Space Invaders
Cosmic rays, hi-energy particles travel space from stars
Create new short-lived anti/particles/photons entering atm.
Victor Hess showed ionising effect sig. greater at 5 km altitude
Most C-rays were fast photons, small nuclei, collide w/ gas atoms in atm = anti/particles detected at ground level
Muon - heavy electron (μ), -ve charge, m0 = 200 times e-
Pion - π meson, can be π+, π-, π° (neutral) p+ > m0 > μ
Kaon - K meson, can also be +/-/°, p+ > m0 > π
m0: p+ > K > π > μ > e