• CERN (the European Organization for Nuclear Research) recently found that Higgs boson decays to fundamental particles known as bottom quarks.
• Testing this and understanding more particles, require an upgradation to the Large Hadron Collider.

Why to study particles?

• Particle physics probes nature at extreme scales, to understand the fundamental constituents of matter.
• Particles communicate with each other in accordance with certain rules.
• These are embedded in what are known as the ‘four fundamental interactions’.
• The particles and three of these interactions are successfully described by a unified approach known as the Standard Model (SM).
• The SM is a framework that required the existence of a particle called the Higgs boson.
• The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator.
• One of the major aims of the Large Hadron Collider (LHC) was to search for the Higgs boson.

How are such tiny particles studied?

• Protons are collected in bunches.
• They are then accelerated to nearly the speed of light and made to collide.
• Many particles emerge from such a collision, termed as an event.
• The emergent particles exhibit an apparently random pattern.
• But they follow the underlying laws that govern part of their behaviour.
• Studying the patterns in the emission of these particles help understand the properties and structure of particles.

What is CERN's proposal?

• Higgs boson was discovered at the CERN Large Hadron Collider (LHC).
• The Higgs boson was detected by studying collisions of particles at different energies.
• But they last only for one zeptosecond which is 0.000000000000000000001 seconds.
• So, detecting and studying their properties requires an incredible amount of energy and advanced detectors.
• CERN has thus announced earlier this year that it is getting a massive upgrade to the LHC.
• This will be completed by 2026.

Why an upgrade?

• Luminosity is a measure of the number of protons crossing per unit area per unit time.
• Initially, the LHC provided collisions at unprecedented energies.
• This allowed scientists to focus on studying new territories.
• But, it is now time to increase the discovery potential of the LHC by recording a larger number of events.
• So upgrading (increasing the luminosity) will increase the rate of collisions.
• Eventually, the probability of most rare events will also increase.
• This offers scope for studying the properties of newly discovered particle and its effect on all other particles.
• In addition, understanding the properties of the Higgs boson will require their abundant supply.
• But the SM has its shortcomings, and there are alternative models that fill these gaps.
• It thus necessitates a High Luminosity LHC (HL-LHC).

How will it help?

• The beam in the LHC has about 2,800 bunches, each of which contains about 115 billion protons.
• The HL-LHC will have about 170 billion protons in each bunch, contributing to an increase in luminosity.
• After the upgrade, the total number of Higgs bosons produced in one year may be about 5 times the number produced currently.
• The experiments will be able to record about 25 times more data in the same period as for LHC running.

How will it be upgraded?

• The protons are kept together in the bunch using strong magnetic fields of special kinds.
• These are formed using quadrupole magnets.
• Focusing the bunch into a smaller size requires stronger fields.
• Therefore greater currents are employed, necessitating the use of superconducting cables.
• Newer technologies and new material (Niobium-tin) will be used to produce the required strong magnetic fields.
• The creation of long coils for such fields is being tested.
• New equipment will be installed over 1.2 km of the 27-km LHC ring.
• This will help in focusing and squeezing the bunches just before they cross.
• The LHC gets the protons from an accelerator chain.
• This will also need to be upgraded to meet the requirements of the high luminosity.
• Moreover, the length of each bunch is just a few cm.
• So, to increase the number of collisions a slight tilt is being produced in the bunches just before the collisions.
• This is to increase the effective area of overlap.