Strontium and yttrium have been bombarded with 6.3 Mev deuterons, with 14-20 Mev neutrons, and with slow neutrons, and induced radioactivity obtained in both elements. The activity in strontium is readily obtained by the action of deuterons or neutrons on strontium and possibly, with very weak intensity, by the action of fast neutrons on yttrium with the emission of a proton. The periods observed in strontium are 3.0±0.1 hours (negative active, maximum energy=0.61 Mev), and 55±5 days (negative active, maximum energy = 1.9 Mev). A gamma-ray is found associated with the 3-hour period. Evidence has been obtained showing that the two periods may be ascribed to isomeric forms of ${\mathrm{Sr}}^{89}$. Activity in yttrium is obtained when strontium is bombarded with deuterons and when yttrium is bombarded with deuterons or neutrons. The periods observed are 120±4 minutes (positive active, maximum energy = 1.2 Mev) and 60.5±2.0 hours (negative active, maximum energy = 2.6 Mev). These periods are due, it is believed, to ${\mathrm{Y}}^{88}$ and ${\mathrm{Y}}^{90}$, respectively. In the possible formation of ${\mathrm{Y}}^{90}$ from Sr+${\mathrm{H}}^2$, it is suggested that the process involves the complete capture of a deuteron, a reaction not previously observed.

• Received 8 September 1937

DOI:https://doi.org/10.1103/PhysRev.52.901