Photonuclear Production of 67Cu From Gallium

Copper-67 is a radioisotope of interest for medical imaging and therapy as well as for understanding stellar and interstellar evolution pertaining to the formation of proton-rich nuclei. Since 67Cu decays 100% to Zn-67, understanding this reaction can shed light on the abundance of this and other p-nuclei elements in the universe. Here, the photonuclear production of Cu-67 from Ga-71 and natural gallium is examined as an alternative to its photoproduction from zinc. Two research and development production runs were performed at Thomas Jefferson National Accelerator Facility using an electron linac. During the first run, an 805-W, 30.9-MeV beam was used to irradiate a 1-mm tungsten radiator to create a bremsstrahlung flux. The resulting gamma photons irradiated 50.9 g of natural gallium encased in a graphite crucible for 24.2 h; 7.02 Bq/W center dot s center dot kg of Cu-67 activity was produced. During the second run, a 4380-W, 31.5-MeV beam was used for 12.0 h on the same target containing 60 g of natural gallium; 6.41 Bq/W center dot s center dot kg of Cu-67 activity was produced. Because of the difficulties in spectroscopically differentiating Cu-67 from Ga-67, prior to each run, an isotopically pure Ga-71 disk was irradiated using a 100-W beam for 1 h, at the same respective energies. These baseline irradiations allowed for separation of Cu-67 from Ga-67 in the spectroscopic measurements of the natural gallium targets.