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.
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| Image: Maximilien Brice, 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.
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| Image: Maximilien Brice, CERN |
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.
Source: Symmetry
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