From Symmetry: “Scientists already planning for LHC long shutdown”

September 10, 2012 Re-posted 12.17.12 by Symmetry
Signe Brewster

Next year, scientific collaborations will take full advantage of the Large Hadron Collider’s time without beam.

“The Large Hadron Collider will go into a long shutdown early next year to allow scientists and technicians to prepare it for higher collision energy in 2015. It has been running at 7 TeV; scientists plan for it to reemerge at upward of 13 TeV. Beginning in February of 2013, highly coordinated teams will spend 20 months preparing its equipment for the change. Higher luminosity means more particle collisions, and the experiments will need more advanced equipment to keep up. With the detectors the most accessible they have been since their original construction, the four big LHC experiments will take the opportunity to perform upgrades and routine repairs. The collaborations already have plans for the new year.

man at cern

Alice Icon New
The ALICE experiment focuses on collisions of heavy ions to study the conditions present just after the big bang. The collisions produce a quark-gluon plasma, a hot soup in which quarks travel freely instead of being bound into particles. They also produce high-energy quarks and gluons that interact with the plasma and then fragment into jets of particles and gamma rays.

ALICE will install a new part to a system that records the energy of particles. The new Di-Jet Calorimeter will broaden the experiment’s ability to measure the energy of individual gamma rays. Scientists can study an individual gamma ray to infer the energy of the quark from which it was emitted. That way, they can study how the quark-gluon plasma affects the energy of the quark and resulting jet of particles.


ATLAS will add a fourth layer of pixels, known as the Insertable B-Layer, to its pixel detector. The increased number of pixels will enable measurements at a location closer to where particle collisions occur and allow scientists more accurately to identify jets of particles produced from bottom quarks.

Identifying these particles is important in the search for the Higgs boson, which, according to the Standard Model, frequently decays into bottom quarks. The ATLAS and CMS experiments discovered a Higgs-like particle this summer.


CMS Logo

The LHC experiments cannot record data from every single collision that occurs, so they select or discard this information at a split second’s notice using automatic triggers. At higher luminosity, the experiments will deal with more collisions and therefore will need better trigger systems.

During the long shutdown, the CMS experiment plans to add a new layer to their muon detector, which will help them to decide which collisions are worth studying.



LHCb’s most important project during the shutdown will be to replace a segment of beam pipe and its support structures. The new pipe will be able to withstand temperature changes and radiation better, and the lighter support structure will reduce background in the detector.

LHCb will also begin to prepare for the next planned shutdown, in 2018, when they will install an upgrade to their detector.

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.