Unit 1 Topic 2 - Nuclear Physics

Electromagnetic force

A fundamental, long-range force that acts between electrically charged particles, resulting in a force of attraction between oppositely charged particles and repulsion between similar charges.

Gravitational force

A fundamental, long-range force of attraction between two objects with mass.

Strong nuclear force

A fundamental, short-range force that acts as attraction/repulsion depending on the distance between particles. It acts as the 'glue' that holds atomic nuclei together through the neutrons holding the protons in place.

Weak nuclear force

A fundamental force responsible for particle decay and the change in characteristics of quarks.

Ionising radiation

High energy radiation that can affect the electrons surrounding an atom so that a charged ion is formed. It includes all wavelengths from ultraviolet to gamma radiation, with alpha and beta particles also included.

Non-ionising radiation

Electromagnetic radiation with low energy, ranging from wavelengths of radio waves to that of visible light.

Antimatter

A form of matter which consists of antiparticles, which have the same properties as particles but opposite charges.

Anti-particles

They have the same properties as particles, however they have opposite charges. They include antiprotons, antineutrons and positrons.

Decay series

A series of radioactive transmutations that an unstable nucleus undergoes to decay until it reaches a state of stability.

Alpha decay

A type of decay where a positively charged helium nucleus, containing 2 protons and 2 neutrons, is emitted from an atom.

Beta negative decay

A type of decay where a neutron spontaneously converts into a proton and creates an electron in the process, with an antineutrino being emitted in the process.

Beta positive decay

A type of decay where a proton spontaneously converts into a neutron, emitting a positron and a neutrino in the process.

Gamma decay

A type of decay that usually accompanies alpha or beta decay, consisting of a high-energy photon with no rest mass or charge.

Transmutation

Where an unstable element undergoes decay and emits a particle, with the goal of bringing the unstable element closer to being stable.

Inverse-square law

States that the intensity of radiation from a source is inversely proportional to the square of the distance from the source.

Inverse penetrative/ionising ability

States that the penetrative ability of a decayed particle is inversely proportional to its ionising ability.

Geiger muller counter

A device that counts the number of radioactive particles that collide with the sensor of the device.

Half-life

The average amount of time it takes for half of all radioactive isotopes of an element to decay.

Half-life formula

N = N0 (1/2)^n, where N is the amount of particles remaining after decay, N0 is the original number of particles and n is the number of half lives that have passed.

Atomic mass units

The unit of measurement for subatomic particles, equal to 1.66 * 10-27kg.

Electron volts

An alternative unit for energy, defined as the energy an electron gains when subjected to one volt of potential difference. It is equal to 1.6 * 10-19 Joules.

Natural transmutation

One nuclei spontaneously decaying into a daughter nuclei.

Artificial transmutation

Causing the decay of an element into a daughter nuclei by combining it with another particle, done as fission or fusion.

Energy-mass equivalence

The principle that mass and energy are interchangeable and represent two forms of the same physical property. EG when an object gains energy, its mass also increases by a small amount.

Energy-mass Formula

ΔE = Δmc^2, where ΔE is the energy content produced in a nuclear reaction, Δm is the mass defect and c is the speed of light.

Mass defect

The difference between the actual mass of atomic nucleus and the sum of the individual masses of its constituent protons and neutrons.

Binding energy

The minimum energy required to disassemble an entire nucleus into its constituent parts, or the amount of energy released when these same parts come together to form a nucleus.

Binding energy per nucleon

The minimum energy required to separate one nucleon from its nucleus.

Nuclear fission

The splitting of a heavier nucleus into lighter nuclei alongside the release of significant energy.

Fission chain reaction

A self-sustaining chain reaction where the neutrons released during nuclear fission cause the new atoms to split further, releasing significant amounts of energy and repeating the cycle exponentially.

Nuclear fusion

The combining of lighter nuclei to form a heavier nucleus, alongside the emission of significant energy.

Energy yield from fission and fusion

Nuclei that undergo fusion see a significant increase in binding energy, whereas nuclei that undergo fission see a small increase. This means that fusion yields approximately 3 to 4 times more energy per unit of mass than fission.