New results from DAMA/LIBRA

TL;DR

The DAMA/LIBRA experiment reports strong, model-independent evidence for dark matter particles in the galactic halo through observed annual modulation in NaI(Tl) detector data over 13 years.

Contribution

This paper presents new results with increased exposure confirming the annual modulation signature of dark matter, strengthening previous evidence with a cumulative 1.17 ton x yr data set.

Findings

Annual modulation amplitude: (0.0116 +- 0.0013) cpd/kg/keV

Phase of modulation: (146 +- 7) days

Period of modulation: (0.999 +- 0.002) yr

Abstract

DAMA/LIBRA is running at the Gran Sasso National Laboratory of the I.N.F.N.. Here the results obtained with a further exposure of 0.34 ton x yr are presented. They refer to two further annual cycles collected one before and one after the first DAMA/LIBRA upgrade occurred on September/October 2008. The cumulative exposure with those previously released by the former DAMA/NaI and by DAMA/LIBRA is now 1.17 ton x yr, corresponding to 13 annual cycles. The data further confirm the model independent evidence of the presence of Dark Matter (DM) particles in the galactic halo on the basis of the DM annual modulation signature (8.9 sigma C.L. for the cumulative exposure). In particular, with the cumulative exposure the modulation amplitude of the single-hit events in the (2 -- 6) keV energy interval measured in NaI(Tl) target is (0.0116 +- 0.0013) cpd/kg/keV; the measured phase is (146 +- 7) days and the measured period is (0.999 +- 0.002) yr, values well in agreement with those expected for the DM particles.