The muon riddle

Day 4,766, 10:53 • Published in Austria Austria • by Mayamoto

This time The xx with Crystalised was chosen for the obligatory background song.




So far I've spoiled you, dear reader, with easy to understand. But today I've got something challenging for you. Here’s a little riddle, which might be heavy stuff for you:

When cosmic radiation hits our atmosphere, muons emerge about 10 km above the ground.
Those heavy leptons have a half-life of just 2.2 microseconds. So they exist for just a very short period of time.
They move with nearly speed of light. But due to their short lifetime, they aren’t able to move more than like 600 meters before they decay.
One should therefore assume that they cannot be detected on the earth's surface 10 km down below.
Nevertheless they are detected at sea level. How does that work?

Muons are pretty much like electrons, but with a 200 times bigger mass. There is no other natural source on earth than cosmic radiation, interacting with the top level atmosphere.

Do you manage to solve the riddle?
Please submit suggested solutions via PM. Best answers may receive a little bonus for the effort.

Everyone else will at least learn something new, maybe even fascinating. The solution to the riddle will be published in a week.


As always, I’d be happy if you vote and subscribe.
Your flying lizard Mayamoto.

Update: Here you'll find the solution.