The STAR Endcap Electromagnetic Calorimeter - 2005 Operation

An Endcap ElectroMagnetic Calorimeter (EEMC) has been built and installed on the west poletip of the STAR detector at RHIC. The EEMC is a Pb-scintillator sampling calorimeter covering the full azimuth for pseudorapidities of 1.1 $<\eta <$ 2 (37$^{\circ}>\theta>$ 15$^{\circ}$). The calorimeter is 21 radiation lengths thick at normal incidence and its 24 layers give a sampling fraction of ~5\%. The active area is divided into 720 projective towers, each read out by its own phototube to provide deposited energy. A copy of the signal from the first 2 and last layer of the towers are read out by individual channels on multi-anode PMTs as pre- and post-shower detectors. At a depth of $\sim$5 radiation lengths there is a shower maximum detector constructed of two planes of crossed triangular scintillator strips (pitch 5mm) each read out by a channel on a MAPMT. All 9360 PMT channels are digitized every 100 ns and buffered awaiting data transfer on receipt of a trigger. The tower energy signals are passed to trigger for decision on the highest tower above a threshold or a summed phi patch (1/6th) above a threshold. The detector was fully instrumented for the first time in the 2005 run. Operation and performance of the detector in the run for triggering, minimum-ionizing-particles and $\pi^0$ reconstruction will be discussed.