Predictions of ²²⁵Ac and ²²³Ra production cross sections from p, α and heavy ion irradiated thorium and uranium targets

-This work studies effective methods for producing ²²⁵Ac and ²²³Ra by bombarding ²³²Th and natural uranium targets with different incident particles. Direct production of ²²⁵Ac via high-energy proton bombardment of ²³²Th inevitably contains ²²⁷Ac impurities, complicating the separation and purification processes. In contrast, obtaining ²²⁵Ac through the generated ²²⁵Ra can avoid ²²⁷Ac contamination. Given the low cross section for the proton-thorium reaction to produce ²²⁵Ra, exploring new methods to improve ²²⁵Ra production efficiency is critical. This study utilized several physical models of the Monte Carlo transport codes FLUKA and PHITS to calculate the production cross sections of ²²⁵Ac, ²²⁵Ra, ²²³Ra, and ²²⁷Th via the bombardment of thorium and uranium targets with energetic protons, α-particles, ⁹Be, and ¹²C across an energy range of 10-800 MeV/u. The predicted cross sections were then compared with existing experimental data. The predictions indicate that the energy thresholds to produce ²²⁵Ac, ²²⁵Ra, and ²²³Ra via α-particle and heavy ion irradiation are lower than those for proton, and the production cross sections are significantly increased, the incident energy corresponding to the peak cross section is mainly below 100 MeV/u. According to the PHITS JQMD-2.0 results, using α-particle bombardment of thorium targets to produce ²²⁵Ra and subsequently obtaining high-purity ²²⁵Ac may be an efficient production pathway. Moreover, when the α-particle energy is below 100 MeV/u, the predicted cross section of ²²⁵Ra for the natural uranium target is higher than that for the thorium target, suggesting that α-particle bombardment of the natural uranium target could be a potential new method to improve ²²⁵Ac production efficiency. This study provides theoretical reference for subsequent experimental cross section measurement and isotope production.