1. Nucleon Structure and Quark-Gluon-Plasma: HERMES and ALICE/STAR
Thomas Peitzmann
Utrecht University/NIKHEF
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

2. Outline HERMES STAR ALICE fragmentation in nuclei elliptic flow
jet physics
ALICE
silicon strip detector
analysis preparations
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

3. NIKHEF Research programs
HERA
~16 M€ per annum excluding investments
LEP
Outreach
ATLAS
& D0
GRID
R&D
NIKHEF Research programs
Theory
Antares
ALICE
& STAR
LHCb
& Babar
2005
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

4. HERMES HERA/DESY investigate spin structure of the nucleon
DIS with polarized leptons on polarized hydrogen target
fragmentation in the nucleus
lepto-production of hadrons off nuclei
hardware contribution
from NIKHEF: Lambda wheels
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

5. HERMES spin decomposition Analysis highlights: N spin decomposition
hyperon production
transversity
PhDs:
10 completed
7 institutes abroad
+5 in preparation
Publications:
expect ~100 by 2007
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

6. Absorption/Energy Loss in Nuclei?
production of hadrons in nuclei vs deuterium
significant suppression of large z hadrons in heavy nuclei
absorption?
energy loss?
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

7. Fragmentation in the Nucleus?
ratio of di-hadron to single hadron for different nuclei
very little dependence on mass of nucleus
important reference measurement for heavy ion collisions
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

8. ALICE/STAR part of one FOM programme ALICE at LHC/CERN
hardware contribution: silicon strip detector
data taking from 2007
STAR at RHIC/BNL
joined in 2002
data taking and analysis
7 PhD
4 STAR, 3 ALICE
45 publications
STAR from 2002 up to now
group will shift completely to ALICE in the near future
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

9. QCD phase diagram
QCD predicts transition from hadronic phase to a quark-gluon-plasma
Tc ≈ MeV
order of transition unknown (but much larger number of d.o.f.)
deconfinement and chiral symmetry restoration
studied in high-energy heavy ion collisions
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

10. The focus of our group
The properties of the QCD Equation of State above Tc
dp/d calculable in lattice QCD
observables: collective motion of low transverse momentum particles as function of mass
The color density of hot and dense QCD matter
induced soft gluon radiation by partons traversing the medium
observables: medium modifications of jets and heavy particle production
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

11. The STAR Detector PMD Magnet Barrel EM Cal (BEMC) Coils
Central
Trigger
Barrel
(CTB)
ZCal
Time
Projection
Chamber
(TPC)
Year 2000
Barrel EM Cal (BEMC)
Silicon Vertex Tracker (SVT) Silicon Strip Detector (SSD)
FTPC Endcap EM Cal FPD
TOFp, TOFr
FPD
Year 2001+
PMD
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

12. Elliptic flow
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

13. Collective motion: velocity of sound
P.F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/
buildup of collective flow depends on the magnitude of the velocity of sound and the relative time spend in various phases
sensitive to difference in equation of state (EoS)
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

14. Self-quenching of elliptic flow
P.F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/
the driving force of elliptic flow (anisotropy of pressure gradient) dominates at “early” times
elliptic flow “monitors” early collective (i.e. equilibrated) behaviour
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

15. Measurement of elliptic flow
asymmetry of number distribution of particles with respect to the reaction plane
Fourier-decomposition: strong 2. order (v2)
early result from STAR: strength of elliptic flow reaches predictions of ideal hydrodynamics at RHIC
ideal
hydrodynamics
STAR
charged
hadrons

16. Identified particle flow
hierarchy of momentum dependent flow for different hadrons
onset of v2 shifts to larger pT for heavier particles
consistent with ideal hydrodynamics
magnitude of difference not consistent with hadron gas, but with QGP
parallel talk by Bai Yuting
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

17. Jets and jet quenching
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

18. Parton energy loss: current understanding
collisional energy loss
original idea by Bjorken
very small effect
more important: induced gluon radiation
interference leads to non-linearity
dominant feature:
energy loss determined by density of color charges
parameterized by transport coefficient
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

19. Measuring jets in AA? how to find this in here?
p+p dijet+X
Au+Au ???
two observables: - high pT single hadron distributions
- dihadron distributions
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

20. Inclusive Hadron Suppression
nuclear modification factor
suppression requires initial density 30x larger than cold nuclear matter
compare to HERMES results
very close to maximum suppression
provides only lower bound on density
Eskola et al., hep-ph/
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

