First results from DAMA/LIBRA and the combined results with DAMA/NaI
R. Bernabei, P. Belli, F. Cappella, R. Cerulli, C. J. Dai, A. d'Angelo, H. L. He, A. Incicchitti, H. H. Kuang, J. M. Ma, F. Montecchia, F. Nozzoli, D. Prosperi,… 展开作者
R. Bernabei, P. Belli, F. Cappella, R. Cerulli, C. J. Dai, A. d'Angelo, H. L. He, A. Incicchitti, H. H. Kuang, J. M. Ma, F. Montecchia, F. Nozzoli, D. Prosperi, X. D. Sheng, Z. P. Ye
The highly radiopure $\simeq$ 250 kg NaI(Tl) DAMA/LIBRA set-up is running at the Gran Sasso National Laboratory of the I.N.F.N.. In this paper the first result obtained by exploiting the model independent annual modulation signature for Dark Matter (DM) particles is presented. It refers to an exposure of 0.53 ton$\times$yr. The collected DAMA/LIBRA data satisfy all the many peculiarities of the DM annual modulation signature. Neither systematic effects nor side reactions can account for the observed modulation amplitude and contemporaneously satisfy all the several requirements of this DM signature. Thus, the presence of Dark Matter particles in the galactic halo is supported also by DAMA/LIBRA and, considering the former DAMA/NaI and the present DAMA/LIBRA data all together (total exposure 0.82 ton$\times$yr), the presence of Dark Matter particles in the galactic halo is supported at 8.2 $σ$ C.L..
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. So…
The DAMA/NaI set-up of the DAMA experiment has been operative during seven annual cycles and has investigated several rare processes. In particular, it has been realised in order to investigate the model independent annual modulation signature for Dark Matter particles in the galactic halo. With the total exposure collected in the seven annual cycles (107731 kg day) a model independent evidence for the presence of a Dark Matter particle component in the galactic halo has been pointed out at 6.3 sigma C.L.. Some of the many possible corollary model dependent quests for the candidate particle ha…
Our prediction that the more massive DAMA/LIBRA detector would detect a smaller number of events per unit of mass and time than the DAMA/NaI system has got confirmation. This is easy to understand, because DM objects are by far not the WIMPs of the Galactic halo that interact only weakly with matter but are apparently instead electrically charged Planckian objects, i.e., daemons which fall from Earth-crossing orbits with V = 30-50 km/s and undergo multiple interaction with condensed matter already in its outer layers, on a path of a few tens of cm. Therefore, one should use not compact massive…
The DAMA/NaI experiment (about 100 kg highly radiopure NaI(Tl)) was proposed, designed and realised to effectively investigate in a model independent way the presence of a Dark Matter particle component in the galactic halo by exploiting the annual modulation signature. With a total exposure of 107731 kg day, collected over seven annual cycles deep underground at the Gran Sasso National Laboratory of the I.N.F.N., it has pointed out -- at 6.3 sigma C.L. -- an effect which satisfies all the peculiarities of the signature and neither systematic effects nor side reactions able to mimic the signat…
We re-analyse the implications of the DAMA/NaI experiment for mirror matter-type dark matter, taking into account information from the energy dependence of the DAMA annual modulation signal. This is combined with the null results from the CDMS experiment, leading to fairly well defined allowed regions of parameter space. The allowed regions of parameter space will be probed in the near future by the DAMA/LIBRA, CDMS, and other experiments, which should either exclude or confirm this explanation of the DAMA/NaI annual modulation signal. In particular, we predict that the CDMS experiments should…
The simplest version of the daemon paradigm suggests the modulated 2-6-keV range events in DAMA/NaI and DAMA/LIBRA detectors are caused by the iodine ions knocked out elastically by the electrically neutral c-daemons moving with V = 30-50 km/s (c-daemon is a complex of negative daemon located in a remainder of formerly captured nucleus where the daemon decomposes nucleons one by one with ~10^-6 s mean interval). Furthermore, after the 2-6 keV event occurred, in subsequent ~10^-6 s, the c-daemon (which becomes negative during this time) recaptures new nucleus with resulting scintillations in ~1…
Recent results of the DAMA/NaI experiment for WIMP direct detection point to a possible annual modulation effect in the detection rate. We show that these results, when interpreted in terms of a relic neutralino, are compatible with supergravity models. Together with the universal SUGRA scheme, we also consider SUGRA models where the unification condition in the Higgs mass parameters at GUT scale is relaxed.
