Determining g_A/g_Vwith High Resolution Spectral Measurements Using an LiInSe₂ Bolometer

Neutrinoless Double-Beta decay (0νββ) processes sample a wide range of intermediate forbidden nuclear transitions, which may be impacted by quenching of the axial vector coupling constant (g_A/g_V), the uncertainty of which plays a pivotal role in determining the sensitivity reach of 0νββ experiments. We performed a series of measurements on a high-resolution LiInSe₂ bolometer in a ‘’source=detector'' configuration to measure the spectral shape of the 4-fold forbidden β-decay of ¹¹⁵In. We then determine the value of g_A/g_V by comparing the spectral shape of theoretical predictions to the experimental β spectrum taking into account various simulated background components as well as a variety of detector effects. In this talk, we will present our measured values for the quenching of g_A/g_V calculated using a variety of nuclear matrix element calculation techniques as well as a world-leading value for the half-life of ¹¹⁵In. This work demonstrates the power of the bolometeric technique to perform precision nuclear physics single-β decay measurements, which can help reduce the uncertainties in the calculation of nuclear matrix elements present in all 0νββ experiments.