$^8$He nuclei stopped in nuclear track emulsion
The fragment separator ACCULINNA in the G. N. Flerov Laboratory of Nuclear Reactions of JINR was used to expose a nuclear track emulsion to a beam of radioactive $^{8}$He nuclei of energy of 60 MeV and enrichment of about 80%. Measurements of decays of $^{8}$He nuclei stopped in the emulsion allow one to evaluate possibilities of $α$-spectrometry and to observe a thermal drift of $^{8}$He atoms in matter. Knowledge of the energy and emission angles of $α$-particles allows one to derive the energy distribution of $α$-decays Q$_{2α}$. The presence of a "tail" of large values Q$_{2α}$ is established. The physical reason for the appearance of this "tail" in the distribution Q$_{2α}$ is not clear. Its shape could allow one to verify calculations of spatial structure of nucleon ensembles emerging as $α$-pairs of decays via the state $^8$Be$_{2+}$.