Three-body resonances inHe6,Li

Abstract

Using the complex scaling method, the low-lying three-body resonances of 6 He, 6 Li, and 6 Be are investigated in a parameter-free microscopic threecluster model. In 6 He a 2 + , in 6 Li a 2 + and a 1 + , and in 6 Be the 0 + ground state and a 2 + excited state is found. The other experimentally known 2 + state of 6 Li cannot be localized by our present method. We have found no indication for the existence of the predicted 1 − soft dipole state in 6 He. We argue that the sequential decay mode of 6 He through the resonant states of its two-body subsystem can lead to peaks in the excitation function. This process can explain the experimental results in the case of 11 Li, too. We propose an experimental analysis, which can decide between the soft dipole mode and the sequential decay mode.

Three-body properties of low-lying12Be resonances

“…In particular, 11 Be is a nucleus with two bound states, both with a two-body halo structure. The ground state of 12 Be is rather well bound but three halo states appear as excited states, and 13 Be is particle unbound, whereas 14 Be has one particle-bound state [34,35]. The complicated drip-line structure for the Be isotopes is primarily due to the second s-state intruder and eventual inversion with the p state in 11 Be [36].…”

“…However, a number of low-lying many-body resonances in light nuclei can still be well described as cluster structures even when they appear in the continuum. Prominent examples are found in stable nuclei such as 12 C and 9 Be [5][6][7][8][9][10][11][12][13], but even ground states like in 6 Be [14][15][16][17] and 10 Li [18][19][20] may appear as resonances.…”

S-matrix andR-matrix determination of the low-energy5He andCsótó1, Hale2 1997Phys. Rev. CSelf Cite

“…We mention here two examples: the large cross section of the t(d, n)α reaction and the problem of the soft dipole resonance in neutron halo nuclei. Only analyses at complex energies were able to reveal that the large reaction cross section is caused by a shadow pole of the scattering matrix in the former case [3,4], and that the soft dipole resonance does not exist in 6 He in the latter one [5]. It is an intriguing question whether or not the results of methods that are not confined to real energies agree with those of conventional analyses for the relatively broad resonances encountered in light systems.…”

Dipole excited states in 11Li with complex scaling

“…The same method has also been applied to study the continuum structure of 9 Be and 9 B [28] assuming these nuclei as three-body systems made by two α-particles and a neutron and a proton, respectively. Application to the two-neutron halo nucleus 6 He can be found in [29][30][31], and in [32] the case of 10 He is considered. When available, the agreement with the experimental data is satisfactory.…”