An enhancement of formation of unstable ${}^8$Be nucleus with the growth of $\alpha$-particle multiplicity in fragmentation of relativistic nuclei

In this paper, the correlation between the formation of the unstable ${}^8$Be nucleus and accompanying $\alpha$ particles in the fragmentation of relativistic ${}^{16}$O, ${}^{22}$Ne, ${}^{28}$Si, and ${}^{197}$Au nuclei in a nuclear track emulsion is investigated. The ${}^8$Be decays are identified in a wide energy range by invariant masses calculated from 2$\alpha$-pair opening angles. The adopted approximations are verified by data on fragmentation of ${}^{16}$O nuclei in a hydrogen bubble chamber in a magnetic field. An increase in the ${}^8$Be contribution to the dissociation with the growth of $\alpha$-particle multiplicity is found.