Calculation of Recoil Ion Effective Track Lengths in Neutron-Radiation-Induced Nucleation

A theoretical model was developed to predict the amount of nucleation that occurs as a result of neutron interactions in superheated liquids. The model utilizes nuclear cross-section data, charged-particle linear energy transfer information, and computations of critical bubble nucleation energy to generate the number of bubbles formed in superheated liquid droplet (“bubble”) neutron detectors exposed to neutron fluxes of specified intensity and energy. Previous experimental attempts to relate effective (energy-depositing) ion track length L to critical bubble radius rc using a dimension-less coefficient were unsuccessful. The formulation of a new coefficient b, equal to the ratio of effective ion track length L to the seed bubble radius ro is now proposed. By parameterizing the value of b within the model, the least-squares best value of b was determined to be 4.3 for both high- and low-energy 252Cf neutrons. Thus, the effective recoil ion track length in radiation-induced nucleation can be determined if the seed bubble radius is known.