An artist’s impression shows the newly discovered subatomic particle, with two charm quarks and one down quark. (Credit: CERN)
The Large Hadron Collider’s subatomic discoveries didn’t stop with the Higgs boson: This week, scientists at Europe’s CERN research center announced that the collider’s LHCb experiment has detected a doubly charmed particle that’s like a proton, but four times as weighty.
The particle is known as the Ξcc⁺, or “Xi-cc-plus.” It flashes in and out of existence in less than the blink of an eye, but just knowing that it exists — and knowing how massive it is — could give physicists a more solid sense of how matter is put together.
Experiments at Europe’s Large Hadron Collider have produced hard-to-come-by evidence of interactions between the Higgs boson and top quarks. The findings, announced today at a conference in Bologna, Italy, “give a strong indication that the Higgs boson has a key role in the large value of the top quark mass,” Karl Jakobs, spokesperson for the LHC’s ATLAS collaboration, said in a news release.
This computer graphic shows one of the first collisions recorded between two lead ions at the Large Hadron Collider’s top energy. The energy in the center-of-mass system is approximately a quadrillion electron-volts. (Credit: CERN / ALICE Collaboration)
Before the LHC’s startup in 2008, the Internet was set abuzz with worries that high-energy collisions could create globe-gobbling black holes or cosmos-wrecking strangelets. Protests were mounted, lawsuits were filed, and physicists at Europe’s CERN particle physics center had to explain in depth why the nightmare scenarios were nothing more than nightmares. Once the collider went into operation, the lawsuits were dismissed and the hand-wringing settled down.
Now the world’s largest collider is operating at near its design limits, and this week, CERN reported that lead-ion collisions in the LHC’s ALICE detectorreached energies beyond a quadrillion electron-volts – a level also known as 1 peta-electron-volt, or 1 PeV.
“This energy is that of a bumblebee hitting us on the cheek on a summer day. But the energy is concentrated in a volume that is approximately 10 -27 (a billion-billion-billion) times smaller,” Jens Jørgen Gaardhøje, professor at the Niels Bohr Institute at the University of Copenhagen and head of the Danish research group within the ALICE experiment, said in a news release.
At first blush, a quadrillion electron-volts sounds like a huge ramp-up from 13 trillion to 14 trillion electron-volts, or 13 to 14 TeV, the traditionally quoted figures for the high end of the LHC’s collision energy. That’s what set off the doomsayers. In the weeks leading up to the ALICE collisions, there was a drumbeat of postings claiming that “CERN LIED” and warning that 1-PeV smashups would have catastrophic consequences.
