Hypernuclear weak decay studies with FINUDA

The FINUDA experiment has recently completed an extensive study of the weak decay of p-shell \u39b- hypernuclei including both mesonic and non-mesonic modes. Charged mesonic decay rates have been determined based on the analysis of \u3c0 12 kinetic energy spectra, never measured before. The study of proton spectra from non-mesonic weak decay for p-shell hypernuclei, both single and in coincidence with a neutron, has triggered the investigation of the two-nucleon induced \u39bNN \u2192nNN decay channel: its weight has been evaluated to be \u3932/\u393NM = 0.21\ub10.07stat +0.03 sys 120.02 sys. Finally, a direct experimental evidence of the occurrence of the weak reaction \u39bnp \u2192nnp in nuclei is presented for the first time. Three events have been found which can be attributed to 7 \u39bLi and 9 \u39bBe two-nucleon induced non-mesonic weak decay; the kinematical analysis is discussed here