Quadrupole magnets help to focus the particles into a tight beam so they are more likely to collide in greater numbers as they reach the LHC detectors. Each quadrupole has four magnetic poles arranged symmetrically around the beam pipe to squeeze the beam either vertically or horizontally.
As part of the shutdown, up to 18 superconducting magnets on the Large Hadron Collider (LHC) will be replaced, including 15 dipole magnets and 3 quadrupole magnet assemblies. Earlier this month technicians lowered a replacement quadrupole magnet assembly down the access shaft to the ALICE cavern. The cavern provides a handy access point to get equipment in and out of the LHC tunnel.
CERN photographers Maximilien Brice and Anna Pantelia took a set of pictures showing the operations with the magnets in the LHC tunnel and the upgrade work that is undergoing in the ALICE cavern. The image gallery is available on the CDS: http://cds.cern.ch/record/1552072?ln=en
Cian O'Luanaigh made a timelapse video showing how the magnet was lowered, raised then lowered once again onto a wheeled transporter that will carry it to position on the LHC.