HIGGS BOSON
WHAT IS HIGGS BOSON ?
- The Higgs boson is a type of boson, a force carrying subatomic particle.
- It carries the force that a particle experiences when it moves through an energy field, called the Higgs field, that is believed to be present throughout the universe.
- For example, when an electron interacts with the Higgs field, the effects it experiences are said to be due to its interaction with Higgs bosons.
- Since all the matter in the universe is made of these particles, working out how strongly each type couples to Higgs bosons, together with understanding the properties of Higgs bosons themselves, can tell us a lot about the universe itself.
WHAT ARE VIRTUAL PARTICLES ?
- According to quantum field theory, which is the theory physicists use to study these interactions, space at the subatomic level is not empty.
- It is filled with virtual particles, which are particles that quickly pop in and out of existence.
- They can’t be detected directly, but according to physicists their effects sometimes linger.
- The LHC creates a Higgs boson by accelerating billions of highly energetic protons into a head-on collision, releasing a tremendous amount of energy that condenses into different particles.
- When a Higgs boson is created in this hot soup, it has a fleeting interaction with virtual particles that creates a Z boson and a photon.
WHAT IS LARGE HADRON COLLIDER (LHC)?
- The Large Hadron Collider is the world’s largest and highest-energy particle collider.
- It was built by the European Organization for Nuclear Research between 1998 and 2008 in collaboration with over 10,000 scientists and hundreds of universities and laboratories, as well as more than 100 countries.
- The LHC creates a Higgs boson by accelerating billions of highly energetic protons into a head-on collision, releasing a tremendous amount of energy that condenses into different particles.
- As it is a heavy particle, the Higgs boson is unstable and decays into lighter particles.
FUNCTIONING OF LHC
- Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide.
- The beams travel in opposite directions in separate beam pipes – two tubes kept at ultrahigh vacuum.
- They are guided around the accelerator ring by a strong magnetic field maintained by superconducting electromagnets.
- The electromagnets are built from coils of special electric cable that operates in a superconducting state, efficiently conducting electricity without resistance or loss of energy.
- This requires chilling the magnets to ‑271.3°C – a temperature colder than outer space.
- For this reason, much of the accelerator is connected to a distribution system of liquid helium, which cools the magnets, as well as to other supply services.
- Thousands of magnets of different varieties and sizes are used to direct the beams around the accelerator.
- These include 1232 dipole magnets, 15 metres in length, which bend the beams, and 392 quadrupole magnets, each 5–7 metres long, which focus the beams.
- Just prior to collision, another type of magnet is used to “squeeze” the particles closer together to increase the chances of collisions.
- The particles are so tiny that the task of making them collide is akin to firing two needles 10 kilometres apart with such precision that they meet halfway.
- All the controls for the accelerator, its services and technical infrastructure are housed under one roof at the CERN Control Centre.
- From here, the beams inside the LHC are made to collide at four locations around the accelerator ring, corresponding to the positions of four particle detectors – ATLAS, CMS, ALICE and LHCb.
EFFECTS OF 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, say, a particle is created with a probability of 0.00001%, 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 short lived, 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.
FINDINGS OF LARGE HADRON COLLIDER
- 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, an 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.
WAY FORWARD
- The Standard Model has made many accurate predictions but it can’t explain what dark matter is.
- Testing its predictions as precisely as possible is a way for physicists to find whether there are any cracks in the Model – cracks through which they can validate new theories of physics.
SYLLABUS: MAINS, GS-3, SCIENCE AND TEHNOLOGY
SOURCE: THE HINDU
