Study of 19F by  -15N plus t-16O Coupled Channel Orthogonality Condition Model. II: Electromagnetic Transitions and Spectroscopic Factors

Abstract

Properties of evenand odd-parity levels of 19 F are shown to be well understood in terms of an a-"N plus t-16 0 coupled channel orthogonality condition model. The properties of the levels investigated are El, E2, E3 and M1 transitions, a-widths and t-widths. In particular, the observed E2 transitions are systematically reproduced with no additional charge. These features are discussed from a viewpoint of a-and t-clustering correlations in the wave functions and also from the interference of these two cluster states. The properties of 19 Ne are also discussed.

Molecule-like structure with covalent neutrons of F isotopes toward the neutron drip line

“…To illustrate the α clustering toward the neutron drip line, we have performed the same calculation for 25,27,29 F. Namely, by using the N constraint, we have calculated the proton-hole states without neutrons in the pf shell and with one or two neutrons in the pf shell. 31 F was unbound in the present model. This contradicts observation [45] and is not discussed here.…”

“…Many cluster-model studies [31,32] have shown that the K π = 1/2 − and 1/2 + 2 bands of 19 F have prominent α + 15 N cluster structure and constitute a parity doublet. When a proton is excited into the sd shell acrossthe Z = 8 magic number, four nucleons in the sd shell have a strong α correlation and an α + 15 N cluster structure develops.…”

“…For example, the properties of 31 Na [1,2] have shown the breakdown of the magic number N = 20 in neutron-rich nuclei. Due to strong deformation of the system, the intruder configuration in which neutrons are excited across the N = 20 shell gap dominates the ground band [3] and is called the "island of inversion."…”

“…Due to strong deformation of the system, the intruder configuration in which neutrons are excited across the N = 20 shell gap dominates the ground band [3] and is called the "island of inversion." Nowadays, systematic breaking of the magic number N = 20 in the neighboring nuclei of 31 Na has been theoretically studied [4][5][6][7][8][9][10] and many observations have been made [11][12][13][14].…”

“…The α-cluster states in 19 F have been investigated theoretically and experimentally in detail in the 1970s. Cluster-model calculations [31,32] have shown that once a proton is excited into the sd shell from the p shell, four nucleons in the sd shell have a strong α correlation and the α-cluster bands emerge. The lowest α + 15 N band, 19 F, α clustering of heavier F isotopes is rather obscure.…”