Speaker
Description
Following the N=28 shell closure, a noticeable change in the slope of the charge radii, often called a "kink", has been observed in neutron-rich calcium isotopes [1,2]. However, the exact size of this kink and its underlying causes remain unclear. Theoretical predictions suggest that several factors might contribute to this behavior, including the presence of large nuclear deformations or significant radial extensions of the nuclear density distribution. To address these questions and explore the origins of the observed kink, we will determine the distribution of magnetization, specifically the differential hyperfine anomaly (also known as Bohr-Weisskopf effect), for 48K. This will be compared with the corresponding distributions in the neighboring isotopes 47K and 49K. To achieve this, we employed the b-Nuclear Magnetic Resonance (NMR) technique [3] to measure the precise magnetic moments of these isotopes. Additionally, laser-rf double resonance spectroscopy [4] will be used to determine the hyperfine structure constant (A) with high accuracy.
The data interpretation will be done with the help of nuclear density functional theory approach with angular momentum symmetry restoration [5] to analyze the variation in these moments across different angular momentum projections and mass. We employ the Hartree-Fock- Bogoliubov formalism to determine the magnetic dipole moments of the isotopes using HFODD code [6]. The spectroscopic moments are then compared with the experimental measurements. The recent results from the experiment will be presented. These findings serve as a benchmark for neutron-rich odd-odd isotopes.
References:
[1] A. Koszorus, X. Yang, W. Jiang, S. Novario, S. Bai, J. Billowes, C. Binnersley, M. Bissell, T.
E. Cocolios, B. Cooper, et al., Nature Physics 17, 439(2021).
[2] R. Garcia Ruiz, M. Bissell, K. Blaum, A. Ekstrom, N. Frommgen, G. Hagen, M. Hammen, K. Hebeler, J. Holt, G. Jansen, et al., Nature Physics 12, 594(2016).
[3] R. D. Harding et al., Phys. Rev. X 10 (2020) 041061.
[4] M.E. Van Hove and R.E. Silverans, Hyperfine Interactions, 38 (1987) 773-792.
[5] P.L. Sassarini et al., J. Phys G 49 (2022) 11LT01.
[6] J Dobaczewski et al., Phys. Rev. C 113 (2026), 024306.