LARGE HADRON COLLIDER

1. Context 

2. What is the Large Hadron Collider?

• The Large Hadron Collider is an expansive and intricate apparatus constructed for the examination of particles, which are the smallest constituents known in nature.
• Its physical structure entails a 27-kilometer-long circular track, situated 100 meters underground along the Swiss-French border. During operation, the collider propels two beams of protons, nearing the speed of light, in opposite directions within a ring of superconducting electromagnets.
• The magnetic field generated by these superconducting electromagnets maintains the protons in a precise beam, guiding them through beam pipes until they ultimately collide. In preparation for collision, a different type of magnet is employed to compress the particles, enhancing the likelihood of collisions.
• Described by the European Organization for Nuclear Research (CERN), which oversees the particle accelerator complex housing the LHC, the challenge is likened to aligning two needles precisely 10 kilometers apart so that they meet midway.
• To accommodate the substantial current carried by the LHC's powerful electromagnets, comparable to that of a lightning bolt, a cooling system using liquid helium is employed.
• This distribution system keeps critical components ultra-cold at a temperature of minus 271.3 degrees Celsius, colder than interstellar space. Due to these stringent requirements, adjusting the temperature of the colossal machine is a challenging task

3. The functioning of the LHC

• A hadron is a subatomic particle made up of smaller particles.
• The LHC typically uses protons, which are made up of quarks and gluons.
• It energises the protons by accelerating them through a narrow circular pipe that is 27 km long.
• Simply put, this pipe encircles two D-shaped magnetic fields, created by almost 9,600 magnets. There is a proton at the 3 o'clock position.
• It is made to move from there to the 9 o'clock position by turning on one hemisphere of magnets and turning on one hemisphere of magnets and turning off the other, such that the magnetic field acting on the proton causes it to move clockwise.
• Once it reaches the 9 o'clock position, the magnetic polarity is reversed by turning off the first hemisphere and turning on the second.
• This causes the proton to move in an anticlockwise direction, from the 9 o'clock position.
• This way, by switching the direction of the magnetic field more and more rapidly, protons can be accelerated through the beam pipe.
• There are also other components to help them along, focus the particles, and keep them from hitting the pipe's walls.
• Eventually, the protons move at 99.999999 per cent of the speed of light.
• In the process, they accrue a tremendous amount of energy according to the special theory of relativity.

4. The effects of a collision

• When two antiparallel beams of energised particles collide head-on, the energy at the point of collision is equal to the sum of the energy carried by the two beams.
• Thus far, the highest centre of mass collision energy the LHC has achieved is 13.6 TeV (teraelectronvolts).
• This is less energy than what would be produced if you clapped your hands once.
• The feat is that the energy is packed into a volume of space the size of a proton, which makes the energy density very high.
• At the moment of collision, there is chaos. There is a lot of energy available, and parts of it coalesce into different subatomic particles under the guidance of the fundamental forces of nature.
• Which particle takes shape depends on the amount and flavour of energy available and which other particles are being created or destroyed around it. 
• Some particles are created very rarely. If a particle is created with a probability of 0.00001 per cent there will need to be at least 10 million collisions to observe it.
• Some particles are quite massive and need a lot of the right kind of energy to be created (this was one of the challenges of discovering the Higgs boson).
• Some particles are extremely shortlived and the detectors studying them need to record them in a similar timeframe or be alert to proxy effects.
• The LHC's various components are built such that scientists can tweak all these parameters to study different particle interactions.

5. The findings of the LHC 

• The LHC consists of nine detectors. Located over different points on the beam pipe, they study particle interactions in different ways.
• Every year, the detectors generate 30, 000 TB of data worth storing and even more overall.
• Physicists pore through this data with the help of computers to identify and analyse specific patterns.
• This is how the ATLAS and CMS detectors helped discover the Higgs boson in 2012 and confirmed their findings in 2013.
• The LHC specialises in accelerating a beam of hadronic particles to certain specifications and delivering it.
• Scientists can choose to do different things with the beam. For example, they have used the LHC to energise and collide lead ions with each other and protons with lead ions.
• Using the data from all those collisions,

1. They have tested the predictions of the Standard Model of particle physics,'
2. The reigning theory of subatomic particles;
3. Observed exotic particles like pentaquarks and tetraquarks and checked if their properties are in line with theoretical expectations; and
4. Pieced together information about extreme natural conditions like those that existed right after the Big Bang.

6. What lies ahead for the LHC

• These successes strike a contrast with what the LHC has not been able to find "new physics", the collective name for particles or processes that can explain the nature of dark matter or why gravity is such a weak force, among other mysteries.
• The LHC has tested some of the predictions of theories that try to explain what the Standard Model can't and caught them short.
• This has left the physics community in a bind.
• One way forward, which is already in the works, is to improve the LHC's luminosity (a measure of the machine's ability to produce particle interactions of interest) by 10x by 2027 through upgrades.
• Another more controversial idea is to build a bigger version of the LHC, based on the hypothesis that such a machine will be able to find 'new physics' at even higher energies.
• While both CERN and China have unveiled initial plans for bigger machines, physicists are divided on whether the billions of dollars they will cost can be used to build less expensive experiments, including other colliders, with guaranteed instead of speculative results.