ARIANNA: the Icarus experiment readout module

Icarus detector is a liquid Argon Time Projection Chamber that requires continuous signal recording for each channel to provide three dimensional images of any ionizing event. A complete drift volume imaging of the next 600 ton module will result in 1.15 Gbit, with a data rate of 1.15 Tbit/s. The collected data can be highly reduced by recognizing Regions Of Interest (ROI) of the signal by means of a custom hit finding unit (DAEDALUS) working pipelined in the data acquisition path. DAEDALUS is an ASIC that implements an algorithm developed for hit detection and proven to be very efficient both on real and on simulated data. Since only ROI's are saved in memory and contiguous regions can be correlated to enhance detector self triggering capability, a high efficiency zero skipping is obtained in real time. A VME board hosting 16 Icarus digital channels has been designed and built as a demonstrator for functionality and performance test. The board, named ARIANNA, and DAEDALUS chip are here presented in detail.