The world’s most powerful particle accelerator that discovered the “God particle” is now hunting for what physicists call the ”glue” that holds our solar system, galaxies, and clusters of galaxies together — dark matter.
After remaining shut for over three years, the cathedral of physics is now open and ‘pilgrims’ are flocking to it from the world over. Located on the French-Swiss border near Geneva, the Large Hadron Collider (LHC) under Conseil Européen pour la Recherche Nucléaire (CERN) had been closed for upgrades.
Two beams of protons began circulating in opposite directions in the 27-kilometer ring at an energy of 450 billion electronvolts (450 GeV) to mark the beginning of a new phase for the particle accelerator, which has been the source of numerous discoveries in the past.
Physicists are hopeful that the resumption of the beam collision under the surface of Earth will help in their now 100-year-old quest to look for dark matter that is thought to be five times more prevalent than ordinary matter in our universe.
Dr. Rohini Godbole, Honorary Professor at the Indian Institute of Science, Bengaluru calls it an astroparticle puzzle. “Dark matter is the biggest puzzle in theoretical physics. I call it an astroparticle puzzle because it is a puzzle for both astrophysicists and particle physicists. It has ramifications for cosmology, early universe, and models of particle interactions,” she said.
WHAT IS DARK MATTER?
Physicists and astrophysicists have long said that galaxies in our universe rotate so fast that the gravity generated by their matter theoretically should not hold them together and they should tear themselves apart. However, they are still intact, making scientists speculate that there is a phenomenon, which we cannot see, that holds them together.
Since it is invisible, scientists call it dark matter.
According to CERN, dark matter is extremely hard to spot since it does not absorb, reflect or emit light and we have only been able to infer its existence from the gravitational effect it seems to have on visible matter. “Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe,” CERN says.
“The latest set of research around dark matter is like describing an animal by studying the minute footprints it leaves behind. The LHC will not only look for dark matter it will also probe beyond the Standard Model and look for answers to discrepancies in the model,” Professor Godbole said. Developed in the 1970s, the Standard Model provides information about how fundamental particles and the three forces are related to each other.
Shut for nearly three years amid Covid-19 pandemic-induced lockdowns, the Large Hadron Collider has gone through maintenance and major upgrades which now equips it with the ability to operate at even higher energy and deliver significantly more data.
Following the upgrades, the ATLAS and CMS experiments, the two general-purpose detectors at the Large Hadron Collider that looked for the god particle to extra dimensions and particles that could make up dark matter, can each expect to receive more collisions during this physics run than in the two previous physics runs combined.
The latest upgrades on the LHC will ensure four years of physics, as experts work around the clock to progressively recommission the machine and safely ramp up the energy and intensity of the beams before delivering collisions to the experiments at a record energy of 13.6 trillion electronvolts.
“The restart of the Large Hadron Collider is crucial since the new upgrades will allow for acceleration of protons at higher energy and higher luminosity, which will in turn lead to more data. Since dark matter has remained elusive, we need more data to detect these invisible particles. More data means more probability of finding these events,” said Dr. Bedanga Mohanty, who is a professor of Physics at the National Institute of Science Education and Research (NISER) in Bhubaneswar.
Physicists will not just focus on dark matter but also study the subatomic particle W boson, which recently threw a bouncer at physicists when they found it to have more mass (weight) than what was initially thought. W boson, is responsible for a fundamental force at the center of atoms, and they exist for only a fraction of a second before they decay into other particles. These particles have been used to explain the workings of the universe
The upgrades will also allow scientists from across the world to study the Higgs boson in great detail and put the Standard Model of particle physics and its various extensions to the most stringent tests yet.