Speaker
Description
$\alpha$ clustering is a well-known phenomenon in light nuclei where two neutrons and two protons strongly correlate to constitute an $\alpha$ particle as a building block of atomic nuclei. A linear alignment of the $\alpha$ clusters, referred to as linear-chain cluster state (LCCS), has been of great interest since 1950s but until now there is no clear experimental evidence demonstrating the existence of such a state. Recently, it was theoretically pointed out that excess nucleons in non-4N nuclei occupy molecular orbitals between $\alpha$ clusters and the excess nucleons may stabilize LCCS. A candidate of LCCS in $^{14}$C was experimentally proposed by H. Yamaguchi et al. [1].
It is an interesting issue whether the similar LCCS also exists in the mirror nucleus $^{14}$O or not. The excess neutrons are replaced by protons in this case, and thus the energy shifts between $^{14}$C and $^{14}$O due to the Coulomb force should reflect spatial distribution of the excess nucleons. Therefore, it is expected to reveal the structure of the LCCS candidate by measuring its energy in $^{14}$O and comparing it with that in $^{14}$C and theoretical calculation.
Since $^{14}$O is an unstable nucleus, it must be generated as a secondary particle. We conducted the experiment to search for $\alpha$ cluster states in $^{14}$O at CRIB facility of CNS, the Univ. of Tokyo in June 2019. In this experiment, we injected a $^{10}$C secondary beam at 36 MeV into the He gas target at 650 Torr, and measured the resonant elastic scattering of $\alpha$+$^{10}$C with the Si detectors at 0 and $\pm$9 degrees by the thick target method. We will report details of the experiment and results in the talk.
References
[1] H. Yamaguchi et. al. Experimental investigation of a linear-chain structure in the nucleus $^{14}$C $Phys. Lett. B,$ 766:11, 2017
