Thursday, November 18, 2010

Smashing Baby: Lead Ion Collisions from the LHC

In November CERN announced the intention of the LHC to switch from protons to lead ions - lead stripped of their electrons - in order to probe "matter as it would have been in the first instants of the Universe’s existence".

Just four days later CERN completed it's transition from protons to lead ion beams and the results of the first few runs are now available for all to see.

These first set of images are from the ATLAS detector.

Before switching to a Lead Ion beam, the LHC had previously hit a high of 7 Tev per beam using proton beams. Using Leed, which contains 82 protons per atom the LHC will be able to collide 164 protons into each other every instance in comparison to the previously used proton beam which would collide only two protons per instance. This change in density due to the Lead is met with a corresponding increase in energy which is expected to reach a high of 287 TeV per beam.

Bellow are the results of the first collisions recorded in the CMS detector.

One of the main objectives for colliding lead-ions is for the production and analysis of quark-gluon plasma. This substance is thought to exist just moments after the big bang that created the universe. Being able to create and explore this substance will shed further light on the properties of the strong interaction on the gluons which bind quarks together to form larger particles such as protons and neutrons.

According to Symmetry Magazine the first measurement recorded more particles in the resultant collision than expected. It was theorised as we reach higher densities of matter a limit will be reached that prevents any more particles coming out of these collisions. As we're still seeing increases in the particles produced in these collisions, that limit appears to be some way off.

In a second group of experiments designed to have the lead ions not hit each other head on but slightly off center, scientists have been able to rule out the possibility that quark gluon plasma created at the LHC would flow more like a gas. That is, whilst the flow is somewhat higher than previously detected, it certainly flows like a liquid.

Available also are other images & videos including illustrations and media produced from collision simulations.

So this is what the primordial universe looks like.

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