The absolute differential cross section for the 'H(p, y)4He reaction has been measured at 8"90' for Ep 2.0-15.0 MeV, corresponding to photon energies E"21. 3-31.1 MeV. The present results are 35% lower than previously measured (p, y) cross sections and are in excellent agreement with recent (y,p) data obtained with monoenergetic pbotons. Comparing our results to current photoneutron cross sections gives a ratio cs(y, p)/ts(y, n) 1.09+0.17 for E"24-31MeV. This ratio is consistent with conventional theoretical predictions, indicating that no charge-symmetry violation in He is required.

Cross sections for the 8 LiG/,tf) 9 Be (ground state) and 8 LiW,f) 7 Li reactions, both important to primordial nucleosynthesis in the inhomogeneous models, have been measured using a radioactive beam technique. The cross section for the former reaction is found to be small, so it is important only for synthesis of 9 Be. The cross section for the latter reaction, however, is found to be large enough to destroy significant quantities of 8 Li, and thus could affect predictions of primordial nucleosynthesis yields.