EXPERIMENTAL STUDIES OF THE ACOUSTIC SIGNATURE OF PROTON-BEAMS TRAVERSING FLUID MEDIA

Recent experiments at Brookhaven National Laboratory and Harvard University demonstrate that a detectable sonic signal is produced by energetic proton beams while traversing a fluid medium. The observed acoustic wave agrees with the predictions of a thermal expansion model. Results are inconsistent with any significant contribution from either microbubble implosion or molecular dissociation, two other suggested means of sonic production. Frequency and amplitude distributions, radiation patterns, temperature, pressure, and medium dependencies are explored. This phenomenon may have immediate applications in beam monitoring and in detecting energetic heavy ions. Signal thresholds may be enough to permit detection of particle showers induced by single particles at the next generation of high energy accelerators or from high energy cosmic rays. The inexpensive transducers and long sonic transmission lengths obtainable in liquids suggest that high energy particle detectors may be feasible with masses many orders of magnitude greater than those currently in use. © 1979.