Fabrication and test of a 70 000 channels electronic pad readout system for multi-step avalanche chambers

Abstract A new readout concept based on a custom-design chip containing both analog and digital functions as well as ultra-thin mounting with the chip-on-board technique is presented. The full readout system as well as fabrication and testing is described. A 70 000 channels system based on this concept was installed in the WA98 experiment at the CERN SPS. The performance of the readout electronics is presented.