Isotopically enriched Pd foils were bombarded with protons to determine the origin of the 1.2-hr activity which was previously discovered in an even-$A$ Ag isotope. The only appropriate activity was found in ${\mathrm{Ag}}^{104}$ which was observed to have a (69±3)-min predominantly $K$-capture activity with intense $\gamma$ rays of 550, 764, and 920 kev. Using the atomic beam magnetic resonance method it was verified that the 69-min activity has $I=5\mathrm{}$. The $I=2\mathrm{}$ resonance in ${\mathrm{Ag}}^{104}$, when counted in an x-ray detector, was found to decay with a 69-min half-life with a small admixture of a 27-min component. When viewed in a $\beta$ counter, only the 27-min component is observed. These characteristics of the $I=2\mathrm{}$ resonance can be explained by placing the $I=2\mathrm{}$ level above the $I=5\mathrm{}$ level with an appreciable amount of isomeric transition. This interpretation is supported by the observation of feeding in the 920-kev $\gamma$ ray which only occurs in the decay of the $I=5\mathrm{}$ state.

Further work with isotopically-enriched Pd foils showed $\gamma$ rays of 120 and 150 kev, and, tentatively, 260 kev which have been assigned to the decay of 59-min ${\mathrm{Ag}}^{103}$. A positive identification of a (15±2)-min activity in ${\mathrm{Ag}}^{102}$ has been made.

• Received 22 January 1960

DOI:https://doi.org/10.1103/PhysRev.118.1599