Study of the Beta Spectrum Shape of ^{92}Rb and ^{142}Cs Decays for the Prediction of Reactor Antineutrino Spectra

The shapes of the beta spectra of ^{92}Rb and ^{142}Cs, two of the beta decays most relevant for the prediction of the antineutrino spectrum in reactors, have been measured. A new setup composed of two ΔE-E telescopes has been used. High-purity radioactive beams of the isotopes of interest were provided by the IGISOL facility using the JYFLTRAP double Penning trap. The resulting beta spectra have been compared with model predictions using beta decay feedings from total absorption gamma spectroscopy measurements and shape corrections employed in the calculation of the antineutrino spectrum, corroborating both further. The procedure can be extended to other relevant nuclei in the future, providing solid ground for the prediction of the antineutrino spectrum in reactors.