Capture rate of the Li-7(n, gamma)Li-8 reaction by prompt gamma-ray detection

Abstract

The reaction Li-7(n, gamma)Li-8 is a trigger reaction which bridges the instability gap at mass 8 while producing heavy elements during the rapid process of primordial nucleosynthesis in the inhomogeneous big-bang models. The reaction rate was remeasured at the most probable neutron energy of 30 keV by detecting prompt gamma-rays from a captured state; 39.3 +/-6.0 micro-b was obtained. This value is 2 times larger than that recently measured and agrees with the estimated value from the thermal neutron capture cross section by using the 1/v law. The result is discussed in terms of both nucleosynthesis and the solar neutrino problem.