Abstract: Uranium resources are of great significance in the energy and national defense sectors and are indispensable strategic resources for all nations. Against the background of the current global nuclear power renaissance and increasing demand for uranium resources, accurately determining the age of uranium deposits is critical for clearly delineating the scope of prospective mineralization targets, making this method highly valuable for uranium exploration in China. As one of the internationally recognized high-precision geochronological methods, the ⁴⁰Ar/³⁹Ar dating technique is widely used in uranium resource exploration. Neutron irradiation that triggers the ³⁹K(n, p)³⁹Ar reaction serves as the fundamental premise for ⁴⁰Ar/³⁹Ar dating. Conventional neutron irradiation of samples using nuclear reactors is plagued by abundant side reactions caused by a broad neutron energy spectrum and pronounced nuclear recoil effects, which severely hinder the accurate determination of geological ages. To promote the application of deuterium-deuterium (D-D) neutron irradiation technique in geochronology and overcome its existing limitations, this study adopted a single-energy D-D neutron source for sample irradiation. The ⁴⁰Ar/³⁹Ar ratio of the ZBH-25 biotite standard material was determined using the step-heating technique on a high-sensitivity noble gas mass spectrometer. Compared with conventional reactor neutron irradiation, D-D neutron sources offer several advantages, including a more uniform neutron energy spectrum, better alignment with the optimal energy range for the ³⁹K(n, p)³⁹Ar reaction, fewer side reactions and reduced nuclear recoil effects, and easier control of irradiation conditions. However, the neutron flux generated by these sources is relatively low (～10⁸ n/cm²/s), which is 4-5 orders of magnitude lower than that of reactor neutrons, resulting in a relatively weak ³⁹Ar signal following sample irradiation. Furthermore, no domestic data are currently available to verify the accuracy of noble gas mass spectrometers for measuring low-signal ³⁹Ar. By evaluating the signal-to-noise ratios and the linear characteristics of ³⁹Ar during analysis, the results show that the ³⁹Ar mass spectrometry peak is clearly distinguishable. The minimum ³⁹Ar signal intensity obtained at each temperature step for all measured samples exceeds the background signal intensity. The NGX-600 mass spectrometer has an abundance sensitivity of less than 10⁻⁶, while the ⁴⁰Ar/³⁹Ar ratios of the various biotite samples are all less than 10⁶. The tailing effect of ⁴⁰Ar on ³⁹Ar measurements is less than 1% and can be considered negligible. The correlation coefficient (R²) between ³⁹Ar signal values and the number of replicate measurements is 0.995 53, indicating that the low-signal ³⁹Ar measurements are stable. The results demonstrate that high-sensitivity noble gas mass spectrometry enables accurate determination of argon isotopes in D-D irradiated ⁴⁰Ar/³⁹Ar samples. However, the consistency of the ⁴⁰Ar/³⁹Ar ratios across different temperature steps is unsatisfactory, which may be attributed to factors such as inhomogeneous neutron irradiation of the samples. Accordingly, improvement strategies for subsequent irradiation protocols and analytical measurements are proposed, laying a solid foundation for the application of D-D neutron sources in the ⁴⁰Ar/³⁹Ar dating technique.