Acoustic detection of UHE neutrinos: a station for measurement of the deep sea acoustic noise

The INFN NEMO (NEutrino Mediterranean Observatory) collaboration, aims at the construction of a km3 underwater Cherenkov neutrino telescope. In this framework NEMO is installing a Test Site facility at 2000 m depth, at ∼25 km offshore the port of Catania (Sicily), that will be used to test a prototype module of the future km3 detector. The collaboration is also studying the possibility to use the thermo-acoustic technique to detect UHE neutrino fluxes. One of the major sources of uncertainty in the reliability of this technique is, presently, the lack of knowledge of the acoustic noise at large depth. For this reason NEMO has developed a station for the measurement of acoustic background, that will be installed at the Test Site. The station is equipped with four large bandwidth hydrophones (1 Hz–50 kHz) whose data, digitized underwater, will be transmitted to shore through optical fibres. The station will also be used, in collaboration with CIBRA, for research on marine mammals.