The search for dark matter weakly interacting massive particles has probed masses down and below a GeV/c2. The ultimate limit is represented by the experimental threshold on the energy transfer to the nuclear recoil. Currently, the experimental sensitivity has reached a threshold equivalent to a few ionization electrons. In these conditions, the contribution of a Bremsstrahlung photon or a so-called Migdal electron due to the sudden acceleration of a nucleus after a collision might be sizeable. These effects are expected theoretically, but have not been observed yet. In the present project, we propose to study how these effects can be observed and develop a technique based on high precision TPC to carry out the first measurement of such processes.
