This Space.com article “Hotspot for Cosmic Rays: Touring the Telescope Array Project in Utah” published on May 27, 2017, reminded me that while CERN’s LHC is the current champ of colliders on Earth, other particles which have been raining down on us for billions of years are colliding with Earth’s atmosphere at even higher energies — the mysterious so-called cosmic rays.
The term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In common scientific usage, high-energy particles with intrinsic mass are known as “cosmic” rays, while photons, which are quanta of electromagnetic radiation (and so have no intrinsic mass) are known by their common names, such as gamma rays or X-rays, depending on their photon energy.
By studying the particles that cascade to Earth, scientists can learn about the energy of the original cosmic rays. Traveling through space, the cosmic rays are rapidly accelerated to energy levels millions of times higher than particles inside the Large Hadron Collider, the most powerful particle accelerator ever built. [The Telescope Array Project: A Photo Tour]
A Forbes.com article “Cosmic Rays May Reveal New Physics Just Out Of LHC’s Reach” published on November 29, 2016, also points out that cosmic rays are speedier than LHC protons.
The Large Hadron Collider (LHC) – presently the world’s most powerful particle accelerator – reaches a maximum collision energy of 14 TeV. Two protons, moving at 299,792,455 m/s apiece, or a tantalizing 99.9999991% the speed of light, collide, leaving a maximum of 14 TeV of energy available for the creation of new particles. But the cosmic rays that collide with atoms in the upper atmosphere have been measured with speeds in great excess of these, resulting in collision energies about ten times as high as anything the LHC can muster.
And this PBS.org article “The Astronomical Particle Colliders That Put Our Own to Shame” published on July 21, 2014, makes the same point; and, furthermore, addresses the fear than some raised about the operation of the LHC.
When the Large Hadron Collider (LHC) began operations, a small but noisy group of people tried to stop it out of fear. Their reasoning: The energies produced as protons slammed into each other at close to the speed of light would be sufficiently high to create miniature black holes or other exotic, destructive things. The fruits of human curiosity would be the literal end of the world.
Those fears were unwarranted for a simple reason: Earth is bombarded by much higher-energy particles all the time, and we haven’t been eaten by a planet-munching black hole yet. In fact, the universe has many naturally-occurring particle accelerators that are far more powerful than the LHC, exceeding even anything we could build in the foreseeable future. Anything exotic we can create in our labs, the cosmos has beaten us to it.
“The energy for particle creation … in the upper atmosphere is more than a factor of twenty greater than at the LHC,” said Glennys Farrar, professor of physics at New York University. Most impressive of all are “ultra-high-energy” cosmic rays, which reach energies 100 million times greater than the fastest protons produced in the LHC.
Can cosmic rays be used to detect Higgs bosons like at the LHC? Unlikely, since a Higgs boson lasts around a zepto second and detectors need to be close to collisions and require massive equipment and processing to separate out exotic particles from bursts of ordinary ones.
Some possible sources of ultra-high-energy cosmic rays are neutron stars.