The world’s largest particle accelerator returned from its hiatus on Sunday following a two-year upgrade that aims to help physicists probe uncharted corners of what makes up the universe – including dark matter and antimatter. The European Organisation for Nuclear Research (CERN) near Geneva, Switzerland said, “After two years of intense maintenance and several months of preparation for restart, the Large Hadron Collider, the most powerful particle accelerator in the world, is back in operation.” The aim of the upgrade was to double the Large Hadron Collider’s (LHC) maximum collision capacity.
Engineers were able to promptly fix a technical hitch, which had delayed the LHC’s initial comeback date by two weeks when a piece of metal caused a short circuit near one of the machine’s superconducting magnets. On 30th March, by using a discharge of current, engineers vapourised the rogue piece of metal.
On Sunday, two minimal-energy beams containing a bare minimum of protons were launched in opposite directions through the LHC’s 27-kilometre ring. However, scientists are waiting to carry out the more crucial experiments for the time being. “Bringing the LHC back on, from a complete [closure] to doing physics, is [more than just] a question of pushing a button and away you go,” says Paul Collier, head of beams at CERN. The next eight weeks may be spent gradually bringing systems online, allowing engineers to carefully tune and maintain the machinery as they go. Interestingly, CERN aims to increase the energy of each beam to 6.5 teraelectron volts (up from the previous 450 gigaelectron volts) and concentrate the beams into narrower regions as they prepare for the first run in the first half of June.
CERN’s director general, Prof Rolf-Dieter Heuer, who was in the control room, said: “The beam went smoothly through the whole machine. It’s fantastic to see it going so well after two years and such a major overhaul of the LHC. I am delighted and so is everyone in the CERN control centre – as are, I’m sure, colleagues across the high-energy physics community.”
The experiments may be performed using four giant detectors distributed around the ring, generating new particles that might enable scientists to deeper examine the fundamental “building blocks” of nature. As more energy is fed into the machine, more massive particles may be produced. This is important because the “new physics” model of the universe – called supersymmetry – postulates that every particle has a heavier partner. It is thought that one of these supersymmetrical particles might be the source of dark matter.
The experiment teams are already observing “splashes” from protons colliding with the shutters that keep the beam on track. The detectors are able to pick up some of the debris when this happens.
In 2012, the LHC managed to prove the existence of the elusive Higgs Boson – an elementary particle that explains why particles have mass. This finding won two scientists the Nobel Prize in 2013 whom, all the way back in 1964, hypothesised the existence of the so-called “God particle”.
Now, CERN are aiming to discover an even more noteworthy trophy: dark matter – the currently undetectable material that apparently accounts for up to 84% of all matter in the universe and ties galaxies together. With the LHC’s new kit, it is equipped with the potential to identify dark matter and make scientific history for the second time. Arnaud Marsollier at CERN said, “The LHC will be running day and night. When we will get results we [are unsure]. What is important is that we will have higher energies [than ever] before.” Experiments at the LHC are now moving towards unexplored territory of the universe and maybe even a new uncharted era of science.
How might research at the LHC productively benefit peoples’ daily lives?