The Source Spectrum of Reactor Antineutrinos

The cumulative beta spectrum of ²³⁵U and ²³⁹Pu thermal neutron induced fission fragments was measured with a magnetic beta spectrometer in the range E_β = 1.5 to 8 MeV. The beta spectra were converted in the correlated [MATH]_e spectrum of a nuclear reactor. Thus a basis is given for reactor neutrino experiments such as the search for neutrino oscillations.