3.8 - DEFINITIONS Flashcards
Alpha decay?
the emission of an alpha particle from an unstable nucleus to make it more stable.
Activity?
the rate of decay of the radioactive nuclei in a given isotope
Background radiation?
radiation that is found in small quantities all around us
Beta decay?
the emission of a beta particle when a proton turns into a neutron (or vice versa) in an unstable nucleus
Binding energy?
The amount of energy/ wok required to split a nucleus into all its separate constituent particles
Chain reaction?
the process of the neutrons released by a fission reaction inducing further fissile nuclei to undergo fission
Closest approach
A method of estimating a nuclear radius by firing an alpha particle at it; calculating the point where all the alpha particle’s kinetic energy is converted into electric potential energy
Contamination?
the introduction of radioactive material to another object. The object is consequently radioactive
Control rods?
Rods found in nuclear reactors which absorb neutrons and control the rate of reaction
Coolant
a substance which passes through nuclear reactors and is responsible for removing heat from the core
Critical mass?
the smallest mass of fissile material required for a sustained nuclear reaction
Electron capture?
a process that occurs in proton-heavy nuclei, in which an electron is drawn into the nucleus, causing a proton to transition into a neutron, also releasing an electron neutrino
Fission?
The process in which a large unstable nucleus splits into fragments (neutrons and energy) which are more stable
Fusion?
The process of binding two smaller nuclei to form a larger nucleus and release energy
Gamma decay?
the emission of gamma rays from an unstable nucleus that has too much energy
Half-life?
the average time it takes for the number of radioactive nuclei in a sample to halve
Inverse square-law?
the intensity of (gamma) radiation at any point is inversely proportional to the square of the distance from the source
Irradiation?
the exposure of an object to radiation; the exposed object does not become radioactive
Mass defect?
the difference in mass between a nucleus and the sum of the masses of its constituent nucleons
Moderator?
a material in nuclear reactors that absorbs energy from fast moving neutrons, to slow them down to speeds that can be absorbed by fissile neutrons to induce fission
Radioactive dating?
the use of radioactive isotopes with known half-lives to date objects. The isotope that is usually used is Carbon-14
Radioactive waste?
the waste produces from the products of fission reactions, which is unstable and radioactive
Decay constant?
the probability of an individual nucleus decaying per second
Intensity?
the radiation energy per second passing normally through each unit area
