  Experiments were performed at a proton accelerator and an infrared laser
acility to investigate the sound generation caused by the energy deposition of
pulsed particle and laser beams in water. The beams with an energy range of 1
PeV to 400 PeV per proton beam spill and up to 10 EeV for the laser pulse were
dumped into a water volume and the resulting acoustic signals were recorded
with pressure sensitive sensors. Measurements were performed at varying pulse
energies, sensor positions, beam diameters and temperatures. The data is well
described by simulations based on the thermo-acoustic model. This implies that
the primary mechanism for sound generation by the energy deposition of
particles propagating in water is the local heating of the media giving rise to
an expansion or contraction of the medium resulting in a pressure pulse with
bipolar shape. A possible application of this effect would be the acoustical
detection of neutrinos with energies greater than 1 EeV.
