Particles and Radiation Flashcards
What is specific charge, its formula and units
Specific charge of a particle is a charge-mass ratio
specific charge = charge/mass (Ckg^-1)
Define isotopes
Atoms with the same number of protons but different number of neutrons
What is strong nuclear force
A force that keeps nuclei stable by counteracting the electrostatic force of repulsion between protons
(attractive from 0.5 to 3fm, repulsive below 0.5fm)
- has a very short range
Sim/diff of corresponding particles/antiparticles
Same mass, same rest energy
all other properties are opposite (e.g charge)
What are photons
Electromagnetic radiation which transfer energy and have no mass
E = hf (energy of photon is proportional to its frequency)
Explain the process of annihilation
Particle and corresponding particle collide where mass is converted to energy
2 photons are released in opposite directions to conserve momentum
Excess energy is used as kinetic energy
Explain the process of pair production?
When a photon is converted to an equal amount of matter and antimatter
Only occurs when photon has greater energy then total rest energy as excess energy is converted into Ek
What are the four fundamental forces
Gravity, electromagnetic, weak nuclear and strong nuclear
What are exchange particles?
Forces between particles are caused by exchange particles
Exchange particles carry energy and momentum
What is weak nuclear force
Responsible for beta decay, electron capture and electron-proton collisions
Exchange particle is W+/- bosons
Which particles are fundamental particles and what does this means?
Leptons are fundamental particles and this means they cannot be broken down further
Which type of particle experiences strong nuclear force
Only hadrons
Which particle type does not experience strong force and give examples
Leptons e.g electrons, neutrinos and anti-neutrinos
Which particles is the only stable baryon
Proton as all other baryons will eventually decay into a proton.
What particle can decay into electrons
Muons (aka heavy electrons)
What do you know about strange particles?
They’re produce via strong nuclear interactions but decay via weak interactions
(e.g kaons decays into pions through weak interaction)
Strong interactions = strangeness is always conserved
Weak interactions = can change by 0 +1 -1
Strange particles must be created in pairs
What is the baryon number of quarks in only baryons
1/3 (including u, d and strange quarks)
What is the charge and strangeness of a strange quark
-1/3e (Q)
-1 strangeness
What are the quark combination of all kaons
K0 = down + antistrange (strangeness = +1)
K+ = Up + antistrange (strangeness = +1)
K- = anti up + strange (strangeness = -1)
Quark combination of all pions (remember to conserve charge)
pi0 = u+/u or d+/d
pi+ = up+/down
pi- = /u + d
Strangeness is all 0
List properties that always should be conserved
Energy and momentum
Charge
baryon number
leptons number
(strangeness only in strong interaction)
Strangeness can only be changed by how much in a weak interaction
By one (-1, +1)
Why is an antineutrino conserved in a beta minus decay
This is to conserve the lepton number
When you have a higher frequency what happens to the size of the wavelength
It decreases
Can protons experience a weak nuclear force
Yes because electrons are able to interact with them
Can a pion 0 experience a electromagnetic force
No because it doesn’t have a charge!
Can a neutrino experience a strong nuclear force?
No because it is a lepton, only hadrons experience SNF.
In electron capture what is the exchange particle and why?
The exchange particle is a W+ boson because the protons positive charge is taken away which results in a neutrino.
What doesn’t change in a beta minus decay
The mass number
What interaction produces strangeness and what interaction decays strangeness into non-strange particles
Strong - production of strangeness (as strangeness is conserved)
Weak - strangeness is lost (via decay)
What do mesons eventually decay into
Kaons eventually decays into pions
What are some key difference between internal conversion and beta decay
- in beta decay an anti neutrino is produced unlike conversion
- in beta decay the proton and neutron number change unlike conversion
- internal conversion is electrostatic force whilst beta decay is weak interaction
Explain why there is a minimum rest energy in pair production
At least the rest mass of the two corresponding particles is needed
Define specific charge
The ratio of charge to mass of the nucleus
What is order of magnitude for the diameter of an atom
10^-11m
