Ghost particles

Physicists have detected “ghost particles” called neutrinos inside an atom smasher for the first time. The tiny particles, known as neutrinos, were spotted during the test run of a new detector at the Large Hadron Collider (LHC) — the world’s largest particle accelerator, located at CERN near Geneva, Switzerland. 

The landmark discovery, made by CERN’s Forward Search Experiment (FASER) collaboration and presented in a Nov. 24 paper in the journal Physical Review D, is not just the first time that neutrinos have been seen inside the LHC, but it’s also the first time they’ve been found inside any particle accelerator. The breakthrough opens up a completely new window through which scientists can investigate the subatomic world. 

“Prior to this project, no sign of neutrinos has ever been seen at a particle collider,” study co-author Jonathan Feng, a physics professor at the University of California, Irvine and co-leader of the FASER collaboration, said in a statement. “This significant breakthrough is a step toward developing a deeper understanding of these elusive particles and the role they play in the universe.”

Every second, about 100 billion neutrinos pass through each square centimeter of your body. The tiny particles are everywhere — they’re produced in the nuclear fire of stars, in enormous supernova explosions, by cosmic rays and radioactive decay, and in particle accelerators and nuclear reactors on Earth.

But despite their ubiquity, the particles remain hard to catch. Because neutrinos have no electrical charge and almost zero mass, they barely interact with other types of matter. True to their ghostly nickname, neutrinos view the universe’s regular matter as incorporeal, and they fly through it at close to the speed of light.

Just because they’re hard to catch doesn’t mean that neutrinos can’t be caught, however. Some of the most famous neutrino detection experiments — such as Japan’s Super-Kamiokande detector, Fermilab’s MiniBooNE, and the Antarctic IceCube detector — have all detected solar-generated neutrinos indirectly through an effect called Cherenkov radiation.

Just as a plane traveling faster than the speed of sound creates a sonic boom, a particle traveling through a light-slowing medium (like water) faster than light is able to creates a faint blue glow in its wake. By looking for this glow, scientists are able to spot the trails of particle byproducts created after neutrinos strike an atomic nucleus dead-on. 

Live Science