A 14-Channel Linear Multiplexer

A new nuclear spectroscopy multiplexer is described that can multiplex up to 14 linear signals within the range of ±10 V. The multiplexer gating is provided by inputs on the rear panel which have a common adjustable threshold. When the multiplexer is used with a multidetector array, the resulting system resolution is the efficiency-weighted average of the resolution of the separate detectors. The apparent system efficiency is the sum of the separate detector efficiencies. Only one channel is open at any time and there are no priority channels. Isolation from any off channel is 65 dB and the noise contribution of all nonselected channels is essentially negligible. The multiplexer was tested using 10 coaxial Ge(Li) detectors and commercially available NIM electronics. The measured system resolution was 2.01 keV at the 1.33 MeV line of 60Co with 400,000 counts in the peak channel. The apparent system efficiency was 158.34%. Additionally, a 10-detector Low Energy Photon Spectrometer (LEPS) array was multiplexed with a system resolution of .93 keV at 122 keV.