- 天同Lv 77 years agoFavorite Answer
I suppose you refer to ionizing radiation, such as x- or gamma rays which have strong penetration through matter.
Be aware that a "mirror" reflects only visible light, i.e. electromagentic waves of wavelength ranging from 400 nm to 700 nm. The "mirror" doesn't have a strong reflection to electromagentic waves of other wavelengths, including x- or gamma rays. X- or gamma rays can penetrate through a "mirror".