On the odd-even staggering of mean-square charge radii in the light krypton and strontium region

Abstract

Recently isotope shifts of 72, Kr and 77-100 Sr have been measured at the ISOLDE/ CERN mass separator facility by collinear laser spectroscopy. The deduced changes in mean square charge radii reveal sharp transitions in nuclear shape from spherical near the magic neutron number N=50 towards strongly deformed for both the neutron deficient and neutron rich isotopes far from stability. The mean square charge radii of the neutron deficient isotopes exhibit a sign change of the odd-even staggering (OES), i.e. below the neutron number N=46 the radius is systematically larger for the odd-N nuclei than for their even-N neighbours. This is in contrast to the situation of normal OES which is observed for the heavier isotopes. The inversion of the OES is interpreted as an effect of polarization, triggered by the addition of an unpaired neutron and driving the soft eveneven core into stable strong deformation. accepted for publication in Europhysics Letters (IS80 and IS304)

Probing the Ga31 ground-state properties in the region near Z=28 with high-resolution laser spectroscopy

“…The statistical, modified-systematic, and atomic-systematic uncertainties are enclosed within parentheses, square brackets, and curly brackets, respectively. chains [56]. It is also observed in the N = 134 region in the francium and radium chains, in which it coincides with a region of octupole deformation [54,57].…”

“…For the neutron-deficient region above Z = 28, a sudden increase in the magnetic moment was observed for 57 Cu, towards the effective single-particle μ(πp 3/2 ) value [15]. While N,Z = 28 are still good magic numbers in this region of the nuclear chart, a softer 56 28 Ni 28 was required to obtain good agreement between experiment and theoretical predictions [16]. However, the electric-quadrupole moments are a better probe of the softness of the core, due to the strong correlation of collectivity with pair scattering across the orbitals.…”

“…The JUN45 calculations are performed starting from a 56 Ni core (see Fig. 4), including the upper pf orbits and the g 9/2 orbit as a valence space for both protons and neutrons.…”

Precision mass measurements of radioactive nuclei at JYFLTRAP

“…At a maximum discontinuity in S 2n the mean-square charge radii increase suddenly. By observing the change in mean-square charge radii and subsequently in the quadrupole moments [24] the Sr isotopes below N = 59 were suggested to be weakly oblate and strongly prolate beyond N = 59. Later similar sudden jumps in the mean-square charge radii at N = 60 were found in Zr and Y isotopes and a similar conclusion was drawn [25,26].…”

Search for octupole-deformed actinium isotopes using resonance ionization spectroscopy

“…However, inverted odd-even staggering has also been observed in regions of the nuclear chart which have not been linked to octupole deformation. In the light krypton and strontium region the observation of inverted odd-even staggering has been interpreted as an effect of polarization of the even-even core toward strong quadrupole deformation driven by the unpaired neutron [64]. Whereas the inverted staggering in the light mercury region has been explained as a quantum phase transition from a slightly quadrupoledeformed ground state toward a strongly deformed ground state when changing neutron number [65].…”