Search for $\alpha$ condensed states in $^{13}$C using $\alpha$ inelastic scattering. (11th August 2021)

• Record Type: Journal Article
• Authors: Inaba, K; Sasamoto, Y; Kawabata, T; Fujiwara, M; Funaki, Y; Hatanaka, K; Itoh, K; Itoh, M; Kawase, K; Matsubara, H; Maeda, Y; Suda, K; Sakaguchi, S; Shimizu, Y; Tamii, A; Tameshige, Y; Uchida, M; Uesaka, T; Yamada, T; Yoshida, H P
• Is Part Of: Progress of theoretical and experimental physics. Volume 2021:Number 9(2021)
• Publication Date: 2021-08-11
• Subjects: D05 -- D11 -- D22; Physics -- Periodicals; Mathematical physics -- Periodicals; 530.05
• DOI: 10.1093/ptep/ptab102
• Languages: English
• ISSNs: 2050-3911

Abstract

Abstract: We searched for the $\alpha$ condensed state in $^{13}$ C by measuring the $\alpha$ inelastic scattering at $E_\alpha = 388$ MeV at forward angles including 0$^\circ$ . We performed a distorted-wave Born approximation calculation with the single-folding potential and multipole decomposition analysis to determine the isoscalar transition strengths in $^{13}$ C. We found a bump structure around $E_x = 12.5$ MeV due to the isoscalar monopole ($IS0$ ) transition. A peak-fit analysis suggested that this bump consisted of several $1/2^-$ states. We propose that this bump is due to the mirror state of the 13.5 MeV state in $^{13}$ N, which dominantly decays to the $\alpha$ condensed state in $^{12}$ C. It was speculated that the $1/2^-$ states around $E_x = 12.5$ MeV were candidates for the $\alpha$ condensed state, but the $3\alpha + n$ orthogonality condition model suggests that the $\alpha$ condensed state is unlikely to emerge as the negative parity states. We also found two $1/2^+$ or $3/2^+$ states at $E_x = 14.5$ and 16.1 MeV excited with the isoscalar dipole ($IS1$ ) strengths. We suggest that the 16.1 MeV state is a possible candidate for the $\alpha$ condensed state predicted by the cluster model calculations on the basis of the good correspondence between the experimental and calculated level structures. However, the theoretical $IS1$ transition strength for this state is significantly smaller than the measured value. Further experimental information is strongly desired to establish the $\alpha$ condensed state in $^{13}$ C.