A1 Journal article (refereed)
β− decay Q-value measurement of 136Cs and its implications for neutrino studies (2023)

Ge, Z., Eronen, T., de Roubin, A., Ramalho, M., Kostensalo, J., Kotila, J., Suhonen, J., Nesterenko, D. A., Kankainen, A., Ascher, P., Beliuskina, O., Flayol, M., Gerbaux, M., Grévy, S., Hukkanen, M., Husson, A., Jaries, A., Jokinen, A., Moore, I. D., . . . Zadvornaya, A. (2023). β− decay Q-value measurement of 136Cs and its implications for neutrino studies. Physical Review C, 108, Article 045502. https://doi.org/10.1103/PhysRevC.108.045502

JYU authors or editors

Publication details

All authors or editorsGe, Z.; Eronen, T.; de Roubin, A.; Ramalho, M.; Kostensalo, J.; Kotila, J.; Suhonen, J.; Nesterenko, D. A.; Kankainen, A.; Ascher, P.; et al.

Journal or seriesPhysical Review C



Publication year2023

Publication date11/10/2023


Article number045502

PublisherAmerican Physical Society (APS)

Publication countryUnited States

Publication languageEnglish


Publication open accessNot open

Publication channel open access

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/90615

Web address of parallel published publication (pre-print)https://arxiv.org/abs/2306.04604#


The β− decay Q value of 136Cs (Jπ = 5+, t1/2 ≈ 13 d) was measured with the JYFLTRAP Penning trap setup at the Ion Guide Isotope Separator On-Line facility of the University of Jyväskylä, Finland. The monoisotopic samples required in the measurements were prepared with a new scheme utilized for the cleaning, based on the coupling of dipolar excitation with Ramsey’s method of time-separated oscillatory fields and the phase-imaging ion-cyclotron-resonance technique. The Q value is determined to be 2536.83(45) keV, which is ≈4 times more precise and 11.4(20) keV (≈6σ) smaller than the adopted value in the most recent Atomic Mass Evaluation AME2020. The daughter, 136Ba, has a 4+ state at 2544.481(24) keV and a 3− state at 2532.653(23) keV, both of which can potentially be ultralow Q-value end states for the 136Cs decay. With our new ground-to-ground state Q value, the decay energies to these two states become −7.65(45) keV and 4.18(45) keV, respectively. The former is confirmed to be negative at the level of ≈17σ, which verifies that this transition is not a suitable candidate for neutrino mass determination. On the other hand, the slightly negative Q value makes this transition an interesting candidate for the study of virtual β-γ transitions. The decay to the 3− state is validated to have a positive low Q value which makes it a viable candidate for neutrino mass determination. For this transition, we obtained a shell-model-based half-life estimate of 2.1+1.6 −0.8 × 1012 yr. Furthermore, the newly determined low reaction threshold of 79.08(54) keV for the charged-current νe + 136Xe (0+) → 136Cs∗ + e− neutrino capture process is used to update the cross sections for a set of neutrino energies relevant to solar 7 Be, pep, and CNO neutrinos. Based on our shell-model calculations, the new lower threshold shows event rates of 2–4 percent higher than the old threshold for several final states reached by the different species of solar neutrinos.

Keywordsnuclear physics

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Ministry reportingYes

Reporting Year2023

Preliminary JUFO rating2

Last updated on 2024-03-04 at 18:55