particle physics 2

accelerator

to accelerate the particles (like protons or electrons) to very high energies

target

a collection of nuclear at rest (in liquid or solid form) that is bombarded and smashed apart by the accelerated particles

detector

a large device that allows one to observe and measure the reaction products of the above collisions

fixed target

accelerated particles bombard target particles at rest; reaction products mainly go forward in the direction of the incident particle, where they are detected by a big detector

collider mode

beams of particles are circulated in opposite directions around a ring and are brought together to make collisions at certain points around the ring; more expensive than the fixed target mode because of the bigger detector required

quantum field theory

the force between two particles is caused by the exchange of discrete particles, called exchange particles or exchange bosons

heisenberg’s uncertainty principle

product of the uncertainty in the measurement of a particle’s energy and the amount of time for the measurement has to be greater than Plank’s constant

quantum electrodynamics

the force is carried by massless particles called photons; the vacuum around an isolated electron is referred to as a Feynman diagram

isolated electron

constantly emitting and reabsorbing virtual photons. Those photons can also convert energy to mass by creating a matter-antimatter pair like the positron and electron. The vacuum around an isolated electron is actually a sea of virtual particles

why do particle accelerators needs to have high energies?

to create new, more massive particles; to probe particles at smaller length scales to look for substructure

why are high energies needed to look at small length scales?

large momentum implies large energy, so to probe the smallest length scales requires the highest energies

how high of an electron bombarding energy was needed for the SLAC experiments?

the goal of the SLAC experiments was to probe a length scale small compared to the size of the proton