Recent results from DAMA/LIBRA-phase1 and perspectives

The DAMA/LIBRA experiment, consisting of about 250 kg of highly radio-pure NaI(Tl) target, is running deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N.; its main aim is the investigation of Dark Matter (DM) particles in the Galactic halo by means of the model independent DM annual modulation signature. In this paper we briefly summarize the results obtained in its first phase of measurements (DAMA/LIBRA–phase1) lasted for 7 annual cycles with a total exposure of 1.04 ton×yr. The DAMA/LIBRA–phase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton×yr, corresponding to 14 annual cycles) give evidence at 9.3 σ C.L. for the presence of DM particles in the galactic halo. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade. At fall 2010 a relevant upgrade of the experiment has been performed: all the PMTs have been replaced by new ones having higher quantum efficiency. After some optimization periods, a new phase of measurement, DAMA/LIBRA–phase2, has began in this new configuration with increased sensitivity. Some of the perspectives of the presently running DAMA/LIBRA–phase2 are mentioned.