Yields of Photoprotons from Twenty Elements

Scintillation counters have been applied to the study of the yields of photoprotons from twenty elements. The relative yields increase by a factor of approximately one hundred as $Z$ increases from 4 to 28, and then decrease to a value, at $Z=50\mathrm{}$, of about one-tenth that of the maximum at $Z=28\mathrm{}$. An upper limit is placed on the yields from several heavy elements. The absolute values are compared with the neutron data of Price and Kerst, and the sum of the two yields is compared with theory.