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

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.