Abstract
The time dependence of extreme ultraviolet (EUV) fluorescence following an ionizing radiation event in liquid helium is observed and studied in the temperature range from 250 mK to 1.8 K. The fluorescence exhibits significant structure including a short strong initial pulse followed by single photons whose emission rate decays exponentially with a time constant. At an even longer time scale, the emission rate varies as “1/time” (inversely proportional to the time after the initial pulse). The intensity of the “1/time” component from particles is significantly weaker than those from particles or neutron capture on It is also found that for particles, the intensity of this component depends on the temperature of the superfluid helium. Proposed models describing the observed fluorescence are discussed.
- Received 7 January 2003
DOI:https://doi.org/10.1103/PhysRevA.67.062716
©2003 American Physical Society