We consider the prospects for testing the dark matter interpretation of the DAMA/LIBRA signal with the Super-Kamiokande experiment. The DAMA/LIBRA signal favors dark matter with low mass and high scattering cross section. We show that these characteristics imply that the scattering cross section that enters the DAMA/LIBRA event rate determines the annihilation rate probed by Super-Kamiokande. Current limits from Super-Kamiokande through-going events do not test the DAMA/LIBRA favored region. We show, however, that upcoming analyses including fully-contained events with sensitivity to dark matt…
A weakly interacting massive particle (WIMP) weighing only a few GeV has been invoked as an explanation for the signal from the DAMA/LIBRA experiment. We show that the data from DAMA/LIBRA are now powerful enough to strongly constrain the properties of any putative WIMP. Accounting for the detailed recoil spectrum, a light WIMP with a Maxwellian velocity distribution and a spin-independent (SI) interaction cannot account for the data. Even neglecting the spectrum, much of the parameter space is excluded by limits from the DAMA unmodulated signal at low energies. Significant modifications to th…
Mirror dark matter provides a simple framework for which to explain the DAMA/Libra annual modulation signal consistently with the null results of the other direct detection experiments. The simplest possibility involves ordinary matter interacting with mirror dark matter via photon-mirror photon kinetic mixing of strength epsilon ~ 10^(-9). We confirm that photon-mirror photon mixing of this magnitude is consistent with constraints from ordinary Big Bang nucleosynthesis as well as the more stringent constraints from cosmic microwave background measurements and large scale structure considerati…
Recently, the DAMA/LIBRA experiment has convincingly confirmed the DAMA/NaI annual modulation signal, experimentally demonstrating the existence of non-baryonic dark matter in the halo of our galaxy. Meanwhile, in another part of town, other experiments such as CDMS and XENON10 have not detected any evidence for dark matter. One promising dark matter candidate which can reconcile the positive DAMA annual modulation signal with the null results from the other experiments, is mirror dark matter. We re-analyse the mirror matter interpretation of the DAMA annual modulation signal utilizing a) the …
Kelso, Hooper and Buckley [arXiv:1110.5338] found CRESST, CoGeNT and DAMA/LIBRA results are consistent with 10 - 15 GeV dark matter particles. Hennawi and Ostriker [arXiv:astro-ph/0108203] analyzed supermassive black hole formation in the centers of galaxies, finding a best fit for dark matter (self-interaction cross-section)/mass ratio = 0.02 cm^{2}/g, with round-off error of 25%. Combining the Hennawi/Ostriker result with the "strong gravity" model for dark matter [arXiv:0706.3050] requires dark matter particles with mass between 10.5 GeV and 17.5 GeV, overlapping the Kelso/Hooper/Buckley da…
We examine the recent CDMS II results in the context of the mirror matter interpretation of the DAMA/NaI experiment.We find that the favoured mirror matter interpretation of the DAMA/NaI experiment -- a $He'/H'$ dominated halo with a small $O'$ component is fully consistent with the null results reported by CDMS II. While the CDMS II experiment is quite sensitive to a heavy $Fe'$ component, and may yet find a positive result, a more decisive test of mirror matter-type dark matter would require a lower threshold experiment using light target elements.
The DAMA collaboration have claimed to detect particle dark matter (DM) via an annual modulation in their observed recoil event rate. This appears to be in strong disagreement with the null results of other experiments if interpreted in terms of elastic DM scattering, while agreement for a small region of parameter space is possible for inelastic DM (iDM) due to the altered kinematics of the collision. To date most analyses assume a simple galactic halo DM velocity distribution, the Standard Halo Model, but direct experimental support for the SHM is severely lacking and theoretical studies ind…
The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted as a signal for the existence of weakly interacting dark matter (WIMPs) in our galactic halo, are examined in light of null results from other experiments. We use the energy spectrum of the combined DAMA modulation data given in 36 bins, and include the effect of channeling. Several statistical tools are implemented in our study: likelihood ratio with a global fit and with raster scans in the WIMP mass and goodness-of-fit (g.o.f.). These approaches allow us to differentiate between the preferred (global best fit) and …
We consider a model in which dark matter consists of a large self-interacting component (SIDM particles) and a small component with strong interactions with baryons (SIMPs). We show that the DAMA annual modulation signal can be caused by SIDM particles interacting with SIMPs trapped in iodine nuclei in the DAMA/NaI detector.
