Localisation of ortho-positronium in argon

M. Tuomisaari*, K. Rytsölä, R. M. Nieminen, P. Hautojärvi

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)


Positronium lifetime measurements in argon are reported for the temperature range from 120K to room temperature and at pressures up to 220 bar. The results indicate the formation of a distinct bubble in the liquid phase and a more diffuse bubble in the gas phase. While at higher densities the experimental results can be rather well reproduced in terms of the density functional theory, at lower densities, below the theoretical bubble formation threshold, spontaneous density fluctuations in the fluid seem to explain the observed behaviour. Depending on the model for the free positronium energy in a homogeneous fluid, the Ps-Ar scattering length has a value between 0.5 and 0.8 AA.

Original languageEnglish
Article number016
Pages (from-to)2667-2681
Number of pages15
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Issue number17
Publication statusPublished - 1986
MoE publication typeA1 Journal article-refereed


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