Particle physics and radioactivity (C24,25,26) Flashcards
what model was there before the atom model
plum pudding model
what were rutherfords observations
most particles go through
some changed angle
what did rutherfords experiment imply
very small nucleus, mostly space
what is 1 u
1/12 the mass of a carbon 12 atom
1.661.x10^-27
what is r nought
1.2fm
what is used to write antiparticles
bar over the letter
4 fundamental forces
strong
weak
electromagnetic
gravity
what is the range of the strong force
femto metre
two classes of matter
hadrons and leptons
what is a hadron
something affected by the strong force
what is a lepton
something not affected by the strong force
What are the six quarks
up down strange charm top bottom
What is a baryon
a type of hadron with 3 quarks
What is a meson
a type of hadron with 2 quarks
What quarks are in a proton
up up down
what are the quarks in a neutron
down down up
Four types of decay
alpha
beta +
beta -
gamma
why does alpha decay occur
nucleaus to heavy
why does beta + decay occur
too many protons
why does beta - occur
too many neutrons
what must be conserved in decay equations
lepton number (postive for regulaur particles and negative for antiparticles)
Describe quark transformation of beta minus decay
down quark –> up quark electron and anti electron neutrino
Explain how a cloud chamber works
radiation ionises vapour, which condenses leaving tracks
how can you differentiate between types of radiation
magnetic field
what is emitted with a positron
neutrino
what is emitted with an electron
anti neutrino
what is a decay chain
the repeated decays of an element into daughter nuclei
what is decay
random and spontaneous
what is half life
the time taken for half the nuclei in a substance to decay
what is the unit of activity
Bequerels Bq, decays per second
what can the decay constant lambda be thought of
the decay probability per unit time
How can decay be modelled using spreadsheets
can use an iterative formula, and test values
How can materials be dated
use half lifes to calculate lambda and use the percentage of already decayed nulcei
What must be true about the elements used to date material
must have very long half life
What is true to notice mass defect
Need very precise measurements of very small masses
Describe annihilation
particle and antiparticle pair meet and turn into energy
describe pair production
a photon becomes a particle antiparticle pair
What is important about nuclei before and after fusion or fission
different amounts of mass
Why is there fusion in elements up to iron
as they produce energy
why is their fission from iron up
as fusion loses energy
What is induced fission
fission caused by the instability of absorbing another particle
What is a thermal neutron
a slow moving neutron used in fission reactors
what does the moderator do?
slows fast moving neutrons
what is a control rod
absorbs neutrons in reactor
