One-dimensional position-sensitive superheated-liquid-droplet in-phantom neutron dosimeter

The one-dimensional (1D) position-sensitive superheated-liquid-droplet in-phantom neutron dosimeter incorporating a sensitive volume emulsion has been fabricated, prepared, and tested. The 1D position-sensitive superheated-liquid-droplet dosimeter (SLDD) is fabricated from a 3/8-in.-o.d., 1/4-in.-i.d., 20-cm-long, PlexiglasTM-walled tube filled with a mixture of superheated-liquid FreonTM droplets and host medium glycerol solution. Washer-shaped piezoelectric acoustic transducers are positioned at both ends of the tube; they determine the number and positions of the acoustic events when the superheated-liquid droplets evaporate upon neutron irradiation. The SLDD is sensitive to a wide range of neutron energy, from thermal (0.0253 eV) up to 10 MeV and higher. The SLDD is irradiated with the 137Cs and 60Co γ sources, as well as a 252Cf neutron source to test for its radiation response and spatial resolution. The SLDD based on the Freon-134a superheated-liquid droplets operating at 20 °C and 1 atm is found to be ideal for measuring neutron depth dose and relative biological effectiveness dose. This study also proves that the position of the radiation-induced nucleation acoustic events can be linearly determined from the differences in the transmission times received by the acoustic transducers on the 1D SLDD. The spatial resolution of the neutron depth dose is 1 mm due to the finite response time (1 μs) of the piezoelectric acoustic transducers.