1. Pion femtoscopy from ALICE
XI GDRE WORKSHOP Heavy Ions at Relativistic Energies
SUBATECH, Nantes, France
June 29 - July 13, 2011
Pion femtoscopy from ALICE
Jan Pluta
Faculty of Physics
Warsaw University of Technology

2. ALICE-femto one year ago
ALICE-femto one year ago? (some results presented during the last GDRE workshop, July 2010)

3. Pion source size from STAR
STAR, Phys. Rev. C 80 (2009) 24905
STAR, arXiv: [nucl-ex]
p + p
(various ways
of fitting)
Au + Au
Cu + Cu
pT dependence of pion source size similar in nuclear and pp collisions
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

4. Identical pion correlation functions
Bose-Einstein peak clearly visible
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 4 4

5. Multiplicity and transverse momentum dependence
identical pions unlike-sign pions
baseline has to be treated properly
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

6. Multiplicity dependence
for comp.: nuclear collisions
M. Lisa, Ann. Rev. Nucl. Part. Sci. 55, 357
visible dependence in pp  HBT radii depend on multiplicity rather than on collision geometry
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

7. Transverse momentum dependence
no significant dependence on transverse momentum
for comparison: in
nuclear collisions
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

8. 7 TeV and new 900 GeV data high-q baseline flatter at 7 TeV
identical pion correlations
120 M events at 7 TeV
2.1 M events at 0.9 TeV
high-q baseline flatter at 7 TeV
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

9. π+π - correlations at 7 TeV
Coulomb
K0S
rich resonance structure ω ρ f0 f2
low-q baseline steeper at 7 TeV
 origin: jets
high-q baseline flatter at 7 TeV
 origin: momentum cons.
Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010

10. one year after … ALICE – femto papers
Two-pion Bose-Einstein correlations in pp collisions at sqrt(s)=900 GeV. By ALICE Collaboration (K. Aamodt et al.). Jul pp. Temporary entry Published in Phys.Rev.D82:052001, e-Print: arXiv:  [hep-th]
Femtoscopy of pp collisions at sqrt{s}=0.9 and 7 TeV at the LHC with two-pion Bose-Einstein correlations. By ALICE Collaboration (K. Aamodt et al.) CERN-PH-EP , Jan pp. e-Print: arXiv:  [hep-ex]
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at $sqrt(s_NN)$ = 2.76 TeV. By ALICE Collaboration (K. Aamodt et al.). CERN-PH-EP-ALICE , Jan pp. Published in Phys.Lett.B696: , e-Print: arXiv:  [nucl-ex]

11. Quark Matter’ 2011 - presentations

14. Examples of correlation functions
…in spherical harmonics
…in Cartesian coordinates
Multiplicity dependence

15. Momentum - dependence

16. The energy (in)dependence
of the emission region size
The change of energy almost
one order of magnitude !!!

18. The non-femtoscopic
background
MC -simulations

19. Non-identical pions
π+π - pairs

20. Fitting the correlation function Bowler-Sinyukov formula
Final functional form
B-background fit

33. Conclusions Linear scaling wit dN/dɳ seen for all energies
kT dependence consistent with hydro
No common scaling for pp and AA
No collision energy dependence of femtoscopic radii for pp collisions
Radii in Pb-Pb collisions at LHC 30% larger than in AuAu collisions at RHIC
Problem with non-femtoscopic correlations