Experiments at the world’s biggest particle smasher (the European Organization for Nuclear Research or CERN) have confirmed the existence of two new subatomic particles. The discoveries, known as Xi_b’- and Xi_b*-, are part of the baryon family of particles.
Baryons are composite particles comprising three quarks bound together by strong force. Protons and neutrons are types of baryons. Xi_b’- and Xi_b*- had been predicted in theories, but it took experiments at CERN’s Large Hadron Collider (LHC) near Geneva to find them.
WHAT ARE SUB-ATOMIC PARTICLES?
Scientists believed that the smallest part of matter was the atom; the indivisible, indestructible, fundamental unit of every things. But soon it was proved that atoms are composed of even smaller ‘Subatomic Particles’.
Subatomic particles are particles that are smaller than an atom. Protons, neutrons, electrons, neutrinos, and positrons are the five most important sub-atomic particles. The first three particles were known to be the building blocks of atoms. Neutrinos and positrons were discovered outside Earth’s atmosphere and of uncertain origin or significance.
TYPES OF SUB-ATOMIC PARTICLES
There are two categories of subatomic particles, Elementary Particles and Composite Particles. Elementary particles are not made up of other particles, they are absolute and discreet units, such as electrons, whereas the composite particles are made up of two or more elementary particles, such as protons and atom nuclei.
ELEMENTARY SUB-ATOMIC PARTICLES
There are twelve elementary subatomic particles divided into two categories, known as Leptons and Quarks. There are six different kinds, or “flavors”, of quarks. These include up, down, charm, strange, top, and bottom quark, each of which possesses variable charge & variable masses.
There are also six different types of Leptons, which include Electrons, Muons, Taus, Electron Neutrinos, Muon Neutrinos, and Tau Neutrinos. Whereas electrons and Muons both have a negative charge of -1 (Muons having greater mass), Neutrinos have no charge and are extremely difficult to detect.
COMPOSITE SUB-ATOMIC PARTICLES
Composite particles are bound states of two or more elementary particles. For example, a proton is made of two Up quarks and one Down quark, while the atomic nucleus of helium (or alpha) is composed of two protons and two neutrons.
ADDITIONAL SUB-ATOMIC PARTICLES – THE FORCE CARRIERS
In addition, there are also the subatomic particles that fall under the heading of Gauge Bosons. These are classified as “force carriers”, i.e. particles that act as carriers for the fundamental forces of nature. These include photons that are associated with electromagnetism, gravitons that are associated with gravity, the bosons of weak nuclear forces, and the eight gluons of strong nuclear forces.
Scientists also predict the existence of several more, what they refer to as “hypothetical” particles, so the list is expected to grow. Today, there are literally hundreds of known subatomic particles, most of which were either the result of cosmic rays interacting with matter or particle accelerator experiments.
CERN’S LARGE HADRON COLLIDER (LHC)
The LHC shot to global fame in 2012 when it unearthed the Higgs boson, the particle that is believed to confer mass. It was a major piece in the ‘Standard Model’ of physics, a theory that describes the basic particles of matter, how they interact and the forces between them. The facility is going through an upgrade to operate at higher energies from early 2015.