  The MIMAC experiment is a $\mu$-TPC matrix project for directional dark
matter search. Directional detection is a strategy based on the measurement of
the WIMP flux anisotropy due to the solar system motion with respect to the
dark matter halo. The main purpose of MIMAC project is the measurement of the
energy and the direction of nuclear recoils in 3D produced by elastic
scattering of WIMPs. Since June 2012 a bi-chamber prototype is operating at the
Modane underground laboratory. In this paper, we report the first ionization
energy and 3D track observations of nuclear recoils produced by the radon
progeny. This measurement shows the capability of the MIMAC detector and opens
the possibility to explore the low energy recoil directionality signature.
