Evidence for $\alpha$-particle condensation in nuclei from the Hoyle state deexcitation

Abstract

The fragmentation of quasi-projectiles from the nuclear reaction $^{40}$Ca+$^{12}$C at 25 MeV/nucleon was used to produce excited states candidates to $\alpha$-particle condensation. Complete kinematic characterization of individual decay events, made possible by a high-granularity 4$\pi$ charged particle multi-detector, reveals that 7.5$\pm$4.0% of the particle decays of the Hoyle state correspond to direct decays in three equal-energy $\alpha$-particles.