Study of the Alpha-Clustering Structure of 20Ne Based on the Resonating Group Method for 16O+ : Analysis of Alpha-Decay Widths and the Exchange Kernel

Abstract

The alpha-clustering structure of 20Ne is investigated on the basis of the one-channel resonating group method for the 16O+α system. Scattering phase shifts are calculated for 0≤L ≤14 in the region 0 <45 MeV. Energy spectra and α-decay widths of the first Kπ=0± bands are well reproduced. Further discussion is made on α-spectroscopic factors, the rms distance between the c.m. of the 16O and alpha cluster, intrinsic quadrupole moments and B(E2) strengths for the bands. It is concluded that the Kπ=0- band states (L ≤9) have strongly an 16O-α molecule-like character and that the ground band states (L ≤8) have rather a shell-model-like character but can also be described fairly well within the framework of the one-channel resonating group method; the exchange kernel melts strongly the 16O-α molecule-like character in the latter band. The exchange kernel is analysed by showing a kind of its equivalent local potential between the 16O and alpha cluster. It is further shown that there appears an excited Kπ=0+ band with spin up to 12+ and that the 11- level seems to belong to the first Kπ=0- band. Two kinds of nucleon-nucleon potentials of the reaction-matrix type and of phenomenological type are examined in the present analysis.