Directional Dark Matter Search with Nuclear Emulsion

Abstract

Dark matter search by using nuclear emulsion, NEWSdm project is described here. The expected Dark matter signal is the recoiled nucleus track stopping within a few 100 nm in material. The short track length makes it difficult to detect. We have developed a fine grained nuclear emulsion to record the trajectory of the recoiled nucleus as several aligned silver grains by the nuclear emulsion. Track length is shorter than visible light wave length (400nm to 700nm). Therefore, dedicated techniques to overcome this limitation have been developed by the Collaboration. Carbon ion beams of relevant energies have been used to demonstrate the directional sensitivity with these techniques. Moreover, the scanning speed with automated microscopes is continuously increasing. WIMPs detection sensitivity with 10 kg nuclear emulsion target with a year exposure at LNGS will cover a large part of the DAMA signal region.