Non-mesonic weak decays of Λ5He and Λ 12C hypernuclei using the (π+, K+) reactions

Abstract

We have measured for the first time yields of both neutron-proton and neutron-neutron pairs emitted from the non-mesonic weak decay of the Λ 5He and Λ 12C hypernuclei, produced via the (π+,K+) reaction. From the yields of both the back-to-back np-pair events and nn-pair events, we have directly determined the ratio of the neutron- and proton-induced decay widths, Γn(Λn → nn)Γp(Λp → np). Meanwhile, we have also determined the quenching of the observed numbers of single nucleons and coincident nucleon pairs compared with theoretical calculations. Our results suggest that contributions from the two-nucleon-induced three-body process ΛNN → NNN are significant. © 2008 American Institute of Physics.