Keep in mind as well that Holmlid adduces not only muons, but kaons and pions as well. Once we introduce (negative) kaons, we have the following decays to deal with:
[image: Inline image 1] The neutral pion assures us that there will either be penetrating gammas or positrons, which lead to 511 keV annihilation photons, a signature that is easy to pick up and that will pass through thin shielding. The energy balance for kaons does not make sense to me; but, then again, neither does that for pions or muons. If we go along with Holmlid and allow negative kaons, we must either also allow positive and neutral kaons, or we must come up with a reason for why they don't occur. But it doesn't matter; negative kaons are no doubt not being detected in the first place. They are a merely means to an end, explaining, however tenuously, where the muons come from. Eric
