3.2.1.4 Particles and Radiation: Particle interactions Flashcards
What are all forces caused by?
Particle exchange
What are exchange particles?
How forces act between two particles. They are virtual particles
What is a virtual particle?
A particle that only exists for a very short amount of time - long enough to transfer energy, momentum and other properties between particles in the interaction.
What causes electrostatic repulsion?
The exchange of virtual photons
What are exchange particles called for the four fundamental forces?
Gauge boson
What is the gauge boson for strong interaction?
Pions, pi+, pi-, and pi0
What particles are affected by strong interaction?
Hadrons only
What is the gauge boson for electromagnetic interaction?
Virtual photon (symbol is gamma)W
What particles are affected by em interaction?
Charged particles only
What is the gauge boson for weak interaction?
W+, W- bosons
What type of particles are affected by weak interaction?
All types
What determines the range of the force?
The size of the exchange particle - heavier exchange particles have a shorter range.
Why does the em force have infinite range?
The photon has zero mass
Describe beta-minus decay
n -> p + e- + electron antineutrino
Describe beta-plus decay
p -> n+ e+ + electron neutrino
Describe electron capture
p + e- -> n + electron neutrino
What is electron capture?
Where proton-rich nuclei ‘capture’ an electron from inside the atom and change into a neutron.
What is the exchange particle for electron capture?
W+ boson
What is the exchange particle for beta-minus decay?
W- boson
What is the exchange particle for beta-plus decay?
W+ boson
What is an electron-proton collision?
Where an electron collides at high speed with a proton - the electron is the particle that’s acting because it’s being fired at the proton, so the boson comes from the electron
Describe electron-proton collision
p + e- -> n + electron neutrino
What is the exchange particle for electron-proton collisions?
W- boson
What is the exchange particle for electro magnetic repulsion?
Virtual photon (gamma)
What is electromagnetic repulsion?
When particles with equal charge get close to each other, they repel.
