Anisotropic Flow in the Forward Directions

The STAR Forward TPCs (FTPCs) extend the STAR acceptance for charged particles into the region 2.5 < |eta| < 4.0. We see the first signal of directed flow (v{sub 1}) at RHIC energies. While v{sub 1} is consistent with zero in the central rapidity region it rises up to 2 percent at pseudorapidities of +-4. With this signal we can verify that elliptic flow (v{sub 2}) is in-plane. The measurement of v{sub 2} in the FTPCs confirms the falloff by a factor of about 2 compared to mid-rapidity previously seen by PHOBOS [1]. In addition we look for higher harmonics (v{sub n}, n>2) where in the case of v{sub 4} a signal is seen in the STAR TPC. With the available statistics for the FTPCs we give an upper limit for these harmonics, since the results agree with zero within the errors. However, the falloff of v{sub 4} from mid-rapidity to forward-rapidities appears to be faster than for v{sub 2}.[1] B.B. Back. Phys. Rev. Lett. 89, 222301 (2002)
Date: March 9, 2004
Creator: Oldenburg, Markus D. & Putschke, Jorn
System: The UNT Digital Library