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

摘要

The radioisotope Nb-90 decays with a positron branching of 53% and a relatively low beta(+)-energy of E-mean = 0.66 MeV and E-max = 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-90(p, xn)-processes were studied over the proton energy range of 7.5 to 19 MeV via the stacked-foil technique using both Zr-nat and 99.22% enriched (ZrO2)-Zr-90 as targets. Thick target yields of Nb-90 were calculated from the measured excitation functions and were verified experimentally. The optimum energy range for the production of Nb-90 via the Zr-90(p, n)-process was found to be E-p = 17 --> 7 MeV, with a yield of 600 MBq Nb-90/muA h. The yield and radionuclidic purity of Nb-90 over the energy range of E-p = 17.6 --> 8.1 MeV were determined experimentally using Zr-nat. At 4 h after EOB the yield of Nb-90 was found to be 290 MBq/muA h and its radionuclidic purity greater than or equal to 95%. [References: 20]