DAMA/NaI results on particle Dark Matter investigation

The model-independent DAMA/NaI results on annual modulation signature

The DAMA/NaI set-up has exploited the annual modulation signature over 7 annual cycles. The presence of a model independent positive evidence in the data of DAMA/NaI has been firstly reported by the DAMA collaboration at the TAUP conference in 1997 and published also in 1998, confirmed in 1999 and 2000, further confirmed in the yeras later and conclusively confirmed in 2003 after the end of experiment occurred in July 2002. Various corollary investigations have also been and are continuing.
During 7 independent experiments of one year each one, it has pointed out - with an exposure of about 1.1 x 105 kg xday - the presence in the lowest energy region of a modulation satisfying the many peculiarities of a particle Dark Matter induced effect, reaching an evidence at 6.3σ C.L..

In the figure the time behaviour of the residual rate of the "single-hit" events in the (2-6) keV energy interval is reported. {Note: keV is keV electron equivalent}. The solid curve represent the cosinusoidal function behaviour expected for a DM signal with a period of 1 year and phase at the 2nd of June. By fitting the experimental data with all parameters kept free in the fit one obtains a modulation amplitude equal to (0.0200 +/- 0.0032) cpd/kg/keV, a phase t0 = (140 +/- 22) days and a period T = (1.00 +/- 0.01) year. This result favour the presence of a modulated cosine-like behaviour with the proper features of Dark Matter particles in the galactic halo at 6.3 σ C.L..