Extraction of radioactive positive ions across the surface of superfluid helium: A new method to produce cold radioactive nuclear beams

Research output: Contribution to journalArticleScientificpeer-review


  • W. X. Huang
  • P. Dendooven
  • K. Gloos
  • N. Takahashi
  • J. P. Pekola
  • J. Äystö

Research units

  • University of Jyväskylä
  • Chinese Academy of Sciences
  • University of Groningen
  • Niels Bohr Institute
  • Osaka Gakuin University


Alpha-decay recoils 219Rn were stopped in superfluid helium and positive ions were extracted by electric field into the vapour phase. This first quantitative observation of extraction was successfully conducted using highly sensitive radioactivity detection. The efficiency for extraction across the liquid surface was 23 ± 4% at 1.60 K, the release time was 90 ± 10 ms at 1.50 K and the barrier for positive ions through a free superfluid-helium surface was 19.4 ± 4.5 K. The pulsed second sound proved to be effective in enhancing the extraction.


Original languageEnglish
Pages (from-to)687-693
Number of pages7
Issue number5
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed

ID: 4440067