This is a bird's-eye view of the E683 experimental apparatus. We had an incident tagged real photon beam. For the data I'll be presenting today, we used an LH2 target; we also have data on LD2 as well as a variety of nuclear targets. Our principle apparatus was the Main Calorimeter, a segmented, sampling calorimeter with four layers and 132 towers. In addition, the Beam Calorimeter was used to measure very far forward energy. Our trigger consisted off no charge into the target, charge out of the target, and large amounts of transverse energy in the MCAL in one of two topologies. The global trigger required the total amount of Et to be above a threshold, while the two-high trigger required two towers to have Et above a threshold. The triggers are essentially redundant; most of our data satisfies both.
Greg Morrow morrow@physics.rice.edu