Directed and elliptic flow of charged particles in Cu + Cu collisions at √sNN=22.4 GeV
This paper reports results for directed flow v1 and elliptic flow v2 of charged particles in Cu + Cu collisions at √sNN=22.4 GeV at the Relativistic Heavy Ion Collider. The measurements are for the 0–60% most central collisions, using charged particles observed in the STAR detector. Our measurements extend to 22.4-GeV Cu + Cu collisions the prior observation that v1 is independent of the system size at 62.4 and 200 GeV and also extend the scaling of v1 with η/ybeam to this system. The measured v2(pT) in Cu + Cu collisions is similar for √sNN throughout the range 22.4 to 200 GeV. We also report a comparison with results from transport model (ultrarelativistic quantum molecular dynamics and multiphase transport model) calculations. The model results do not agree quantitatively with the measured v1(η),v2(pT), and v2(η).