First Measurement of g_A^eff via Low Threshold, High Resolution Spectral Measurements Using In-115 Bolometer

0νββ is a nuclear process under investigation by numerous experiments, which if detected would demonstrate that neutrinos are Majorana particles. 0νββ samples a wide range of intermediate forbidden nuclear transitions, which are governed by the quenched axial vector coupling constant (g_A^eff), the uncertainty of which plays a pivotal role in the uncertainty of the nuclear matrix elements. The recently reexamined role of g_A^eff in these transitions has prompted measurements of g_A^eff in highly forbidden decays via beta spectrum shape investigation with high resolution, low threshold bolometers. In this talk, we present measurements performed on a LiInSe₂ bolometer, with a 4-fold forbidden beta decay of In-115. This decay is sensitive to similar nuclear effects as 0νββ. We extracted the value of g_A^eff through the use of a Markov Chain Monte Carlo taking into account experimentally determined background levels. We will discuss the obtained results along with possible impacts this study has for future 0νββ measurements.