Collinear resonance ionization spectroscopy of neutron-deficient francium isotopes

Phys Rev Lett. 2013 Nov 22;111(21):212501. doi: 10.1103/PhysRevLett.111.212501. Epub 2013 Nov 19.

Abstract

The magnetic moments and isotope shifts of the neutron-deficient francium isotopes (202-205)Fr were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1% was measured for (202)Fr. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to (205)Fr, with a departure observed in (203)Fr (N=116).