Eur. Phys. J. C (2013) 73: 2648
https://doi.org/10.1140/epjc/s10052-013-2648-7

Regular Article - Experimental Physics

Final model independent result of DAMA/LIBRA–phase1

¹ Dipartimento di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
² INFN, sez. Roma “Tor Vergata”, 00133, Rome, Italy
³ Dipartimento di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
⁴ sez. Roma, INFN, 00185, Rome, Italy
⁵ Laboratori Nazionali del Gran Sasso, INFN, Assergi, Italy
⁶ IHEP, Chinese Academy, P.O. Box 918/3, Beijing, 100039, China
⁷ Dipartimento di Ingegneria Civile e Ingegneria Informatica, Università di Roma “Tor Vergata”, Rome, Italy
⁸ University of Jing Gangshan, Jiangxi, China

^* e-mail: rita.bernabei@roma2.infn.it

Received: 22 July 2013
Revised: 27 September 2013
Published online: 26 November 2013

Abstract

The results obtained with the total exposure of 1.04 ton × yr collected by DAMA/LIBRA–phase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. during 7 annual cycles (i.e. adding a further 0.17 ton × yr exposure) are presented. The DAMA/LIBRA–phase1 data give evidence for the presence of Dark Matter (DM) particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radio-pure NaI(Tl) target, at 7.5σ C.L. Including also the first generation DAMA/NaI experiment (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles), the C.L. is 9.3σ and the modulation amplitude of the single-hit events in the (2–6) keV energy interval is: (0.0112±0.0012) cpd/kg/keV; the measured phase is (144±7) days and the measured period is (0.998±0.002) yr, values well in agreement with those expected for DM particles. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade.