Forward-rapidity Elliptic Flow at RHIC

At RHIC energies large azimuthal anisotropies are observed in particle production with respect to the reaction plane for non-central heavy-ion collisions (i.e., azimuthal flow). Elliptic flow is measured by the 2$^{nd}$ harmonic (v$_{2})$ coefficient of the Fourier expansion of the azimuthal distribution. The observed anisotropies and the measured v$_{2}$(p$_{t})$ values suggest an almost perfect fluid state is created, consistent with the production of a quark-gluon plasma. Most measurements of identified-particle v$_{2}$(p$_{t})$ behavior at RHIC have been done near mid-rapidity, although a strong pseudorapidity dependence is seen for the charged-hadron, p$_{t}$-integrated v$_{2}$ values[1]. The interpretation of the integral v$_{2}$ data is complicated, however, by the rapidity dependent change in $<$p$_{t}>$ for each particle type. This talk will present new results of the BRAHMS experiment on $\pi $, K and p v$_{2}$(p$_{t})$ behavior at y $\approx $ 0, 1, and 3. The associated spectra will also be presented to help disentangle the kinematic factors affecting the integral v$_{2}$ values. These results can be used to better define the longitudinal expansion of the medium created through heavy-ion reactions at RHIC energies. [1] B.B. Back et al., PRL \textbf{94, }122303(2005).