Spins and Magnetic Moments ofK49andK51: Establishing the

J. Papuga

¹

,

M. L. Bissell

²

,

Kim Dieter Kreim

³

et al.

Abstract

The ground-state spins and magnetic moments of (49,51)K have been measured using bunched-beam high-resolution collinear laser spectroscopy at ISOLDE CERN. For 49K a ground-state spin I = 1/2 was firmly established. The observed hyperfine structure of 51K requires a spin I > 1/2 and strongly suggests I = 3/2. From its magnetic moment μ(51K) = +0.5129(22)μ(N) a spin-parity I(π) = 3/2+ with a dominant π1d(3/2)(-1) hole configuration was deduced. This establishes for the first time the reinversion of the single-particle levels and illustrates the prominent role of the residual monopole interaction for single-particle levels and shell evolution.

Shell structure of potassium isotopes deduced from their magnetic moments

“…It is more than 90% for all isotopes up to 45 K, but for 47,49 K the wave function is dominated by the π2s −1 1/2 ⊗ ν(pf ) configuration. This was already concluded in [22], the conclusion based on the measured ground-state spin and g factor. The only noticeable difference between both calculations is found for 49 K, where the contribution from π1d The inversion of the nuclear spin from I = 3/2 to I = 1/2 at N = 28 and the re-inversion back to I = 3/2 at N = 32 is related to the evolution of the proton orbitals (πsd) while different neutron orbitals are being filled.…”

“…Nuclear spins, magnetic moments and changes in mean square charge radii were extracted model independently. From the intensity ratios of the hyperfine components, the nuclear spin of 48 K and 51 K were determined to be I = 1 [26] and I = 3/2 [22], respectively. Since only three peaks are observed in the hyperfine spectrum of 49 K, a spin of I = 1/2 can be unambiguously assigned [22].…”

“…From the intensity ratios of the hyperfine components, the nuclear spin of 48 K and 51 K were determined to be I = 1 [26] and I = 3/2 [22], respectively. Since only three peaks are observed in the hyperfine spectrum of 49 K, a spin of I = 1/2 can be unambiguously assigned [22]. A single peak in the hyperfine spectrum of 50 K corresponds to I = 0 [26].…”

“…Our recent hyperfine structure measurements of potassium isotopes using the collinear laser spectroscopy technique provided unambiguous spin values for 48−51 K and gave the answer to the question as to what happens with the proton sd orbitals for isotopes beyond N = 28. By measuring the nuclear spins of 49 K and 51 K to be 1/2 and 3/2 [22] respectively, the evolution of these two states in the potassium isotopes is firmly established. This is presented in Fig.…”

Novel chiral Hamiltonian and observables in light and medium-mass nuclei

“…Already several years back, 47 K was shown to have a 1/2 + ground state via a laser spectroscopy experiment [100], with 3/2 + becoming a low-lying excited state at 360 keV. Recently, high-resolution collinear laser spectroscopy measurements determined that the ground-state spin inversion is maintained in 49 K but a re-inversion occurs for 51 K [101]. Available experimental data is summarised in Fig.…”