Effect of atomic electrons on 7.6 eV nuclear transition in $^{229}$Th$^{3+}$

TL;DR

This study investigates how atomic electrons influence the nuclear 7.6 eV transition in $^{229}$Th$^{3+}$, revealing significant effects for certain electronic transitions through the electronic bridge process.

Contribution

The paper provides the first detailed calculation of electronic bridge process probabilities affecting the $^{229}$Th$^{3+}$ nuclear transition, highlighting the impact of specific electronic transitions.

Findings

Electronic bridge process can significantly enhance the nuclear transition probability.

The ratio of electronic bridge to nuclear radiative transition varies from 0.01 to 20 depending on the electronic transition.

Certain electronic transitions can increase the nuclear transition rate by two orders of magnitude.

Abstract

We have considered an effect of atomic electrons due to the electronic bridge process on the nuclear $^{229m}$Th -- $^{229g}$Th transition in ^{229}$Th$^{3+}$. Based on a recent experimental result we assumed the energy difference between the isomeric and the ground nuclear states to be equal to 7.6 eV. We have calculated the ratios of the electronic bridge process probability Gamma_EB to the probability of the nuclear radiative transition (Gamma_N) for the electronic 5f_5/2 --> 6d_3/2,6d_5/2,7s and the 7s --> 7p_1/2,7p_3/2 transitions and found Gamma_EB/Gamma_N ~ 0.01-0.1 for the former and Gamma_EB/Gamma_N ~ 20 for the latter.