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FOR AGES 10 AND UP

INFORMATION - SUBATOMIC PARTICLES - BASIC

Dear Friend:

Atom is a very tiny particle. Its nucleus is even 100,000 times smaller than the atom as a whole,

which contains almost all the mass of the atom.

There are hundreds of particles tinier than even atoms.

These are called Subatomic Particles.

You cannot 'see' them, but scientists have 'observed' them by various experiments.

There are two kinds of particles.

Fermions and Bosons.

Particles with half-integer spins (1/2) are called Fermions, in honor of Italian Physicist Enrico Fermi.

Particles with spin equal to zero or with whole-integer spin (0, 1) are called Bosons, in honor of Indian physicist Satyendranath Bose.

Scientists have divided all of the particles into Two broader groups:

Hadrons and Leptons.

Those who are sensitive to the Strong Nuclear Force are called hadrons and

those who are immune to it are called leptons.

The family of leptons consists of 6 particles.

Electron, Muon, and Tau particle.

Each of these particles has a different Neutrino associated with it.

Electron neutrino, Muon neutrino, and Tau neutrino.

Thus, neutrinos are of three kinds.

Leptons are all Fermions. Leptons seem to have no internal structure.

Hadrons are composite particles. They are made up of more fundamental particles called Quarks.

Hadrons are further divided into two smaller families.

Baryons and Mesons.

Hadrons that are fermions are called baryons.

Hadrons that are bosons are called mesons.

Baryons are fermions and are made up of 3 quarks.

Baryons include: Neutron, Proton, Lambda particle, Omega minus particle, antiproton, and anti neutron.

Mesons are bosons and are made up of a quark and an anti quark.

Mesons include: Pion, Kaon, and psi meson.

Just as periodic table of elements, scientists have arranged these subatomic particles into so called the Eightfold Way.

For example, the family of mesons with zero spin forms hexagonal pattern with one particle at each vertex and two particles in the center.

Some of the particles can be arranged into a triangular shape or a pyramidal shape.

Omega minus particle was predicted in this way, which made earn the Nobel Prize to Murray Gell-Mann in 1969.

Also, hidden in the patterns of the Eightfold Way was the suggestion that there are even smaller and more fundamental particles - which are now known as Quarks.

Isn't it amazing. What a power of organizing!

GREAT!!!

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