Imaging Fluorescence of He₂^*Excimers Created by Neutron Capture in Liquid He II—a New Approach for Turbulent Flow Research

We show unequivocal evidence for formation of excimers in liquid He II created by ionizing radiation produced through neutron capture. Laser beams induced fluorescence of the excimers. The fluorescence was recorded by a camera at a rate of 55.6 Hz with the ability to determine the location of an event with an uncertainty of 5 microns. The technique enables measurement of turbulence around macroscopic size (liter+) objects or vortex matter in three dimensions under conditions of extreme Reynolds number. Using thermal counterflow techniques we explored excimer flow in cryogenic He.