Analog Multiplexer for the Aleph Electromagnetic Calorimeter

An analog multiplexer, designed for the electromagnetic calorimeter of the ALEPH experiment on LEP is described. It allows a substantial reduction in output cabling by presenting analog signals from 32 detector towers sequentially on a single output pair. Charge integrating input elements largely eliminate both calibration dependence on detector capacitance and crosstalk problems. Factors influencing the calibration precision, noise performance and speed of response are discussed.