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The $^{11}$C nucleus is a proton-rich, unstable isotope with intriguing exotic features. Unlike its neutron-rich isobar-analogue nucleus $^{11}$Be with pronounced neutron halo, $^{11}$C doesn’t form a strong proton halo due to Coulomb suppression.
$^{11}$C and $^{11}$B are the mirror nuclei. Based on calculations of the antisymmetrized molecular dynamics (AMD), the generator coordinate method, and the orthogonality condition model, the 3/2$^{-}_{3}$ states in $^{11}$C ($^{11}$B) were suggested to be 2$α$ +$^3$He(t) cluster states, which are analogous to the Hoyle state and have increased radii correspondingly.
One of last experiments on a resonance reaction $^{12}$C($^{11}$C,α$^{7}$Be) [1] has shown that the 8.10-MeV state in $^{11}$C is a resonance, is a head of the K$^{\pi}$ = 3/2$^−$ rotational band and probably has a three-center (2$α$ + $^{3}$He) cluster structure, similar to the 8.56-MeV state in $^{11}$B. While authors [1] mentioned that the obtained low statistics prevent drawing any strong conclusions.
In order to try to solve open questions regarding excited states of $^{11}$C, we made our own experiment $^{10}$B($^{7}$Li,$^{6}$He)$^{11}$C. Experiment was done using $^{7}$Li beam (E$_{LAB}$ = 58 MeV) U-400 of cyclotron @ FLNR JINR, Dubna. Angular distributions were measured for the g.s. and the 8.1 MeV states of $^{11}$C. DWBA analysis was done for the new experimental data. Radial dependences of the form-factor were obtained.
- Ziming Li et al., Phys. Rev. C 107, 014320 (2023)
