Modelling and Systematics of $\tfrac{1}{2}[521]\,\nu$ Quasiparticle Rotational Bands in $N = 99,\;101,\;103$ Isotonic Chains

TL;DR

This study models the [521] u quasiparticle rotational bands in N=99, 101, 103 isotones using a semi-empirical approach, revealing how parameters like inertia, decoupling, and Coriolis effects evolve with neutron and proton numbers.

Contribution

It introduces a semi-empirical model with a Python routine to optimize parameters for quasiparticle bands, providing detailed insights into their physical behavior across isotonic chains.

Findings

Inertia parameter increases with Z, indicating decreasing deformation.

Decoupling parameter varies with neutron number, reflecting configuration purity.

Coriolis coefficients exhibit chain-specific sign changes and Z-dependence.

Abstract

We analyze the $\tfrac{1}{2}[521]\,\nu$ quasiparticle rotational bands along the $N = 99,\;101,\;103$ isotonic chains using semi-empirical model in which first and higher order Coriolis terms are treated perturbatively. A dedicated Python routine optimizes five parameters bandhead energy, inertia A, decoupling a, and Coriolis coefficients B and C for each nucleus. The calculations match experimental level spacings to within 5 keV. Staggering keeps a common phase across the three chains yet grows with spin and, on average, with both neutron and proton number. The inertia parameter rises smoothly with Z (e.g., A for N = 99: 10.6 to 12.4 keV), signaling a decrease in the moment of inertia as axial deformation weakens. Decoupling parameter a increases and then saturates for N = 99 and 103, indicating purer K = 1/2 structure at high Z; the N = 101 chain shows the opposite trend, pointing to stronger configuration mixing. The first order Coriolis term B becomes increasingly negative with Z, whereas the higher order term C shows chain specific sign changes. The present work, explore the dynamics of various physical parameters associated with {\nu}1/2[521] quasiparticle rotational bands and helps to understand observed signature effects.