5-11 February 2017
Hyatt Regency Chicago
America/Chicago timezone

Performance of ALICE EMCal and DCal in Electron Identification

Not scheduled
2h 30m
Hyatt Regency Chicago

Hyatt Regency Chicago

151 East Wacker Drive Chicago, Illinois, USA, 60601
Board: C20


Erin Frances Gauger (University of Texas (US))


A Large Ion Collider Experiment (ALICE) is a major experiment at the Large Hadron Collider (LHC) at CERN. It is specifically designed to investigate the Quark-Gluon Plasma (QGP), a state of matter in which quarks and gluons are momentarily deconfined. The QGP is short-lived, and must therefore be studied indirectly by identifying the final-state particles produced in heavy-ion collisions. The final-state particle of interest in this poster is the electron. Electrons must be identified to study, for instance, the semi-leptonic decay channels of heavy-flavor hadrons. Because heavy-flavor quarks are created early in the collision, they travel and interact with the QCD medium. This makes them an important probe of the QGP.

One of the detectors important in identifying electrons is the Electromagnetic Calorimeter (EMCal). The ALICE EMCal is a sampling calorimeter with 77 layers of lead and polystyrene scintillator and is composed of $\sim$6.0$\times$$\sim$6.0$\times$24.6 cm$^{3}$ towers (cells). It has an azimuthal and pseudo-rapidity coverage of 107$\degree$ (80$\degree$\textless $\varphi$\textless 187$\degree$) and $|\eta|$\textless 0.7, respectively. For Run 2, the EMCal has been expanded to include the Di-jet Calorimeter (DCal), which is located on the opposite side of the beam axis from the original EMCal. The DCal spans an additional azimuthal angle of 67$\degree$ (260$\degree$\textless $\varphi$\textless 327$\degree$) and covers the pseudo-rapidity region $|\eta|$\textless 0.7. The EMCal has an effective radiation length ($\chi_{0}$) of $\sim$2.3 mm, a nuclear interaction length ($\lambda_{\rm{int}}$) of $\sim$24.6 cm, and an effective Moli\`{e}re radius ($R_{\rm{M}}$) of 3.20 cm. Finally, the EMCal detector is used to improve statistics at high-$p_{\rm{T}}$ using the EMCal gamma trigger.

The energy loss and shower shape parameters in the EMCal can be used to distinguish electrons from hadrons. These parameters are particularly useful when an analysis requires electrons with high-$p_{\rm{T}}$. In this poster, the electron identification performance of the EMCal with DCal in Run 2 is investigated using both minimum bias and EMCal gamma-triggered data from pp ($\sqrt{s}$ = 13 TeV) and Pb-Pb ($\sqrt{s_{\rm{NN}}}$ = 5.02 TeV) collisions.
Preferred Track Future Experimental Facilities, Upgrades, and Instrumentation
Collaboration ALICE

Primary author

Erin Frances Gauger (University of Texas (US))

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