings
ALICE
» SSD module tests
T.Peitzmann
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

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, …
» even more difficult!
T.Peitzmann
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
T.Peitzmann
RHIC: Joining The


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STAR -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

central Au+Au collision at
sNN=200GeV in the STAR TPC
– substantial contribution
to be built up!

see talk by R. Snellings
T.Peitzmann
LHC: Preparations for ALICE

hardware contribution: silicon strip
detector
– design and prototyping well under
way

physics simulation
– efforts being started
T.Peitzmann
Hardware Contributions
•Detector
5mm
•FE module
50 cm
•Endcap
ADC racks
outside magnet
25 m
•FEROM
Alice Inner
Tracking System
•CF support
•Cooling
200 m
•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)

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first silicon strip detector module
– NIKHEF/UU + IRES design
– manufactured at IRES by Ukraine
people
– to be tested at NIKHEF/UU
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)
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
T.Peitzmann
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
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example: impact parameter vs.
charged multiplicity
– HIJING simulations
– 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
T.Peitzmann
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
T.Peitzmann