文摘
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.