First results from the FINUDA experiment at DAΦNE

Abstract In spring 2003 the FINUDA detector was installed at the ϕ factory DAΦNE in the Laboratori Nazionali di Frascati of INFN (Italy). In October 2003 the commissioning of the apparatus was accomplished and the first data taking started with a set of nuclear targets 6 Li, 7 Li, nat C, 27 Al, 51 V. The data collection will continue until a total integrated luminosity of 250 pb −1 is recorded. Light and medium A hypernuclei will be abundantly produced by the strangeness exchange reaction induced by the stopped K − coming from the decay of ϕ ( 1020 ) mesons. The aim of the experiment is to simultaneously measure the excitation energy spectra of the produced hypernuclei, with a resolution better than 1 MeV, the lifetime of the Λ embedded in the different hypernuclei and the partial widths Γ π , Γ n p and Γ n n for mesonic and non-mesonic hypernuclear decays. Information on neutron-rich hypernuclei and rare hypernuclear two-body decays might be available too, with the statistics that will be collected at the end of the run. In the present paper, first results concerning in-beam detector calibration, spectrometer performances and very preliminary hypernuclear formation and decay spectra will be presented.