A Post Shower detector for the FMS to study Drell Yan and Direct Photons

One of the goals of the 2017 run at STAR was to measure the direct photon and Drell Yan electrons in polarized $pp$ collisions in order to understand the Sivers and Collins effects. To make such a measurement a postshower detector (FPOST) for the Forward Meson spectrometer (FMS) was commissioned and installed for the 2017 run. The FMS together with its preshower (FPS) detector and the new FPOST cover $2<\theta<8$ of STAR. The FPOST itself is located downstream the FMS as its name suggests. Like the FPS the FPOST is a scintillator hodoscope with a channel size that matches that of the FMS. Its purpose is to discriminate the hadrons that punch through and the partially contained showers that leak out of the FMS. This talk will discuss the design requirements and performance of the FPOST during the 2017 run.