Experimental beta-spectra from 239Pu and 235U thermal neutron fission products and their correlated antineutrino spectra☆

Abstract The beta spectrum from 239 Pu thermal neutron fission fragments was measured on-line with a magnetic spectrometer in the energy interval E β = 1.5 to 8.0 MeV. The beta spectrum was converted into the correlated electron antineutrino spectrum taking into account the Z distribution of the fission products. With a total uncertainty for this ν e -spectrum of 4.7, 5.2 and 11% at 3.0, 0.5 and 7.0 MeV, respectively, a basis for neutrino experiments at nuclear power reactors is given. The previously obtained 235 U antineutrino spectrum was refined by this improved conversion method.