Precision Measurement of the Decay Rate of 7Be in Host Materials

A controlled and precise determination of the cross-sections of the fusion reactions 7Be(p,gamma)8B and 3He(4He,gamma)7Be, which play an important role in determining the solar neutrino flux, necessitates the knowledge of a precise value of the electron-capture half-life of 7Be. This half-life may depend on the material hosting the 7Be atoms via small modifications of the electron density around the 7Be nucleus. In this brief communication we report on the measurement of 7Be implanted in four materials: copper, aluminum, sapphire and PVC. The four results are consistent with a null host dependence within two standard deviations and their weighted average of 53.236(39)d agrees very well with the adopted value in the literature, 53.22(6)d. The present results may exhibit a slight (0.22%) increase of the half-life at room temperature for metals compared to insulators that requires further studies.