Hoyle-analogue States Research Articles

Hoyle-analog state in C13 studied with antisymmetrized molecular dynamics

The cluster states in $^{13}{\rm C}$ are investigated by antisymmetrized molecular dynamics. By investigating the spectroscopic factors, the cluster configurations of the excited states are discussed. It is found that the $1/2^+_2$ state is dominantly composed of the $^{12}{\rm C}(0^+_2)\otimes s_{1/2}$ configuration and can be regarded as a Hoyle analogue state. On the other hand, the p-wave states ($3/2^-$ and $1/2^-$) do not have such structure, because of the coupling with other configurations. The isoscalar monopole and dipole transition strengths from the ground to the excited states are also studied. It is shown that the excited $1/2^-$ states have strong isoscalar monopole transition strengths consistent with the observation. On the other hand, the excited $1/2^+$ states unexpectedly have weak isoscalar dipole transitions except for the $1/2^+_1$ state. It is discussed that the suppression of the dipole transition is attributed to the property of the dipole operator.

Formation and decay of resonance states in Be9 and B9 nuclei: Microscopic three-cluster model investigations

We study nature of the low-lying resonance states in mirror nuclei $^{9}$Be and $^{9}$B. Investigations are performed within a three-cluster model. The model makes use of the hyperspherical harmonics, which provides convenient description of three-cluster continuum. The dominant three-cluster configurations $\alpha+\alpha+n$ and $\alpha+\alpha+p$ in $^{9}$Be and $^{9}$B, respectively, are taken into account. Dominant decay channels for all resonance states in $^{9}$Be and $^{9}$B are explored. Much attention is paid to the controversial $1/2^{+}$ resonance states in both nuclei. We study effects of the Coulomb interaction on energy and width of three-cluster resonances in the mirror nuclei $^{9}$Be and $^{9}$B. We also search for the Hoyle-analogue state which is a key step for alternative way of $^{9}$Be and $^{9}$B syntheses in a triple collision of clusters in a stellar environment.

Formation and decay of resonance state in 9Be and 9B nuclei. Microscopic three-cluster model investigations

We study nature of the low-lying resonance states in mirror nuclei 9Be and 9B. Investigations are performed within a three-cluster model. The model make uses of the hyperspherical harmonics, which provide convenient description of three-cluster continuum. Much attention is paid to the controversial 1/2+ resonance states in both nuclei. We study effects of Coulomb interaction on energy and width of three-cluster resonances in the mirror nuclei 9Be and 9B. We look for the Hoyle-analogue states which allows for alternative way of 9Be and 9B synthesis in a triple collision of clusters.

α-cluster structures and monopole excitations inC13

The structure of $1/2^{\pm}$ states in $^{13}$C up to around the $3\alpha+n$ threshold ($E_x = 12.3$~MeV) is investigated with a full four-body $3\alpha+n$ orthogonality condition model (OCM) calculation, where the $3\alpha$ OCM, the model space of which is the subspace of the $3\alpha+n$ model, describes well the structure of the low-lying states of $^{12}$C including the $2^{+}_2$, $0^{+}_3$, and $0^{+}_4$ states, which have been recently observed above the Hoyle state ($0^+_2$). A full spectrum up to the $1/2^{-}_5$ ($1/2^{+}_3$) state is reproduced consistently with the lowest five $1/2^{-}$ (three $1/2^{+}$) states of experimental spectrum. It is shown that the $1/2^{-}_2$ and $1/2^{-}_3$ states are characterized by the dominant cluster configurations of $^{9}$Be($3/2^-$,$1/2^-$)+$\alpha$, while the ground state $1/2^-_1$ has a shell-model-like structure. The observed monopole transition strengths to the $1/2^{-}_{2,3}$ states are consistently reproduced for the first time. These results indicate that the excited $1/2^-$ states have cluster structures. They are compared to those by the previous work with the shell model. On the other hand, the $1/2^{+}_{1}$ state is found to have a loosely bound neutron structure in which the extra neutron moves around $^{12}$C(g.s) core with $1S$ orbit, reflecting the fact that this state appears by $1.9$ MeV just below the $^{12}$C(g.s)+$n$ threshold, while the $1/2^{+}_{2}$ and $1/2^{+}_{3}$ states are characterized by $^{9}$Be+$\alpha$ structures. We found that the $1/2^+_5$ state located above the $3\alpha+n$ threshold is the Hoyle analogue state in $^{13}$C, the wave function of which is described by product states of constituent clusters, $(0S)^3_{\alpha}(S)_n$, with the probability of $52$ %.

Study of cluster structure in 13C with AMD+HON-constraint method

The 3α + n cluster states of 13C are discussed on the basis of antisymmetrized molecular dynamics with the constraint on the harmonic oscillator quanta. We predict two different kinds of the cluster states, the hoyle analogue state and the linear-chain state. The former is understood as the 0+2 state (Hoyle state) of 12C accompanied by a valence neutron occupying the s-wave. The latter constitute the parity doublet bands of Kπ = 1/2± owing to its parity asymmetric intrinsic structure.

Three-Body Cluster Structures and Hoyle-Analogue States in $^{11}$B

The structures of 11 B are studied with the 2α+t orthogonality condition model (OCM) for exploring Hoyle-analogue states in 11 B. We found that the 12.56-MeV state (J π =1 /2 + ) around the α + α + t threshold is a strong candidate for the Hoyle-analogue state.

α+α+t cluster structures and Hoyle-analogue states in 11B

The structures of 11B are studied with the 2α+t orthogonality condition model (OCM) for exploring Hoyle-analogue states in 11B.

CLUSTER STRUCTURES AND SINGLE-CLUSTER MOTIONS IN 11B AND 13C

The structures of 11 B and 13 C are studied up to Ex ~ 15 MeV with the semi-microscopic three-body and four-body cluster models, 2α+t and 3α+n orthogonality condition models (OCM). We discuss the cluster states and Hoyle-analogue states in 11 B and 13 C .

CLUSTER STRUCTURES IN 3/2- AND 1/2+ STATES OF 11B

Cluster structures of 3/2- and 1/2+ states in 11 B are investigated with a semi-microscopic α + α + t cluster model based on the Gaussian expansion method. The [Formula: see text] state, characterized by the monopole transition strength as large as the Hoyle state ([Formula: see text] at Ex = 7.65 MeV in 12 C ), was found to have a loosely bound α+α+t cluster structure, although its features is not similar to those of the Hoyle state with the dilute 3α-condensate-like character (0Sα)3, in which the α particle is occupied in a single 0S-orbit with about 70% probability. We indicate that the 12.56-MeV state (Jπ = 1/2+) around the α + α +t threshold observed in the 7 Li (7 Li ,11 B *)t reaction etc. is a strong candidate for the Hoyle-analogue state with the main configuration of (0Sα)2(0St) from the analyses of the single-cluster motions in 11 B .