Nuclear physics definitions Flashcards
Nuclide
The atomic species with a specific mass number A and proton number Z
Isotope
Nuclides that have the same number of protons but different number of neutrons
Atomic mass unit (1u)
One atomic mass unit (1u) is equal to one-twelfth of the mass of a carbon-12 atom
Mass defect
The difference between the total mass of the separate nucleons and the combined mass of the nucleus
Nuclear binding energy
The energy equivalent of the mass defect of a nucleus. It is the energy required to separate to infinity all the nucleons of a nucleus
Binding energy per nucleon
The total energy needed to completely separate all the nucleons in a nucleus to infinity divided by the number of nucleons in the nucleus
Nuclear fission
The splitting of a heavy nucleus into two lighter nuclei of approximately the same mass
Nuclear fusion
Occurs when two light nuclei combine to form a nucleus of greater mass
Radioactivity/radioactive decay
The process whereby a radionuclide is transformed into a more stable nuclide by emitting some forms of ionizing radiation
Radioactive decay - spontaneous
Radioactive decay is spontaneous because the probability of decay of a nucleus is unaffected by any external factors such as temperature, pressure or chemical composition
Radioactive decay - random
Radioactive decay is random as it is impossible to predict which nucleus will decay next even though the probability of decay per unit time is identical for all nuclei.
Decay constant
Probability per unit time of the decay of a nucleus
Half life
The half time of a radioactive nuclide is the time taken for the number of undecayed nuclei to be reduced to half its original number
Activity
The activity of a radioactive source is the number of radioactive decays per unit time in the source
