Aqueous harvesting of Zr 88 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 $^{88}\\mathrm{Zr}$ secondary beam produced from a 140-MeV/u $^{92}\\mathrm{Mo}$ 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 $^{88}\\mathrm{Zr}$ and accompanying $^{88}\\mathrm{Y}$ 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 $^{88}\\mathrm{Zr}$ average thermal-neutron-capture cross section (${\\ensuremath{\\sigma}}_{T}$) and resonance integral ($I$) were determined to be ${\\ensuremath{\\sigma}}_{T}=(8.04\\ifmmode\\pm\\else\\textpm\\fi{}0.63)\\ifmmode\\times\\else\\texttimes\\fi{}{10}^{5}$ b and $I=(2.53\\ifmmode\\pm\\else\\textpm\\fi{}0.28)\\ifmmode\\times\\else\\texttimes\\fi{}{10}^{6}$ b. The ${\\ensuremath{\\sigma}}_{T}$ 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 $^{88}\\mathrm{Y}$ thermal-neutron-capture cross section was determined to be less than $1.8\\ifmmode\\times\\else\\texttimes\\fi{}{10}^{4}$ b. This work demonstrates the steps needed to make cross-section measurements with samples produced via aqueous isotope harvesting.