We start from the hypothesis that the dark matter of the Galactic disc contains Planckian particles carrying a negative electric charge of up to Z=10, which we call dark electric matter objects (daemons). Daemons are capable of catalysing proton-fusion reactions, which may account for the observed solar neutrino deficiency. The inevitable poisoning of the catalytic property of daemons as they capture heavy nuclei (A20) in the interior of the Sun is used to estimate the decay time of a daemon-containing nucleus (nucleon) in quantum-relativistic processes, which remain largely unknown. This time is τex∼10−7 s. This may mean that the lower limit on the mass of an intranucleonic particle interacting with a daemon is ∼108–1010 GeV and, possibly, even ∼1014–1015 GeV. The desirability of a search for multiple events occurring with an interval ∼τex along the ‘slow’ daemon trajectories on operating installations dedicated to detection of the proton decay is pointed out.