Readout electronics for Venus muon drift tubes at TRISTAN

A simple and low-cost readout electronics system for the Venus muon drift tubes was developed. The muon detector was constructed from about 900 extruded aluminum drift tubes. Each tube is composed of two layers of four isolated cells, staggered by a half cell. Each set of the readout system consists of a memory board (TKO module), a main-address-generator boards, eight module-address-generator boards, and 64 front-end boards in a tree structure. Thus, each memory board can handle up to 512 channels of drift cell. The front-end board contains not only eight channels of preamplifiers and comparators, but also 40-MHz direct-counting 6-bit TDCs (time-to-digital converters). This board is located directly on an eight-cell drift tube. Relatively easy position resolution (~1 mm) made it possible to use TTL/CMOS ICs for most of the readout electronics. The location of TDC and address generators near drift tubes reduces the number of long signal cables. Therefore, total construction cost was reduced significantly