Final model independent results of DAMA/LIBRA-phase1 and perspectives of phase2
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inal Model Independent Results of DAMA/LIBRA–Phase1 and Perspectives of Phase21 R. Bernabeia, b, P. Bellib, *, F. Cappellac, d, V. Caraccioloe, S. Castellanoe, R. Cerullie, C. J. Daif, A. d’Angeloc, d, S. d’Angeloa,b, A. Di Marcoa, b, H. L. Hef, A. Incicchittid, H. H. Kuangf, X. H. Maf, F. Montecchiab, g, D. Prosperic, d, †, X. D. Shengf, R. G. Wangf, and Z. P. Yef, h a
Dip. di Fisica, Università di Roma “Tor Vergata”, I00133 Rome, Italy b INFN, sez. Roma “Tor Vergata”, I00133 Rome, Italy cDip. di Fisica, Università di Roma “La Sapienza”, I00185 Rome, Italy d INFN, sez. Roma, I00185 Rome, Italy eLaboratori Nazionali del Gran Sasso, I.N.F.N., Assergi, Italy fInstitute of High Energy Physics, Chinese Academy of Sciences, P.O. Box, 918/3, Beijing 100049, China g Dip. di Ingegneria Civile e Ingegneria Informatica, Università di Roma “Tor Vergata”, I00133 Rome, Italy h University of Jing Gangshan, Jiangxi, China *email: [email protected] Abstract—This paper shortly summarizes the results obtained with the total exposure of 1.04 ton × yr col lected by DAMA/LIBRA–phase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. during 7 annual cycles. The DAMA/LIBRAphase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles) give evidence at 9.3 σ C.L. for the presence of Dark Matter (DM) particles in the galactic halo, on the basis of the exploited model independent DM annual mod ulation signature by using highly radiopure NaI(Tl) target. The modulation amplitude of the singlehit 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 par ticles. No systematic or side reaction able to mimic the exploited DM signature has been found or sug gested by anyone over more than a decade. Some of the perspectives of the presently running DAMA/LIBRA–phase2 are outlined. DOI: 10.1134/S1063779615020045 †1
1. INTRODUCTION
The presently running DAMA/LIBRA [1–12] experiment, as the former DAMA/NaI [13–25], has the main aim to investigate the presence of DM parti cles in the galactic halo by exploiting the model inde pendent DM annual modulation signature (originally suggested in [26]). Moreover, the developed highly radiopure NaI(Tl) targetdetectors [1] assure as well sensitivity to a wide range of DM candidates, interac tion types and astrophysical scenarios. As a consequence of the Earth’s revolution around the Sun, the Earth should be crossed by a larger flux of DM particles around ⯝2 June and by a smaller one around ⯝2 December. This DM annual modulation signature is very distinctive since the effect induced by DM particles must simultaneously satisfy all the fol lowing requirements: the rate must contain a compo nent modulated according to a cosine function (1) with one year period (2) and a phase that peaks 1 The article is published in the original. † Deceased.
roughly ⯝2 June (3)
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