Production of 99Mo in inverse kinematics heavy ion reactions

Abstract

Following the successful production of the radioimmunotheranostic nuclide 67Cu through the reaction of a 70Zn beam on a hydrogen gas target, our interest turned to the 99Mo/99mTc generator system. We produced 99Mo in inverse kinematics, with a100Mo beam at 12.0 MeV/nucleon impinging on a 4He gas target. The gas target was kept at liquid nitrogen temperature and pressures of 0.134(3), 0.280(6) and 1.33(3) atm. The produced isotopes and the beam were collected on a thick Al catcher foil. The 99Mo radioisotope can be produced in a one nucleon transfer occurring in peripheral reactions. Two competing factors determine the yield in such reactions, one is the cross-section which favors high mass targets, the other is the effective range which favors low-mass targets. Thus, at low 4He densities, higher beam energy at the exit of the gas target, most of the 99Mo production is generated in the Al foil, while at higher densities, most is generated in the gas target. The activity obtained at the end of the bombardment (given in Becquerel per particle nano-Amps per hour of irradiation), including the 4He gas and Al catcher contribution, were determined as 4.8(14), 2.5(7) and 3.8(11) kBq/(pnAh) for ρgas = 0.83, 0.18 and 0.09 mg/cm3, respectively. These results are competitive to other accelerator production methods; however, the method reported has the additional advantages of needing significantly less amount of expensive enriched isotope and offers an easier and cleaner collection/separation method.