New concept in clusterings and alpha-particle condensates

Abstract

Gas-like α cluster states are investigated in 16O with the use of 4α OCM (Orthogonality Condition Model) and GEM (Gauss Expansion Method). α-particle condensed state is found slightly above the 4α threshold as the 06+ state. The candidates of the α+12C(02+) rotational states are also found at a few MeV above the condensate. The 06+ state is shown to have an analogue structure to the Hoyle state (12C(02+)) and its relation with the α+ Hoyle -like rotatinal states is also discussed. We further investigate the ground-state band in 20Ne by using the THSR-type wave function, which has been used for gas-like α cluster states. It is found that the single THSR wave function can describe well the corresponding states of the ground-state band in 20Ne, which indicates that even for describing non-gas-like cluster states the density parameter of the nucleus, which characterizes the THSR wave function, is more reasonable than the inter-cluster distance parameter, which characterizes the ordinary cluster model wave function.