β spectrum of tritiated graphene: Combining nuclear quantum mechanics with density functional theory

We present the results of a multimethodological study aimed at investigating the interaction between graphene and tritium during its 𝛽-decay to helium, under different levels of loading and geometrical configurations. We combine density-functional theory (DFT) to evaluate the interaction potentials, with calculations of the decay rate, in order to study the consequences that the presence of the substrate has on the 𝛽-decay spectrum of tritium. We determine the shape of the event rate, accounting for the effects of (part of) the corresponding condensed-matter degrees of freedom. In the context of future neutrino experiments, our results provide important information aimed at the optimization of hosting material. Furthermore, our work outlines a novel theoretical and computational scheme to account for the different timescales involved in the process and to address a question at the boundary between high- and low-energy physics. This requires nonconventional declinations of DFT combined with full quantum treatments of the nuclear configuration involved in the decay process. Our results pave the way for future studies aimed at determining the physics reach of upcoming neutrino mass experiments.