Forward Physics with the MPC-EX+MPC Detector with RHIC-PHENIX*

Measurements of the gluon wavefunction of a nucleus at low momentum fraction can help our understanding of QCD evolution. It is also an important input for interpreting the formation of the Quark-Gluon Plasma (QGP) observed in heavy ion collisions and the possible formation of QGP droplets in asymmetric ion collisions. Late in the PHENIX data-taking campaign a Si-W preshower, the MPC-EX, was added to the existing forward muon pison calorimeter extending the ability to separate $\pi^{0}$ decay photons to very high energy. Particles entering the preshower + calorimeter at 3.0 $<$ $\eta$ $<$ 3.8 can originate from a high-$x$ parton in the beam with a low-$x$ gluon in the target nucleus. In this talk we outline the current performance of the detector in the 2016 $d$+Au $\sqrt{s_{_{NN}}}$ = 200 GeV collision data and the current and near-future prospects of measurements with this detector and their impact on our understanding of the gluon wavefunction of the nucleus.