Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant gA, which can be investigated through forbidden β decays. We present the first measurement of the 4th-forbidden β decay of In115 with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, gA, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at T1/2=(5.26±0.06)×1014 yr.
Pagnanini, L., Benato, G., Carniti, P., Celi, E., Chiesa, D., Corbett, J., et al. (2024). Simultaneous Measurement of the Half-Life and Spectral Shape of in 115 β Decay with an Indium Iodide Cryogenic Calorimeter. PHYSICAL REVIEW LETTERS, 133(12) [10.1103/PhysRevLett.133.122501].
Simultaneous Measurement of the Half-Life and Spectral Shape of in 115 β Decay with an Indium Iodide Cryogenic Calorimeter
Pagnanini L.;Carniti P.;Chiesa D.;Gotti C.;Pessina G.;Pozzi S.;Puiu A.;Sisti M.;
2024
Abstract
Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant gA, which can be investigated through forbidden β decays. We present the first measurement of the 4th-forbidden β decay of In115 with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, gA, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at T1/2=(5.26±0.06)×1014 yr.
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