Teaching Standard Model at high school

Glossary

This Glossary explains most of the new terms appearing in the history of the Standard Model, on a basic level.

Detector A device for observing (mostly charged) particles, and observing the path of them. The mentioned detectors work by the following principle: the particle passing through the detector ionizes the material in the detector.  The effect of the  initial ionization should be amplified in order to produce a measurable signal.
As an example, consider the GM counter (two high-voltage electrodes with gas between them): the charged particle ionizes some of the gas molecules in the tube. The high voltage accelerates the now charged ions, which collide with more molecules ionizing them. This produces an 'avalanche' effect, giving a measurable signal (often connected to a speaker this results in an audible click). One GM counter detects only the passing of a particle and doesn't show its path: by using several of them, one could reconstruct the path.
The detectors for path-reconstruction shouldn't interact too strongly with the particle otherwise the path would be modified too much. This effect also depends on the initial momentum of the particle.
Bubble chamber (1952, Donald Glaser) The bubble chamber consists of a tank of unstable transparent liquid - often superheated hydrogen (which provides a source of proton targets) - in which passing charged particles initiate boiling as a result of the energy they deposit (by ionizing atoms) as they force their way through the liquid. (We see here that the bubble chamber is both target and detector: the protons are the target studied; the electrons 'detect' the passage of charged particles - via the Coulomb interaction which ionizes the atoms.)
A strong magnetic field is applied to the chamber, and the path of the charged particles will curl by the Lorentz-force according to their charges.
The few electron volts (eV) of energy needed to ionize the atoms is small compared with the energies of the particles involved in the interactions (typically in the GeV range; 1 GeV = 109eV), and so these particles are not deviated much from their curved paths in the magnetic field in which the bubble chamber is placed. (Electrons and positrons are an exception - their tracks spiral characteristically.)
As the bubbles grow fast, pictures are taken of the chamber.
Bubble chambers are no longer  in use: they are replaced by detectors with more favourable properties.
Cloud chamber (Charles T. R. Wilson, 1910, Nobel Prize 1927) A cloud chamber contains supercooled gas. The passing charged particle causes ionization which results in forming condensation nuclei. The path of the particle appears as a thin line of vapour. The gas particles may interact with the initial particle and the paths of the resulting charged particles will appear.
Cloud chambers were later substituted by bubble chambers.
Cosmic rays High energy particles (mostly protons) from all directions collide the Earth all the time. Most of these particles interact with the upper layer of the atmosphere resulting in a cascade of secondary cosmic ray particles (eg. muons). Some of them reach the surface of the Earth, but they are easier to study by high-altitude balloons.
A proportion of the cosmic rays come from the Sun's chromosphere. The origin of the rest is still unknown.
Accelerator A device used to produce high-speed (thus high-energy) beams of chaged particles. An accelerator uses electric field to accelerate the particles, and magnetic field to modify the direction of the beam and to focus it.
Cyclotron (Ernest Orlando Lawrence, 1931, Nobel Prize 1932) The earliest type of accelerators. It makes use of the magnetic force on a moving charge to bend moving charges into a semicircular path between accelerations by an applied electric field. The applied electric field accelerates electrons between the half disks of the magnetic field region. The field is reversed at appropriate frequency to accelerate the electrons back across the gap.
Synchrotron An accelerator where the accelerated particles have a circular path. Compared to the cyclotron, the radius of the path doesn't change (the particles travel in a circular tube), so the magnetic field must be synchronized to the momenta of the particles.
Boson A particle with a spin of an integer number (0, 1, 2...). Fundamental bosons are the mediators for interactions.
Fermion A particle with a spin of an odd half integer number (1/2, 3/2, 5/2...). Fundamental fermions are the building blocks of matter.
Hadron A particle consisting of quarks. ('heavy' particles)
Lepton A fundamental matter particle that does not participate in strong interactions (eg. electron, muon, neutrinos...). ('light' particles)
Meson  A particle (hadron) consisting of a quark-antiquark pair (eg. pion, kaon...). Mesons are bosons.
Pion  The lightest type of mesons. They are often produced in high energy particle collisions.
Baryon A particle (hadron) consisting of 3 quarks (eg. proton, neutron, lambda...). Baryons are fermions.
Quarks The building blocks of all hadrons. There are 6 'flavours' of quarks and each may come in 3 different 'colours'. Note that 'colour' and 'flavour' are just the names of the new quantum numbers and don't have to do anything with the original meaning of these words.
Feynman-diagram (Richard Philips Feynman, Nobel Prize 1965) A graphical way to represent an interaction by means of exchanging particles. Developed by Feynman to describe the electromagnetic interaction by interchanging photons first, but later it proved to be useful for other kind of interactions too.
Ionization The process by which a neutral atom or molecule acquires a positive or negative charge.
Interference The result of the superposition (addition of amplitude) of waves.
Photoelectric effect The effect of a metal surface emitting electrons if exposed to light (electromagnetic waves). The effect only occurs when the energy of one photon (hf) is larger than the work needed to separate the electron from the metal.
Weak interaction An interaction that is responsible for the decay of heavier leptons and quarks (eg. this results in the beta-decay of the nucleus). Particle that have a 'weak charge' feel the weak force.
Strong interaction An interaction between particles with a 'color charge' (ie. quarks). This interaction is responsible for holding the quarks together in a nucleon, and holding the nucleons together to form a nucleus.
Electromagnetic interaction An interaction between particles with an electric charge.
Standard Model The current theory of fundamental particles and their interactions. It includes all the matter-particles (quarks and leptons) and 3 kind of particles mediating the 3 kind of interactions (strong, electromagnetic and weak). Gravity is (presently) not part of the Standard Model.
Interaction According to the Standard Model, all interactions are realized by the mediation of certain particles. The particle responsible for the electromagnetic interaction is the foton, those responsible for the weak interaction are the W+, W- and Z0 particle, and the strong interaction is mediated by 8 gluons.
Exclusion Principle (Wolfgang Pauli, Nobel Prize in 1945) No two fermions of the same type can exist in the same state at the same place and time.
Uncertainity Principle (Werner Heisenberg, Nobel Prize in 1932) Some properties of a particle cannot be measured with exact precision at the same time. Such quantities are: the momentum and the location of the particle; the energy and the time required for measurement.
Antimatter According to Dirac's Theorem, all particles have an associated antiparticle with all properties (charge, spin) but mass being the opposite. In the current theory these antiparticles behave the same way as the particles (a system made of matter and one made of antimatter can't be distinguished by their inner processes).