The Large Hadron Collider

So with the big switch on coming this Wednesday a lot of people are probably wondering what the point is, why all the fuss, and indeed what is the Large Hadron Collider?

Well the LHC is a particle accelerator, the largest one ever built and also the largest and most expensive machine ever built, coming in at around 6.4 billion Euros. The LHC isn’t in itself an experiment, rather a large particle physics laboratory where many different experiments are planned to be preformed, and it is expected to make some extraordinary discoveries.

How it works

The whole machine is constructed in a 27 kilometer long tunnel beneath the Swiss-France border in the space previously occupied by another collider, the Large Electron Positron. In this space are beampipes, giant rings into which protons are inserted into beams, and sped up with magnets. These protons reach fantastic speeds, 99.99999999%, that’s 8 9s, of the speed of light.

To achieve this, you need some very powerful magnets. The only reason this powerful collider could be built is because of new superconducting and super-strong magnet technology. Each of these magnets in the circle is about 35 tones and there are 1,232 of them. The maximum fields inside these magnets go up to 9 Tesla, with is about 200,000 times the magnetic field of the Earth. To work, these magnets have to be kept incredibly cold, down to -271 degrees celsius, which is only 1.9 degrees above the coldest theoretical possible temperature (when molecules stop moving). To put that in perspective, the coldest part of space would be about -270 C (there are 3 inescapable degrees of microwave background radiation), so these magnets are kept colder then the universe itself.

At four different locations on the LHC are ‘interaction points’ where the beams that carry the protons are bent together using more magnets. At these points the two beams collide smashing individual protons together unleashing vast amounts of energy in a very small space and heat about 100 000 times that of the sun. The particles are so tiny that the task of making them collide is akin to firing needles from two positions 10 km apart with such precision that they meet halfway. This impact will be a brief example of the conditions present just after the Big Bang, and where it is hoped to witness some things humankind has never before seen. At each of these four intersections there are four main experiments.

ATLAS

ATLAS is one of two general-purpose detectors at the LHC. It will investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter. It is a giant machine, the biggest of the experiments, weighing in at about 100 jumbo jets and filling a cavern capable of housing Notre Dame Cathedral.

CMS

The CMS experiment is the other general-purpose detector that will investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter. Although it has the same scientific goals as the ATLAS experiment, it uses different technical solutions and design of its detector magnet system to achieve these.

Standing for the Compact Muon Solenoid (FUN FACT: it’s not very compact), it is the heaviest of the experiments weighing in at over 12,500 tonnes. This weight is mostly because it has to generate a large magnetic field.

LHCb

The LHCb experiment will help us to understand why we live in a Universe that appears to be composed almost entirely of matter, but no antimatter. It specialises in investigating the slight differences between matter and antimatter by studying a type of particle called the ‘beauty quark’, or ‘b quark’, hence the name Large Hadron Collider beauty experiment.

ALICE

ALICE is A Large Ion Collider Experiment. Rather than protons, ALICE is looking at lead ion collisions in the hunt for quark-gluon plasma.

Everything today is made up of atoms. Each atom has a nucleus, and is composed of protons and neutrons surrounded by electrons. Protons and neutrons are made up of quarks, which are bound together by particles called gluons. This incredibly strong bond means that isolated quarks haven’t been found, so hopefully with the heat generated in this experiment, the protons and neutrons will melt, freeing the quarks from their bonds with the gluons.

So some big impressive machines. So what is hoped to be found and answered here?

The Why

For the past few decades, physicists have been able to describe the fundamental particles that make up the Universe and the interactions between them. This understanding is encapsulated in the Standard Model of particle physics, but it contains gaps and cannot tell us the whole story.

Higgs boson

The LHC was built to find never before seen particles, primarily the Higgs boson particle. What is the origin of mass? Why do tiny particles weigh the amount they do? Why do some particles have no mass at all? At present, there are no established answers to these questions. The most likely explanation may be found in the Higgs boson, a key undiscovered particle that is essential for the Standard Model to work. First hypothesised in 1964, it has yet to be observed.

Why matter?

Another question that it is hoped will be answered is ‘why are we made of matter’? The Big Bang is the favored model of creation, however it gets it wrong somewhere. It tells us that matter and antimatter were created in equal amounts at the birth of the universe. The problem is that when matter and antimatter meet, they annihilate each other, transforming into energy. So it would seem there was more matter then antimatter for some to be left behind, but it is unknown why.

Dark Matter

The LHC may also create one of the great cosmic mysteries, dark matter. What is dark matter? Well that is an interesting question. Basically, the universe is a lot heavier then what visual indications would indicate. Much, much heavier. There are a lot of theories as to what dark matter is, so rather then dwell on that, lets try and understand why we believe it is there. Years ago the speed of the planets in our galaxy was grafted. The closer you were to the sun, the faster you moved as you were affected by its gravity more. So your graph and a nice downward trend. Years later, (I’m afraid I don’t remember who L, just that it was a women), decided to conduct the same test on stars as they sat in our galaxy, the Milky Way. Her graphs were left with a curious straight line, the stars on the outer edge of the Milky Way were moving in the same manner as those close to the center. This shouldn’t be, something else was having a gravitational effect. So once all the numbers were crunched, about 96% of the universe is unidentified, made up of something, that something is called dark matter and dark energy. We can’t see it, but its affect on gravity suggest that it is there.

Of all the different types of particles created in the big bang physicists have so far found and categorised 36, the ordinary matter particles. But theory predicts another 36 were also created. They’re called super-symmetric particles and they’re mirror images of the ordinary ones. Some of them could make up dark matter and should be created in the collider.

Black Holes

There is another, more sci fi possibility from the LCH as well, the creation of mini black holes. Despite all the hoopla, there is nothing to worry about hear as they would only exists for a fraction of a second. In fact, they wouldn’t be observed at all, the splash of energy as they evaporate would be what is detected to confirm their presence. So why sci fi? Well the fact that they are created would be an indicator of extra dimensions, it would mean the universe has more dimensions then the three space ones that we are sensitive to. Our universe might just be one sheet in a multitude of parallel universes.

So how is this possible? The standard model of particle physics predicts that the energies created by the LHC are too low to create black holes, extension to this predict the existence of extra spatial dimensions that would make black holes possible. So their creation would be an indication that the extensions are correct.

Watch in Action

Wednesday 10th September at 9am CEST some protons will be sent through the ring, but not collided, collisions aren’t expected until October.

For live status reports and more reading/pictures, keep an eye on this page throughout the day:

FIRST BEAM NEWSFEED: http://lhc-first-beam.web.cern.ch/lhc-first-beam/Welcome.html

LIVE WEBCAST: http://webcast.cern.ch/

Will the LHC Destroy us All?

No.

Despite the attention given to a few skeptics that disagree, the science just doesn’t agree. While the LHC will produce things never before seen, they will nevertheless be things that have been predicted.

Perhaps the biggest nail in the coffin for skeptics is the fact that collisions with higher energy happen in nature routinely, and the universe is still here.

Isn’t this all just reworded from the CERN website?

Uhh, I have to go.

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