The Universe in particles

On June 3 this year, billions of collisions occurred in a 27-km-long circular tunnel between Switzerland and France. But this is not a cause for concern as these collisions were part of the second season of experiments at CERN (the European Organisation for Nuclear Research), which is the world’s leading laboratory for Particle Physics.

The first season of collisions at eight TeV (teraelectronvolt) confirmed the presence of Higgs boson, the elusive particle that seems to provide mass to all other particles. In the second season, proton beams will be made to collide at 13 TeV, nearly double the energy at which experiments were carried out in the first season. Researchers hope these experiments would further increase our understanding of subatomic particles. By releasing the beams of protons into the Large Hadron Collider (LHC) in both directions, and controlling them with powerful superconducting magnets, the researchers managed to generate stable beams. Researchers now have a source for a truly new set of data. “Let’s see what they will reveal to us,” says Rolf Heuer, director-general of CERN.

When protons with high energy collide, they fragment into the most basic of its components. These are being detected by sensors placed around the LHC. “It is a big jump from 8TeV to 13TeV. Particles could behave one way at 8 eight TeV and in another way at 13 TeV,” says Varun Sharma, a <g data-gr-id="64">PhD</g> student at CERN. Sharma works on the Compact Muon Solenoid (CMS), one of the seven particle detectors that helps see the subatomic particles produced during the collisions. Sharma is hoping to study the <g data-gr-id="65">sub particles</g> of quarks—one of the fundamental particles in physics. These sub particles or <g data-gr-id="66">preons</g> have been discussed theoretically and their presence would be confirmed if their signature can be detected.

During the second season, seven experiments are planned. Detectors ATLAS, CMS, ALICE and LHCb will look at a wide range of physics phenomena—from Higgs boson and dark matter to the difference between matter and antimatter. Experiments like TOTEM would use detectors to measure the <g data-gr-id="67">protons</g> as they emerge from collisions. The LHCf experiment would measure neutral particles. The MoEDAL experiment would look for magnetic monopoles to investigate the possibility of extra dimensions and the nature of dark matter. (see box: ‘Data scope’) “We strongly believe that something unknown is just around the corner,” says Ehud Duchovni of Weizmann Institute of Science, Israel. 

This makes the research an exciting adventure, he adds. Michael Hance, a researcher at the Lawrence Berkeley National Laboratory in the US, who works on the ATLAS experiment, is looking at events with bosons that may come from the decay of some heavy new particle. “During the <g data-gr-id="68">first-run</g> of the LHC, we searched for evidence of physics beyond the Standard Model <g data-gr-id="69">but</g> unfortunately, we did not see convincing signs of anything new. During the second season, we hope to find outside of what the Standard Model predicts. This could be a new particle or a new force of nature,” says Hance.

“The universe is composed of approximately 68.3 <g data-gr-id="58">per cent</g> dark energy, 26.8 <g data-gr-id="59">per cent</g> dark matter and 4.9 <g data-gr-id="60">per cent</g> ordinary or visible matter. What we know about the universe belongs to the last 4.9 <g data-gr-id="61">per cent</g>,” says Brajesh Choudhary, professor, Department of Physics and Astrophysics, University of Delhi. “The field of research is wide open when it comes to the remaining aspects of fundamental physics,” he adds.

Huge amounts of data would be generated during the second season—150 million sensors are taking images 40 million times per second. “This is just the beginning,” says Markus Schulz, who works on distributed computing at CERN. The quantum of data generated is expected to increase from 25 <g data-gr-id="57">peta bytes</g> (PB) per year in 2012 to 400 PB per year by 2024, providing scientists a wealth of information 

to enrich our understanding of the universe. While it is not yet clear how the “new physics” would help in precise terms, the research has long-term value. As Sharma says, “We can use electricity because we understand electrons. We are already using protons to treat cancer”.   

DATA SCOPE: Some of the mysteries that will be probed.