Deformation and $\alpha$ clustering in excited states of $^{42}$Ca

TL;DR

This study investigates the coexistence of deformed states and alpha clustering in excited states of calcium-42 using advanced nuclear modeling techniques, successfully reproducing known rotational bands and predicting new cluster structures.

Contribution

It applies deformed-basis antisymmetrized molecular dynamics with GCM to explore low-lying states and alpha clustering in $^{42}$Ca, revealing coexistence and predicting additional rotational bands.

Findings

Reproduces known rotational bands in $^{42}$Ca.

Predicts coexistence of multiple deformed and cluster states.

Identifies alpha-$^{38}$Ar cluster components in certain bands.

Abstract

The coexistence of various low-lying deformed states in $^{42}$Ca and $\alpha$--$^{38}$Ar correlations in those deformed states have been investigated using deformed-basis antisymmetrized molecular dynamics. Wave functions of the low-lying states are obtained via parity and angular momentum projections and the generator coordinate method (GCM). Basis wave functions of the GCM calculation are obtained via energy variations with constraints on the quadrupole deformation parameter $\beta$ and the distance between $\alpha$ and $^{38}$Ar clusters. The rotational band built on the $J^\pi = 0_2^+$ (1.84 MeV) state as well as the $J^\pi = 0_3^+$ (3.30 MeV) state are both reproduced. The coexistence of two additional $K^\pi = 0^+$ rotational bands is predicted; one band is shown to be built on the $J^\pi = 0_3^+$ state. Members of the ground-state band and the rotational band built on the $J^\pi = 0_3^+$ state contain $\alpha$--$^{38}$Ar cluster structure components.