Recovery of no-carrier-added 41Ca, 44Ti, and 26Al from high-energy proton-irradiated vanadium targets

Abstract

Many useful and needed radionuclides for medicinal, astrophysical, and environmental research are produced naturally in inefficient quantities or not-at-all. In the method described here, rare cosmogenic isotopes were produced via spallation reactions in metallic vanadium and separated without adding any carriers. In the SINQ facility at the Paul Scherrer Institut, the vanadium targets were irradiated for two years with high-energy protons (≤590 MeV). After a cooling period of eight years, only relatively long-lived radionuclides such as 32Si, 44Ti, 41Ca, and 26Al remain present. After target dissolution, 32Si was first separated for a prospective half-life redetermination. The remaining 32Si-free solution was used for extracting 44Ti, 41Ca, and 26Al, three key isotopes which are scientifically interesting for nuclear astrophysics research as well as medical applications. Each separation scheme employed ion-exchange and extraction chromatography; developed and optimized using inactive model solutions analyzed with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The irradiated samples were tracked with γ-ray spectroscopy for γ-ray emitting impurities. As a result, radiochemically pure sample solutions of 44Ti, 41Ca, and 26Al were obtained as "ready for use"in different application fields.