Nuclear Structure Decay Studies for Reactor Antineutrino Physics

There are several intriguing features involving recent measurements and calculations of reactor antineutrino spectra including a deficient in the total number of measured antineutrinos, a spectra distortion in the region of 5-7 MeV antineutrino energy, and a fine structure which can be attributed to the decay of just a few out of the total 800 fission fragments making up the spectra. A full understanding of these aspects requires a solid basis of the underlying nuclear physics, namely the beta-decay properties of fission fragments used as inputs to calculate the spectra. Using the CARIBU facility at Argonne National Laboratory, we have performed new measurements on several key isotopes including $^{\mathrm{92}}$Rb, $^{\mathrm{142}}$La, and $^{\mathrm{141}}$Cs. The decay of $^{\mathrm{92}}$Rb was studied with the SATURN array, while the decays of $^{\mathrm{142}}$La and $^{\mathrm{141}}$Cs were observed with the Gammasphere array. The results of these analyses will be presented and their impact on reactor antineutrino calculations will be discussed.