Gregory W. Severin

A ¹⁷²Hf/¹⁷²Lu radionuclide generator system to produce ¹⁷²Lu for laboratory scale applications in lutetium-based radiochemistry development was established and evaluated. The parent ¹⁷²Hf radionuclide was produced through 35.2 MeV proton irradiation of natural lutetium metal foil at the Brookhaven Linac Isotope Producer. Four resins were investigated for ¹⁷²Hf separation from bulk Lu target material: LN resin, ZR resin, in-house synthesized hydroxamate, and methyl-substituted hydroxamate resins, all with comparable performance. Separated ¹⁷²Hf was consolidated and used to create a ZR resin-based 4.9(3) MBq ¹⁷²Hf/¹⁷²Lu generator which was eluted 49 times over two years with no observed breakthrough of ¹⁷²Hf, and an average elution efficiency of 98(1)%. The eluted ¹⁷²Lu was used to radiolabel the macrocyclic chelator DOTA with an apparent molar activity of 8(2)x10² kBq/nmol.

Adsorptive partitioning of dilute krypton (Kr) and xenon (Xe) onto Stony Brook Metal–Organic Framework (SBMOF-1) and activated charcoal (AC) from carrier nitrogen was experimentally measured at temperatures ranging from 195 to 293 K. For this purpose, a closed-loop system for gas adsorption experiments was developed. From the Kr adsorption measurements, the adsorption equilibrium constant for Kr on SBMOF-1 was calculated, yielding a value for the enthalpy of adsorption of −19 ± 1 kJ·mol^–1. The partition coefficients were utilized to estimate the extraction rates of ⁷⁶Kr, ⁷⁷Kr, and ¹²²Xe isotopes during isotope harvesting at the Facility for Rare Isotope Beams (FRIB). We conclude that both materials showed promising results for the extraction of noble gases from FRIB effluents using temperature swing adsorption.

Experimental neutron-capture cross-sections of arsenic radioisotopes, especially arsenic-73 (⁷³As) and arsenic-74 (⁷⁴As) have not previously been measured. However, these cross-section measurements are important to obtain for applications such as stockpile stewardship and astrophysics. Although many methods for developing thin-film arsenic targets are available in literature, they are not directly applicable to the fabrication of radioarsenic thin-film targets, where a carrier is needed. Gold can be used as a substrate backing for neutron-capture cross-section measurements and arsenic has been shown to co-deposit with gold in hydrochloric acid. Therefore, this study investigations the feasibility of using gold as a carrier to develop radioarsenic targets on a gold substrate backing.