Particle Physics

Copyright © October 2004 Ted Nissen





1      Particles

1.1   Illustration

1.1.1   Sense of Scale diagram




1.1.5   Description     Electron    This negatively charged particle surrounds the nucleus of an atom which is positively charged by its protons and thus the electrons are kept bound to the nucleus. The electrons are assembled in shells around the atomic nucleus and that unique shell assembly determines the characteristics of the atom. Atoms are kept from passing thru one another because of the electrons negative charge. This repulsion of like charges keeps electrons apart. The electron was the first subatomic particle discovered in 1897 by J.J. Thomson     Quarks    Up Quark  Classified as a fermion (matter) the up quark is the least massive of all the quarks. It combines with the down quark to form the atomic nucleus (Protons & Neutrons). Individual quarks have never been observed but particle physicists are convinced of their existence because of indirect evidence. Murray Gell-Mann and George Zweig independently announced the theoretical existence of quarks in 1964.    Down Quark  Down quarks and up quarks make up the protons and neutrons that form atomic nuclei and therefore they are responsible for the vast bulk of all matter that we experience and see. Two down quarks and an up quark comprise a neutron (-1/3 + 1/3 +2/3=0). One down quark and two up quarks comprise a proton (-1/3 + 2/3 + 2/3=1). Murray Gell-Mann and George Zweig quark hypothesis was confirmed at the Stanford Linear Accelerator Center in 1968     Gluon    The gluon which carries the strong force works at small distances –1013 cm or less. The gluon “glues” quarks together in groups of threes to form protons and neutrons and in different combinations to form other particles. Protons and neutrons are held together by the strong force without which would move away from each other due to the repulsion caused by their like electrical charges. Deutsches Elektronen Synchrotron in Hamburg Germany first discovered this particle in 1979 thru indirect evidence