0. Experimental High-energy Heavy-ion Physics in Heidelberg
Kai Schweda
66th NuPECC meeting, Egelsbach
10 Oct 2009

1. Heavy-ion group at Heidelberg
group leader: J. Stachel
faculty: P. Glässel, N. Herrmann, K. Reygers, R. Schicker, K.S.
9 postdocs
10 Ph.D. students
3 diploma students
5 junior researchers
3 engineers
10 Oct 2009
66th NuPECC meeting, Egelsbach

2. Phase diagram of strongly interacting matter
ALICE at LHC: explore high-energy frontier
CBM at FAIR: explore high baryon-density frontier
10 Oct 2009
66th NuPECC meeting, Egelsbach

3. ITS: measures secondary vertex, open heavy-flavor, c and b
Size: 16 x 26 meters
Weight: 10,000 tons
Detectors: 18
TRD
ITS
TPC
ITS: measures secondary vertex, open heavy-flavor, c and b
TPC: tracks and identifies charged particles, (e,), , K, p
TRD: identifies electrons above 1 GeV, fast trigger (6s) 3

4. 66th NuPECC meeting, Egelsbach
ALICE TPC Calibration
TPC installed in ALICE, running continuously May-October 2008, and since Aug 2009
100 million events (cosmics, krypton, and laser) recorded
Second iteration of calibration completed, more to come
transverse momentum resolution
particle identification via dE/dx
dE/dx resolution:
measured <5%
design %
resolution at 10 GeV:
measured 6.5%
design %
performance meets design, TPC ready for collisions
10 Oct 2009
66th NuPECC meeting, Egelsbach

5. 66th NuPECC meeting, Egelsbach
TRD commissioning
7/18 supermodules installed in ALICE
cosmic ray data taking in and 2009
horizontal tracks acquired (TRD L1 trigger commissioned and used)
reconstruction and first iteration for calibration parameters (gain, drift velocity) completed
cosmic event triggered by TRD L1
Tracking in TPC and 2 TRD SM
Uniformity better than 10%
Run 85752, event 8
10 Oct 2009
66th NuPECC meeting, Egelsbach

6. TRD readout electronics
2 custom designed ASICS
- pre-amplifier/shaper (PASA) - ADC/tracklet-processor (TRAP):
contain 275k CPUs to process 65 MBytes of raw data
tracking and trigger decision within 6.5s
selection of high momentum electrons
70kW cooling power required
PASA
TRAP
Multi Chip Module (MCM)
10 Oct 2009
66th NuPECC meeting, Egelsbach

7. HD contribution to TRD of ALICE
Technical coordination
Infrastructure at CERN
Installation and commissioning at CERN
Construction and electronics development
Chamber testing
Electronics integration and pretrigger
Detector control system
Data quality and integrity assurance
Alignment
Online monitoring
Noise analysis
10 Oct 2009
66th NuPECC meeting, Egelsbach

8. HD contribution to TPC of ALICE
Technical coordination
Electronics development
10 Oct 2009
66th NuPECC meeting, Egelsbach

9. Fast parton probing the medium
z = p(h)/pparton
Ejet  pparton
Eγ = pparton
p ≠ pparton
Leading
Hadron
quark-gluon plasma
Fast parton emerges in spray of collimated hadrons  jet
Measure hadron distribution f(z)  fragmentation function
Medium modification of f(z) compared to vacuum  probe QGP
10 Oct 2009
66th NuPECC meeting, Egelsbach

10. 66th NuPECC meeting, Egelsbach
Jet- quenching
Nuclear modification factor:
Energy loss of parton leads to deficit of hadrons at large momentum
No “Effect”:
R < 1 at small momenta
R = 1 at higher momenta where hard processes dominate
Jet-quenching:
Suppression: R < 1
10 Oct 2009
66th NuPECC meeting, Egelsbach

11. 66th NuPECC meeting, Egelsbach
b-quark tagged jets
novel effects for heavy-quarks predicted
quark vs. gluon energy loss in the medium  exp. access to color factor  challenge to models
b-quark jets are pure samples of quark jets
harder fragmentation of the b-quark
jet-energy is known more precisely
better handle on the fragmentation function
S. Wicks et al., NPA 784, (2007) 426.
10 Oct 2009
66th NuPECC meeting, Egelsbach

