2018 September 20
2018 November 23
The W measurement at RHIC (Relativistic Heavy Ion Collider) provides unique access to the sea quark polarization of the proton. By measuring decay leptons from parity-violating W bosons, which only coupled to left-handed quarks and right-handed antiquarks, a clean, fragmentation free measurement is possible in addition to natural flavor separation. In this talk, we present status and results of single longitudinal spin asymmetry ($A_L$) measurements at PHENIX with data collected in 2011-2013.