Particle Physics: Discovering and Describing Particle Interactions
Text Reading: Giancoli, Physics - Principles with Applications, Chapter 32: 1-6
- 32.1 High energy interactions between atoms, or their subparticles protons, neutrons, and electrons, reveal the existence of other subparticles. To produce these collisions, physicists accelerate charged particles (protons and electrons) in magnetic fields generated in cyclotrons, synchrotrons, and linear accelortators. By crossing beams of accelerated particles, physicists at CERN can fracture subatomic particles into constituent components.
- 32.2 Feynman diagrams are used to explain how two particles interact by creating EM fields that affect each other, or by exchanging photons. Each force is associated with a particle: electromagnetic force with photons, strong nuclear force with mesons, and weak nuclear forces by W+, W-, and Z0. Gravitational force is associated with the graviton, a particle which has not been observed.
- 32.3 All particles have corresponding antiparticles, which have the same mass as their corresponding particle, but the opposite charge except for the hHggs bosun and the photon are their own antiparticles. The current universe lacks antiparticles in quantity.
- 32.4 As with other interactions where energy is exchanged and conserved, particle interactions conserve specific characteristics, such as the baryon number and lepton numbers (along with energy and momentum, of course).
- 32.5 Neutrinos are low-to-no nass particles that can be detected through their weak interactions with heavy particles.
- 32.6 Particles are classified as
Particles can decay from one form to one or more others as long as key characteristics are conserved.
- Fundamental particles
- gauge bosons (gluons, photons, W, Z particles) which mediate fundamental forces
- Higgs boson (produces mass)
- Leptons (electrons, neutrinos, muons)
- mesons (quark + antiquark)
- baryons (3 quarks - proton, neutron, etc.)
- 32.7 Particles are considered stable if they last for a long time, but most subatomic particles produced by collisions decay quickly to other particles.
|Wavelength and Resolution||
h: Planck's constant
Read the following weblecture before chat: Subatomic Particle Interactions
Use the Accelerators and Particle Detectors option at The Particle Adventure to discover how physicists experiment with and describe particle interactions.
Chat Preparation Activities
- Forum question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
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If you want lab credit for this course, you must complete at least 12 labs (honors course) or 18 labs (AP students). One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!
- Lab Instructions: Cloud Chamber
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