First model independent results from DAMA/LIBRA-phase2
  The first model independent results obtained by the DAMA/LIBRA-phase2
experiment are presented. The data have been collected over 6 annual cycles
corresponding to a total exposure of 1.13 ton $\times$ yr, deep underground at
the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. The DAMA/LIBRA-phase2
apparatus, $\simeq$ 250 kg highly radio-pure NaI(Tl), profits from a second
generation high quantum efficiency photomultipliers and of new electronics with
respect to DAMA/LIBRA-phase1. The improved experimental configuration has also
allowed to lower the software energy threshold. New data analysis strategies
are presented. The DAMA/LIBRA-phase2 data confirm the evidence of a signal that
meets all the requirements of the model independent Dark Matter (DM) annual
modulation signature, at 9.5 $\sigma$ C.L. in the energy region (1-6) keV. In
the energy region between 2 and 6 keV, where data are also available from
DAMA/NaI and DAMA/LIBRA-phase1 (exposure $1.33$ ton $\times$ yr, collected over
14 annual cycles), the achieved C.L. for the full exposure (2.46 ton $\times$
yr) is 12.9 $\sigma$; the modulation amplitude of the single-hit scintillation
events is: $(0.0103 \pm 0.0008)$ cpd/kg/keV, the measured phase is $(145 \pm
5)$ days and the measured period is $(0.999 \pm 0.001)$ yr, all these values
are well in agreement with those expected for DM particles. No systematics or
side reaction able to mimic the exploited DM signature (i.e. to account for the
whole measured modulation amplitude and to simultaneously satisfy all the
requirements of the signature), has been found or suggested by anyone
throughout some decades thus far.
