Aqueous harvesting of Zr88 at a radioactive-ion-beam facility for cross-section measurements

Isotope harvesting is a method of collecting the long-lived radioisotopes that build up during the operation of ion-beam facilities in a way that is useful for subsequent research. As a demonstration of this method for the collection of a group IV metal at a fragmentation facility, the high-energy Zr88 secondary beam produced from a 140-MeV/u Mo92 primary beam at the National Superconducting Cyclotron Laboratory (NSCL) was stopped in a water target. The setup aimed to mimic the aqueous beam dump that will be implemented at the Facility for Rare Isotope Beams (FRIB). The collected Zr88 and accompanying Y88 decay daughter were radiochemically extracted from the solution and made into target samples suitable for neutron-capture cross-section measurements. These samples were then irradiated at two reactor facilities, and the Zr88 average thermal-neutron-capture cross section (σT) and resonance integral (I) were determined to be σT=(8.04±0.63)×105 b and I=(2.53±0.28)×106 b. The σT value agrees well with previous results and I, determined for the first time here, was found to be the largest measured resonance integral by two orders of magnitude. The Y88 thermal-neutron-capture cross section was determined to be less than 1.8×104 b. This work demonstrates the steps needed to make cross-section measurements with samples produced via aqueous isotope harvesting.