1. Momentum Correlations
Status of PPR 6.3,
Momentum Correlations
Soft Physics Meeting, , Jan Pluta, Warsaw University of Technology

2. The structure
- shifted by Mercedes C

3. The structure (2)

4. Mercedes changes in the text
Consistent notation
New version of “Conclusion from experiments at AGS, SPS and RHIC”
Some changes in the structure,
Language corrections
New figures
Jan’s comment: Keep “small relative velocities”.

5. added
by Mercedes

6. ...added
by Mercedes
...but pleasse,
suply the
“oscillations
in transverse
radii”
(M.Lisa et al.)

7. New Elements
Nonidentical
Particle
Correlations

8. Nonidentical particle correlations (The idea: assymmetry analysis)
Catching up
Effective interaction time larger
Stronger correlation
Moving away
Effective interaction time smaller
Weaker correlation
“Double” ratio
Sensitive to the space-time asymmetry in the emission process
Kinematics selection
R.Lednicky, V. L.Lyuboshitz,
B.Erazmus, D.Nouais,
Phys.Lett. B373 (1996) 30.

9. STAR: Correlation functions and ratios
Good agreement for like-
sign and unlike-sign pairs
points to similar emission
process for K+ and K- CF
Out
Clear sign of emission
asymmetry
Side
Two other ratios done as
a double check – expected
to be flat
Long
Preliminary
by Adam Kisiel

10. STAR: Hit merging in the TPC
Tracks can cross in the TPC for pairs with only one sign of k*Side
If the tracks cross – they can merge, if they merge at the outer part of the TPC, they are not tracked
Cut rejects from the denominator pairs, that would be merged if in the same event

11. ALICE: Nonidentical particles (pi+,K-)
Assumed time shift
by Emilia Lubańska

12. ALICE: Correlation functions (pi+,K-)
by Emilia Lubańska

13. Double ratios: out,side,long
(physics + merging)
by Emilia Lubańska

14. HBT correlations
in ITS
stand alone

15. Stand alone ITS for HBT analysis
(Alberto Pulvirenti)
Motivation:
some running time for a “high rate” data taking, e.g. for muon studies,
in this case the TPC (slow response) cannot be used,
is ITS capable to perform track reconstruction and perform HBT studies?
Tracking in the ITS stand alone:
the first attempt made in (1999) Alice-ITS-99-34, SUBATECH-99-09
new version based on the Denby-Peterson Neural Tracking,
full C++ implementation into AliRoot,
SIMULATIONS
160 events, HIJING param particles/event
“good” track - 5 points sharing the same GEANT label,
efficiency - (70-80)%

16. Stand alone ITS for HBT analysis
(Alberto Pulvirenti)
ANALYSIS:
only one dim. analysis with respect to Qinv
The method of “weights” by R.Lednicky used to create correlations
Perfect PID assumed ( realistic PID “under study”)
HBT analyser of P. Skowronski used to calculate correlation function

17. Stand alone ITS for HBT analysis
(Alberto Pulvirenti)
RESULTS
Gaussian source distribution with (6, 8, 10, 12)fm assumed
Intercept parameter: lambda (0.5,0.75, 1.0)
open points - no correlations
full points - R=8fm
corrected correlation function

18. Stand alone ITS for HBT analysis
(Alberto Pulvirenti)
CONCLUSIONS
Correlation effect is clearly visible.
Linear correlations of the results with the simulated values.
Reconstructed values underestimate the simulated ones.
Works are in progress.

19. Direct photons
interferometry

20. Direct photons interferometry with PHOS (by Dmitri Peressounko )
Specific features of direct photons:
emitted in all stages of the collision,
keep information about the “beginning/hottest” stage of the collision,
Kt dependence select contribution from different stages,
do not suffer from FSI, direct interpretation of the correlation funct.
but most of photons are produced in decay of long living hadrons,
this contribution can be estimated and subtracted.
Registration of two photons by PHOS:
R=5fm => Q=50MeV
If Kt=1GeV, Q/Kt=0.05; 460cm*0.05=23cm - distance between photons in PHOS
One crystal unit =2.5cm
Two local maxima should be separated by one crystal unit
Size of the cluster increase logarithmically with energy

