Nuclear Charge Radii ofSr78−100by Nonoptical Detection in Fast-Beam Laser Spectroscopy

Abstract

We report the application of a new nonoptical detection scheme in laser spectroscopy on ion beams of on-line isotope separators. The method consists of ground-state depopulation by optical pumping in collinear laser-ion-beam interaction, state-selective neutralization, and charge-state-separated fast-atom counting. Strontium isotope-shift measurements are extended into the strongly deformed region of the neutron-rich isotopes up to '^Sr. The radii are generally well described by the droplet model including empirical deformations obtained from BiE2) values.

Saturation of deformation atN=60 in the Sr isotopes

“…This result is, nonetheless, surprising in that saturation does not occur at neutron midshell as usually observed, but already at the sudden onset of deformation at N = 60. Our observation is in qualitative agreement with results from recent laser spectroscopic studies [11]. Although deformations derived from r.m.s, values of nuclear radii are basically different (since besides static they also contain dynamic components) from those deduced from B(E2) values, the general trend appears to be the same.…”

Recent developments in collinear laser spectroscopy at COLLAPS/ISOLDE

“…Charged particle detection is usually superior to fluorescence detection, since considerably higher efficiencies can be reached. Therefore different detection schemes have been developed, for example state-selective neutralization [10], state-selective ionization [8], and resonance ionization detection [11].…”

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

“…Although this traditional interpretation of radii in the framework of a macroscopic model including deformation fails in the neighbourhood of shell closures (see [7,8,11]), it can serve as a guide to the understanding of unusual odd-even effects occurring in the region where the nuclei approach strongly deformed shapes. The OES is most transparently presented in terms of the difference D between the radius of an odd-N isotope and the mean value of the radii of its even-N neighbours,…”

“…[7][8][9][10][11] and they are complemented by an experiment on the odd-Z isotopic series of Rb [12].…”

“…The global changes in ms charge radii for Kr [11] and Sr [7][8][9][10] An important contribution to the ms charge radii stems from nuclear deformation. To first order this can be expressed by the droplet model formula [13] …”