0. Recent Results from ALICE at the LHC
Kai Schweda
Physikalisches Institut
University of Heidelberg
Seminar, TU München
22 Nov 2010

1. Building Blocks of Matter
Quantum Chromodynamics (QCD) is the established theory of strongly interacting matter.
Gluons hold quarks together to from hadrons:
Gluons and quarks, or partons, typically exist in a color singlet state: confinement.
meson
baryon
22 Nov 2010
Seminar, TU München

2. Quark Gluon Plasma Quark Gluon Plasma: deconfined and
Source: Michael Turner, National Geographic (1996)
Quark Gluon Plasma:
deconfined and
thermalized state of quarks and gluons
 Study partonic EoS at highest collider energies
22 Nov 2010
Seminar, TU München

3. QCD phase diagram
22 Nov 2010
Seminar, TU München

4. High-energy nucleus-nucleus Collisions

5. Outline Introduction LHC and ALICE Global event properties in pp @ LHC
Hard probes: heavy-quark production
First results from 2.76 TeV
Summary
22 Nov 2010
Seminar, TU München

6. Large Hadron Collider LHC at CERN Alice LHC 7 TeV c - 10 km/h
Tevatron TeV c km/h
RHIC GeV c km/h
Geiger and Marsden MeV c * 5%

7. Nominal LHC Running Conditions
Collision system
√sNN(TeV)
L0 (cm-2s-1)
Run time (s/year)
geom (b)
p + p
14.0
1034 *
107
0.07
Pb + Pb
5.5
1027
106 **
7.7
p + Pb
8.8
1029
106
1.9
Ar + Ar
6.3
2.7
*Lmax (ALICE) = 1030cm-2s-1
** Lint (ALICE) ~ 0.5 nb-1/year
22 Nov 2010
Seminar, TU München

8. Expectations for LHC Cross-sections of interesting probes
expected to increase relative to RHIC by factors
~ 10 ( ) to
~ 102 ( ) to
> 105 (very high pT jets)
LHC is the ultimate machine for quark matter studies with hard-probes
22 Nov 2010
Seminar, TU München

9. The ALICE Collaboration
> 1000 members
~ 100 institutes
30 countries
150 million US $
22 Nov 2010
Seminar, TU München

10. Size: 16 x 26 meters
Weight: 10,000 tons
Detectors: 18
TRD
ITS
TPC 10

11. 3 x 2 Layers Silicon Technology
Strips
SSD
Inner Tracking System
~ 10 m2 Si detectors, 6 layers
double sided Strips, Drift, Pixels
Pixels
SPD
Drift
SDD

12. Inner Tracking System SSD SDD SPD Lout=97.6 cm Rout=43.6 cm
6 Layers, three technologies (keep occupancy ~constant )
Silicon Strip (double-sided) 4.9 m2 2.6M channels
Silicon Drift m2 133k channels
Silicon Pixels m2 9.8M channels
22 Nov 2010
Seminar, TU München

13. Silicon Pixel Alignment
SPD
Point resolution
σΔx = √2 x σspatial ‏
Data:
σspatial = 14 μm
Simulation:
σspatial = 11 μm
ALICE: K. Aamodt et al., J. Inst. 5 (2010) P03003.
22 Nov 2010
Seminar, TU München 13

14. Time Projection Chamber
Most challenging TPC ever built
Radius: mm
Drift length:2 x 2500 mm
Drift time: 92 µs
Gas mixture Ne-CO2-N2
Gas volume: 90 m3
readout pads
Material: (η=0) 3% X0
5 m
22 Nov 2010
Seminar, TU München

15. TPC im Juni ‘06 15

16. TRD readout-electronics
PASA
TRAP
2 custom made chips
- pre-amplifier (PASA) - signal processor (TRAP):
in total 275k CPUs, 65 MBytes of raw data processed within 6.5s
Multi Chip Module (MCM)
22 Nov 2010
Seminar, TU München

17. Assembly of 1st TRD Module - Heidelberg
Chip-Module mit Kühlelementen
TRD Modul
6th layer completed
transport to CERN Sep 2006
Installation of 2nd layer
22 Nov 2010
Seminar, TU München

18. 22 Nov 2010
Seminar, TU München

19. 23-November-2009: first p+p collision recorded in ALICE !

20. 22 Nov 2010
Seminar, TU München

21. p+p Data on Tape* p+p @ 0.9 TeV, 8 M minimum bias ( 111 b-1)
TeV, 35k minimum bias (486 mb-1)
7 TeV, 820 M minimum bias (12 nb-1) M high multiplicity (15 nb-1) M muon triggers (130 nb-1)
*p+p data taking finished 04-Nov-2010
22 Nov 2010
Seminar, TU München

22. Charged  Particle Density
ALICE 7 TeV:
Eur.Phys.J.C68: ,2010;
ALICE 0.9/2.36 TeV:
Eur.Phys.J.C68:89-108,2010.
Multiplicity increases faster than predicted by models
Challenge to theory
22 Nov 2010
Seminar, TU München

23. Momentum Distribution
Spectrum measured from very low to high momentum, small uncertainties in extrapolation
Average momentum not well described by either models
K. Aamodt at al., PLB 693 (2010) 53.
22 Nov 2010
Seminar, TU München

24. Particle Identification
TPC dE/dx: separate p from K up to 1.1 GeV
Time of flight: separate K from up to ~ 1.5 GeV
22 Nov 2010
Seminar, TU München

