NUCLEAR PHYSICS Flashcards
Nucleons
Protons and Neutrons
Mass defect
The difference between total mass of constituent nucleons and mass of nucleus
Binding energy
The energy released when a nucleus is formed from its constituent nucleons OR the energy required to separate a nucleus into its constituent nucleons.
Binding energy per nucleon
The energy released per nucleon when a nucleus is formed from its constituent nucleons.
When will radioactive decay happen?
When the binding energy per nucleon of the products is higher than the binding energy of the reactants, so energy is released and the products are more stable.
Why do fusion and fission both release energy?
The binding energy per nucleon of the products in each case is higher than the binding energy per nucleon of the initial nuclei. Iron has the highest binding energy per nucleon, so splitting apart nuclei heavier than this releases energy and fusing nuclei lighter than this releases energy.
Beta minus particle
Fast moving electron
Beta plus particle
Fast moving positron
Alpha particle
Helium nucleus (2 protons and 2 neutrons)
Gamma ray
A photon of electromagnetic radiation of very high energy that is emitted in the decay of certain radioactive nuclei and in electron-positron annihilation.
Background radiation
Low levels of radiation in the environment.
Activity
The activity, A, of a radioactive sample is the number of nuclei decaying every second.
Count rate
The number of ionising particles detected per second.
Becquerel
The unit of radioactive decay, 1 Becquerel is equivalent to one decay per second.
Ionising radiation
It is radiation that has enough energy to remove tightly bound electrons from the orbit of an atom during an interaction, causing the atom to become charged or ionised.
Unstable atoms
When the binding energy per nucleon is not high enough to hold the nucleus together, unstable atoms will lose neutrons and protons as they attempt to become stable.
Spontaneous decay
The idea that radioactive decay happens on its own without any outside influence (eg. temperature) to get the isotope to decay.
Random decay
The idea that one cannot know or predict precisely when the next decay will happen or which nucleus will decay. The radioactive atom will have a fixed probability of decaying in a given time interval.
Geiger
Muller tube: An instrument used for measuring ionising radiation.
Photon
A discrete packet of electromagnetic radiation energy which contains a particular amount of energy that depends on the frequency of that radiation.
Isotope
Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.
Neutrino
A neutral subatomic particle that is emitted from beta – decay and interacts only through the weak interaction.
Decay constant
It is a measure of how quickly an isotope will decay: the bigger the value of the constant, the faster the rate of decay.
