Guide to the Large Hadron Collider

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Other experiments

Totem experiment, part of the Large Hadron Collider at CERN
Totem weighs 20 tonnes

One of the LHCf detectors
LHCf is a minnow compared to some of the other detectors

David Shukman visits the LHC nerve centre

The LHC has six detectors in total: the four main ones and two smaller specialised machines, Totem and LHCf.

These specialised machines are designed to focus on so-called "forward particles".

These protons and heavy ions will come into close contact within the machine but will not collide head-on, like in the main experiments.

LHCf is located near the Atlas detector and will be used to simulate cosmic rays.

These are naturally occurring charged particles from outer space which bombard the Earth's upper atmosphere.

When they collide with other molecules - mainly oxygen and nitrogen - in the upper atmosphere it can trigger a so-called "particle shower".

Scientists are interested in cosmic rays as they can disrupt electronics and may also play a part in climate change and electrical storms.

It is hoped that by studying cosmic rays inside the LHC, scientists will be able to large calibrate ground-based detectors and better interpret results from them.

Although LHCf is a separate experiment it will be closely aligned with Atlas, hence its location.

Similarly, Totem (Total Cross Section, Elastic Scattering and Diffraction Dissociation) is aligned with the CMS detector and will measure the size of protons and how they scatter, amongst other things.

To do this it will measure particles produced very close to the main beam lines using specially designed detectors housed in vacuum chambers known as "roman pots".

Eight of these will be placed in pairs near the collision point of the CMS experiment.

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