Abstract$$^{225}$$ 225 Ac is a radio-isotope that can be linked to biological vector molecules to treat certain distributed cancers using targeted alpha therapy. However, developing $$^{225}$$ 225 Ac-labelled radiopharmaceuticals remains a challenge due to the supply shortage of pure $$^{225}$$ 225 Ac itself. Several techniques to obtain pure $$^{225}$$ 225 Ac are being investigated, amongst which is the high-energy proton spallation of thorium or uranium combined with resonant laser ionization and mass separation. As a proof-of-principle, we perform off-line resonant ionization mass spectrometry on two samples of $$^{225}$$ 225 Ac, each with a known activity, in different chemical environments. We report overall operational collection efficiencies of 10.1(2)% and 9.9(8)% for the cases in which the $$^{225}$$ 225 Ac was deposited on a rhenium surface and a ThO$$_{2}$$ 2 mimic target matrix respectively. The bottleneck of the technique was the laser ionization efficiency, which was deduced to be 15.1(6)%.

MYRRHA will be the world’s first large-scale Accelerator Driven System project at power levels scalable to industrial systems. ISOL@MYRRHA will produce Radioactive Ion Beams (RIBs) using the Isotope Separation On-Line (ISOL) technique, with increased isotope production by high intensity primary beams over a long period while maintaining a high-quality RIB. Higher atom flux produced prevalently affects the ISOL ion source. A surface ion source is chosen as a first source because of its reliability and simple design. To understand the hot cavity’s behaviour, finite element thermal-electric simulations were performed. To start, a heating system study with experimental results from the SPES project was reproduced. This concept was then modified by: electrically insulating the source from its support, adding a feedthrough, transforming a passive thermal screen into an active part. With this heating system upgrade, the ion source temperature profile can be adjusted, especially at its exit part where high temperature is expected to play a crucial role in ion production and extraction.

Thulium-167 is a promising radionuclide for nuclear medicine applications with potential use for both diagnosis and therapy (“theragnostics”) in disseminated tumor cells and small metastases, due to suitable gamma-line as well as conversion/Auger electron energies. However, adequate delivery methods are yet to be developed and accompanying radiobiological effects to be investigated, demanding the availability of 167Tm in appropriate activities and quality. We report herein on the production of radionuclidically pure 167Tm from proton-irradiated natural erbium oxide targets at a cyclotron and subsequent ion beam mass separation at the CERN-MEDICIS facility, with a particular focus on the process efficiency. Development of the mass separation process with studies on stable 169Tm yielded 65 and 60% for pure and erbium-excess samples. An enhancement factor of thulium ion beam over that of erbium of up to several 104 was shown by utilizing laser resonance ionization and exploiting differences in their vapor pressures. Three 167Tm samples produced at the IP2 irradiation station, receiving 22.8 MeV protons from Injector II at Paul Scherrer Institute (PSI), were mass separated with collected radionuclide efficiencies between 11 and 20%. Ion beam sputtering from the collection foils was identified as a limiting factor. In-situ gamma-measurements showed that up to 45% separation efficiency could be fully collected if these limits are overcome. Comparative analyses show possible neighboring mass suppression factors of more than 1,000, and overall 167Tm/Er purity increase in the same range. Both the actual achieved collection and separation efficiencies present the highest values for the mass separation of external radionuclide sources at MEDICIS to date.

225Ac is a radio-isotope that can be linked to biological vector molecules to treat certain distributed cancers using targeted alpha therapy. However, developing 225Ac-labelled radiopharmaceuticals remains a challenge due to the supply shortage of pure 225Ac itself. Several techniques to obtain pure 225Ac are being investigated, amongst which is the high-energy proton spallation of thorium or uranium combined with resonant laser ionization and mass separation. As a proof-of-principle, we perform laser ionization and mass separation on two samples of 225Ac, each with a known activity, in different chemical environments. We report overall operational collection efficiencies of 10.1(2)% and 9.9(8)% for the cases in which the 225Ac was deposited on a rhenium surface and a ThO2 mimic target matrix respectively. The bottleneck of the technique was the laser ionization efficiency, which was deduced to be 15.1(6)%.