Cross section data for the production of the positron emitting niobium isotope 90 Nb via the 90 Zr ( p , n ) - reaction

The radioisotope Nb decays with a positron branching of 53% and a relatively low β+-energy of Emean = 0.66 MeV and Emax = 1.5 MeV. Its half-life of 14.6 h makes it especially promising for quantitative investigation of biological processes with slow distribution kinetics using positron emission tomography. To optimise its production, the excitation functions of Zr(p, xn)-processes were studied over the proton energy range of 7.5 to 19 MeV via the stacked-foil technique using both Zr and 99.22% enriched ZrO2 as targets. Thick target yields of Nb were calculated from the measured excitation functions and were verified experimentally. The optimum energy range for the production of Nb via the Zr(p, n)-process was found to be Ep = 17 → 7 MeV, with a yield of 600 MBq Nb/μA h. The yield and radionuclidic purity of Nb over the energy range of Ep = 17.6 → 8.1 MeV were determined experimentally using Zr. At 4 h after EOB the yield of Nb was found to be 290 MBq/μA h and its radionuclidic purity ≥ 95%.