A new measurement of 174Hf alpha decay

A new measurement of ¹⁷⁴Hf alpha decay to the ground state of ¹⁷⁰Yb was performed deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN (Italy). The experimental data were accumulated over 97.7 days with a 16.87 g Cs₂HfCl₆ single crystal. A new half-life value of ¹⁷⁴Hf α decay: T_1/2 = $\left({3.8}_{-0.9}^{+1.7}\right)\times {10}^{16}$ yr, was evaluated. The total internal α activity of the crystal is 18.6(4) mBq/kg, and should be further improved, especially in terms of ¹⁴⁷Sm contamination (0.25 mBq/kg), in order to achieve a higher experimental sensitivity.