Analysis of the effect of core structure upon dineutron correlation using antisymmetrized molecular dynamics

Abstract

We extend the method of antisymmetrized molecular dynamics to investigate dineutron correlation. We apply this method to 10 Be as an example and investigate the motion of two neutrons around a largely deformed 8 Be core by analyzing the two-neutron overlap function around the core. We show that the core structure plays an important role in dineutron formation and expansion from the core and that the present framework is effective for the studies of dineutron correlation.

Structure of Be13 studied in proton knockout from B14

“…is expected to be two α particles in a dumbbell configuration coupled to a neutron [1]. There is, however, no complete understanding of the nature of its first excited state, 9 Be(1/2 + ). It has been described as a resonance [2], a virtual state in 8 Be + n [3,4], or a genuine three-body α + α + n resonance, where the 5 He + α configuration dominates at small distances and 8 Be + n at large distances [5,6].…”

“…It has been described as a resonance [2], a virtual state in 8 Be + n [3,4], or a genuine three-body α + α + n resonance, where the 5 He + α configuration dominates at small distances and 8 Be + n at large distances [5,6]. Another interesting feature of 9 Be is a parity inversion, where its I π = 1/2 + state is found at an energy ≈ 1 MeV lower than the I π = 1/2 − state.…”

“…The 10 Be(g.s.) structure can also be described using cluster models [8,9]. The motion of the two neutrons around the strongly deformed 8 Be core was investigated with a mixing of a minor (sd ) 2 component into the major p 2 component [9].…”

Enhanced Electric Dipole Strength for the Weakly Bound States in Ne27

“…The corresponding theoretical partial lifetime of 0.8−2.0 ps is comparable to the upper limit of 2.4 ps experimentally constrained from the upper bound of the 1/2 + lifetime and the branching ratio for the 1/2 + decay to the 3/2 + gs state. In this respect, it is interesting to note that the configurations of the 3/2 − and 1/2 + states in 27 Ne may correspond to [N n z λΩ] = [330 1/2] and [200 1/2] Nilsson orbitals at the deformation of β 2 ≈ 0.4 [35], respectively. In this picture, the E1 transition can be viewed as the single-particle excitation of the valence neutron weakly bound to the deformed core [36], suggesting the deformation as an important ingredient to account for the E1 enhancement.…”

Knockout and fragmentation reactions using a broad range of tin isotopes

“…This technique together with the use of knockout reactions have shown to be a particularly powerful tool to investigate unstable nuclei, the main observables being the cross sections and the longitudinal momentum distributions of the reaction residues [11][12][13][14][15][16][17].…”