A compact acoustic calibrator for ultra-high energy neutrino detection
  With the aim to optimize and test the method of acoustic detection of ultra-high energy neutrinos in underwater telescopes a compact acoustic transmitter array has been developed. The acoustic parametric effect is used to reproduce the acoustic signature of an ultra-high-energy neutrino interaction. Different reseach and development studies are presented in order to show the viability of the parametric sources technique to deal with the difficulties of the acoustic signal generation: a very directive transient bipolar signal with pancake directivity. The design, construction and characterization of the prototype are described, including simulation of the propagation of an experimental signal, measured in a pool, over a distance of 1 km. Following these studies, next steps will be testing the device in situ, in underwater neutrino telescope, or from a vessel in a sea campaign. 
S. Adri\'an-Mart\'inez, M. Ardid, M. Bou-Cabo, G. Larosa, C.D Llorens,   J. A. Mart\'inez-Mora
physics.ins-det astro-ph.IM