Measurement of the energy of the $8.3$-ev $^{229}$Th isomer using the photoelectric effect

It is proposed to use the photoelectric effect on inner s shells of the $^{229}$Th atom to more accurately determine the energy of its $8.3$-eV isomer. The calculation has been performed using the Feinberg–Migdal shaking theory, which gives the probability of the formation of the isomer up to $0.5 \times 10^{ - 3}$ on the $K$ shell. As a result, two lines separated by the energy of the isomer has been predicted in the spectrum of photoelectrons. Other applications of the method to study the properties of the isomer, including that through shaking at the formation of radioactive beams at storage rings, have also been discussed. Furthermore, the experimental detection of the effect will make it possible to determine more accurately its partial lifetime.