Particles Flashcards
Specific charge
Charge/mass
What type of particles does the strong nuclear force act on?
Hadrons
How does the strong nuclear force keep the nucleus stable?
Counteracts electrostatic forces of repulsion between the protons in the nucleus. It only acts on nucleons.
What is the range of the strong nuclear force?
It has a short range. It is repulsive below 0.5 fm, and attractive up to 3-4 fm.
What is the exchange particle of the strong nuclear force?
Gluons and pions.
What type of particles does the weak nuclear force act on?
All particles. It is responsible for decay interactions. and quarks change flavour during interactions.
What is the exchange particle for the weak nuclear force?
W+ and W- bosons.
Is strangeness conserved in the weak nuclear force?
Strangeness is not conserved.
What is the range of the weak nuclear force?
It has a short range of 10^-18 m.
What type of particles does the electromagnetic force act on?
Charged particles. It is responsible for the repulsion and attraction of charged particles.
What is the exchange particle for the electromagnetic force?
Virtual photons.
What is the range of the electromagnetic force?
It has an infinite range.
What type of particles does the gravitational force act on?
All particles with mass.
What is an exchange particle?
It is a force carrier - exchange particles carry energy and momentum between particles.
What is an anti-particle?
Particles that have the same rest energy and mass as a given particle, but all other properties are opposite.
Electron capture
p + e- = n + ve
W+ boson
Electron-proton collision
p + e- = n + ve
W- boson
Beta plus decay
p = n + e+ + ve
W+ boson
Beta minus decay
n = p + e- + ve
W- boson
What is annihilation?
A particle and an anti-particle collide, masses are converted into energy. Energy is released in the form of two photons.
Application: PET scanner
A positron emitting isotope is used, positrons collide and annihilate with naturally occurring electrons in the body. This emits gamma photons that can be easily detected in order to image the inside of the body.
What is pair production?
Photons are converted into mass: a particle and an anti-particle. This can only occur when the photon has an energy greater than the total rest energy of both particles. Excess energy is converted into kinetic energy of particles.
What is the only stable hadron?
Protons. All baryons will eventually decay into a proton.
Is strangeness conserved in the strong nuclear force?
Strangeness is conserved.
What is always conserved in particle interactions?
Energy, momentum, charge, lepton number, baryons number.
What is a muon?
A heavy electron. Decays into electrons.
What is the quark composition of a proton?
uud
What is the quark composition of a neutron?
udd
What is the quark composition of baryons?
Three quarks or three anti-quarks.
What is the quark composition of mesons?
A quark and an anti-quark.
