Evaluation of bound-state $β^-$-decay half-lives of fully ionized atoms

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Auteurs principaux: Choudhary, Priyanka, Qi, Chong
Format: Preprint
Publié: 2025
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author Choudhary, Priyanka
Qi, Chong
author_facet Choudhary, Priyanka
Qi, Chong
contents Bound-state $β^-$-decay is a rare radioactive process where the created electron is trapped in an atomic orbital instead of being emitted. It can be observed in highly ionized atoms in particular when normal beta decay is energetically forbidden, but bound-state decay is still possible. In this work we present a systematic theoretical study on the bound-state $β^-$-decay of fully ionized atoms where key nuclear inputs include the nuclear matrix elements (expressed through $ft$ values) and the lepton phase-space volume function. We present a method to evaluate nuclear matrix elements for fully forbidden $β^-$ transitions in neutral atoms, from the inverse electron capture process using the Takahashi-Yokoi model and account for the impact of electron capture to different atomic orbitals on the resulting half-lives. Decay rates for bound-state $β^-$-decays of nuclei $^{163}$Dy, $^{193}$Ir, $^{194}$Au, $^{202}$Tl, $^{205}$Tl, $^{215}$At, $^{222}$Rn, $^{243}$Am, and $^{246}$Bk are calculated, where the normal beta decay is forbidden. In addition, we compute the bound-state $β^-$ decay rates for nuclei $^{187}$Re, $^{227}$Ac, and $^{228}$Ra, observing enhancements by factors of $10^2$ to $10^4$ relative to their neutral-atom counterparts. Our results show that the half-lives of certain bare nuclei are significantly shorter than those of the corresponding neutral atoms, identifying them as promising candidates for future experimental investigation. The theoretically predicted half-lives of the bound-state $β^-$ decay could provide valuable inputs for various astrophysical studies.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08199
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Evaluation of bound-state $β^-$-decay half-lives of fully ionized atoms
Choudhary, Priyanka
Qi, Chong
Nuclear Theory
Bound-state $β^-$-decay is a rare radioactive process where the created electron is trapped in an atomic orbital instead of being emitted. It can be observed in highly ionized atoms in particular when normal beta decay is energetically forbidden, but bound-state decay is still possible. In this work we present a systematic theoretical study on the bound-state $β^-$-decay of fully ionized atoms where key nuclear inputs include the nuclear matrix elements (expressed through $ft$ values) and the lepton phase-space volume function. We present a method to evaluate nuclear matrix elements for fully forbidden $β^-$ transitions in neutral atoms, from the inverse electron capture process using the Takahashi-Yokoi model and account for the impact of electron capture to different atomic orbitals on the resulting half-lives. Decay rates for bound-state $β^-$-decays of nuclei $^{163}$Dy, $^{193}$Ir, $^{194}$Au, $^{202}$Tl, $^{205}$Tl, $^{215}$At, $^{222}$Rn, $^{243}$Am, and $^{246}$Bk are calculated, where the normal beta decay is forbidden. In addition, we compute the bound-state $β^-$ decay rates for nuclei $^{187}$Re, $^{227}$Ac, and $^{228}$Ra, observing enhancements by factors of $10^2$ to $10^4$ relative to their neutral-atom counterparts. Our results show that the half-lives of certain bare nuclei are significantly shorter than those of the corresponding neutral atoms, identifying them as promising candidates for future experimental investigation. The theoretically predicted half-lives of the bound-state $β^-$ decay could provide valuable inputs for various astrophysical studies.
title Evaluation of bound-state $β^-$-decay half-lives of fully ionized atoms
topic Nuclear Theory
url https://arxiv.org/abs/2507.08199