The Analog Ring Sampler: an ASIC for the front-end electronics of the ANTARES neutrino telescope

The ANTARES detector is a 0.1-km²-scale high-energy neutrino telescope. It will be located in the Mediterranean Sea at a depth of 2400 in. It consists of a matrix of optical modules each containing a photomultiplier tube. An ASIC named the Analog Ring Sampler has been developed to process photomultiplier tube signals. It measures their arrival time and their charge and samples their shape when this differs from that characteristic of single photoelectrons. The digital output is multiplexed and transmitted to the shore through further electronics and an optical link. The main circuit blocks of the ASIC are discussed in this paper.