charm e- + X(K)

1. Feasibility study of Heavy Flavor tagging with charged kaons in Au-Au Collisions at √s=200 GeV triggered by High Transverse Momentum Electrons.E.Kistenev, Brookhaven National Laboratory, USA for the PHENIX collaboration • Motivation • Simulation outlook • PHENIX tools • Outlines of analysis (2002 data) • Future e to trigger, K to tag charm e- + X(K) beauty e- + X(K) Drell-Yan e- Study by Mickey Chiu, J. Nagle

2. K- p+ u e+ D+ _ K+ D0 po p- g g Motivation Charm dominates in the e sample above Pt(e) = 2GeV/c Rate expectations: s(pp) inel ~ 42 mb s(pp->ccX) ~ 500 mb <nbin>mb, AuAu ~ 250 N(cc)/event ~ 3.1 PRL 88(2002) 192303 (%)

3. Outlook from simulation PYTHIA in pp - triggering on high Pt electrons will most likely result in well established charm signal (opposite sign pairs); in AuAu - signal may be totally masked by the combinatorial background

4. Detectors: RICH – measures cherenkov rings; Drift Chambers – measure momenta; Pad Chambers – resolve ambiguities; EMCal – provides second momentum measurement, measure Time-of-Flight and resolves ambiguities. Electron Id in AuAu collisions in PHENIX • 2% signal loss compared to photons due to light attenuation;

5. Electron Id in AuAu collisions in PHENIX • EMCal ToF for electrons: • systematic needs further studies; • resolution is better then 400 ps for electrons with momenta around 1 GeV/c.

6. Charged Hadron Id in AuAu collisions in PHENIX 2001 PHENIX published data • Detectors: • Drift Chambers – measure momenta; • High Resolution ToF – measure Time-of-Flight (limited acceptance); • TEC – measure dE/dx; • EMCal –measureTime-of-Flight with limited resolution in the whole acceptance of the PHENIX central arms. 2002 Phys. Rev. Lett. 88, 242301 (2002).

7. Charged Kaon Id in AuAu collisions in PHENIX (via ToF in 2002 EMCal) • Fluctuations in hadronic showers degrade calorimeter timing resolution (s ~ 700 ps for 1GeV/c kaon momenta); • Systematic is consistent with measured in the test beam exposure.

8. 2002 Charged Hadron Id in AuAu collisions in PHENIX EMCal • 2002 charged hadron identification limits: • p/K – 0.95 GeV/c; • K/P – 1.7 GeV/c

9. Event selection and data sample • Minimum bias trigger (92% of the total cross section); • Well measured vertex; • At least one reconstructed electron with Pt > 0.5 GeV/c.

10. Charged Kaons in the electron-triggered events (130 GeV)

11. eK correlations in the electron-triggered events (opposite sign pairs) uncorrected data, normalization adjusted to allow for shapes conparison.

12. eK correlations in the electron-triggered events (same sign pairs) uncorrected data, normalization adjusted to allow for shapes conparison.

13. CsI Readout Plane GEM, mMega Future PHENIX e- p e+ V0 p e- p outer PHENIX detectors e+ TPC/HBD Silicon Tracker

14. Conclusions • timing measurements in PHENIX EMCal successfully used to identify charged kaons in the momentum range up to ~ 1GeV/c; • shape of the invariant Pt distributions of charged kaons identified in EMCal is consistent with published PHENIX results; • eK correlations in minimum bias AuAu collisions at 200GeV are dominated by the combinatorial background due to many binary collisions; • - PHENIX has proposed a new silicon vertex tracker. Kaons identified in the acceptance of the central detector and tracked down to displaced vertices will tag the nature of decay particles.