The PHENIX Muon Piston Calorimeter

The Muon Piston Calorimeter (MPC) is a new electromagnetic calorimeter which has been integrated into the muon forward spectrometers of the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The calorimeter acceptance is $2\pi$ in azimuth and $3.1<\eta<3.65$ in pseudorapidity. The MPC uses PbWO$_{4}$ scintillator crystals with APD readout developed for PHOS as part of the ALICE experiment at CERN. We present an overview of the detector, results from beam tests at the Meson Test Beam Facility at Fermi National Laboratory and first results from the operation of the MPC during the 2006 RHIC run.