Nuclear Spins and Magnetic Moments of Some Neutron-Rich Rubidium and Cesium Isotopes

The nuclear spins and magnetic moments of some neutron-rich rubidium and cesium isotopes have been measured at the ISOLDE facility, CERN, using on-line atomic-beam magnetic resonance (ABMR) techniques. The following results have been obtained: 89Rb, I = 3/2, μ = 2.38(3) n.m.; 90Rb, I = 0; 90mRb, I = 3, μ = 1.61(2) n.m.; 91Rb, μ = 2.18(3) n.m.; 92Rb, I = 0; 95Rb, I = 5/2; 138Cs, μ = 0.701(7) n.m.; 139Cs, I = 7/2, μ = 2.70(3) n.m.; 140Cs, I = 1, μ = ± 0.134(2) n.m.; 141Cs, I = 7/2, μ = 2.42(3) n.m.; 142Cs, I = 0; 143Cs, I = 3/2; 144Cs, I = 1; and 145Cs, I = 3/2. The errors in the magnetic moments are mainly due to the unknown hyperfine anomaly, for which a 1% uncertainty is adopted relative to the reference nuclides 85Rb and 133Cs. The results obtained are discussed in terms of different models for nuclear structure.