Transcript Nucleon Structure and Quark-Gluon-Plasma: HERMES and ALICE/STAR Thomas Peitzmann

Nucleon Structure and
Quark-Gluon-Plasma:
HERMES and ALICE/STAR
Thomas Peitzmann
Utrecht University/NIKHEF
T. Peitzmann, NUPECC Groningen, Nov. 18,
Outline
• HERMES
– fragmentation in nuclei
• STAR
– elliptic flow
– jet physics
• ALICE
– silicon strip detector
– analysis preparations
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
~16 M€ per annum excluding investments
ATLAS
& D0
GRID
R&D
Theory
Antares
ALICE
& STAR
LHCb
& Babar
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
NIKHEF Research programs
Outreach
HERA
LEP
2005
HERMES
• HERA/DESY
• investigate spin
structure of the
nucleon
– DIS with polarized
leptons on polarized
hydrogen target
hardware contribution
from NIKHEF: Lambda wheels
• fragmentation in the
nucleus
– lepto-production of
hadrons off nuclei
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
spin decomposition
HERMES
Analysis highlights:
• N spin decomposition
• hyperon production
• transversity
PhDs:
• 10 completed
• 7 now @ institutes abroad
• +5 in preparation
Publications:
• expect ~100 by 2007
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Absorption/Energy Loss in
Nuclei?
• production of hadrons
in nuclei vs deuterium
h
M
R
(Nh (z,n ) Ne (n )) A
(z,n ) =
(Nh (z,n ) Ne (n ))D
• significant suppression
of large z hadrons in
heavy nuclei
n > 7GeV
– absorption?
– energy loss?
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Fragmentation in the Nucleus?
• ratio of di-hadron to single
hadron for different nuclei
(N2h (z 2 ,z1) N1h (z1)) A
R2h (z 2 ) =
(N2h (z 2 ,z1) N1h (z1))D
z1 > 0.5
• very little dependence on
mass of nucleus
• important reference
measurement for heavy
ion collisions
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
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
QCD phase diagram
• QCD predicts
transition from
hadronic phase to a
quark-gluon-plasma
– Tc ≈ 160-170 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
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
The STAR Detector
Magnet
Barrel EM Cal
(BEMC)
Coils
Silicon Vertex
Tracker (SVT)
Silicon Strip
Detector (SSD)
Central
Trigger
Barrel
(CTB)
PMD
ZCal
FTPC
Endcap EM Cal
FPD
Time
Projection
Chamber
(TPC)
TOFp, TOFr
FPD
Year 2000
Year 2001+
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Elliptic flow
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Collective motion: velocity of
P.F. Kolb and U.sound
Heinz, in Quark Gluon Plasma, nucl-th/0305084
• 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
Self-quenching of elliptic flow
P.F. Kolb and U. Heinz, in Quark Gluon Plasma, nucl-th/0305084
• 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
Measurement of elliptic flow
• asymmetry of number
distribution of particles
with respect to the
reaction plane
• Fourier-decomposition:
strong 2. order (v2)
ideal
hydrodynamics
STAR
charged
hadrons
• early result from STAR:
strength of elliptic flow
reaches predictions of
ideal hydrodynamics at
RHIC
Identified particle flow
• hierarchy of
momentum dependent
flow for different
hadrons
parallel talk by Bai Yuting
– 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
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Jets and jet quenching
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
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
CR
DE ª
a S ³ q̂ ³L2
4
• dominant feature:
– energy loss determined
by density of color
charges
• parameterized by
transport coefficient
q̂ =
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
kT2
l
µ r glue
Measuring jets in AA?
how to find this
p+p dijet+X
two observables:
(STAR@RHIC)
in here?
Au+Au ???
- high pT single hadron distribution
- dihadron distributions
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Inclusive Hadron Suppression
• nuclear modification factor
Eskola et al., hep-ph/0406319
d 2N AA dydpT
RAA • 2 pp
AA
d N dydpT ³ Ncoll
2
q̂ = 0 GeV fm
• suppression requires
initial
fm density 30x larger
q 5
than
GeV cold nuclear matter
q̂ = 1GeV2 fm
2
– compare to HERMES
results
• very close to maximum
q̂ = 5 - 15 GeV fm
suppression
2
– provides only lower bound
on density
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
Surface emission
?
Eskola et al., hep-ph/0406319
• 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
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
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
8 < pT(trig) < 15 GeV/c
Emergence of dijets
pT(assoc)>6 GeV
STAR Preliminary
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
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
The perfect fluid at RHIC,
the wQGP at the LHC?
wQGP = weaklyinteracting plasma
less flow at
higher energies?
beware: remember
the predictions for
RHIC!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
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
Solenoid magnet 0.5 T
Cosmic rays trigger
ALICE: the dedicated
Forward detectors:
• PMD
• FMD, T0, V0, ZDC
Specialized detectors:
• HMPID
• PHOS
Central tracking system:
• ITS
•TPC
• TRD
• TOF
HI experiment
MUON Spectrometer:
• absorbers
• tracking stations
• trigger chambers
• dipole
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
The Alice ITS
•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
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
•DAQ
SSD: the first real ladder!
T. Peitzmann, NUPECC Groningen, Nov. 18, 2005
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
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
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
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