1. 1 The CMS Heavy Ion Program Michael Murray Kansas

2. 2 CMS is a running experiment

3. 3 Overview The detector Soft Physics  Multiplicity  ,k,p at low pt  Flow Hard Physics  Jets  Photons  Quarkonia  Photon nucleus Z Jet Event

4. 4 Rapidity Range A new telescope for new probes High Rate, Trigger Y=4

5. 5 LHC RHIC SPS Hard probes are rare

6. 6 The Central Detector Pixels Strips EM Cal HCal Coil Muons Iron

7. 7 A transverse slice through CMS

8. 8 HCAL ECAL Tracker Coil A slice along Z

9. 9 Castor 5.2<  <6.6 ZDC  >8.3 Forward Detectors

10. 10 HIJING default settings Pixels hits count Multiplicity/event Pseudo rapidity Find hits in pixels, using an energy cut. We also have a tracklet analysis.

11. 11 |  |<1 Low p T hadrons Find tracks in pixels and use energy loss vs momentum for particle ID p T (GeV/c)  pT pT Efficiency dN dp T

12. 12 1. Find the reaction plane calorimeters and tracker 2. Use 2, 4 particle correlations or Lee Yang Zeros Ecal  0.37 V2 with tracker Elliptic Flow Reaction plane x z y  rad p T (GeV/c) V2V2 d  dE

13. 13 Triggering L /cm 2 /s Bunch cross Interaction rate Level 1Event size HLT rate offline pp10 34 25ns40MHz1/4001MB100 KHz 150Hz PbPb10 27 125ns8KHz1/12.5- 10MB 8 Khz10-100 Hz Trigger increases p T range by > 2 for many probes

14. 14 dN ch /d  = 5000 Iterative cone (R>=0.5) with background subtraction:  calculate average energy and dispersion in tower (in eta rings) for each event  subtract average energy and dispersion from each tower  find jets with a jet finder algorithm (any) using the new tower energies  recalculate average energy and dispersion using towers free of jets  recalculate jet energies Done, but can do more iterations Space resolution is less then the tower size Finding Jets MC Jet E T (GeV) Rec E T

15. 15 1.0 Efficiency ~ 70 %, fake rate ~ 1% p T (GeV/c)  <0.5 Single strips Double strips Pixels Z (m) Y (m) Efficiency % Fakes % 1.0 0.5   pT  %   z  cm 2.0<  <2.5  <0.5 Pointing useful for heavy quarks p T (GeV/c) Tracking

16. 16 jet trigger data High Pt Assume luminosity = 0.5 nb -1 10% Central Energy loss from HYDJET No trigger R AA p T (GeV/c) Charged particles |  |<2.5 p T (GeV/c)

17. 17 Efficiency = 60% Fake = 3.5% S/B=4.5 Photons Photon ID based only on cluster shape and isolation cuts using a multi-variate analysis. We reconstruct photon energy with Island algorithm

18. 18 I =0..5 nb -1 Jet fragmention from  jet events Require photon E T > 70GeV

19. 19 cc Suppression: RHIC similar to SPS Regeneration compensate screening J/  not screened at RHIC (T D ~2Tc) LHC: recombination or suppression Suppression of B’onium states  Large Cross-section: 20 x RHIC  melts only at LHC: T D ~4 T C Fewer of bb pairs: less regeneration Much cleaner probe than J/  '' J/  Quarkonia Branching ration is 5.9% for J/ , 2.5%Y (BR:2.5%) Background is from decays from  /K, b-,c-mesons Suppression of charmonion

20. 20 J/    +  - dN ch /d  = 5000 dN ch /d  = 2500 For 0.5 nb -1 we reconstruct 180K J/  Signal/Background: ~5 for |  |<0.8, 1 for |  |<2.4  = 35 MeV |  |<2.4 Produced Reconstructed 2500 Reconstructed 5000 p T (GeV/c) M  (GeV)

21. 21 |  |<2.4,  = 90MeV mass resolution, 90 MeV |  |<2.4 Y ~ 25 000, Y' ~ 7 000, Y'' ~ 4 000 Signal/Background: 1 |  |<0.8, 0.1 for |  |<2.4) Y   +  - M  (GeV) Produced Reconstructed 2500 Reconstructed 5000 p T (GeV/c)

22. 22 Photon nucleus Max photon energy ~ 80 GeV  Pb:  S ≈ 1. TeV/n   S ≈ 160 GeV M  (GeV) M ee (GeV)

23. 23 Summary CMS has an excellent opportunity to study partonic matter at both soft and hard scales, via Multiplicity Soft spectra Flow Forward Physics Quarkonia Hard spectra Photons Jets Z

24. 24 Backup slides

25. 25 CMS acceptance ECAL, PbWO4 0.0174x0.0174 Inner detector HCAL (sampling) 0.087x0.087 (HB) 0.087->0.17 (HE) HF Muon Spectrometer Cast or CMS: Inner detector (|  |<2.5) ECAL (|  |<3) HCAL (|  |<3) HF (3<|  |<5) Muon (|  |<2.4) Castor (5<|  |<6.7) ZDC (|  |>8)