Abstract In this study, ²¹⁸Ac and ²²¹Th nuclides were produced via the heavy-ion induced fusion evaporation reaction ⁴⁰Ar + ¹⁸⁶W. Their decay properties were studied with the help of the gas-filled recoil spectrometer SHANS and a digital data acquisition system. The cross section ratio between ²²²Pa and ²¹⁸Ac was extracted experimentally, with measured value 0.69(9). Two new possible α decay branches to ²²¹Th are suggested. The valence neutron configurations for the daughter ²¹⁷Ra are discussed in terms of the hindrance factors.