Evaluation of proton induced reactions on 100Mo:: New cross sections for production of 99mTc and 99Mo

The use of the Mo-99-->Tc-99m generator in nuclear medicine is well established world wide. The production of the Mo-99 (T-1/2 = 66 h) parent as a fission product of U-235 is largely based on the use of reactor technology. From the early 1990's accelerator based production methods to provide either direct produced Tc-99m or the parent Mo-99, were studied and suggested as potential alternatives to the reactor based production of Mo-99. A possible pathway for the charged particle production of Tc-99m and Mo-99 is irradiation of molybdenum metal with protons via the reaction Mo-100(p,2n)Tc-99m and Mo-100(p,pn)Mo-99, respectively. The earlier published excitation functions show large differences in their maximum that result in large differences in the calculated yields. We therefore decided to study the excitation function for these proton-induced reactions. In this work the newly measured excitation functions as well as an evaluation of earlier measured data and a discussion of the observed disagreements are presented.