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

charm e- + X(K)beauty e- + X(K)

Drell-Yan e-

e to trigger, K to tag

• Motivation

• Simulation outlook

• PHENIX tools

• Outlines of analysis (2002 data)

• Future

Motivation

Rate expectations:

(pp) inel ~ 42 mb(pp->ccX) ~ 500 b<nbin>mb, AuAu ~ 250N(cc)/event ~ 3.1

K-

+e+

D+

D0_ K+

-o

K-+X K++X e+X K-e++X D0 53 3.4 6.7 >5

D+ 24.2 5.8 17.2 >5

Ds+ /Ds

- >30 8

Charm dominates in the e sample above Pt(e) = 2GeV/c

PRL 88(2002) 192303(%)

Outlook from simulation

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

PYTHIA

Electron Id in AuAu collisions in PHENIX

-2% signal loss compared to photons due to light attenuation;

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

EMCal ToF for electrons:

-systematic needs further studies;

-resolution is better then 400 ps for electrons with momenta around 1 GeV/c.

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.

2001

2002

PHENIX published data

Charged Hadron Id in AuAu collisions in PHENIX

Phys. Rev. Lett. 88, 242301 (2002).

Charged Kaon Id in AuAu collisions in PHENIX (via ToF in 2002 EMCal)

• Fluctuations in hadronic showers degrade calorimeter timing resolution ( ~ 700 ps for 1GeV/c kaon momenta);

• Systematic is consistent with measured in the test beam exposure.

2002 Charged Hadron Id in AuAu collisions in PHENIX EMCal

• 2002 charged hadron identification limits: /K – 0.95 GeV/c;– K/P – 1.7 GeV/c

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.

MB events 2.25 107

Vertex in 25 cm range 1.7 107

N(electrons)>0 1.68 106

Pt(e)>0.5 GeV/c 8 105

Charged Kaons in the electron-triggered events

(130 GeV)

eK correlations in the electron-triggered events (opposite sign pairs)

uncorrected data,

normalization adjusted to allow for shapes conparison.

eK correlations in the electron-triggered events (same sign pairs)

uncorrected data,

normalization adjusted to allow for shapes conparison.

TPC/HBD

Silicon Tracker

GEM, mMega

CsI Readout Plane

Future PHENIX

e+

e-

e-

e+

pp

p

V0

outer PHENIX detectors

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.