Radioisotope yields from 1.85-GeV protons on Mo and 1.85- and 5.0-GeV protons on Te

Radioisotope yields from 1.85-GeV proton interactions in a natural isotopic composition Mo target and those from 1.85- and 5.0-GeV protons in natural Te targets were measured at Lawrence Berkeley National Laboratory’s Bevatron. The radioisotope yields were determined by $\gamma$-counting the targets using 100-cm${}^3$ coaxial Ge detectors following the irradiations. Cross sections were determined for the production of 36 radioactive nuclides, ranging from $Z=35\mathrm{}$, $A=74\mathrm{}$ to $Z=43\mathrm{}$, $A=97\mathrm{}$, from the Mo target and for 43 radioactive nuclides, ranging from $Z=35\mathrm{}$, $A=75\mathrm{}$ to $Z=53\mathrm{}$, $A=130\mathrm{}$ from the Te targets. The average deviations of the experimental cross sections from those predicted by the semiempirical isotopic cross sections of Silberberg and Tsao were 53% for $p$+Mo at 1.85 GeV, 66% for $p$+Te at 1.85 GeV, and 35% for $p$+Te at 5.0 GeV. These deviations are higher than those found previously for medium and heavy targets and for elemental cross sections. The minimum production cross section of ${}^{91}$Nb, which may be of interest as a cosmic-ray chronometer, was found to be $18\pm 3$ mb for the $p$+Mo reaction.