Novel CSL bounds from the noise-induced radiation emission from atoms

We study spontaneous radiation emission from matter, as predicted by the Continuous Spontaneous Localization (CSL) collapse model. We show that, in an appropriate range of energies of the emitted radiation, the largest contribution comes from the atomic nuclei. Specifically, we show that in the energy range $E\sim 10\,-\,10^{5}$ keV the contribution to the radiation emission from the atomic nuclei grows quadratically with the atomic number of the atom, overtaking the contribution from the electrons, which grows only linearly. This theoretical prediction is then compared with the data from a dedicated experiment performed at the extremely low background environment of the Gran Sasso underground National Laboratory, where the radiation emitted from a sample of Germanium was measured. As a result, we obtain the strongest bounds on the CSL parameters for $r_C\leq 10^{-6}$ m, improving the previous ones by more than an order of magnitude.