“Most of these experiments required the reduction of the cosmic ray muon flux in order to be successful, and the group necessarily became expert in the operation of deep underground laboratories.” -Frederick Reines
High-energy particles from space, generated from stars, white dwarfs, neutron stars, black holes, active galaxies and more, can far exceed the energies achievable by accelerators like the LHC. Even if you take into account the severe difference in available energy for producing new particles, cosmic rays still have the edge. But because there are so many interactions for them to undergo before they strike the ground, the signal gets incredibly messy.
The production of a cosmic ray shower, produced by an incredibly energetic particle from far outside our Solar System. Image credit: Pierre Auger Observatory, via http://apcauger.in2p3.fr/Public/Presentation/.
Preliminary detection results showed a discrepancy between what’s predicted — that a certain percent of the energy should be in photons vs. muons — and additional tests were deemed necessary. Now they’ve implemented a new method with the most advanced detector arrays, and the discrepancy is stronger than ever. Could this be the sign of new physics that particle physicists have been hoping for?