High-Precision <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Q</mml:mi></mml:math>-Value Measurement Confirms the Potential of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Cs</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>135</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> for Absolute Antineutrino Mass Scale Determination
A. de Roubin, Joel Kostensalo, T. Eronen, L. Cañete, R. P. de Groote, A. Jokinen, A. Kankainen, D. A. Nesterenko, I. D. Moore, S. Rinta-Antila, J. Suhonen, M. Vilén
Abstract
The ground-state-to-ground-state $\ensuremath{\beta}$-decay $Q$ value of $^{135}\mathrm{Cs}(7/{2}^{+})\ensuremath{\rightarrow}^{135}\mathrm{Ba}(3/{2}^{+})$ has been directly measured for the first time. The measurement was done utilizing both the phase-imaging ion-cyclotron resonance technique and the time-of-flight ion-cyclotron resonance technique at the JYFLTRAP Penning-trap setup and yielded a mass difference of 268.66(30) keV between $^{135}\mathrm{Cs}(7/{2}^{+})$ and $^{135}\mathrm{Ba}(3/{2}^{+})$. With this very small uncertainty, this measurement is a factor of 3 more precise than the currently adopted $Q$ value in the Atomic Mass Evaluation 2016. The measurement confirms that the first-forbidden unique ${\ensuremath{\beta}}^{\ensuremath{-}}$-decay transition $^{135}\mathrm{Cs}(7/{2}^{+})\ensuremath{\rightarrow}^{135}\mathrm{Ba}(11/{2}^{\ensuremath{-}})$ is a candidate for antineutrino mass measurements with an ultralow $Q$ value of 0.44(31) keV. This $Q$ value is almost an order of magnitude smaller than those of nuclides presently used in running or planned direct (anti)neutrino mass experiment.