arXiv subjects

M. Płoszajczak

Publications and source records attributed to M. Płoszajczak.

40 records · Page 3Linked to original sources

arXiv2011

Charge radii and neutron correlations in helium halo nuclei

Within the complex-energy configuration interaction framework, we study correlations of valence neutrons to explain the behavior of charge radii in the neutron halo nuclei $^{6,8}$He. We find that the experimentally observed decrease of the charge radius between $^6$He and $^8$He is caused by a subtle interplay between three effects: dineutron correlations, a spin-orbit contribution to the charge radius, and a core swelling effect. We demonstrate that two-neutron angular correlations in the $2^+_1$ resonance of $^6$He differ markedly from the ground-state correlations in $^{6,8}$He.

nucl-th↗

arXiv2010

Simplified modeling of cluster-shell competition in $^{20}$Ne and $^{24}$Mg

We investigate properties of the Generator Coordinate Method (GCM) on a collective basis of Antisymmetrized Quasi-Cluster (AQC) states to describe the cluster-shell competition in $^{20}$Ne and $^{24}$Mg due to the spin-orbit interaction. By introducing a single additional parameter in the antisymmetrized-cluster basis function, a continuous transformation of the $α$ cluster(s) into independent nucleons can be described. We apply this GCM trial wave function to study in details the transition from cluster states $[ ^{16}$O+$α]$ and $[ ^{16}$O+$α+ α]$ to shell model (SM) states $[ ^{16}$O+${\rm 4N} ]$ and $[ ^{16}$O+${\rm 8N} ]$, respectively. An optimal value of the strength of the spin-orbit interaction is deduced by reproducing level spacing in $^{20}$Ne. A possible connection to the group theoretical understanding of the cluster-shell configuration transition is also discussed.

nucl-th↗

arXiv2009

Exceptional points in the scattering continuum

The manifestation of exceptional points in the scattering continuum of atomic nucleus is studied using the real-energy continuum shell model. It is shown that low-energy exceptional points appear for realistic values of coupling to the continuum and, hence, could be accessible experimentally. Experimental signatures are proposed which include the jump by $2π$ of the elastic scattering phase shift and a salient energy dependence of cross-sections in the vicinity of the exceptional point.

nucl-th↗

arXiv2003

Dynamics of open quantum systems

The coupling between the states of a system and the continuum into which it is embedded, induces correlations that are especially large in the short time scale. These correlations cannot be calculated by using a statistical or perturbational approach. They are, however, involved in an approach describing structure and reaction aspects in a unified manner. Such a model is the SMEC (shell model embedded in the continuum). Some characteristic results obtained from SMEC as well as some aspects of the correlations induced by the coupling to the continuum are discussed.

nucl-th↗