Determining g_{A}/g_{V} with High-Resolution Spectral Measurements Using a LiInSe_{2} Bolometer.

Area of Science:

• Nuclear Physics
• Particle Physics

Background:

• Neutrinoless double beta decay (0νββ) experiments are crucial for understanding fundamental physics.
• The axial vector coupling constant (g_{A}/g_{V}) quenching significantly impacts 0νββ decay calculations and experimental sensitivity.
• Accurate measurements of nuclear transitions are vital for refining theoretical models.

Purpose of the Study:

• To measure the spectral shape of the fourfold forbidden beta decay of Indium-115.
• To determine the quenching factor of the axial vector coupling constant (g_{A}/g_{V}) for ^{115}In.
• To demonstrate the utility of high-resolution bolometers for precision nuclear decay measurements.

Main Methods:

• Utilized a high-resolution LiInSe_{2} bolometer in a "source=detector" configuration.
• Measured the beta decay spectral shape of ^{115}In.
• Compared experimental data with theoretical predictions, incorporating background and detector effects.

Main Results:

• Provided evidence for the quenching of g_{A}/g_{V} at >5σ, with a model-dependent quenching factor of 0.655±0.002.
• Measured the half-life of ^{115}In to be [5.18±0.06(stat)_{-0.015}^{+0.005}(sys)]×10^{14} yr within the interacting shell model.
• Demonstrated the bolometeric technique's capability for precision single-beta decay measurements.

Conclusions:

• The study confirms quenching of the axial vector coupling constant in nuclear transitions.
• Precision measurements of nuclear decay properties are essential for improving 0νββ sensitivity calculations.
• Bolometeric techniques offer a powerful approach for advancing nuclear physics research and reducing uncertainties in decay calculations.