|The Analogue Ring Sampler: An ASIC for the Front-End Electronics of the ANTARES Neutrino Telescope.|
|F. Druillole1*, D.Lachartre2, F. Feinstein3, E. Delagnes*, H. Lafoux*, C.Hadamache|
The ANTARES telescope is a prototype for detecting high-energy neutrinos at the 0.1 km2 scale. It will be located in the Mediterranean Sea at a depth of 2400 meters. It will consist of a matrix of optical modules containing photomultiplier tubes. An ASIC called ARS1 has been developed to process phototube signals in order to measure their arrival time, their charge and their shape when they differ from that characteristic of Single Photoelectrons (SPEs). The ARS1 chip processes analogue signals from one optical module and it converts information into digital data. All information is transmitted to the shore through further multiplexing electronics and an optical link. The ARS1 integrates 24 DACs, 2 8-bit ADCs, a 16-memory-cells pipeline to store SPE events, a complex gauge discriminator and a 4-channels 128-cell deep 1-GHz/s analogue sampler. The signal processing is event-driven. The Pulse Shape Discriminator (PSD) identifies online SPE pulses, for which only the charge and the arrival time are measured, from more complex pulse shapes, which are processed by the sampler. Since SPE pulses account for 99% of the events, this dual path in the signal processing provides an important reduction in power consumption as well as in the amount of transmitted data. Each main circuit block is described in order to explain the operation of the ARS1 chip.