Acoustic signals produced by irradiating ethanol with 400 MeV/n Xe ions were experimentally studied. The signals were detected by an array of piezoelectric PZT elements. They were categorized into two types: one was a primary product of the incident fast ions; the other was a secondary product resulting from an energy release to ethanol just before the ions stopped and subsequently diffused in ethanol. A possible mechanism of the secondary signal is discussed in association with the Bragg peak formation.