21. Direct photons interferometry with PHOS (by Dmitri Peressounko )
Unfolding algorithm
Resolution of:
relative distance cm
energy: sig(E)/E - 4%
systematic - increasing
(small influence on correl.)
Probability to unfolded (filed boxes)
and find cluster separated (empty boxes)
as a function of distance between them

22. Direct photons interferometry with PHOS (by Dmitri Peressounko )
Resolution:
Qside
Qout

23. Direct photons interferometry with PHOS
(by Dmitri Peressounko )
Splitting of complicated clusters: p, p(bar), n, n(bar)
Contribution much smaller than those of direct photons

24. Direct photons interferometry with PHOS
(by Dmitri Peressounko )
Photon pairs in high multiplicity envirnment
HILING, central Pb+Pb collisions
photon conversion before PHOS, heavier resonances

25. Direct photons interferometry with PHOS
(by Dmitri Peressounko )
CONCLUSION
Possibility of measurement of two-photon correlations
up to Kt=3MeV, even in central Pb+Pb collisions
accessing space-time informatin
about all major stages of the collisions.

26. Influence of
Resonances

27. Resonance influence on particle correlations
(Ludmila Malinina and Boris Batiounia)
Motivation:
2/3 of pions comes from resonance decays,
It makes the interpretation of correlation results
more complicated
Simulation:
Thermal source with Boltzmann gas of resonances:
short lived: e.g. Rho - mean lifetime fm/c
moderatelylived: omega - mean lifetime fm/c,
long lived: etha’ - mean lifetime fm/c
secondary interactions: sigma=400mb

28. Resonance influence on particle correlations
(Ludmila Malinina and Boris Batiounia)
Correlation function for different resonance sources

29. Resonance influence on particle correlations
(Ludmila Malinina and Boris Batiounia)
3-dim. correlation function for omega source and rescattering

30. Simulation chain

31. Correlations in
(pp) collisions

32. Correlations in (pp) collisions
(Piotr Skowroński)
1. The size expected fm (1fm assumed in simulations)
events generated using PYTHIA
(correlatins outside the interferometry region
for very small multiplicities, Nch>5 taken)
3. Analysis the same as for Pb+Pb

33. Correlations in (pp) collisions
(Piotr Skowroński)

34. Two Particle Resolution (Piotr Skowroński, Grzegorz Gałązka)
Resolution values are very close to the ones in Technical Proposal
Improvement in Qout is connected to better pt resolution and higher magnetic field 1
1.3
0.5
0.6 11
6.3
600 < pt
0.8
1.1
0.4
6.4
4.2
300< pt < 600
0.9
3.4
2.7
pt < 300 TP
PDC04
Qlong
Qside
Qout
Resolution (r.m.s) [MeV]
pt range [MeV]

35. Two Particle Resolutions (2)
Resolution (r.m.s) [MeV]
Qinv
Qout
Qside
Qlong
PDC04 TP
p+p+
0.9
1.3
3.4
3.8
0.4 1
0.8
K+K+
2.3
4.2
6.4
9.5
0.6
0.5
1.9 pp
4.0
8.0
9.4
13.0
0.7
3.2
4.3
p+K-  x x
4.4
4.1
1.2
1.7
1.1
p+p
5.8
2.1
1.8
K+p
8.3
1.0
2.6

36. New data on reslution

37. New data on reslution

38. New data on reslution

39. New data on reslution

40. Track Merging – ident. (1)
Anti-Merging cut as implemented by STAR
Cutting on average distance between two tracks in TPC
Space coordinates of tracks are calculated assuming helix shape using track parameters as reconstructed in the inner part of TPC

41. P I D

42. Single event pion-pion interferometry... by Hania GOS

43. CorrFit CorrFit is a tool developed in STAR by Adam Kisiel
CorrFit is able to find parameters that fits correlation function taking to the account:
Final State Interaction (Coulomb and strong)
They are not corrected for but treated as a source of correlations!
Detector resolution
Can work with any model of the freeze-out distribution
Not limited to Gaussian source distribution !
Is able to fit non-identical particles correlation functions

44. 2 notes in preparation

45. ...to do Finish the text of PPR (2-4 weeks)
Continue works with resoltion, PID, mergind etc.
Finish works with CORFIT
Cooperate with other groups of Soft Physics at ALICE (asHBT, strange particles etc.)
Cooperate with theorists; EPOS+Hydro, etc.
Be ready for data taking!!! (2007)