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The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator, intended to collide opposing particle beams at an energy of 7 TeV. It lies in a tunnel 27 kilometres in circumference, on depth of 175 metres under the Franco-Swiss border near Geneva, Switzerland.
The Large Hadron Collider was built by the European Organization for Nuclear Research (CERN) with the intention of testing various predictions of high-energy physics, including the existence of the Higgs boson and of the large family of new particles predicted by supersymmetry. It is funded by and built in collaboration with over 10 000 scientists and engineers from over 100 countries as well as hundreds of universities and laboratories.
On 10 September 2008, the proton beams were successfully circulated in the main ring of the LHC for the first time. On 19 September 2008, the operations were halted due to a serious fault between two superconducting bending magnets. Due to the time required to repair the resulting damage and to add additional safety features, the LHC is scheduled to be operational in mid-November 2009
Purpose
It is anticipated that the collider will either demonstrate or rule out the existence of the elusive Higgs boson, the last unobserved particle among those predicted by the Standard Model. Experimentally verifying the existence of the Higgs boson would shed light on the mechanism of symmetry breaking, through which the particles of the Standard Model are thought to acquire their mass. In addition to the Higgs boson, new particles predicted by possible extensions of the Standard Model might be produced at the LHC.
Moreover, physicists hope that the LHC will help answer key questions such as:
-Is the Higgs mechanism for generating elementary particle masses in the Standard Model indeed realised in nature? If so, how many Higgs bosons are there, and what are their masses?
-Are electromagnetism, the strong nuclear force and the weak nuclear force just different manifestations of a single unified force, as predicted by various Grand Unification Theories?
-Why is gravity so many orders of magnitude weaker than the other three fundamental forces?
-Is Supersymmetry realised in nature, implying that the known Standard Model particles have supersymmetric partners?
-Why are there apparent violations of the symmetry between matter and antimatter?
-What is the nature of dark matter and dark energy?
-Are there extra dimensions,as predicted by various models, and can we detect them?
Of the discoveries the LHC might make, the possibility of the discovery of the Higgs particle and supersymmetric partners have been keenly awaited by physicists for over 30 years, although neither of these can be considered certainties. Stephen Hawking said in a 2008 BBC interview that "I think it will be much more exciting if we don't find the Higgs. That will show something is wrong, and we need to think again. I have a bet of one hundred dollars that we won't find the Higgs." Of supersymmetry it has been said "If the LHC does find supersymmetry, this would be one of the greatest achievements in the history of theoretical physics". And Hawking adds that "Whatever the LHC finds, or fails to find, the results will tell us a lot about the structure of the universe."
The expectation that the Higgs boson will be discovered at the LHC is reinforced by the impressive agreement between the precise measurements of particle processes at the LEP and the Tevatron and the predictions of the Standard Model. Moreover, there are strong theoretical reasons leading physicists to expect that the LHC will discover new phenomena beyond those predicted by the Standard Model. Referring to the so-called hierarchy problem, namely the fact that the Higgs boson mass is subject to quantum corrections which would make it so large as to undermine the internal consistency of the Standard Model.
Ion collider
The LHC physics program is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with ion collisions are included in the program. While lighter ions are considered as well, the baseline scheme deals with lead ions. This will allow an advancement in the experimental program at the Relativistic Heavy Ion Collider (RHIC). The aim of the heavy-ion program is to provide a window on a state of matter known as Quark–gluon plasma, which characterized the early stage of the life of the Universe.
The Large Hadron Collider was built by the European Organization for Nuclear Research (CERN) with the intention of testing various predictions of high-energy physics, including the existence of the Higgs boson and of the large family of new particles predicted by supersymmetry. It is funded by and built in collaboration with over 10 000 scientists and engineers from over 100 countries as well as hundreds of universities and laboratories.
On 10 September 2008, the proton beams were successfully circulated in the main ring of the LHC for the first time. On 19 September 2008, the operations were halted due to a serious fault between two superconducting bending magnets. Due to the time required to repair the resulting damage and to add additional safety features, the LHC is scheduled to be operational in mid-November 2009
Purpose
It is anticipated that the collider will either demonstrate or rule out the existence of the elusive Higgs boson, the last unobserved particle among those predicted by the Standard Model. Experimentally verifying the existence of the Higgs boson would shed light on the mechanism of symmetry breaking, through which the particles of the Standard Model are thought to acquire their mass. In addition to the Higgs boson, new particles predicted by possible extensions of the Standard Model might be produced at the LHC.
Moreover, physicists hope that the LHC will help answer key questions such as:
-Is the Higgs mechanism for generating elementary particle masses in the Standard Model indeed realised in nature? If so, how many Higgs bosons are there, and what are their masses?
-Are electromagnetism, the strong nuclear force and the weak nuclear force just different manifestations of a single unified force, as predicted by various Grand Unification Theories?
-Why is gravity so many orders of magnitude weaker than the other three fundamental forces?
-Is Supersymmetry realised in nature, implying that the known Standard Model particles have supersymmetric partners?
-Why are there apparent violations of the symmetry between matter and antimatter?
-What is the nature of dark matter and dark energy?
-Are there extra dimensions,as predicted by various models, and can we detect them?
Of the discoveries the LHC might make, the possibility of the discovery of the Higgs particle and supersymmetric partners have been keenly awaited by physicists for over 30 years, although neither of these can be considered certainties. Stephen Hawking said in a 2008 BBC interview that "I think it will be much more exciting if we don't find the Higgs. That will show something is wrong, and we need to think again. I have a bet of one hundred dollars that we won't find the Higgs." Of supersymmetry it has been said "If the LHC does find supersymmetry, this would be one of the greatest achievements in the history of theoretical physics". And Hawking adds that "Whatever the LHC finds, or fails to find, the results will tell us a lot about the structure of the universe."
The expectation that the Higgs boson will be discovered at the LHC is reinforced by the impressive agreement between the precise measurements of particle processes at the LEP and the Tevatron and the predictions of the Standard Model. Moreover, there are strong theoretical reasons leading physicists to expect that the LHC will discover new phenomena beyond those predicted by the Standard Model. Referring to the so-called hierarchy problem, namely the fact that the Higgs boson mass is subject to quantum corrections which would make it so large as to undermine the internal consistency of the Standard Model.
Ion collider
The LHC physics program is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with ion collisions are included in the program. While lighter ions are considered as well, the baseline scheme deals with lead ions. This will allow an advancement in the experimental program at the Relativistic Heavy Ion Collider (RHIC). The aim of the heavy-ion program is to provide a window on a state of matter known as Quark–gluon plasma, which characterized the early stage of the life of the Universe.