Speaker
Description
Alpha clusters in light nuclei are known to play a significant role in nucleosynthesis. Among them, the Hoyle state with a three-alpha cluster structure is crucial for the synthesis of $^{12}\mathrm{C}$ via the triple-alpha-fusion reaction. An ab initio no-core Monte Carlo Shell Model calculations predicted that alpha clusters present not only in the Hoyle state, but also in the ground state of $^{12}\mathrm{C}$ [1]. It is thus interesting to experimentally measure the alpha cluster component in the ground state of $^{12}\mathrm{C}$ and compare it with the ab initio and cluster model predictions. It could help to understand the coexistence and competition of the cluster and shell-model-like components in nuclei. Recent studies show that the alpha knockout reaction is a promising tool for probing the strength of alpha clusters in the ground state [2].
At the RCNP Cyclotron Facility, we conducted measurements of the alpha knockout reaction $^{12}\mathrm{C}$(p,pα). A 400 MeV proton beam was accelerated and irradiated onto a natural carbon target. By measuring the proton and alpha particles in coincidence using a double-arm spectrometer, we successfully obtained the alpha separation energy spectrum of $^{12}\mathrm{C}$. From the reaction yield, the differential cross-section will be determined, enabling us to extract the strength of alpha clusters in the ground state of $^{12}\mathrm{C}$.
In this presentation, we will provide a detailed introduction of the experiment and discuss the results.
[1] T. Otsuka, T. Abe et. al, Nat Commun 13, 2234 (2022).
[2] J. Tanaka, Z.H. Yang et. al, Science 371, 260-264 (2021).
