Today at 10:28 a.m. the world's largest particle accelerator (Large Hadron Colider: LHC) started up for the first time. The LHC fires selected particles directly at one another around a 27 kilometer ring at speeds around 99.99% the speed of light. The collisions will create energy never before seen outside of a telescope, roughly equivalent to the energy used in the Big Bang. These collisions, which occur 600 million times a second, will generate temperatures more than 100,000 times that of our Sun's core!
Several experiments are being undertaken to find out more about what our universe is composed of, how these components interact, and how the interaction brings about matter.
The six experiments at the LHC are all run by international collaborations, bringing together scientists from institutes all over the world. Each experiment is distinct, characterised by its unique particle detector.
The two large experiments, ATLAS and CMS, are based on general-purpose detectors to analyse the myriad of particles produced by the collisions in the accelerator. They are designed to investigate the largest range of physics possible. Having two independently designed detectors is vital for cross-confirmation of any new discoveries made.
Two medium-size experiments, ALICE and LHCb, have specialised detectors for analysing the LHC collisions in relation to specific phenomena.
Two experiments, TOTEM and LHCf, are much smaller in size. They are designed to focus on ‘forward particles’ (protons or heavy ions). These are particles that just brush past each other as the beams collide, rather than meeting head-on
The ATLAS, CMS, ALICE and LHCb detectors are installed in four huge underground caverns located around the ring of the LHC. The detectors used by the TOTEM experiment are positioned near the CMS detector, whereas those used by LHCf are near the ATLAS detector.
In the following TED video presentation, Brian Cox describes the experiment he is working on at the LHC:
ALICE.
ALICE "...will collide lead ions to recreate the conditions just after the Big Bang under laboratory conditions." Brian does a wonderful job of describing this experiment and the promise that it has in allowing us to better understand our existence.