The DAMA/NaI Collaboration has observed a 4-sigma C.L. model independent effect investigating the annual modulation signature in the counting rate of an NaI(Tl) set-up (total exposure of 57986 kg day) and the implications of this effect have been studied under different model-dependent assumptions. In this paper we extend one of the previous analyses, the case of a WIMP with a purely spin-independent coupling, by discussing in detail the implications on the results of the uncertainties on the dark matter galactic velocity distribution. We study in a systematic way possible departures from the …
Inelastic dark matter, in which WIMP-nucleus scatterings occur through a transition to an excited WIMP state ~ 100 keV above the ground state, provides a compelling explanation of the DAMA annual modulation signal. We demonstrate that the relative sensitivities of various dark matter direct detection experiments are modified such that the DAMA annual modulation signal can be reconciled with the absence of a reported signal at CDMS-Soudan, XENON10, ZEPLIN, CRESST, and KIMS for inelastic WIMPs with masses O(100 GeV). We review the status of these experiments, and make predictions for upcoming on…
The DAMA experiments are running deep underground in the Gran Sasso National Laboratory. Several interesting results have been achieved so far. Here a maximum likelihood method to search for the WIMP annual modulation signature is discussed and applied to a set of preliminary test data collected with large mass highly radiopure NaI(Tl) detectors. Various related technical arguments are briefly addressed.
Mirror atoms are expected to be a significant component of the galactic dark matter halo if mirror matter is identified with the non-baryonic dark matter in the Universe. Mirror matter can interact with ordinary matter via gravity and via the photon-mirror photon kinetic mixing interaction -- causing mirror charged particles to couple to ordinary photons with effective electric charge $εe$. This means that the nuclei of mirror atoms can elastically scatter off the nuclei of ordinary atoms, leading to nuclear recoils, which can be detected in existing dark matter experiments. We show that the d…
In this note we present an extension of our previous analysis of some preliminary experimental results of the DAMA/NaI Collaboration which might be indicative of a yearly modulation effect. Here we present a direct way for obtaining from the experimental data the relevant cosmological implications for relic neutralinos. We find that some of the configurations singled out by the DAMA/NaI results would have cosmological properties compatible with a neutralino as a dominant component of cold dark matter (on the average in the Universe and in our galactic halo).
This note, with its five questions, is intended to contribute to a clarification about a claimed "evidence" by the DAMA group of an annual modulation of the counting rate of a Dark Matter NaI(Tl) detector as due to a neutralino (SUSY-LSP) Dark Matter candidate.
The original annual-modulation region, singled out by the DAMA/NaI experiment for direct detection of WIMPs, is extended by taking into account the uncertainties in the galactic astrophysical velocities. Also the effect due to a possible bulk rotation for the dark matter halo is considered. We find that the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L. with a further extension in the upper bound, when a possible bulk rotation of the dark matter halo is taken into account. We show that the DAMA results, when interpreted in the framework of the Minimal Supersymmetric e…
Main arguments on the Dark Matter particle direct detection approach are addressed on the basis of the work and of the results of the about 100 kg highly radiopure NaI(Tl) DAMA experiment (DAMA/NaI), which has been operative at the Gran Sasso National Laboratory of the I.N.F.N. for more than one decade, including the preparation. The effectiveness of the WIMP model independent annual modulation signature is pointed out by discussing the results obtained over 7 annual cycles (107731 kg day total exposure); the WIMP presence in the galactic halo is strongly supported at 6.3 standard deviation C.…
Mirror matter-type dark matter is one dark matter candidate which is particularly well motivated from high energy physics. The theoretical motivation and experimental evidence are pedagogically reviewed, with emphasis on the implications of recent orthopositronium experiments, the DAMA/NaI dark matter search, anomalous meteorite events etc.
A mirror sector of particles and forces provides a simple explanation of the inferred dark matter of the Universe. The status of this theory is reviewed - with emphasis on how the theory explains the impressive DAMA/NaI annual modulation signal, whilst also being consistent with the null results of the other direct detection experiments.
Many observations suggest that much of the matter of the universe is non-baryonic. Recently, the DAMA NaI dark matter direct detection experiment reported an annual modulation in their event rate consistent with a WIMP relic. However, the Cryogenic Dark Matter Search (CDMS) Ge experiment excludes most of the region preferred by DAMA. We demonstrate that if the dark matter can only scatter by making a transition to a slightly heavier state (Delta m ~ 100kev), the experiments are no longer in conflict. Moreover, differences in the energy spectrum of nuclear recoil events could distinguish such a…
The most recent results from direct searches for dark matter particles in the galactic halo are examined in terms of an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale without gaugino masses unification. We show that the annual modulation effect at 8.2 $σ$ C.L. recently presented by the DAMA Collaboration, as the result of a combined analysis of the DAMA/NaI and the DAMA/LIBRA experiments for a total exposure of 0.82 ton yr, fits remarkably well with what expected for relic neutralinos for a wide variety of WIMP distribution functions. Bounds derivable…
