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

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 Si-32, Ti-44, Ca-41, and Al-26 remain present. After target dissolution, Si-32 was first separated for a prospective half-life redetermination. The remaining Si-32-free solution was used for extracting Ti-44, Ca-41, and Al-26, 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 gamma-ray spectroscopy for gamma-ray emitting impurities. As a result, radiochemically pure sample solutions of Ti-44, Ca-41, and Al-26 were obtained as "ready for use " in different application fields.