Precise and accurate determination of the {sup 8}B decay spectrum

Accurate measurements of the {sup 8}B neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the {sup 8}B neutrino spectrum can be obtained from the measurement of the {beta}-delayed {alpha} spectrum. We report on an {alpha}-{alpha} 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%.