Particles and Radiation Flashcards
Isotope
Atoms with the same number of protons but different number of neutrons
Carbon dating
Calculating the percentage of of carbon-14 in an object and using the half life to calculate an approximate age
Strong Nuclear Force
- Keeps nuceli stable by counteracting the electrostatic force of repulsion between protons.
- Only acts on nucleons
SNF Range
Attractive up to 3fm
Repulstive below 0.5fm
Unstable Nuclei
- Nuclei with too many protons or neutrons or both.
- SNF not strong enough to keep them stable so they will decay
Alpha Decay
- Only occurs in large nuclei with too many neutrons and protons
- Releases a helium nucleus (2 proton, 2 neutron)
Beta Minus Decay
- Occurs in nuclei that are neutron rich
- Proton number increases by 1
- Neutron decays into a proton
- Electron is released (not from a shell)
- Electron neutrino is released
Discovery of Neutrinos
Energy levels were not the same after a beta minus decay, energy was not conserved. Lead to the hypothesis of neutrinos
Particles and Antiparticles have the same…
Same rest energy and mass, everything is opposite sign
Annihilation
- When a particle and its antiparticle collide
- Their masses are converted into energy
- This energy and kinetic energy release photons in opposite directions to conserve momentum
PET scanner
Positrons are introduced into the patient and then they annihilate with electrons emitting gamma photons which are easily detected
Pair Production
- Photon is converted into equal amount of matter and antimatter
- Only occur when photon has a greater energy than the 2 particles
Exchange Particle
Particle that carry energy and momentum between particles experiencing a force
Strong Force: Exchange Particle and Range
Gluon
3 x10 ^-15
Weak Force: Exchange Particle and Range
W boson (+ or -)
10^-18