  We have simultaneously measured the energy spectra of neutrons and protons
emitted in the non-mesonic weak decays of 5_Lambda-He and 12_Lambda-C
hypernuclei produced via the (pi^+,k^+) reaction with much higher statistics
over those of previous experiments. The neutron-to-proton yield ratios for both
hypernuclei at a high energy threshold (60 MeV) were approximately equal to
two, which suggests that the ratio of the neutron- and proton-induced decay
channels, Gn(Lambda n -> nn)/Gp(Lambda p -> np), is about 0.5. In the neutron
energy spectra, we found that the yield of the low-energy component is
unexpectedly large, even for 5_Lambda-He.
