Precise and accurate determination of the 8B decay spectrum

Accurate measurements of the 8B neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the 8B neutrino spectrum can be obtained from the measurement of the β-delayed α spectrum. We report on an α-α coincidence measurement performed at the IGISOL facility in Jyvaeskylae, Finland. Our measurement allows extensive cross-checks to be performed and gives a more intense neutrino spectrum at high energies compared to the present standard. The deviation reaches 4% at the end point of the spectrum. Below 11 MeV, the deviation is less than 1%.