A Photodiode - Readout (SPED) Sampling Calorimeter

We have built and tested a new type of sampling calorimeter using scintillator as the active material, and thin vacuum photodiodes for signal readout, the new feature. We measured an energy resolution of about 22%/√E for electrons of 10-37.5 GeV. For muons the signal to noise ratio is somewhat greater than 2. The main merits of such a design are the excellent gain stability (gain = 1), absence of the need for high voltages or for highly stabilized voltages or for elaborate calibration systems, and the ability to operate in high magnetic fields.