Total absorption spectroscopy study of the beta decay of fission products for reactor anti-neutrino energy spectra calculation

Thanks to its high efficiency for the detection of gamma-radiation, total absorption spectroscopy is an ideal technique to establish the true beta-decay feeding. The knowledge of the decay scheme is used to determine the distribution of anti-neutrino energy released in the decay. The anti-neutrino energy spectrum is used to calculate the total anti-neutrino flux emitted by reactor cores and the number of reactor anti-neutrino interactions with the detector matter. The number of measured anti-neutrino interactions with detector matter is about 6\% smaller than the expected number of events. The measurements of beta decay of fission products by means of total absorption technique allow to verify expected number of anti-neutrino interactions with matter. In this contribution we would like to present the results of total absorption measurement of the beta decay of 86Br, 89Rb, 89Kr, 90gsRb, 90mRb, 90Kr and 139Xe, nuclei abundantly produced in the reactor core. The results and their impact on the anti-neutrino spectra reconstruction will be presented and discussed.