  The results of a measurement of the proton spectra following the Non--Mesonic
Weak Decay of $\mathrm{^5_{\Lambda}He}$, $\mathrm{^7_{\Lambda}Li}$ and
$\mathrm{^{12}_{\Lambda}C}$ are presented and discussed. The experiment was
performed at the ($e^+$ $e^-$) collider DA$\Phi$NE at Laboratori Nazionale di
Frascati of INFN. It is the first measurement for $\mathrm{^7_{\Lambda}Li}$,
and for all the spectra the lower limit on the energy of the protons is 15 MeV,
never reached before. All the spectra show a similar shape, namely a peak at
around 80 MeV as expected for the free $\Lambda p \to np$ weak reaction, with a
low energy rise that should be due to Final State Interactions and/or
two--nucleon induced weak processes. The decay spectrum of
$\mathrm{^5_{\Lambda}He}$ is somehow similar to the ones reported by previous
measurements and theoretical calculations, but the same doesn't happen for the
$\mathrm{^{12}_{\Lambda}C}$ one.
