We have measured $\beta -\alpha$ angular correlations in $A=8\mathrm{}$ in order to extract a value for the weak-magnetism element as part of a test of conservation of vector current. Possible contributions to the angular correlation from vector second-forbidden matrix elements and a second-class induced-tensor matrix element are shown to be small on the basis of experimental evidence and wave-function calculations.

• Received 2 November 1973

DOI:https://doi.org/10.1103/PhysRevLett.32.314