8.0 Nuclear Physics Flashcards
Outcomes of the alpha scattering experiment
Calculations of the size of the nucleus
Set up of the alpha scattering experiment
Monoenergetic particles fired through a thin gold foil in a vacuum
Paths in the alpha scattering experiment
Most passed straight through, some experienced small diffraction, 1 in 10000 had diffraction > 90°
Results of the alpha scattering experiment
Atom must contain small concentration of positive charge and mass
Properties of alpha radiation
Low penetration and high ionisation
Properties of beta radiation
Mid penetration and mid ionisation
Properties of gamma radiation
High penetration and low ionisation
Identification of radiation
Absorption experiments using penetrative abilities
Alpha radiation range
5-10cm, stopped by paper or skin
Beta radiation range
1 meter, stopped by a few mm of aluminium
Gamma radiation range
Virtually infinite, Stopped by several cm of lead or meters of concrete
Applications of radiation
Thickness measurements
Inverse-square law for gamma
intensity is inversely proportional to the square of the distance
Sources of background radiation
Radon gas, cosmic rays, Medial sources
Define spontaneous
Decays occur on their own, without influence by external factors
Define random
Decays are unpredictable
Decay probability
Probability of decay is constant for a given nucleus
N-Z stable line shape
Initially linear along N=Z with curve above N=Z
What decay occurs when N > stable line
Beta minus
What decay occurs when N < stable line
Beta plus
What decay occurs when nucleus is too large
Alpha
Release of gamma radiation
After a decay, atom is often excited so releases energy in form of a gamma photon
Why is technitium-99m used as a gamma source
Short half life, available, easy to produce
Processes for estimating nuclear radius
Closest approach using coulombs law, electron diffraction
Uses of alpha particles
Smoke alarms
Uses of beta radiation
Detecting width
How should sources be stored
in a lead box
How should sources be handled
Use handling tools, use low active sources, keep away from others
How is the nuclear radius formula derived
From experimental data
Define mass difference
the difference between the mass of the nucleus and the total mass of its individual nucleons
Define binding energy
the energy required to break a nucleus into its individual protons and neutrons
Define nuclear fission
A large nucleus splits into two smaller nuclei, releasing energy
Define nuclear fusion
Two light nuclei fuse to form a heavier nucleus, releasing energy
What is a thermal neutron
A neutron that is in thermal equilibrium with its surroundings, having less energy
Process of induced fission
Nucleus absorbs a neutron, becoming unstable and undergoing fission, releasing energy
How can a chain reaction occur during nuclear fission
Neutrons produces by a fission reaction can cause others to undergo fission, repeating into a chain reaction
Define critical mass
The minimum amount of material required to sustain a nuclear chain reaction
Function of the moderator
To control the energies of the neutrons to improve their ability to cause fission
Function of control rods
To control the number of neutrons that are in the reactor
Function of the coolant
The substance used to transfer the generated heat
Materials of the moderator
Graphite, heavy water, water
Materials of the control rods
Boron, silver
Fuels used
Uranium (235), Plutonium
Protective considerations for nuclear reactions
remote handling, shielding, emergency shut down
Nuclear waste management
Cool in water baths, vitrify, store in lead or steel barrels, deep geological disposal
What is vitrification
The process of turning nuclear waste into glass to ease the storage process
