Speaker
Description
The proton-induced $\alpha$ knockout reaction, ($p$,$p\alpha$), is a powerful probe of the $\alpha$ formation in the nucleus. The author and the collaborators have shown that a modern theoretical calculation of the $\alpha$ amplitude combined with the ($p$,$p\alpha$) reaction calculation by the distorted wave impulse approximation can quantitatively reproduce the existing experimental data [1]. Although the $\alpha$ formation is known in the light mass nuclei as the $\alpha$ clustering and also in very heavy nuclei as the $\alpha$ decay, the universality of the $\alpha$ formation throughout the nuclear chart has been a question. Triggered by a theoretical prediction by S. Typel [2], $\alpha$ formation on the surface of medium mass nuclei, Tin isotopes $^{112,116,120,124}$Sn, has been experimentally confirmed [3]. Recently, the author and the collaborator have shown that the $\alpha$ reduced width, which is a key quantity for describing the $\alpha$ decay lifetime, can also be determined by the ($p$,$p\alpha$) reaction [4]. In this contribution, I will review the recent progress in the $\alpha$ formation phenomena studied by the above-mentioned ($p$,$p\alpha$) reaction, and give a perspective on the cluster knockout reactions and novel clustering phenomena.
[1] K. Yoshida, Y. Chiba, M. Kimura, Y. Taniguchi, Y. Kanada-En'yo, and K. Ogata, Phys. Rev. C. 100, 044601 (2019).
[2] S. Typel, Phys. Rev. C 89, 064321 (2014).
[3] Junki Tanaka et al., Science 371, 260 (2021).
[4] Kazuki Yoshida and Junki Tanaka. Phys. Rev. C 106, 014621 (2022).
