Unexpectedly Enhanced Alpha-Particle Preformation In Ti-48 Probed By The (P, P Alpha) Reaction

The formation of alpha particles on nuclear surfaces has remained a fundamental problem since the dawn of nuclear physics. This alpha-particle formation strongly affects the alpha-decay lifetimes of heavy and superheavy elements, level scheme of light nuclei, and synthesis of elements in stars. However, despite its importance, the alpha-particle formation in medium-mass nuclei is seldom investigated. Based on the Ti-48(p, p alpha) Ca-44 reaction analysis, this study reports that alpha-particle formation in the medium-mass Ti-48 nucleus is pronounced more compared to that expected through mean-field approximations. Moreover, the estimated average distance between the alpha particle and residue equals approximately 4.5 fm. This result poses a challenge to describe the four nucleon correlations using microscopic nuclear models.