The Large Hadron Collider started working again after a gap. An LHC experiment, ‘The Large Hadron Collider beauty (LHCb) experiment’, has observed three never-before-seen particles.
Write a brief note on the Large Hadron Collider (LHC) and its LHCb Experiment.
What is LHC?
The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator built by CERN, the European Council for Nuclear Research.
It is a giant, complex machine built to study particles that are the smallest known building blocks of all things.
Structurally, it is a 27-km-long track-loop buried 100meters underground on the Swiss-French border.
In its operational state, it fires two beams of protons almost at the speed of light in opposite directions inside a ring of superconducting electromagnets.
The magnetic field created by the superconducting electromagnets keeps the protons in a tight beam and guides them along the way as they travel through beam pipes and finally collide.
The particles are so tiny that the task of making them collide is akin to firing two needles 10 km apart with such precision that they meet halfway.
Since the LHC’s powerful electromagnets carry almost as much current as a bolt of lightning, they must be kept chilled.
The LHC uses a distribution system of liquid helium to keep its critical components ultracold at minus 271.3 degrees Celsius, which is colder than interstellar space.
About Large Hadron Collider beauty (LHCb) Experiment
The Large Hadron Collider beauty (LHCb) experiment specializes in investigating the slight differences between matter and antimatter by studying a type of particle called the "beauty quark", or "b quark".
An abundance of different quark types are created by the LHC before they decay quickly into other forms.
To catch the b quarks, LHCb has developed sophisticated movable tracking detectors close to the path of the beams circling in the LHC.
The LHCb experiment is situated at one of the four points around CERN’s Large Hadron Collider (LHC) where beams of protons are smashed together, producing an array of different particles.
How does it Work?
The aim of the LHCb experiment is to record the decay of particles containing b and anti-b quarks, collectively known as ‘B mesons’.
The experiment’s 4,500 tonne detector is specifically designed to filter out these particles and the products of their decay.
Rather than flying out in all directions, B mesons formed by the colliding proton beams (and the particles they decay into) stay close to the line of the beam pipe, and this is reflected in the design of the detector.
Other LHC experiments surround the entire collision point with layers of sub-detectors, like an onion.
But the LHCb detector stretches for 20 meters along the beam pipe, with its sub-detectors stacked behind each other like books on a shelf.
Quarks are elementary particles that come in six “flavors”: up, down, charm, strange, top, and bottom.
They usually combine together in groups of twos and threes to form hadrons such as the protons and neutrons that make up atomic nuclei.
But they can also combine into four-quark and five-quark particles, called tetraquarks and pentaquarks.
These exotic hadrons were predicted by theorists about six decades ago around the same time as conventional hadrons but they have been observed by LHCb and other experiments only in the past 20 years.
The Large Hadron Collider beauty (LHCb) experiment has observed three never-before-seen particles; a new kind of “pentaquark” and the first-ever pair of “tetraquarks”.
Pentaquark was observed in an analysis of “decays” of negatively charged B mesons.
The second kind is a doubly electrically charged tetraquark.
It is an open-charm tetraquark composed of a charm quark, a strange antiquark, and an up quark and a down antiquark.
It was spotted together with its neutral counterpart in a joint analysis of decays of positively charged and neutral B mesons.
Previous Runs and ‘God Particle’ Discovery
Ten years ago, scientists at CERN had announced to the world the discovery of the Higgs boson or the ‘God Particle’ during the LHC’s first run.
The discovery concluded the decades-long quest for the ‘force-carrying’ subatomic particle, and proved the existence of the Higgs mechanism, a theory put forth in the mid-sixties.
The Higgs boson and its related energy field are believed to have played a vital role in the creation of the universe.
The LHC’s second run (Run 2) began in 2015 and lasted till 2018. The second season of data taking produced five times more data than Run 1.
After three years of maintenance and upgradation, LHC started working again and now it will operate round-the-clock for four years at unprecedented energy levels of 13 tera electron volts.
The third run will see 20 times more collisions as compared to Run 1.
Electron volt and Tera electron volts An electron volt is the energy given to an electron by accelerating it through 1 volt of electric potential difference.
A TeV is 100 billion, or 10-to-the-power-of-12, electron volts.
Higgs boson/God Particle
The Higgs boson is the fundamental particle associated with the Higgs field.
The Higgs field is a field that gives mass to other fundamental particles such as electrons and quarks.
A particle’s mass determines how much it resists changing its speed or position when it encounters a force.
Not all fundamental particles have mass. The photon, which is the particle of light and carries the electromagnetic force, has no mass at all.
The Higgs boson was proposed in 1964 by Peter Higgs, François Englert, and four other theorists to explain why certain particles have mass.
Scientists confirmed its existence in 2012 through the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN in Switzerland.
This discovery led to the 2013 Nobel Prize in Physics being awarded to Higgs and Englert. ‘New Physics’
The term new physics refers to a range of fundamental developments and paradigm shifts that occurred in the physical sciences during the last half of the twentieth century.
These include The theory of quarks, which is essential to the standard model of fundamental particle physics
The study and application of macroscopic manifestations of quantum phenomena such as superconductivity, super-fluidity, lasing, and other types of spontaneous quantum self-organization;
The realization of electroweak unification and the quests for grand and total unification of the four fundamental interactions;
The burgeoning successes in gravitational physics, including gravitational wave and black hole physics; Inflationary, fundamental-particle, and quantum cosmology, which ultimately rely on total unification and quantum gravity schemes.
CERN began in the 1950s as the European Organization for Nuclear Research.
Today it is also known as the European Laboratory for Particle Physics.
It is one of the world's most prestigious research centers in the field of Particle Physics.
Its business is fundamental physics - finding out what makes our Universe work, where it came from and where it is going.
At CERN, some of the world's biggest and most complex machines are used to study nature's tiniest building blocks, the fundamental particles. By colliding these minute particles of matter physicists unravel the basic laws of nature.
CERN is the world’s largest nuclear and particle physics laboratory.
CERN is based in Geneva on the French-Swiss border. Presently CERN has 23 member states. India is an associate member of the CERN.
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