Study of the Involvement of ${}^8$Be and ${}^9$B Nuclei in the Dissociation of Relativistic ${}^{10}$C, ${}^{10}$B, and ${}^{12}$C Nuclei

The results obtained by estimating the contribution of ${}^8$Be and ${}^9$B nuclei to the coherent dissociation of ${}^{10}$C, ${}^{10}$B, and ${}^{12}$C relativistic nuclei in nuclear track emulsions (white'' stars) are presented. The selection of white’’ stars accompanied by ${}^9$B leads to a distinct peak appearing in the distribution of the excitation energy of 2$\alpha$2$p$ ensembles and having a maximum at 4.1 $\pm$ 0.3 MeV. A ${}^8$Be nucleus manifests itself in the coherent-dissociation reaction ${}^{10}$B $\to$ 2He + H with a probability of (25 $\pm$ 5)%, (14 $\pm$ 3)% of it being due to ${}^9$B decays. The ratio of the branching fractions of the ${}^9$B + $n$ and ${}^9$Be + $p$ mirror channels is estimated at 6 $\pm$ 1. An analysis of the relativistic dissociation of ${}^{12}$C nuclei in a nuclear track emulsion revealed nine 3$\alpha$ events corresponding to the Hoyle state.