What does the acronym PET stand for? Why is PET a good example with which to begin a discussion of elementary particle physics?

PET stands for Positron Emission Tomography, which is a non-invasive imaging technique used in medical diagnostics to study the function of organs and tissues in the body.

In PET, a radioactive substance, usually a form of glucose, is injected into the patient, which emits elementary particles called positrons as it decays. Positrons are the antimatter counterpart of electrons and have the same mass but opposite charge.

When a positron comes into contact with an electron, a process called annihilation occurs. This process results in the production of two photons, which are other elementary particles. These photons move in opposite directions, and their detection allows for the creation of detailed images of the organs and tissues being examined.

PET serves as an excellent introductory example to discuss elementary particle physics for the following reasons: 1. It demonstrates the practical application of particle physics in medicine and other fields. 2. PET involves various elementary particles such as electrons, positrons, and photons, giving insight into particles' behavior and interactions. 3. The concept of antimatter (positrons) and the annihilation process illustrate fundamental principles in particle physics. 4. PET provides opportunities to discuss radioactive decay, another important topic in particle physics. By starting with PET, students can gain a better understanding of the importance of particle physics and its real-world applications, as well as familiarize themselves with some essential concepts and particles involved in the field.