Measurement of the centrality and pseudorapidity dependence of the integrated elliptic flow in lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS detector

The integrated elliptic flow of charged particles produced in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, $v_2$, was measured in the pseudorapidity range $|\eta|\leq$ 2.5 with the event-plane method. In order to include tracks with very low transverse momentum $p_T$, thus reducing the uncertainty in $v_2$ integrated over $p_T$, a $1 \mu b^{-1}$ data sample recorded without a magnetic field in the tracking detectors is used. The centrality dependence of the integrated $v_2$ is compared to other measurements obtained with higher $p_T$ thresholds. A weak pseudorapidity dependence of the integrated elliptic flow is observed for central collisions, and a small decrease when moving away from mid-rapidity is observed only in peripheral collisions. The integrated $v_2$ transformed to the rest frame of one of the colliding nuclei is compared to the lower-energy RHIC data. The integrated elliptic flow of charged particles produced in Pb+Pb collisions at $\sqrt{{s}_{\mathrm {NN}}}=2.76$ TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, $v_2$ , was measured in the pseudorapidity range $|\eta |\le 2.5$ with the event-plane method. In order to include tracks with very low transverse momentum $p_{\mathrm {T}}$ , thus reducing the uncertainty in $v_2$ integrated over $p_{\mathrm {T}}$ , a $1~\mu \hbox {b}^{-1}$ data sample recorded without a magnetic field in the tracking detectors is used. The centrality dependence of the integrated $v_2$ is compared to other measurements obtained with higher $p_{\mathrm {T}}$ thresholds. The integrated elliptic flow is weakly decreasing with $|\eta |$ . The integrated $v_2$ transformed to the rest frame of one of the colliding nuclei is compared to the lower-energy RHIC data. The integrated elliptic flow of charged particles produced in Pb+Pb collisions at sqrt(s_NN)=2.76 TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, v_2, was measured in the pseudorapidity range |eta