A new approach is proposed for searching for millicharged particles (mCPs) using signals from collapsing supernovae. Massive mCPs born during core collapse arrive at Earth-based detectors with a time delay relative to massless neutrinos, creating a background-free window after the neutrino burst passes. A calculation of electron recoil signals in detectors XENONnT, JUNO, DUNE, and Hyper-Kamiokande for typical supernova scenarios is performed. It is shown that with an mCP charge coupling ε = 10⁻⁹ and masses from sub-MeV to MeV, more than 10 events per year can be expected. This method can strengthen the existing constraint on ε from supernova cooling analysis by roughly an order of magnitude.
When a massive star dies, its core collapses, and a supernova explosion occurs. The cataclysm births streams of particles — like ripples from a thrown stone. The first to arrive are swift neutrinos, which pierce the Earth, hardly interacting. Then, hours later, ghost particles with a tiny charge appear.
Underground detectors catch faint flashes from these particles colliding with electrons. Because of their mass, they travel slower than neutrinos and arrive later, like an echo. Detectors could register up to tens of events per year — dozens of times more than previous estimates. Perhaps these ghost particles are dark matter — the invisible scaffolding of the Universe.
🎯 Neutrinos from supernova 1987A outpaced light by three hours — proving they have a tiny mass.