Applicability of simplified alpha spectroscopy for radionuclidic purity tests at 225Ac production sites

This study evaluated the feasibility of a simplified alpha spectroscopy method using a collimator for radionuclidic purity testing at 225Ac production sites. Monte Carlo radiation transport simulations indicated that the full width at half maximum for the peak due to alpha particles with 4.8 MeV emitted from 226Ra, a potential impurity in cyclotron-produced 225Ac, could be under 300 keV. Experimental results confirmed that this peak was distinctly separated from the primary alpha particle peaks of 225Ac and its progeny. Further simulations were implemented to evaluate the minimum detectable activity for 226Ra in an 225Ac solution with activity between 100 Bq and 10 000 Bq. The findings suggested that at least 0.5% contamination of 226Ra (activity ratio) can be detected by measuring an 225Ac solution over 3600 s. This simplified alpha spectroscopy method shows promise as a viable measurement technique to support future criteria for radionuclidic purity testing at 225Ac production sites.