Subatomic Particles

1. Subatomic Particles Ashley Fagan Ainslie Thompson Alanna Murphy Aja Lapointe Shanna Fredericks Melanie MacDonald

3. The Discovery of Subatomic Particles • On April 30,1897 J.J. Thomson discovered the electron • Professor Thomson used a simple velocity selector device in combination with a • cathode-ray tube. • Subatomic particles were accelerated from the cathode (-) to the Anode (+) with • a known speed

4. The definition of a subatomic particle according to the American Heritage Dictionary is: Any of various units of matter below the size of an atom, including the elementary particles and hadrons.

5. Subatomic Particles: • The diameter of a single atom ranges from 0.1 - 0.5 nm • (1 nm = 10-9m) • As small as the atom is, it is made of smaller subatomic particles: Electrons, Neutrons, and Protons

6. Quark: is a theoretical particle that is believed to be the constituent of hadrons. Lepton: A class of light, elementary subatomic particles which have no constituent parts. Neutrino: is an essentially massless, neutral lepton. Hadron: A class of subatomic particles which do have constituent parts.

7. What is a Quark? Quarks were "invented" by Murray Gell-Mannand George Zweig of Caltech in 1964. The name "quark" apparently originated in the phrase "three quarks" used by James Joyce in his novel Finnegans Wake.

8. The Quark Mass is so small that they could probably travel through a mile and a half thickness of lead without hitting another particle. • Quark Confinement: • Quarks can not exist by themselves. • All quarks must be bound to another quark or antiquark by the exchange of gluons.

9. What is a lepton? There are six leptons, three of which have electrical charge and three of which don't. The best known charged lepton is the electron (e). The other two charged leptons are the muon (µ) and the tau, which are electrons with a lot more mass. The charged leptons are all negative. The other three leptons are the neutrinos. They have no electrical charge and little, if any, mass. There is one type of neutrino for every type of electrically charged lepton.

10. Half a century ago, a physicist "invented" the neutrino to make an equation balance. It was an odd particle, to say the least. Tiny, energetic, with no mass or electric charge, and it was virtually undetectable.

11. Hard to see or not, scientists now believe that nature is full of the shadowy neutrino. According to rough calculations, a hundred trillion neutrinos whistle through your body every second. • Some varieties of neutrino can even pass right through the Earth --and giant clouds of interstellar • gas and dust-without leaving a trace, and without being changed in the process.

12. Hadrons Hadrons have no net strong charge (or color charge) but they do have residual strong interactions due to their color-charged substructure. Many types of hadrons were discovered in the 50's and 60's. The idea of the quarks was first proposed to explain the many observed hadrons. There are two classes of hadrons: baryons and mesons.

13. The End!