Atomic electron shell excitations in double-$\beta$ decay

Abstract

The problem of the transition of electron shells of atoms to excited states in the process of neutrinoless double-$\beta$ decay is investigated. This subject is crucial for modeling the energy spectrum of $\beta$-electrons, which is sensitive to the mass and Majorana nature of neutrinos. The dependence of the obtained results on the atomic number indicates the determining role of the Feinberg--Migdal effect in the electron shell excitations. We report the overlap amplitudes of the electron shells of the parent atom and the daughter ion for eleven atoms, the two-neutrino double-$\beta$ decay of which was observed experimentally. In around one-fourth of the cases where the structure of the electron shells is inherited from the parent atom, there is a transition to the ground state or the excited state with the lowest energy. The de-excitation of the daughter ion in the latter scenario is accompanied by the emission of photons in the ultraviolet range, which can serve as an auxiliary signature of double-$\beta$ decay. The average excitation energy of the electron shells ranges between 300 and 800 eV, with the variance ranging from $(1.7\mathrm{keV}{)}^2$ in calcium to $(14\mathrm{keV}{)}^2$ in uranium.

arXiv comment13 pages, 2 tables; accepted for publication in Pis'ma v ZhETF

References in corpus (9)

• Background free search for neutrinoless double beta decay with GERDA Phase II
• Value of the axial-vector coupling strength in $\beta$ and $\beta \beta$ decays: A review
• Q value of the 100Mo Double-Beta Decay
• Neutron-Antineutron Oscillations: Theoretical Status and Experimental Prospects
• Extended Black Box Theorem for Lepton Number and Flavor Violating processes
• Exact relativistic tritium beta-decay endpoint spectrum in a hadron model
• The non-resonance shake mechanism of the neutrinoless double electronic capture
• Shake-off in the 164Er neutrinoless double electronic capture and the dark matter puzzle
• Overlap of electron shells in $\beta$ and double-$\beta$ decays

Cited by in corpus (1)

• Exchange contribution to the variance of the excitation energy of the electron shell of the daughter atom in double-$\beta$ decay