Possible evidence for production of an artificial radionuclide in cavitated water

We report the results of an experiment of cavitation, carried out by means of a sonotrode working at a frequency of 20 kHz and a power of 100 W. The analysis of water was carried out through an ICP mass spectrometer continuously during the cavitation process, in the mass regions from 90 to 150 amu and from 200 to 255 amu, that include also the rare earth elements. We found a significant peak corresponding to a nuclide with atomic mass (137.93 +/- 0.01) amu and a half-life 12 +/- 1 seconds, identified with Eu-138. This result, together with those of two previous experiments (which evidenced changes in concentration of stable elements and production of transuranic elements induced by cavitation), seems to support sononuclear reactions (in particular sononuclear fusion). We propose some possible classical mechanisms for the explanation of these findings.