Calculation of the rate of nuclear excitation by electron transition in an $^{84m}\mathbf{Rb}$ plasma under the hypothesis of local thermodynamic equilibrium using a multiconfiguration Dirac-Fock approach

One promising candidate for the first detection of nuclear excitation in plasma is the 463-keV, 20.26-min-lifetime isomeric state in Rb84, which can be excited via a 3.5-keV transition to a higher lying state. According to our preliminary calculations, under specific plasma conditions, nuclear excitation by electron transition (NEET) may be its strongest excitation process. Evaluating a reliable NEET rate requires, in particular, a thorough examination of all atomic transitions contributing to the rate under plasma conditions. We report the results of a detailed evaluation of the NEET rate based on multiconfiguration Dirac Fock (MCDF) atomic calculations, in a rubidium plasma at local thermodynamic equilibrium with a temperature of 400 eV and a density of 10−2g/cm3 and based on a more precise energy measurement of the nuclear transition involved in the excitation.