Status and analysis system of directional dark matter search with nuclear emulsion

Abstract

We have been doing research and development for direct dark matter search by nuclear emulsion which is a solid state detector. This experiment enable directional detection of dark matter with the large mass target and model independent. Until now, we constructed a base of fully automatic analysis system and nuclear emulsion which can detect sub-micron tracks. We have demonstrated that it is possible to detect recoiled tracks of 100 nm or more by neutron irradiation. This track length is correspond to 37 keV in C(N,O) target. Additionally, we evaluated the angular resolution of the energy basis by using an ion implant system, and obtained 25 degrees or better resolution in 80 keV carbon ions. The fully automatic analysis system which can analyze very short tracks lead the experiment to next phase, we will do a quantitative study of the background toward gram scale test experiment at the Gran Sasso underground laboratory.