[en] The use of nuclear emulsions in particle physics dates back to the very early stages. They are now used when an extremely high position resolution is required like in the search for short lived particles. The capability to detect nuclear recoils induced by WIMPs relies on the possibility to detect sub-micrometric trajectories. Recently nuclear emulsions with silver grains of 20 nm diameter were developed, opening the way for the reconstruction of nanometric particles. This challenging purpose requires the development of fully automated optical readout systems for a fast scanning of the emulsion films. This is meant for a pre-selection of recoil candidates. Once candidates have been identified, a fine grained X-ray microscope is used to detect the grains making up the tracks. We report here the present results on the current development along this line

[en] The most convincing candidate as main constituent of the dark matter in the Universe consists of weakly interacting massive particles (WIMP). WIMPs must be electrically neutral and interact with a very low cross-section (σ < 10⁻⁴⁰ cm²) which makes them detectable in direct searches only through the observation of nuclear recoils induced by the WIMP rare scatterings. In the experiments carried out so far, recoiled nuclei are searched for as a signal over a background produced by Compton electrons and neutron scatterings. Signal found by some experiments have not been confirmed by other techniques. None of these experiments is able to detect the track, typically less than one micron long, of the recoiled nucleus and therefore none is able to directly detect the incoming direction of WIMPs. We propose an R and D program for a new experimental method able to observe the track of the scattered nucleus based on new developments in the nuclear emulsion technique: films with nanometric silver grains, expansion of emulsions and very fast completely automated scanning systems. Nuclear emulsions would act both as the WIMP target and as the tracking detector able to reconstruct the direction of the recoiled nucleus. This unique characteristic would provide a new and unambiguous signature of the presence of the dark matter in our galaxy

[en] Nuclear emulsion is a perfect choice for a detector for directional DM search because of its high density and excellent position accuracy. The minimal detectable track length of a recoil nucleus in emulsion is required to be at least 100 nm, making the resolution of conventional optical microscopes insufficient to resolve them. Here we report about the R&D on a super-resolution optical microscope to be used in future directional DM search experiments with nuclear emulsion as a detector media. The microscope will be fully automatic, will use novel image acquisition and analysis techniques, will achieve the spatial resolution of the order of few tens of nm and will be capable of reconstructing recoil tracks with the length of at least 100 nm with high angular resolution.