Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark M
atter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 neutrons per year per kilogram, fully compatible with the design of a 10 kg$times$year exposure.
The OPERA experiment aims at the direct confirmation of the leading oscillation mechanism in the atmospheric sector looking for the appearance of $ u_{tau}$ in an almost pure $ u_{mu}$ beam (the CERN CNGS beam). In five years of physics run the exper
iment collected $17.97 times 10^{19}$ p.o.t. The detection of $tau$s produced in $ u_{tau}$ CC interactions and of their decays is accomplished exploiting the high spatial resolution of nuclear emulsions. Furthermore OPERA has good capabilities in detecting electron neutrino interactions, setting limits on the $ u_{mu} rightarrow u_{e}$ oscillation channel. In this talk the status of the analysis will be presented together with updated results on both oscillation channels.
The OPERA experiment aims at measuring the u_{mu} -> u_{tau} oscillation through the u_{tau} appearance in an almost pure u_{mu} beam (CNGS). For the direct identification of the short-lived {tau} lepton, produced in u_{tau} CC interactions, a m
icrometric detection resolution is needed. Therefore the OPERA detector makes use of nuclear emulsion films, the highest spatial resolution tracking device, combined with lead plates in an emulsion cloud chamber (ECC) structure called brick. In this paper the nuclear emulsion analysis chain is reported; the strategy and the algorithms set up will be described together with their performances.
