The evidence for dark matter (DM) is overwhelming from astrophysical and cosmological observations at all scales. Yet, its existence is inferred indirectly through gravitational effects, but its nature is still unknown. Among the preferred DM particle candidates are Weakly Interacting Massive Particles (WIMPs), new particles beyond the standard model (SM) with weak-scale couplings to SM particles. WIMPs in the Milky Way halo are expected to scatter off the nuclei of a particle detector located in the Earth, with an interaction rate that depends on their relative velocity with respect to the Earth. As a consequence of the Earth rotation around the Sun, this velocity varies with 1 year periodicity, and so does the expected interaction rate (annual modulation). For more than 20 years, the DAMA/LIBRA experiment at the Gran Sasso Underground Laboratory (Italy) has claimed a positive dark matter detection: an annual modulation in the low-energy detection rate compatible with the expected signal induced by dark matter particles. This signal is in strong tension with the negative results of other very sensitive experiments. However, until recently a direct comparison using the same target material (NaI(Tl)) was lacking.
ANAIS (annual modulation with NaI Scintillators) is a dark matter direct detection experiment located at the Canfranc Underground Laboratory (LSC, Spain). Its main goal is to test in a model independent way the DAMA/LIBRA positive result. ANAIS-112, consisting of 112.5 kg of NaI(Tl) scintillators, was installed at the LSC in 2017 and since then is taking data smoothly with excellent performances. Last year we released results from the first two years of data, which are compatible with the absence of modulation and in some tension with DAMA/LIBRA result. Moreover, the results support our goal of reaching a 3sigma sensitivity to the DAMA/LIBRA result with about 5 years of data-taking.
In this seminar I will briefly review the DAMA/LIBRA puzzle and the status of the experiments trying to reproduce it. Then I will introduce the ANAIS-112 experimental set-up, the detector performance and analysis methods. Finally, I will present the latest results and an update of the experimental sensitivity.
Zoom Coordinates: https://cern.zoom.us/j/98768015328, pass 092020