Physics

Large Hadron Collider limbers up after two-year overhaul

The Compact Muon Solenoid (CMS) general-purpose detector at the Large Hadron Collider was used in the warm up exercise (Image: CERN)
The Compact Muon Solenoid (CMS) general-purpose detector at the Large Hadron Collider was used in the warm up exercise (Image: CERN)
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Proton-proton collision at 900 GeV as determined by the inner silicon trackers in the ALICE detector (Image: ALICE/CERN)
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Proton-proton collision at 900 GeV as determined by the inner silicon trackers in the ALICE detector (Image: ALICE/CERN)
Proton beams collide for a total energy of 900 GeV in the ATLAS detector on the LHC (Image: ATLAS/CERN)
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Proton beams collide for a total energy of 900 GeV in the ATLAS detector on the LHC (Image: ATLAS/CERN)
Recommissioning requires adjusting hundreds of electromagnets (Image: CERN)
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Recommissioning requires adjusting hundreds of electromagnets (Image: CERN)
The Compact Muon Solenoid (CMS) general-purpose detector at the Large Hadron Collider was used in the warm up exercise (Image: CERN)
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The Compact Muon Solenoid (CMS) general-purpose detector at the Large Hadron Collider was used in the warm up exercise (Image: CERN)
The LHCb detector (Image: CERN)
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The LHCb detector (Image: CERN)
Proton-proton collision at 900 GeV in the LHCb detector (Image: LHCb/CERN)
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Proton-proton collision at 900 GeV in the LHCb detector (Image: LHCb/CERN)
THE ALICE detector (Image: CERN)
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THE ALICE detector (Image: CERN)
The ATLAS detector (Image: CERN)
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The ATLAS detector (Image: CERN)
Two beams of protons at 450 GeV collide in the the CMS detector for a total collision energy of 900 GeV (Image: CMS/CERN)
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Two beams of protons at 450 GeV collide in the the CMS detector for a total collision energy of 900 GeV (Image: CMS/CERN)

Restarting the world's largest particle accelerator after a two-year overhaul isn't just a matter of throwing a switch and making sure the lights go on. It's an eight-week process of baby steps – one's that involve billions of electron volts. But the Large Hadron Collider (LHC) took a major step forward this week as the CERN team fired up two counter-rotating proton beams that were injected into the LHC using the Super Proton Synchrotron, then accelerated to an energy of 450 GeV each.

During the power up, the 27-km (16.7-mi) ring generated low-energy proton-proton collisions that sent subatomic particles to the ALICE, ATLAS, CMS, and LHCb detector experiments. According to CERN, the purpose of the power up at 9:30 am CET on Tuesday was to help scientists and engineers properly adjust the accelerator and tune the detectors, so they can handle the 6.5 TeV beams that will produce 13 TeV collisions.

As the particles cascaded through the layers of the detectors and subdetectors, the CERN teams monitored them and adjusted the equipment, systems and algorithms, to ensure the subdetectors fire at the precise place and time a particle passes. The idea is that by using these banks of detectors, scientists can reconstruct what happens when the protons collide and from that, learn more about their make up. It's a bit like slamming two pocket watches together and trying to figure out how they work by watching the gears fly out.

According to CERN, the testing by the LHC Operations team will take a total of eight week to make sure that the beams circulate properly and the collider can be recommissioned. This involves testing the many subsystems and fine tuning hundreds of electromagnets. Once this is accomplished, the team can begin to work up to full-power high-energy collisions.

CERN physicists discuss the potential new physics the LHC's "second season" could shed light on in the video below.

Source: CERN

Welcome to LHC season 2: new frontiers in physics at #13TeV

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