21. Surface emission ? large energy loss: opaque core
Eskola et al., hep-ph/
large energy loss: opaque core
emissions from surface
inclusive measurements insensitive above certain density
more information from correlation measurements?
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

22. Dihadrons in heavy ion collisions
near-side correlation unchanged
away-side peak suppressed in central Au+Au
consistent with surface emission
distributions in d+Au similar to p+p
suppression is final state effect
more intuitive hint for “jet” suppression, but quantitatively much more difficult
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

23. Emergence of away-side peak
Equivalent to year 2 analysis
STAR Preliminary
Au+Au, 0-5%
pT(trig)
pT(assoc) > 2 GeV/c
High statistics year 4 dataset allows increase in Q2
Emergence of the away side peak with increased trigger pT
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

24. 8 < pT(trig) < 15 GeV/c
Emergence of dijets
8 < pT(trig) < 15 GeV/c
pT(assoc)>6 GeV
STAR Preliminary
Start off with 2 assoc, then move to 6 assoc
increase associated pT threshold also: clear jet-like peaks seen on near and away side in central Au+Au collisions!
yields info on upper and lower limit of density!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

25. Where does the energy go?
mean pT of away-side associated hadrons
= remaining jet fragments?
Leading hadrons
Medium
significant softening of associated hadrons!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

26. The perfect fluid at RHIC, the wQGP at the LHC?
wQGP = weakly-interacting plasma
less flow at higher energies?
beware: remember the predictions for RHIC!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

27. Elliptic flow at LHC energies from ideal hydrodynamics
From Heinz, Kolb, Sollfrank
Whatever the outcome will be, elliptic flow is a day-one measurement at the LHC with very likely similar impact as at RHIC
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

28. ALICE: the dedicated HI experiment
Solenoid magnet 0.5 T
Cosmic rays trigger
ALICE: the dedicated HI experiment
Forward detectors:
PMD
FMD, T0, V0, ZDC
Specialized detectors:
HMPID
PHOS
Central tracking system:
ITS
TPC
TRD
TOF
MUON Spectrometer:
absorbers
tracking stations
trigger chambers
dipole
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

29. The Alice ITS FE module Support and cooling Endcap FEROM SSD DAQ
Strong contribution to outer layers (SSD)
project leader SSD (6 labs)
Main vertex 15 µm in central PbPb
Vertex charm, strange decays 50 µm
Δp/p (pT>1 GeV, with TPC) 14%->3%
Particle ID (dE/dx)
FE module
Support and cooling
Endcap
FEROM
SSD
DAQ
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

30. SSD: the first real ladder!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

31. NIKHEF/UU ALICE hardware activities (SSD)
Design of SSD support (with Turin)
Design ladder frames (with St. Petersburg)
Design of SSD cooling system (with CERN)
Design of front-end modules (with Kharkov and Strasbourg)
Design ladder cabling (with Kharkov)
Design SSD cabling (industrial production)
Design and production of front-end module test equipment
Design and production of EndCap electronics
Design and production of read-out modules
Ladder assembly (with Nantes)
Final SSD assembly
Bottom line: ITS project on schedule and NIKHEF SSD contribution will finish on time (2006)
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

32. ALICE group: current manpower
Utrecht and NIKHEF Amsterdam
Amsterdam manpower:
Staff physicist: 3
PhD students: 2
Utrecht manpower:
Staff physicist: 4
Post-doc: 1
PhD students: 5
Students: 2
Amsterdam infrastructure:
Mechanical and electronics workshop
Ladder assembly room
Utrecht infrastructure:
Faculty mechanical and electronics workshop
Mechanical and electronic workshop of the SAP department (4 fte)
Assembly room
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

33. ALICE group: current physics activities
Have strong role in STAR EMC analysis
1 fte staff, 1 post-doc, 3 PhD's (until 2009) and 2 students
Had a leading role in correlation analysis with the reaction plane in STAR
Effort is scaled down to 1 PhD (until 2007) and 0.2 fte staff
Have a coordinating role in correlation analysis with the reaction plane in ALICE (Physics Performance Report)
Effort 4 fte staff and 2 PhD
Will increase further with 3 PhD’s and 1 post-doc
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005

34. Summary important nuclear physics contributions from NIKHEF
HERMES with nuclear physics program in parallel to spin
ALICE/STAR nuclear physics at the highest energies
rich physics harvest from STAR
elliptic flow
jet quenching
ALICE well under way for data taking in 2007
strong Dutch contribution to SSD
prepare physics analysis
elliptic flow as day-one topic
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005