particles and anti particles Flashcards
what are photons
packets of electromagnetic radiation
what is visible light
one type of electromagnetic radiation
what is the electromagnetic spectrum
a continuous spectrum of all the possible frequencies of electromagnetic radiation
how are frequency and wavelength linked
frequency (f) and wavelength (lambda) are linked by f = c/lambda
what is the speed of light in a vacuum
3.00 x 10^8 ms^-1
how does electromagnetic radiation exist
as photons of energy
what does the energy of a photon depend on
the energy of a photon depends on the frequency of the radiation. E = h x f = hc/lambda
what does every particle have
each particle has a matching antiparticle with the same mass and rest energy, but with opposite charge
what is an antiparticle
a negatively charged particle with the same mass as a proton
what is an antineutrino
is the antiparticle of the neutrino
what is 1 MeV
1 x 10^6 eV
how can you create matter and antimatter
from energy. when energy is converted to mass you get equal amounts of matter and antimatter
what is the equivalence of energy and mass
energy can turn into mass and mass can turn into energy
what is the rest mass
the energy equivalent of the particles mass, measured in MeV
what happens if you fire two protons at each other at high speed
you end up with a lot of energy at the point of impact. this energy might be converted into more particles.
what happens if a proton is formed in the collision and what is that called
there will always be an antiproton to go with it. its called pair production
where is each particle-antiparticle pair produced
from a single photon
what is the form of energy that gets converted into matter and antimatter
its in the form of a photon
when does pair production only happen
if one photon has enough energy to produce that much mass - only gamma ray photons have enough energy
where does it happen near and why
it tends to happen near a nucleus which helps conserve momentum
what pairs do you usually get produced
electron-positron rather than any other pair because they have a relatively low mass
what is the minimum energy for a photon to undergo pair production
the total rest energy of the particles produced
what is the formula for minimum energy for a photon to undergo pair production
E(min) = h x f(min) = 2E(0) (the E then 0 is just the rest energy)
what is the result of a particle meeting an antiparticle
annihilation
what happens during annihilation
all the mass of the particle gets converted back into energy
how long do antiparticles exist for
usually only for a fraction of a second before annihilation occurs, so you dont get them in ordinary matter
what is annihilation between
a particle-antiparticle pair, which both have a rest energy of E.
what do both photons need
need to have a minimum energy, E(min), which when added together equals at least 2E for energy to be conserved in this interaction
what does 2E equal for annihilation
2E(min) = 2E(0)
What does E(min) equal
E(min) = h x f(min) = E
