Total cross section of the 3H(p,n)3He reaction from threshold to 4.5 MeV

Abstract

We report new measurements of the total cross section for the 3H(p,n)3He reaction from threshold (Ep = 1.02 MeV) to Ep, = 4.5 MeV. The experiment utilized specially prepared Ti-3H targets, and neutrons were detected using a 4 π detector. A weak resonant structure due to an excited state in 4He is observed which was not seen in previous cross section measurements. A new expression for the 3He(n,p)3H thermonuclear reaction rate for temperatures below 10 GK is presented which will allow for more accurate calculations of the yields of light elements produced by big-bang nucleosynthesis.