Search

Arguments on the investigation of the DarkMatter particles in the galactic halo are addressed. Recent results obtained by exploiting the annual modulation signature are summarized and the perspectives are discussed.

The DAMA/NaI experiment (≃ 100 kg highly radiopure NaI(Tl)) at the Gran Sasso National Laboratory of the I.N.F.N. had the unique feature to effectively investigate the presence of Dark Matter particle in the galactic halo by exploiting the model independent annual modulation signature. With a total exposure of more than 10 5 kg × day, collected over seven annual cycles, it has pointed out at 6.3 σ C.L. an effect which satisfies all the many peculiarities of the signature. Neither systematics nor side reactions able to account for the observed effect were found. No experiment whose result can be directly compared in a model independent way with the experimental one of DAMA/NaI is available so far. Several (but still few with respect to the possibilities) corollary model dependent quests for the candidate particle have also been carried out. At present the second generation DAMA/LIBRA set-up (≃ 250 kg highly radiopure NaI(Tl)) is in operation. Positive model dependent hints have also been pointed out by indirect searches for Dark Matter particles in space experiments and are not in contradiction with DAMA/NaI. Thus, the ongoing of model independent experiment deep underground and the new space experiments foreseen in incoming years will certainly further increase our knowledge of the field.

The long-standing model-independent annual modulation effect measured by DAMA Collaboration is examined in the context of asymmetric mirror dark matter, assuming that dark atoms interact with target nuclei in the detector via kinetic mixing between mirror and ordinary photons, both being massless. The relevant ranges for the kinetic mixing parameter are obtained taking into account various existing uncertainties in nuclear and particle physics quantities as well as characteristic density and velocity distributions of dark matter in different halo models., 27 pages, 5 figures, 2 tables; version in publication on Eur. Phys. J. C

In this paper, the model independent annual modulation effect observed by DAMA during four independent experiments of one annual cycle each (57986 kg $\times$ day total statistics) is analysed in terms of a particle dark matter candidate which can only inelastically scatter by making a transition to a slightly heavier state, as previously suggested in the literature.

An investigation of the WIMP annual modulation signature is in progress at the Gran Sasso National Laboratory of the I.N.F.N. by means of the similar or equal to 100 kg NaI(TI) DAMA set-up; the results obtained during four annual cycles have already been published. In this paper we will further address in some details the main arguments, which have allowed us to exclude known systematic effects as a possible source of the annual modulation observed in the rate at very low energy. In particular. the (more recently released) data of the DAMA/NaI-3 and DAMA/NaI-4 running periods are considered as quantitative examples.

Galaxy hierarchical formation theories, numerical simulations, the discovery of the Sagittarius Dwarf Elliptical Galaxy (SagDEG) in 1994 and more recent investigations suggest that the dark halo of the Milky Way can have a rich phenomenology containing non thermalized substructures. In the present preliminary study, we investigate the case of the SagDEG (the best known satellite galaxy in the Milky Way crossing the solar neighbourhood) analyzing the consequences of its dark matter stream contribution to the galactic halo on the basis of the DAMA/NaI annual modulation data. The present analysis is restricted to some WIMP candidates and to some of the astrophysical, nuclear and particle Physics scenarios. Other candidates such as e.g. the light bosonic ones, we discussed elsewhere, and other non thermalized substructures are not yet addressed here., 17 pages, 10 figures, to appear in Eur. Phys. J. C

The results of an experimental search for spontaneous cluster decay in I-127 are presented. Several possible channels have been investigated considering an exposure of 33834 kg . day collected by a large-mass highly radiopure NaI(Tl) set-up deep underground in the Gran Sasso National Laboratory of the INFN. New lower limits on the lifetime of Ne-24(10), Mg-28(12), Mg-30(12), Si-32(14), Si-34(14), Ca-48(20), Sc-49(21) cluster radioactivity in I-127 have been achieved.

The similar or equal to 100 kg highly radiopure NaI(TI) set-up of the DAMA project (DAMA/NaI) has investigated the model- independent WIMP annual modulation signature over seven annual cycles for a total exposure of 107731 kg x day, obtaining a model- independent evidence for the presence of a dark matter particle component in the galactic halo at 6.3 sigma C.L.. Some of the many possible corollary model-dependent quests for the candidate particle have be m investigated with the total exposure as well.

The NAIAD experiment (NaI Advanced Detector) for WIMP dark matter searches at Boulby mine (UK) is described. The detector consists of an array of encapsulated and unencapsulated NaI(Tl) crystals with high light yield. Six crystals are collecting data at present. Data accumulated by four of them (10.6 kg x year exposure) have been used to set upper limits on the WIMP-nucleon spin-independent and WIMP-proton spin-dependent cross-sections. Pulse shape analysis has been applied to discriminate between nuclear recoils, as may be caused by WIMP interactions, and electron recoils due to gamma background. Various calibrations of crystals are presented., Comment: 22 pages, 9 figures, to be published in Astroparticle Physics

The possibility to effectively exploit the directionality of the measured counting rate as a signature for WIMPs by using anisotropic scintillators is revisited and discussed in some details.

The about 100 kg highly radiopure NaI(Tl) set-up of the DAMA project (DAMA/NaI) took data over seven annual cycles up to July 2002 and has achieved results on various rare processes. Its main aim has actually been the exploitation of the model independent WIMP annual modulation signature. After this conference the total exposure, collected during the seven annual cycles, was released. This cumulative exposure (107731 kg day) has given a model independent evidence for the presence of a Dark Matter particle component in the galactic halo at 6.3 sigma C.L.; this main result is summarised here. Some of the many possible corollary model dependent quests for the candidate particle are mentioned. At present, after about five years of new developments, a second generation low background set-up (DAMA/LIBRA with a mass of about 250 kg NaI(Tl)) was built and is taking data since March 2003. New R&D efforts toward a possible NaI(Tl) ton set-up, we proposed in 1996, have been funded and started in 2003., Contributed paper to the Conf. "Beyond the Desert 03", Rindberg Castle, Germany, June 2003

In this paper the possibility of searching for neutrino oscillations with an artificial neutrino source is discussed and a comparison with reactor experiments is carried out.