Particle Physics

• Gluons bind quarks together and are subject to the strong interaction.
• The nucleus of an atom consists of protons and neutrons at the center of the atom.
• Protons are positively charged while neutrons are neutral.
• Both protons and neutrons have similar masses.
• Electrons are negatively charged, 1/1800 the mass of neutrons/protons, and in motion around the nucleus.
• The nucleus of an atom contains a dense, positively charged nucleus containing protons.
• Electrons are thought to orbit the nucleus like planets orbit the sun.
• In 1932, Chadwick used alpha particles to strike Be metal and formed a very penetrating type of radiation with no charge and a similar mass to a proton, which was called the neutron.
• By the early 1900s, the atomic model consisted of neutrons and protons in the nucleus.
• Nucleon number (A) (mass number) is the number of protons plus the number of neutrons in the nucleus i.e the total number of nucleons.
• Proton number (Z) (atomic number) is the number of protons in the nucleus.
• Alpha particle: 4 2+ Proton: 1 - Electron: 0 - Neutron: 1.
• He: 2 H: 1 - e: -1 - n: 0.
• Two atoms may have the same number of protons but different numbers of neutrons i.e they have the same proton number but different nucleon number.
• The kaon (K+), which is made of an up quark and a strange antiquark, lives much longer than most mesons, which is why it was called "strange" and gave this name to the strange quark, one of its components.
• Kaons are assigned a strangeness number of S = 1.
• There is partial conservation of strangeness – conserved during strong force interactions, but not weak force interactions.
• Each of the baryons is assigned a baryon number B=1, which can be considered to be equivalent to assigning each quark a baryon number of 1/3.
• Mesons, with one quark and one antiquark, have a baryon number B=0.
• No known decay process or interaction in nature changes the net baryon number.
• The neutron and all heavier baryons decay directly to protons or eventually form protons, the proton being the least massive baryon.
• The proton has nowhere to go without violating the conservation of baryon number, so if the conservation of baryon number holds exactly, the proton is completely stable against decay.
• An extremely small part of the mass of a hadron is due to the quarks in it.
• Gauge Bosons are the exchange particles, which may exist for only a short time, and are the mediators of a force.
• When two charged particles interact, they do so by exchanging a virtual photon, which is impossible to detect and hence the term virtual is used to describe the photon involved.
• The Feyyaman Diagram represents two electrons approaching then repelling each other.
• Each atom is said to be an isotope of the other.
• Isotopes are chemically indistinguishable because they have the same number of electrons and occupy the same place in the periodic table.
• Most elements are isotopic mixtures.
• Hydrogen has three forms: Hydrogen 1, Deuterium 2, Tritium 3.
• Ordinary hydrogen contains 99.99% of the Hydrogen-1 atoms.
• Water made from deuterium is called heavy water.
• A force is the effect on a particle due to the presence of other particles.
• The interactions of a particle include all the forces that affect it, but also include decays and annihilations that the particle might go through.
• We call the particles which carry the interactions force carrier particles.
• At a fundamental level, a force isn't just something that happens to particles, it is a thing which is passed between two particles.
• You can think about forces as being analogous to the situation where two people are standing on an ice pond, one person moves their arm and is pushed backwards, and the other person grabs at an invisible object and is driven backwards.
• Friction is caused by residual electromagnetic interactions between the atoms of the two materials.
• Nuclear bonding is caused by residual strong interactions between the various parts of the nucleus.
• The planets orbit because of the gravity that attracts them to the sun! Even though gravity is a relatively weak force, it still has very important effects on the world.