Experimental investigation of bubble occurrence and locality distribution of bubble detectors bombarded with high-energy helium ions

Large-sized bubble detectors with microscopic droplets of superheated liquids of dichlorodifluoromethane (Freon-12), dichlorotetrafluoroethane (Freon-114), tetrafluoroethane (Freon-134a), and mixture of Freon-12 and Freon-114, respectively, were irradiated with 150 MeV/amu helium ions at the HIMAC accelerator in NIRS, Chiba, Japan. Distributions of bubbles produced by the helium ions have been studied in each type of the detectors. The origin of the bubbles has been investigated. The detection efficiency of each type of the bubble detectors for helium ions with respect to the energy of the ions has been obtained. The phenomenon of bubble occurrence and its possible applications to the determination of He intensity from accelerators, research of track formation mechanism, energy loss straggling and neutron detection in the space and at higher altitude are discussed.

► Four types of 23-cm long bubble detectors (BD) were irradiated to 150 MeV/amu He ions.
► Direct bubble, recoil bubble, scattering bubble are formed, recognized and classified.
► Detection efficiency of BD for He ions is 10−3–10−4 (bubble cm−3)/(He cm−2).
► It is at the same level of efficiency as detecting fast neutrons.
► Space neutron detection by BD must take the effect of cosmic ray He ions into account.