Physics

The Large Hadron Collider



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Far beneath the ground of modern day civilization, beneath the French-Swiss border, lies the greatest particle physics experiment of all time. It's the Behemoth machine that will recreate the "Big Bang" The "Big Bang" as a theory comes from the idea that the universe has expanded from a hot, dense initial condition to some finite time in the past and is still expanding to this day. George Lemaitre coined the phrase "Big Bang theory" when he hypothesized about the primeval atom.

In order to recreate the Big Bang, scientists have created an the world's most powerful particle accelerator- the Large Hadron Collider. Many people around the world were very fearful and concerned that when the Behemoth machine was fired, that the world was going to end. One young girl in India believed this so strongly that she took her own life before the experiment was carried out.

The LHC was the largest and most complex scientific experiment to ever be built and conducted. In fact it is a 5 billion dollar, 27 km ring of superconducting magnets that will whip protons around in an opposite direction 11, 245 times per second. The experiment was designed to study nature at the smallest particle scales imaginable. The protons will travel at a few billionths of the speed of lights and the protons will repeatedly be smashed head-on at four points around a ring. A collision energy of 14 trillion electron volts!

Now that is impressive! Put that energy into a volume a million million times smaller that a female mosquito and you have recreated the conditions present in the universe before the Big Bang. Einstein's theory of relativity, E=mc2, has allowed physicists to look at the world from its most basic level. Huge energy densities allow new particles to be created from this air because of the relationship between energy and mass.

The primary objective of the LHC is to find the Higgs boson particle, which would verify the 40 years old theory to explain the origin of mass. If we can understand Higgs, then we can understand the only missing piece in the standard model of particle physics. If we don't find the missing piece then how can we understand why the heaviest of nature's dozen or so particles is more than a billion times more massive than the lightest?

Although verify Higgs boson particle is the primary focus of this experiment, researchers are also hoping to discover information about black holes. Black holes created would disappear immediately however, their appearance would imply that the universe has additional spatial dimensions that go far beyond the standard model.

A far more likely discovery is supersymmetric particles. Supersymmetry is a hypothetical property of the universe that stated that three of nature's four fundamental forces(the electromagnetic, strong and weak forces) were once unified.

What is inside of the LHC? Well, some pretty amazing physics. The protons will smash head-on inside the LHC at CERN and will produced by the first stripping electrons from hydrogen atoms. They will then pass through a series of increasingly large accelerators build over the last 50 years and then injected into the 27 km long LHC ring. Once in the ring, the protons will be boosted to higher energies and guided around the ring in opposite directions by 9593 magnets and eventually will be forced to collide at four separate points around which enormous particle builders have been built.

What are the external features of the LHC? Atlas/CMS are cylindrical general purpose detectors designed to search for new particles, such as Higgs boson. The ATLAS cavern is huge and can hold most of Westminster Abbey, while the CMS weighs 12,500 tonnes. This experiment is so big because of the size of their magnets, which are needed to bend the particle beams and allow researchers to track the particle beams. There is a vast amount of material that will absorb and measure the energy of the particles.

Highly sophisticated computer programs will analyse tens of millions of electronic signals constantly being shunted to the ATLAS and CMS control rooms above ground. Researchers will spend many years to come searching through the signatures of the new particles produced when the beams collided.

Lhcb is located beneath the Geneva aeroport and is specifically made to study the trillion B mesons that the LHC will produce each year. There are particles contained at the bottom of the quark. These will allow physicists to study the behaviour of mesons and their antimatter partners, which could in fact, reveal the presence of new particles before they appear in the ATLAS and CMS. The LHCb may also solve the mystery about why matter and antimatter did not annihilate each other immediately after the Big Bang and leave a universe filled with radiation.

ALICE is an experiment that will provide matter at the most extreme densities and temperatures by creating the quark gluon plasma that is thought to have existed 10-25 seconds after the Big Bang. This would happen before the protons and neutrons even existed. The UHC would have to be filled with lead ions and electrically charged atoms, which would be hundreds of time heavier than any protons.

Each LHC beam will store an energy equivalent to 100 kg of TNT going off. Any hint that the protons are veering off course will cause a magnetic switchbox to kick the beam down two 700 metre long tunnels into a block of graphite shielded by 1000 tonnes of steel and concrete, which will act as a "bullet trap".

Tunnel: The LHC is a 27 km long tunnel originally built for the now dismantled Large Electron Position(LEP) Collider.

The most intriguing sight in the underground cavern is the CERN and the ATLAS detector. One of four big experiments has been built around the proton collision regions. ATLAS is 45m-long , 25m-high and weighs 7000 tonnes that are made with packed concrete layers.

Once the LHC is running optimally, the four LHC experiments will put out over 15 petabytes of data each year from the debris of the proton collisions. In order to analyse this gigantic amount of data, scientists are turning to the internet to help compute the data.

One of the biggest challenges for scientists is cooling the 38000 tonnes of magnet to a temperature of -271 degrees celcius using truckloads of liquid helium. If the superconducting wire coils inside the magnets get much warmer that this, they will resist electrical current and be unable to produce magnetic fields strong enough to bend the protons around the ring.

After all eight LHC sectors have been cooled, their power systems must be checked and engineers need to make sure that there are no leas in the 40000 junctions in the cryogenic plumbing, the LHC ring will be one of the coldest places on earth. All that needs to be done now is to inject the protons, whip them up to higher energies with electromagnetic kicks and then sit back and watch for the results.

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