Eur. Phys. J. C (2010) 67: 39-49
https://doi.org/10.1140/epjc/s10052-010-1303-9

Regular Article - Experimental Physics

New results from DAMA/LIBRA

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 INFN, sez. Roma, 00185, Rome, Italy
⁵ Laboratori Nazionali del Gran Sasso, I.N.F.N., Assergi, Italy
⁶ IHEP, Chinese Academy, P.O. Box 918/3, Beijing, 100039, China
⁷ Lab. Sperim. Policentrico di Ingegneria Medica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
⁸ University of Jing Gangshan, Jiangxi, China

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

Received: 10 February 2010
Revised: 12 March 2010
Published online: 23 March 2010

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 × 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 × yr, corresponding to 13 annual cycles. The data further confirm the previous positive results obtained investigating the presence of Dark Matter (DM) particles in the galactic halo by means of the model independent Dark Matter annual modulation signature; the confidence level is now 8.9 σ 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.