# Collective-coupling analysis of spectra of mass-7 isobars:^{7} He,^{7} Li,^{7} Be, and^{7} B

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Juris Svenne, Jul 02, 2015 Available from:- [Show abstract] [Hide abstract]

**ABSTRACT:**The fundamental ingredients of the MCAS (multi-channel algebraic scattering) method are discussed. The main feature, namely the application of the sturmian theory for nucleon-nucleus scattering, allows solution of the scattering problem given the phenomenological ingredients necessary for the description of weakly-bound (or particle-unstable) light nuclear systems. Currently, to describe these systems, we use a macroscopic, collective model. Analyses show that the couplings to low-energy collective-core excitations are fundamental but they are physically meaningful only if the constraints introduced by the Pauli principle are taken into account. For this we introduce in the nucleon-nucleus system the Orthogonalizing Pseudo-Potential formalism, extended to collective excitations of the core. The formalism leads one to discuss a new concept, Pauli hindrance, which appears to be important especially to understand the structure of weakly-bound and unbound systems. - [Show abstract] [Hide abstract]

**ABSTRACT:**Sturmian theory for nucleon-nucleus scattering is discussed in the presence of all the phenomenological ingredients necessary for the description of weakly-bound (or particle-unstable) light nuclear systems. Currently, we use a macroscopic potential model of collective nature. The analysis shows that the couplings to low-energy collective-core excitations are fundamental but they are physically meaningful only if the constraints introduced by the Pauli principle are taken into account. The formalism leads one to discuss a new concept, Pauli hindrance, which appears to be important to understand the structure of weakly-bound and unbound systems.Nuclear Physics A 06/2007; 790(1). DOI:10.1016/j.nuclphysa.2007.03.148 · 2.50 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**A Multi-Channel Algebraic Scattering (MCAS) theory has been used to study the interaction of a nucleon with light-mass nuclei as a coupled-channel problem. The method can be solved for all energies so that bound states as well as resonances of the compound nucleus can be specified, even if the compound nucleus is nucleon unstable. A resonance finding prescription ensures that all resonances of the system can be found no matter how weak and/or narrow. Spectra of mass-7 nuclei and of the proton unstable 15F are discussed, the Coulomb displacement energy considered, and first results on using MCAS details in a radiative capture cross section calculation presented.