The (p,n) reaction on lithium and the ground state of the 6Be nucleus

Abstract

The time-of-flight method has been used to study the neutron spectra from the reactions of ⁶Li and ⁷Li with 9 MeV protons. Neutron groups were observed corresponding to transitions to the ground state of ⁶Be and to the three lower states of ⁷Be, as well as a continuous distribution of low-energy neutrons due to more complex reactions. Observation of the group of neutrons from the reaction ⁶Li(p,n)⁶Be is the first experimental evidence of the existence of the ⁶Be nucleus. The Q-value of the reaction ⁶Li(p,n)⁶Be is equal to −5·2 MeV and the width of the ground state of ⁶Be is less than 0·3 MeV. The differential cross-sections for neutron formation were measured at angles of 0, 15, 30, 60 and 120°.