Nonmicroscopic and microscopic descriptions of condensate states in the 12C and 16O nuclei

Marianne Dufour,Rimantas Lazauskas,Pierre Descouvemont

doi:10.1088/1742-6596/436/1/012005

Abstract

12C and 16O nuclei are investigated within nonmicroscopic and microscopic theoretical frameworks, respectively. For the 12C nucleus viewed as a 3α system, 3-body Faddeev equations are solved in configuration space. Positions of the resonant states are obtained through the complex scaling method. We show that the nonlocal potential developed by Z. Papp and S. Moszkowski appears to be well-adapted to study 3α system. In particular, we show evidence for 12C states of positive-parity which share common features with the well-known 0+2 Hoyle state, currently interpreted as a condensate state. For the 16O nucleus, a 12C+α multicluster generator coordinate method is used to solve the 16-nucleon problem. The 16O nucleus is described by four α cluster. We comment the difficulty to interpret broad resonant states. The phase-shift analysis of the 12C(0+2) + α channel reveals the existence of two 0+ states located above the 4α threshold which can be interpreted as condensate states.

Highlights

Owing to the compactness and strong binding of the α particles, the idea that they tend to keep their own identity inside the nuclei is at the origin of cluster models
Α being boson, nuclear states are described by nα symmetrized wave functions
For the 12C nucleus viewed as a 3α system, 3-body Faddeev equations [5] are solved in configuration space

Summary

Introduction

Owing to the compactness and strong binding of the α particles, the idea that they tend to keep their own identity inside the nuclei is at the origin of cluster models. Α being boson, nuclear states are described by nα symmetrized wave functions. We show the importance to calculate phase shifts in each channel of reaction to interpret broad resonances. Non-microscopic calculations based on these interactions fail to describe bound states of the 12C nucleus and reveal the necessity to introduce phenomenological multi-body forces involving additional parametrization [12].

Results

Conclusion