ELSEVIER SUPPLEMENTS zyxwvutsrq Nuclear Physics B (Proc. Suppl.) 110(2002) 61-63 www.elsevier.com/locale/npe Results with the DAMA/NaI(Tl) experiment at LNGS R. Bernabei=, M. Amatob, P. Belli”, F. Cappella*, R. Cerulli”, C.J. Dai’, H.L. He=, G.Ignestib, A. Incicchittib, H.H. Kuangc, J.M. Ma”, F. Montecchiaa, F. Nozzolia, D. Prosperib aDip.to di Fisica, Universitb di Roma “Tor Vergata” and INFN, sez. Roma2, I-00133 Rome, Italy bDip.to di Fisica, Universitb di Roma “La Sapienza” and INFN, sez. Roma, I-00185 Rome, Italy cIHEP, Chinese Academy, P.O. Box 918/3, Beijing 100039, China DAMA experiment is an observatory for rare events mainly devoted to WIMP search at the Gran Sass0 National Laboratory of the I.N.F.N.. In this paper, the results obtained with the 2: 100 kg NaI(T1) set-up will be summarized, pointing out in particular those regarding the investigation of the WIMP annual modulation signature. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 1. INTRODUCTION 2. INVESTIGATION OF THE WIMP In the framework of the DAMA experiments the z 100 kg NaI(T1) set-up allowed us to explore several kinds of rare processes regarding WIMPS, processes forbidden by Pauli exclusion principle, exotics, charge non conserving processes and so- lar axions (see Fig 1) [1,2]. A full description of the apparatus can be found in ref.[3]. Here only ANNUAL MODULATION SIGNA- TURE As we have already pointed out, the annual modulation signature is very distinctive[3-6,8,7] because a WIMP induced seasonal effect must si- multaneously satisfy several requirements. Only systematic effects able to fulfill these require- ments could fake this signature; therefore, for some other effect to mimic such a signal is highly unlikely. Figure 1. Exclusion plot for the axion coupling constant, gaTT, versus the axion mass, m,. The limit achieved by this experiment is shown to- gether with theoretical expectations and previous direct searches for solar axions[2]. recent results on the investigation of the WIMP annual modulation signature will be summarized. Up to now results have been obtained by analysing the data of four annual cycles; cumu- lative analyses of a 57986 kg-day statistics have been carried out both in model independent and in model dependent ways [4-6,8,7,9]. A detailed investigation of possible systematics has been also performed[7]. 2.1. The model independent analysis A model independent analysis has given evi- dence for the presence of an annual modulation of the rate of the single hit events in the lowest energy interval [4-7,9] (see Fig 2). The x2 test on the data disfavors the hy- pothesis of unmodulated behaviour (probability: 4 . 1004), while a behaviour compatible with the one expected for a WIMP signal is found by fit- ting the residuals with a cosine function. 0920-5632/02/S - see front matter 0 2002 Elsevier Science B.V. All rights reserved. PII SO920-5632(02)01451-2