First determination of the one-proton induced Non-Mesonic Weak Decay width of p-shell Λ-Hypernuclei

Previous studies of proton and neutron spectra from Non-Mesonic Weak Decay of eight Λ-Hypernuclei ( A = 5–16) have been revisited. New values of the ratio of the two-nucleon and the one-proton induced decay widths, Γ2N /Γp , are obtained from single proton spectra, Γ2N /Γp = 0.50 ± 0.24, and from neutron +0.05sys and proton coincidence spectra, Γ2N /Γp = 0.36 ± 0.14stat −0.04sys , in full agreement with previously published ones. With these values, a method is developed to extract the one-proton induced decay width in units of the free Λ decay width, Γp/ΓΛ, without resorting to Intra Nuclear Cascade models but by exploiting only experimental data, under the assumption of a linear dependence on A of the Final State Interaction contribution. This is the first systematic determination ever done and it agrees within the errors with recent theoretical calculations.