Physics (Particle Physics) U1

What is the charge and mass of a proton

• Proton charge:
  1.60 × 10^-19

• Proton mass:
  1.67 × 10^-27

What is the charge and mass of a neutron

• Neutron charge:
  0

• Neutron mass:
  1.67 × 10^-27

What is the charge and mass of an electron

• Electron charge:
  -1.60 × 10^-19

• Electron mass:
  9.11 × 10^-31

What are isotopes

Isotopes are atoms of an element that have the same number of protons, but a different number of neutrons

What is isotopic data and how can it be used?

Isotopic data is the abundance of an isotope of an element in a sample

This can be used to trace origins in carbon dating.

(It involves using the ratio of the amount of stable carbon-12 to the amount of unstable carbon-14 in dead and alive tissue)

What are the 3 forces present in the nucleus

3 forces present in the nucleus:

1. Electrostatic forces of attraction —forces of repulsion between
   positively charged protons
   

2. Gravity — attractive gravitational forces due to the mass of the nucleons which pulls them towards the centre of the atom
   

3. Nuclear strong force — force that binds together quarks and hence protons and neutrons keeping them in place in the nucleus
   
   
   
   
   
   

What are properties of the nuclear strong force

Properties of the nuclear strong force:

• Much stronger than electrostatic forces of attraction
  

• Repulsive up to 0.5fm (to ensure that the nucleons weren’t drawn to a point, preventing matter from collapsing)
  

• Attractive up to 3fm (to override the electrostatic force of attraction and prevent the matter from seperating)
  

• Falls as distance increases after 1fm

What happens in beta minus decay

Beta minus decay:

• A neutron decays into a proton

• A beta minus particle is emitted (an electron)

• An anti electron neutrino is emitted
  (This conserves lepton number)

What happens in beta plus decay

Beta plus decay:

• A proton decays into a neutron

• A beta plus particle is emitted (a positron)

• An electron neutrino is emitted
  (This conserves lepton number)

What caused the hypothesis for the neutrino particles?

• When the number of Beta particles is plotted against kinetic energy, the graph shows a curve

• This demonstrates that both beta particles have a continuous range of energies

• This is because the energy released in beta decay is shared between the beta particles

• If beta decay was a simple 2 body process, the electron/positron emitted would have a specific energy

• So an extra particle is released which carries the extra kinetic energy and momentum

What is a photon

A photon is a discrete wave packet or quantum of electromag