A Study of the Hyperfine Structure of Samarium-153 and Samarium-155

Abstract

It was the purpose of this investigation to study the hyperfine structure of the β-unstable isotopes of samarium using the atomic beam magnetic resonance technique. A brief review is given of the nuclear and atomic theory necessary for the interpretation of the experiments. The hyperfine interaction constants (Mc/sec) for Sm153, and the nuclear moments inferred from them, are summarized below: A1 = - 2.100(5) B1 = 289.042(4) A2 = - 2.573(6) B2 = 306.521(21) C2 = - 0.0003(9) A3 = - 3.115(4) B3 = 165.824(20) C3 = - 0.0087(12) μI = - 0.021(1) n.m. Q = 1.1(3) barns From the quadrupole moment it follows that the nuclear deformation δ = 0.25(5). The magnetic moment disagrees with the predictions of the Nilsson model for either spin 3/2 state with which the Sm153 ground state might be associated. Also determined was the spin of Sm155. The result, I = 3/2, confirms the assignment from the less direct evidence available from radioactive decay studies. The more extensive measurements necessary to determine the moments were not attempted.