25. (Anti)-Proton Production at LHC
At LHC energies: Ratio of anti-p/p  1
No need for exotic baryon transport mechanism
Address hadro-chemistry in PbPb within 1 day
ALICE, Phys. Rev. Lett. 105, (2010).
22 Nov 2010
Seminar, TU München

26. Particle Spectra Large momentum coverage of identified particles
Address hadro-chemistry in PbPb within 1 day
22 Nov 2010
Seminar, TU München

27. Photon Pair  Conversions
Photon conversions  +Z  e+e- + Z allow for detailed study of material budget
Material budget between collisions vertex and TPC now known to better than 7%
Precise knowledge of material budget and alignment essential for open charm studies !
22 Nov 2010
Seminar, TU München

28. 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.
22 Nov 2010
Seminar, TU München

29. Heavy  quark Correlations
Charm and anti-charm quarks created in pairs and thus correlated
Look for modificaions in Pb+Pb collisions
PYTHIA: p + 14 TeV
Heavy-quark production correlated due to QCD processes such as pair creation (backward), gluon splitting (forward), etc.
Expetced for pp
Modified in PbPb --> probe early thermalization
X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366.
G. Tsildeakis, H. Appelshäuser, K.S., J. Stachel, arXiv: , subm. To NPA.
22 Nov 2010
Seminar, TU München

30. Where does all the charm go ?
J/ c
D*+ Ds D0 D±
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
22 Nov 2010
Seminar, TU München

31. Heavy-quark detection
Open-charm reco. in ALICE
D0  K
D+  K
D*  D0
Under study:
Ds  KK
D0  K
c  pK
c  
c  K0S
e.g., D0  K- +  , c = 123 m
displaced decay vertex is signature of heavy-quark decay
22 Nov 2010
Seminar, TU München

32. D*+ identified up to 12 GeV/c
D*+  D0 + + Signal
D*+ identified up to 12 GeV/c
22 Nov 2010
Seminar, TU München

33. Open-charm spectra from ALICE
1/7 of total statistics, up to 12 GeV/c; extend to 20 GeV/c
22 Nov 2010
Seminar, TU München

34. Open-charm ratios from ALICE
Ratios coincide with results at lower energies
22 Nov 2010
Seminar, TU München

35. Quarkonia production J/  e+e- (central barrel, y  0)
J/  +- (forward directions, -4 < y -2.5)
Charmonium production still challenge to models
22 Nov 2010
Seminar, TU München

36. p+p Summary
ALICE has identified most hadrons consisting of 1st and 2nd generation quarks (u,d,s,c), also charged leptons (e,) down to lowest momentum
Essential input for models - soft vs hard processes
Open and hidden charm production cross sections underway
Key reference for Pb+Pb physics program
Much more to come…
22 Nov 2010
Seminar, TU München

37. First Pb+Pb collisions in ALICE !

38. Charged-particle multiplicity
ALICE, submitted for publication, arXiv: [nucl-ex].
22 Nov 2010
Seminar, TU München

39. Anisotropy Parameter v2
coordinate-space-anisotropy  momentum-space-anisotropy y py x px
Initial/final conditions, EoS, degrees of freedom

40. v2 in the low-pT Region
P. Huovinen, private communications, 2004
v2 approx. linear in pT, mass ordering from light  to heavier 
characteristic of hydrodynamic flow, sensitive to EOS !
22 Nov 2010
Seminar, TU München

41. Elliptic flow in ALICE 22 Nov 2010 Seminar, TU München
ALICE, submitted for publication, arXiv: [nucl-ex].
22 Nov 2010
Seminar, TU München

42. LHC: Tentative Schedule
23-Nov-2009: 1st pp collisions at 900 GeV
30-Nov-2009: protons accelerated to 1.18 TeV in both rings
Dec-2009: 1st pp collisions at 2.36 TeV
2010/11*: long run with pp collisions at 7(8) TeV
08-Nov-2010: 1st Pb+Pb collisions at 2.76 TeV
Nov 2011: one more month of Pb+Pb collisions
2012: Machine consolidation and training
2013: pp and Pb+Pb at full energy
*technical stop during Dec/Jan
22 Nov 2010
Seminar, TU München

43. ALICE - harvesting physics!
22 Nov 2010
Seminar, TU München

44. Particle Intensity Interferometry
Source size dependence on transverse pair momentum not observed
22 Nov 2010
Seminar, TU München

45. Non-ideal Hydro-dynamics
Spectra and flow reproduced by ideal hydrodynamics calcs.
Shear viscosity to entropy density ratio close to AdS/CFT bound
Hydro-limit exceeded at LHC ?
M.Luzum and R. Romatschke, PRC (2008); P. Romatschke, arXiv:
22 Nov 2010
Seminar, TU München 45

46. Hanbury-Brown Twiss Interferometry
Width in correlation function  1/R
Measure source size R
R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956);
G. Goldhaber et al., Phys.Rev.Lett.3,181(1959).

22 Nov 2010
Seminar, TU München

47. More Open  charm from ALICE
D0  K-+
D+  K -++
Study open charm production in as many channels as possible
22 Nov 2010
Seminar, TU München

48. TPC commissioning transverse momentum resolution, B=0.5 T
particle identification via dE/dx
resolution:
measured 5.7%
design %
resolution at 10 GeV:
measured 6.0%
design %
22 Nov 2010
Seminar, TU München

49. First Pb+Pb collisions in ALICE !
22 Nov 2010
Seminar, TU München