Beam test of an imaging high-density projection chamber

A beam test of a high-density projection chamber with optical readout is presented. The device consists of a prototype of the DELPHI HPC calorimeter on which a parallel-plate, light-emitting structure was installed, replacing the original multiwire proportional chamber readout system. It produces detailed images of the energy deposited by electromagnetic showers; hadronic interactions are easily discriminated from these. The computerized readout system gives full quantitative information on the events, showing good energy and position resolutions. (orig.)