Structure of 11Li in the cluster-orbital shell model for the 9Li + n + n system

Abstract

The properties of '"Li are studied in detail in the cluster-orbital shell model assuming the structure of 'Li+n+n. The interactions acting between the constituent particles are carefully determined consistently with available data. Large and flexible bases for the valence neutrons are represented as a superposition of gaussian functions. The anomalously Iarge radius of "Li is nicely reproduced.The density dist~butions calculated clarify the picture of the neutron halo. The binding energy is, however, calculated to be l-l.4 MeV short. A possible resolution of this point is discussed from the viewpoint of the di-neutron clustering.The quadrupole moment of "Li is predicted to be almost the same as that of 'Li.

Electron scattering on two-neutron halo nuclei: The case of 6He

“…For neutron halos the charge radius is expected to be the one of the core. Elastic electron scattering on 11 Li or 6 He will be important to confirm that this picture of neutron halo nuclei is correct. As one slightly increases the energy transfer to the nucleus the halo will break up, and coincidence (e, e ′ x) measurements can be made, with x either a halo neutron or the stable core.…”

“…Very soon it was suggested that these nuclei could be understood as a core surrounded by one or more neutrons, which extend to several times the nuclear radius [5]. This picture was supported by subsequent studies that proved the validity of the few-body models as an appropriate method to describe the most general properties of halo nuclei [6][7][8][9][10].…”

“…For a general overview of their basic properties see for instance [11]. Among halo nuclei a lot of attention has been paid to two-neutron halo systems from which 6 He (α + n + n) and 11 Li ( 9 Li +n + n) are their maximum exponents [12]. They are samples of the so called Borromean nuclei, that have the property of being bound while all the two-body subsystems made by two of the three constituents are unbound.…”

“…To illustrate the model we will consider the case of electron- 6 He scattering. Although estimates of the elastic scattering reaction will be given, most of the work will be devoted to (e, e ′ n) and (e, e ′ α) reactions at quasielastic kinematics.…”

“…The differential cross section for exclusive (e, e ′ x) processes is given in section IV. Sections V and VI are devoted to the theoretical description of the different ingredients involved in the electron- 6 He scattering process and to the presentation of the results, respectively. Concluding remarks are given in section VII.…”