3.8 - DEFINITIONS

Question 1

Alpha decay?

Answer 1

the emission of an alpha particle from an unstable nucleus to make it more stable.

Question 2

Activity?

Answer 2

the rate of decay of the radioactive nuclei in a given isotope

Question 3

Background radiation?

Answer 3

radiation that is found in small quantities all around us

Question 4

Beta decay?

Answer 4

the emission of a beta particle when a proton turns into a neutron (or vice versa) in an unstable nucleus

Question 5

Binding energy?

Answer 5

The amount of energy/ wok required to split a nucleus into all its separate constituent particles

Question 6

Chain reaction?

Answer 6

the process of the neutrons released by a fission reaction inducing further fissile nuclei to undergo fission

Question 7

Closest approach

Answer 7

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

Question 8

Contamination?

Answer 8

the introduction of radioactive material to another object. The object is consequently radioactive

Question 9

Control rods?

Answer 9

Rods found in nuclear reactors which absorb neutrons and control the rate of reaction

Question 10

Coolant

Answer 10

a substance which passes through nuclear reactors and is responsible for removing heat from the core

Question 11

Critical mass?

Answer 11

the smallest mass of fissile material required for a sustained nuclear reaction

Question 12

Electron capture?

Answer 12

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

Question 13

Fission?

Answer 13

The process in which a large unstable nucleus splits into fragments (neutrons and energy) which are more stable

Question 14

Fusion?

Answer 14

The process of binding two smaller nuclei to form a larger nucleus and release energy

Question 15

Gamma decay?

Answer 15

the emission of gamma rays from an unstable nucleus that has too much energy

Question 16

Half-life?

Answer 16

the average time it takes for the number of radioactive nuclei in a sample to halve

Question 17

Inverse square-law?

Answer 17

the intensity of (gamma) radiation at any point is inversely proportional to the square of the distance from the source

Question 18

Irradiation?

Answer 18

the exposure of an object to radiation; the exposed object does not become radioactive

Question 19

Mass defect?

Answer 19

the difference in mass between a nucleus and the sum of the masses of its constituent nucleons

Question 20

Moderator?

Answer 20

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

Question 21

Radioactive dating?

Answer 21

the use of radioactive isotopes with known half-lives to date objects. The isotope that is usually used is Carbon-14

Question 22

Radioactive waste?

Answer 22

the waste produces from the products of fission reactions, which is unstable and radioactive

Question 23

Decay constant?

Answer 23

the probability of an individual nucleus decaying per second

Question 24

Intensity?

Answer 24

the radiation energy per second passing normally through each unit area