ISOTOPE SHIFTS AND NUCLEAR-CHARGE RADII OF KRYPTON ISOTOPES ACROSS THE N = 50 SHELL CLOSURE

Optical isotope shifts have been measured in the 5s[3/2]20-5p[3/2]2 transition in atomic krypton (=760 nm) using collinear-fast-beam laser spectroscopy. Isotope shifts were determined for the short-lived neutron-rich isotopes Kr88 and Kr90, as well as for all the stable isotopes between A=78 and 86, thus extending the data in this element, for the first time, beyond the N=50 shell closure. The deduced changes in the nuclear charge radii show a decrease of the charge radius with increasing neutron number below N=50, and a much more rapid increase above it. A preliminary interpretation of the results is given in terms of the droplet model. © 1990 The American Physical Society.