Invisible Nucleon Decay
To look for invisible modes of decay, the SNO+ experiment must detect the resulting nuclear deexcitation that comes from the decay process in the oxygen nucleus. Muons produced by cosmic rays can penetrate into the detector and produce a similar signal, which gives SNO+ an advantage compared with other detectors due to its extraordinary depth. Recent results from the experiment set new limits on the partial lifetime of the proton through any invisible decays [1].
Figure 2. Plot of the reconstructed energy spectrum of events passing all of the analysis cuts for nucleon decay. The data is fit with spectra for each of the major background components determined through simulations using RAT—a simulation package developed using Geant4. The blue curve shows the sum of each of the components, with a bound surrounding it representing the total uncertainty.
References
[1] M. Anderson et al. (The SNO+ Collaboration), Phys. Rev. D 99, 032008 (2019)