Using low energy electrons to neutralize electrostatic charges on cryogenic test mass mirrors of future gravitational wave detectors

. - Electrostatic charging is a limiting noise source for gravitational wave detection already at room temperature. The development of a mitigation method compliant with cryogenics is mandatory to preserve the performances envisaged by the upcoming generation of gravitational wave detectors. We have recently proposed the use of selected energy electrons (below few hundreds eV) impinging on the mirror surface to neutralize electrostatic charges of both polarities. Here we present the experimental evidence of the method on a 20 nm SiO2/Si substrate.