A joint Fermilab/SLAC publication

LHC restart back on track

03/31/15

The Large Hadron Collider has overcome a technical hurdle and could restart as early as next week.

Photo of LHC X-ray 1
Maximilien Brice, CERN

On Monday, teams working on the Large Hadron Collider resolved a problem that had been delaying the restart of the accelerator, according to a statement from CERN.

On March 24, the European physics laboratory announced that a short circuit to ground had occurred in one of the connections with an LHC magnet. LHC magnets are superconducting, which means that they can maintain a high electrical current with zero electrical resistance. To be superconducting, the LHC magnets must be chilled to almost minus 460 degrees Fahrenheit.

The short circuit occurred between a superconducting magnet and its diode. Diodes help protect the LHC's magnets by diverting electrical current into a parallel circuit if the magnets lose their superconductivity.

When teams discovered the problem, all eight sections of the LHC were already cooled to operating temperature. To fix the problem, they knew that they might have to go through a weeks-long process of carefully rewarming and then recooling one section.

The short circuit was caused by a fragment of metal caught between the magnet and the diode. After locating the fragment and examining it via X-ray, engineers and technicians decided to try to melt it. They could do this in a way similar to blowing a fuse. Importantly, the technique would not require them to warm up the magnets.

They injected almost 400 amps of current into the diode circuit for a few milliseconds. Measurements made today showed the short circuit had disappeared.

Now the teams must conduct further tweaks and tests and restart the final commissioning of the accelerator. The LHC could see beams as early as next week.

Photo of LHC X-ray 2
Maximilien Brice, CERN

 

LHC restart timeline

February 2015
LHC Magnets Cooled

The Large Hadron Collider is now cooled to nearly its operational temperature.

Info-Graphic by Sandbox Studio, Chicago
 

LHC filled with liquid helium

The Large Hadron Collider is now cooled to nearly its operational temperature.
Read more…
LHC Magnets Powered

A first set of superconducting magnets has passed the test and is ready for the Large Hadron Collider to restart in spring.

Info-Graphic by Sandbox Studio, Chicago
 

First LHC magnets prepped for restart

A first set of superconducting magnets has passed the test and is ready for the Large Hadron Collider to restart in spring. Read more…
LHC Experiments Ready

Engineers and technicians have begun to close experiments in preparation for the next run.

Info-Graphic by Sandbox Studio, Chicago
 

LHC experiments prep for restart

Engineers and technicians have begun to close experiments in preparation for the next run.
Read more…
March 2015
LHC accelerator ready

The Large Hadron Collider has overcome a technical hurdle and could restart as early as next week.

Info-Graphic by Sandbox Studio, Chicago
 

LHC restart back on track

The Large Hadron Collider has overcome a technical hurdle and could restart as early as next week. Read more…
April 2015
First beam seen at LHC

The Large Hadron Collider has circulated the first protons, ending a two-year shutdown.

Info-Graphic by Sandbox Studio, Chicago
 

LHC sees first beams

The Large Hadron Collider has circulated the first protons, ending a two-year shutdown. Read more…
energy record broken at LHC

The Large Hadron Collider accelerated protons to the fastest speed ever attained on Earth.

Info-Graphic by Sandbox Studio, Chicago
 

LHC breaks energy record

The Large Hadron Collider accelerated protons to the fastest speed ever attained on Earth.
Read more…
May 2015
Low-Energy Collisions seen at the LHC

LHC sees first low-energy collisions

Info-Graphic by Sandbox Studio, Chicago
 

LHC sees first low-energy collisions

The Large Hadron Collider is back in the business of colliding particles.
Read more…
record-energy collisions achieved at the LHC

The Large Hadron Collider broke its own record again in 13-trillion-electronvolt test collisions.

Info-Graphic by Sandbox Studio, Chicago
 

LHC achieves record-energy collisions

The Large Hadron Collider broke its own record again in 13-trillion-electronvolt test collisions.
Read more…
June 2015
LHC Collisions for Physics

Data collection has officially begun at the Large Hadron Collider.

Info-Graphic by Sandbox Studio, Chicago
 

LHC arrives at the next energy frontier

Data collection has officially begun at the Large Hadron Collider.
Read more…

 

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