12. Heavy - flavor: a unique probe
mc,b » QCD : new scale
mc,b ≈ const., mu,d,s ≠ const.
initial conditions: test pQCD, R, F probe gluon distribution
early partonic stage: diffusion (), drag () flow, jets, correlations probe thermalization
hadronization: chiral symmetry restoration confinement statistical coalescence J/ enhancement / suppression Q2
time
X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366.
10 Oct 2009
66th NuPECC meeting, Egelsbach

13. Where does all the charm go ?
J c Ds D0 D±
Statistics plot: H. Yang and Y. Wang, U Heidelberg.
Total charm cross section: open charm hadrons, e.g. D0, D*, c, … or c,b  e() + X
Quarkonia, e.g. J/ carries 1% of total charm
10 Oct 2009
66th NuPECC meeting, Egelsbach

14. Heavy-quark detection
e.g., D0  K- +  , c = 123 m
displaced decay vertex is signature of heavy-quark decay
10 Oct 2009
66th NuPECC meeting, Egelsbach

15. 66th NuPECC meeting, Egelsbach
LHC Schedule
Nov 2009: 1st pp collisions very short run at 900 GeV
pp collisions at TeV
end of 2010: 3-4 weeks Pb+Pb collisions at TeV
*short technical stop over Christmas period
10 Oct 2009
66th NuPECC meeting, Egelsbach

16. Some selected key measurements
open charm: D0  K + 
quarkonia: J/ and trigger
0  , photons from pair-conversions
can be addressed in first year of data taking with p+p collisions
10 Oct 2009
66th NuPECC meeting, Egelsbach

17. Open charm performance
Full reconstruction of D0  K + , D*  D0 + +
Address heavy-quark production in 1st year of data taking
essential input for J/ generation models
M (GeV/c2)
D* D0 + +
ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.
Simulation: 109 p+p, 108 p+Pb, 107 Pb+Pb collisions
10 Oct 2009
66th NuPECC meeting, Egelsbach

18. J/ trigger for pp collisions
expect some 1k J/ per year in min. bias pp collisions
establish single-e and J/ trigger (L1 & L3)
allows detailed heavy-quark and jet studies
Study J/ suppression / enhancement in Pb+Pb collisions
J/ e+e-
A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel, Phys. Lett. B 652 (2007) 259.
10 Oct 2009
66th NuPECC meeting, Egelsbach

19. Photon pair-conversions
in detector material:  + Z e+ + e- + Z
use TPC as pair spectrometer
Meaure  yield up to 20 GeV/c with first year pp data
access to direct photons
 - tagged jets for jet-energy calibration



10 Oct 2009
66th NuPECC meeting, Egelsbach

20. FOPI experimental program
Reference data from elementary reactions
K0 ,  production
p- + C, Al, Cu, Sn, 1.15 GeV/c,
K0 , K+, K-, ,  production in
p- + LH2, C, Pb @ 1.7 GeV/c,
Systematics of strangeness data from hi reactions
K0 , K+, K-, , K*, , *(1385) production
Search for kaonic bound states
System beam energy events
Ni + Ni AGeV, M
Al + Al AGeV, M
Ni + Ni AGeV, M
Ni + Pb AGeV, 100M
Ru+ Ru AGeV, 210M
Search for exotica in elementary reaction
existance of ppK- - bound state
p + p GeV, 80M
Strangeness: comprehensive system-size scan nearly completed
10 Oct 2009
66th NuPECC meeting, Egelsbach

21. FOPI III (2008 – 2010) with improved PID
K- - PID:
S/B > 10
MMRPC TOF Barrel
p<0.8 GeV/c
supermodules,
150 counters,
4500 electronic channels,
6 m2 active area
Performance:
system ~ 90 ps
RPC ~ 65 ps
Worlds best performing multiparticle TOF system so far!
Time-of-flight R&D: future technologies for CBM/FAIR
Electronics development
10 Oct 2009
66th NuPECC meeting, Egelsbach

22. Charmed hadrons at FAIR energies
Look for statistical hadronization of charm at top FAIR energies
c most sensitive !
Need total charm cross section as reference:  measure D-mesons !
total charm energy scan at LHC, RHIC, FAIR  provide input to theory: scales F, R gluon distribution
10 Oct 2009
66th NuPECC meeting, Egelsbach

23. HD physics program with ALICE
Jets and jet-quenching
Leading hadron correlations
Underlying event correlated with jet-production
Heavy-quark tagged jets
Photon-tagged jets
Photon and neutral meson production
Momentum correlations of charged particles
Heavy-quark production: open charm and beauty
Quarkonia production
Collective effects, heavy-quark flow
Femtoscopy
Diffractive scattering
10 Oct 2009
66th NuPECC meeting, Egelsbach