Spins of Rubidium Isotopes of Masses 81, 82, 83, and 84

The nuclear spins of four neutron-deficient isotopes of rubidium have been determined by the atomic-beam magnetic-resonance method. The isotopes, with half-lives between 4.7 hours and 80 days, are produced in quantities of ${10}^{13}$ to ${10}^{14}$ atoms by alpha spallation reactions in the Berkeley 60-inch cyclotron. Detection of the beam is accomplished by allowing the neutral beam to fall on a sulfur surface at room temperature, then removing the surface from the apparatus and counting with low-background high-efficiency scintillation counters which accept $K$ x-rays accompanying $K$ capture and internal conversion. Since all four isotopes are made in one bombardment, the identification is important (and is the subject of a separate discussion). The experimental results are: ${\mathrm{Rb}}^{81}$, $I=\frac{3}{2}$; ${\mathrm{Rb}}^{82}$, $I=5\mathrm{}$; ${\mathrm{Rb}}^{83}$, $I=\frac{5}{2}$; ${\mathrm{Rb}}^{84}$, $I=2\mathrm{}$.