As a matter of fact, that experiment has been done. The Nobel prizewinner Luis Alvarez developed this cosmic ray technique for the pyramids of Giza.
Alvarez would bristle whenever someone said that he failed to discover any hidden chambers in the Great Pyramid. In truth, he succeeded in proving that there were no hidden chambers in the Great Pyramid.
Good grief! Am I the LAST person to hear about this??!! Thank you, Physicist. I'll go catch up on the subject at once! :)
IIRC he worked on the "Second Pyramid". The Great Pyramid is known to have a variety of chambers but comparitively few chambers had been found in the Second Pyramid. Alvarez described in his autobiography how he received a call during the experiment that positive results had been found, but after travelling all the way back to Egypt, he found that the results were due to an experimental error known as "double binning".
"In truth, he succeeded in proving that there were no hidden chambers in the Great Pyramid."
Waaaaah! Are too! It's just that they're lined with an alien material unknown to science that threw off his instruments.
Question: Since muons seemingly pass through everything, pretty much, how do you detect one?