Embed Size (px)
Citation preview
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
T.Peitzmann
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
T.Peitzmann
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
T.Peitzmann
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, …
T.Peitzmann
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
T.Peitzmann
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
T.Peitzmann
LHC: Preparations for ALICE
l hardware contribution: silicon stripdetector– design and prototyping well under
wayl physics simulation
– efforts being started
T.Peitzmann
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
T.Peitzmann
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
T.Peitzmann
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
T.Peitzmann
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
T.Peitzmann
Charge Sharing Around Dead Strip
T.Peitzmann
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
T.Peitzmann
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
