Improved energies for the 5.2 keV M1 and 42.0 keV M2 nuclear transitions in ⁸³Rb

Abstract.

The low-energy electron spectrum following the decay of ⁸³Sr was analysed at high instrumental resolution by an electrostatic spectrometer. Significantly improved energies of $5235.7\pm 0.8$ and $42078.0\pm 1.8$ eV were determined from the conversion electron spectra for the nuclear transitions depopulating the first 3/2^- and the second $9/2^{+}$ excited states in ⁸³Rb to the $5/2^{-}$ ground state, respectively. The M1 character for the 5.2keV nuclear transition was confirmed and the E2 admixture parameter $\delta^{2}(E2/M1)=(2.6\pm 0.2)\times 10^{-5}$ was obtained. Values of $2.8\pm 0.2$, $3.8\pm 0.2$, $1.4\pm 0.3$, $1.4\pm 0.4$, and $4.1\pm 0.3$ eV were determined for the K, L₁, L₂, L₃, and M₁ natural atomic level widths of rubidium, respectively.