Researchers at the Large Hadron Collider (LHC) in Switzerland sent two beams of protons hurtling in opposite directions and crashed them together at the highest energy level yet achieved at the LHC. The research is part of the CMS experiment, which stands for Compact MuonSolenoid. For each of the 150,000 proton-proton collisions the researchers identified, about 22 charged particles (hadrons) were produced.
The scientists wanted to create a snapshot of a “typical” collision between two proton beams, which could help the researchers sift through background noise for signs of new effects. Previous models to make predictions for detecting new particles rely on estimates with an uncertainty of 30 to 40 percent, which could be problematic for detecting rare particles, the researchers said.
To get a precise count of the number of particles produced in an average proton collision, the team analyzed data with the LHC’s magnet turned off. This meant the scientists could accurately count the number of charged particles, because they arrive at the CMS detector itself rather bending from the magnetic field and ending up in the main collider’s beam pipe, Yen-Jie Lee, an assistant professor of physics at the Massachusetts Institute of Technology and one of the study’s lead researchers, said in a statement.
The LHC is an underground ring measuring about 16 miles (27 kilometers) in circumference. It accelerates particles to nearly the speed of light using powerful magnets. The CMS experiment is one of a handful of detectors built into the LHC machine.
The energy intensity at the atom smasher has increased by 60 percent — from about 7 teraelectronvolts (TeV) to 13 TeV — since its first run, which lasted from 2010 to 2013. This is still a tiny amount of energy; 1 TeV is about the energy of motion of a flying mosquito. Within a proton though, this is squeezed into a space about a million, million times smaller than a mosquito, according to the European Organization for Nuclear Research (CERN), which operates the LHC.
The LHC’s energy boost means that 30 percent more particles are produced per collision, the researchers found.
“At this high intensity, we will observe hundreds of millions of collisions each second,” Lee said.
The increased energy also gives physicists a better chance of discovering new particles like the Higgs boson, which was first detected in 2012. According to Albert Einstein’s equation e = mc2, the higher the energy (e) of the experiment, the higher the mass (m) of the new particles could be.
“We are opening up a new region of these collisions that we have never opened up before,” said Daniela Bortoletto, a physicist who was previously involved with the CMS collaboration but now works on ATLAS, a rival experiment at the LHC. “We are really exploring terra incognita!”
The ATLAS group also observes collisions between a set of two proton beams and is in the process of replicating the CMS experiment to count the number of hadrons produced.
Bortoletto said that these measurements are fundamental to physics because they help “get to the diamond in a terrain full of dirt.”
“It’s part of the mankind desire to understand where we came from,” Bortoletto told Live Science. “And we’ve done really remarkably well in explaining a lot of the phenomena.”
Bortoletto says the measurements described in this paper are necessary to discover new particles in the higher energy regime. While she said the theories behind the building blocks of the universe are impressively accurate so far, there is still something missing.
The Standard Model, the reigning theory of particle physics, is based on the idea that all matter is made of particles of two basic types, called quarks and leptons, and the forces that act on them.
However, it is not a flawless design, and there are gaps to fill in. Discovering unknown — and sometimes invisible — particles could help physicists, like Bortoletto, see the bigger picture.
Read more at Discovery News
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