Speaker
Description
Alpha clustering, which is prominently observed in light nuclei, also plays a significant role in the surface region of heavy nuclei. Recent studies have emphasized the correlation between alpha formation at the nuclear surface and the cross sections of alpha knockout reactions in Sn isotopes [1].
We previously proposed a method to evaluate the local alpha-removal strength using mean-field theory (Hartree-Fock + BCS), which is standard for heavy nuclei. In this approach, four nucleons with different spin and isospin are removed from the same spatial coordinate [2]. The local alpha-removal strength quantifies the alpha formation at a specific coordinate in the nucleus and enables the evaluation of transitions to both ground and excited states. However, this method assumes point-like alpha particles and does not account for rearrangement effects in the final state, leaving room for improvement.
In this study, we construct an alpha annihilation operator without assuming point-like particles, but assuming that the constituent nucleons distribute as the 0s orbital. Incorporating the finite size of the alpha particle allows us to separate its center-of-mass coordinate, leading to a more realistic evaluation of the alpha-removal strength.
We calculate the transition matrix elements of the alpha annihilation operator between the initial and final nuclear states, both obtained using Hartree-Fock-Bogoliubov theory. While the use of mean-field theory restricts the final states to ground states, it enables the inclusion of rearrangement effects in the final nucleus.
We will present results for several isotopes, including Sn isotopes, for which systematic measurements of alpha knockout cross sections have been reported.
[1] J. Tanaka et al., Science 371, 260 (2021).
[2] T. Nakatsukasa and N. Hinohara, Phys. Rev. C 108, 014318 (2023).
| Presentation Style | Oral Presentation |
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