Systematic measurements of proton-induced reactions on enriched molybdenum

Between 2008 and 2010, shortages in the world-wide supply of $^{\mathrm{99}}$Mo highlighted weaknesses in the current fission-based production method of $^{\mathrm{99m}}$Tc, a critical medical isotope. This crisis sparked interest in developing alternative production methods, including the direct production of $^{\mathrm{99m}}$Tc from proton-induced reactions on enriched $^{\mathrm{100}}$Mo targets. One complication with this method is that $^{\mathrm{99m}}$Tc must be chemically extracted from the irradiated target. Therefore radiopharmaceuticals will contain a mixture of all Tc-species produced from the proton bombardment, affecting radiochemical purity, specific activity and total production yield of $^{\mathrm{99m}}$Tc---factors critical for the feasibility of this production method. Reactions on trace impurities in the enriched targets have been shown to impact these factors dramatically. Precise cross-section measurements for all Mo $+$ p reactions that lead to Tc or Mo species are required for proper assessment of this production technique. Cross-section measurements for the main reaction of interest, $^{\mathrm{99m}}$Tc(p,2n), have been performed in recent years, however, other reactions producing Tc have been mostly neglected. We will introduce a systematic study of proton-induced reactions on 92, 94-98, 100 Mo currently being performed at Notre Dame. First results on $^{\mathrm{96}}$Mo $+$ p reactions will be presented.