Nuclear Physics Flashcards
What as the first model of the atom like
A plum pudding - a sphere of positive chafe with tiny negative electrons stuck in
What was rutherfords experiment
He fired a beam of electrons at thin gold foil, he used a circular detector screen to measure the angle that alpha was deflected at
What were the results of rutherfords experiment
- most particles went straight throug
- some were deflected
- a few were deflected back by 180
What could be shown from rutherfords experiment
- most of the atom is free space
- there must be a positively charged nucleus
- the nucleus must be small and contain lots of mass, therefore has a great sense
What is closest approach and how is it measured
The closest distance a particle can get to another particle before being repelled
When electric potential energy equal initial kinetic energy
What is the use of closest approach
To Estimate a maximum size of a nuclear radius
What is electron diffraction used for
Estimating nucleus radius
What must happen to electrons to get them to diffract
There wavelength must be around 10(-15), therefore they must have a high energy by accelerating them to a high speed
How do you get an electron beam to diffract
Fire it at a material 1 atom thick
What does the diffraction pattern look like for an electron
A central bright maxima, with dimmer circular rings, the intensity will never be zero
What is an approx radius of an atom
0.05nm
What is the approx radius of a nucleus
1fm
What is the relationship between radius and nucleon number
Radius is dp to the cube root of the nucleon number
What is alpha absorbed by
Paper or a few cm of air
What is the range of beta
It’s absorbed by 3mm of aluminium or a metre or so of air
