Particles and radiation Flashcards
What are the four fundamental forces?
Strong nuclear, weak nuclear, electromagnetic, and gravitational.
What is the strong nuclear force and over what distances does it act?
It is a very short range force and acts between nucleons in order to hold the nucleus together as all the protons are trying to repel each other.
Name and describe the three types of radioactive decay?
-Alpha decay, this is where an alpha particle made up of two neutrons and two protons are emitted.
-Beta decay, this is where a neutron decays into a proton, an electron and an antineutrino which are subsequently emitted from the nucleus.
-Gamma emission, this is where the nucelons inside the nucleus lose energy by emitting a gamma ray photon.
What is an anti-particle?
An anti-particle is a particle with the same mass but all of its other properties are opposite such as charge.
What is rest mass energy?
The amount of energy relesaed by converting all of the mass of a particle at rest into energy. This can be calculated by using the equation e=mc^2.
What is a mega electron volt and how is it calculated?
The energy of nuclear particles is usually given in MeV. One MeV is equivelent to 1.6 * 10^-19 J. It is defined as the amount of energy required to acclerate an electron of charge ‘e’ through a potential difference of 1 volt.
Volts = energy / charge
What is annihilation and how does it ocur?
Annihilation is where a particle meets with its corresponding anti-particle. When they meet, the total mass of the pair will be converted into energy in the form of two gamma ray photons.
What is pair production and how does it occur?
In this process, a photon with enough energy can interact with a large nucleous and be converted directly into a particle, anti-particle pair.
What is a fundamental particle?
Fundamental particles are particles which appear to have no structure and therefore cannot be broken down into smaller parts.
What is a quark and what are the names of the 6 different types?
Quarks are fundamental particles which make up protons and neutrons. They come in six different flavours: up, down, strange, charm, bottom and top. These quarks all have corresponding anti-quarks.
What is a gluon and what does it do?
Gluons are one of the four exchange particles. They act between quarks holding them together.
What are exchange particles?
Exchange particles are particles involved with the interaction of particles via the four fundamental forces. These particles are created, emitted, absorbed and destroyed by the interacting particles.
What are the different types of exchange particles and what force do they correspond with?
Electromagnetic force - photon.
Strong nuclear force - Gluon.
Weak nuclear force - W+, W-, Z0
Gravity - graviton.
What is the electro-magnetic force?
This is a force which occurs between charged particles. Virtual photons are created during this interaction. The force acts over infinite distances however, the strength of the force decreases with an inverse square relationship.
What is the strong nuclear force? (detail)
This is a force which acts between quarks, its exchange particle is a gluon. The force holds nucleons together and therefore also holds nuclei together. It is the strongest of the fundamental forces.
