Observation of second metastable state in superheated emulsion detector

The superheated emulsion detector (SED), a well-known detector for neutrons, ions, electrons and photons, contains droplets of superheated liquid held in a viscoelastic gel. It is well known that these droplets are in a metastable state, decaying both spontaneously and when induced by energetic radiation. Here, it is shown that the SED comprises droplets of more than one metastable states nucleating to vapor bubbles at different frequencies. To the best knowledge of the authors the existence of two metastable states of the active liquid in SED has not been reported before.