Celestial neutrals

Neutral cosmic rays from a source on the celestial sphere have been reported in a recent issue of Physics Letters by Clyde Cowan and his collaborators at Catholic University. Neutral particles entering their detector produced muons that subsequently decayed into electrons. They found that the number of these neutral events, plotted as a function of sidereal time, peaked when the Milky Way passed over the detector. (As Cowan remarks, “No beings live on sidereal time, except maybe the angels.”) Cowan believes that the detector is either seeing neutrinos acting in a surprising way or else a new variety of neutral particle.