1. First physics from the ALICE electromagnetic calorimeters
0 and  spectra
Neutral-charged correlations
Gustavo Conesa Balbastre
for the ALICE collaboration

2. First physics from electromagnetic calorimeters
Calorimeters offer the unique capability to identify photons, electrons and hadrons (neutral mesons) in a wide momentum range 0<pT<100 GeV/c
Elementary QCD calculation in pp
perturbative: NLO, NNLO for various processes including exclusive processes with photon in final state
Non perturbative: structure function, fragmentation function, initial and final state effects
Reference data for AA
Medium generated effects in AA
Medium color density: quenching of high pt hadrons, photons unaffected (?), modification of FF,
Additional photon sources: thermal, jet conversion, bremsstrahlung
The observables
0, , direct photon spectra
Correlation with hadron correlation
-jet
Q vs g quenching

3. RHIC experience: Direct photons 0 and  in AA collisions
[PHENIX, QM2009]
Neutral meson spectra at RHIC was the first evidence of a parton energy loss in a quark matter. RAA scales with Npart. What expects us at LHC?

4. RHIC experience: -hadron and hadron-hadron correlations
-h correlations [PHENIX, QM2008]
h-h correlations
[STAR]
Suppression of away-side peak in central Au-Au collisions proves a parton energy loss in a quark matter.

5. ALICE: The dedicated HI Experiment

6. ALICE setup for 2010 Full TPC+ITS
4/11 EMCAL
=40, ||<0.7 4 5 3 6 2 7 1 8 9 17 10 16 15 11 12 14 13 4
3/5 PHOS
=60, ||<0.12 1 3 2

7. PHOton Spectrometer: PHOS
High granularity and resolution spectrometer:
10,752 (17,920) lead-tungstate crystals (PbWO4), 3(5) modules (5664 crystals per module)
crystal size: 22  22  180 mm3
depth in radiation length: 20
Distance to IP: 4.4 m
Acceptance:
pseudo-rapidity [-0.12,0.12]
azimuthal angle 60º(100o)
For E > 10 GeV,
E/E < 1.5% and x = [0.5,2.5] mm
Focus on low and moderate pT
High resolution 0 and 
Thermal photons
CPV (not installed yet)
Crystals
EMC

8. 24 Strip Modules per Super Module
Pb/Sc Shashlik
4k (13K) channels
4 Super Modules for runs
Complete (10 SM) for 2011? runs
EMCAL
Module:
2x2 towers
12 Modules per strip module
24 Strip Modules per Super Module
Coverage =1.4, =40o (107o)
Granularity  = = 0.014
Resolution E/E=11%/√E, x=[3,50]
Focus on moderate to high pT
0 and 
prompt direct photon
jet 8

9. DCAL Same towers than the EMCAL, shorter Super Modules in .
Including PHOS, acceptance is =1.4, =60º
To be installed for 2012 runs
Focus on /0/jet-jet correlations

10. Scope of first physics
Inclusive spectrum of 0 production in pp collisions at 900 GeV and 7 TeV in mid-rapidity and pT range from to GeV/c
Measure inclusive spectrum of ,  and other neutral mesons production in pp collisions at 7 TeV in pT range from 3-5 to GeV/c
Physics:
Constrain pQCD and non perturbative aspects of QCD
Provide reference spectrum for Pb-Pb collisions at 2.76 TeV

11. Neutral meson measurement in ALICE
ALICE provides 3 independent ways to identify 0 and  mesons, through invariant mass analysis of photon pairs and external conversion electrons:
H->    (both on PHOS or EMCAL)
H->   
e+e- (CTS, PHOS or EMCAL)
H->   
e+e- e+e- (CTS)
Performance plots, p+p at 7 TeV, coming next

12. PHOS h-> +  0 175 million minimum bias events.
Cluster selection (better tuning under study).
Ecl>0.3 GeV
Ncell3
0 plots lines:
Red line: fit to combinatorial.
Blue points: histogram minus combinatorial fit.
Blue line: - fit of blue points.

13. PHOS h-> + Estimation of decalibration and comparison with MC
Current PHOS decalibration is 7%
0 reconstruction efficiency
Efficiency limited to < GeV when the 2 photons merge into a single cluster in the calorimeter.

14. PHOS h-> + raw yield
175 million Minimum Bias events.
We identify 0 up to 20 GeV, we expect to arrive to 30 GeV.

15. EMCAL h-> +  0 188 million minimum bias events.
Cluster selection (better tuning under study)
Ecl>0.3 GeV
Ncell2

16. EMCAL h-> + Data MC Data 0 width vs pT in real data and MC
Still important decalibration in EMCAL, we are working to get the MC values.
Reconstruction efficiency descends fast after 6-7 GeV because of the large cell size / clusterizer, being our measurement limit actually about 10 GeV
We are working in a new clusterization procedure that will allow us to arrive to 20 GeV.

17. EMCAL h-> + 188 million minimum bias events
√s= 7TeV
188 million minimum bias events
pT reach 10 GeV due to size of cells and clusterizer used.
We plan to improve clusterizer and arrive to 20 GeV.

18. h-> + -> e+e-e+e-, data candidate

19. CTS h-> + -> e+e-e+e-
For pT > 1 GeV
Photon conversion probability of about 8%
Photon reconstruction efficiency is of 70% with close to 100% purity

20. CTS h-> + -> e+e-e+e-, raw yields
For ~108 minimum bias p+p events at 7 TeV, the accessible pT range is:
0 : to 10 GeV/c
 : 0.6 to 6 GeV/c

21. PHOS-CTS h-> + -> e+e- 0
Events per 5 MeV/c2
Events per 10 MeV/c2
√s= 7 TeV
√s= 7 TeV
140 million p+p events at 7 TeV
p0 can be identified with pT>0.5 GeV/c
is visible with pT>2 GeV/c

22. PHOS-CTS h-> + -> e+e-
√s= 7 TeV
√s= 7 TeV

23. EMCAL-CTS h-> + -> e+e-
140 million minimum bias events.
Non linearity correction not applied yet
masks the 
Events per 5 MeV/c2
√s= 7 TeV

24. EM Cluster - Hadron correlation analysis
performance
01/09/2010
performance
01/09/2010
√s= 7 TeV
√s= 7 TeV
Correlation of Charged Tracks / PHOS clusters / EMCAL clusters with charged hadrons measured in TPC+ITS.
Left Plot: Near (mainly 0 for EM calorimeters) and away side correlation shows a jet-like structure
Right plot: Applying isolation cuts to clusters or 0, the away side correlation remains: single pi0 - jets and/or direct-photon - jet ?
Consolidate the isolation cut, extract kT, FF.

25. Summary
ALICE has measured 0 and  neutral mesons with its calorimeters and central tracking system.
The agreement between the analysis seems to converge, but work is needed, specially on calibration and non linearity effects in the calorimeters.
For the end of the p+p collisions at 7 TeV data taking period at LHC we expect to measure 0 in the range 0.3 < pT <30 GeV and  in the range 0.6 < pT < 10 GeV.
We are getting ready for and looking forward to Pb+Pb collisions in a couple of months …