NUCLEAR PHYSICS Flashcards
(36 cards)
Activity
The rate of decay of the radioactive nuclei in a given isotope. It is
proportional to the total number of nuclei in the sample and is measured in
Becquerels.
Alpha decay
The emission of an alpha particle (2 protons and 2 neutrons) from
an unstable nucleus (usually one with too much mass) to make it more stable.
Alpha radiation is strongly ionising and is stopped by a few centimetres of air or a
sheet of paper.
Atomic mass unit
A unit used to express atomic masses. One AMU is equal to
the one twelfth of the mass of a carbon atom.
Background radiation
Radiation that is found in small quantities all around us. It
originates from natural sources such as rocks and cosmic rays as well as
man-made sources such as nuclear accidents and medical sources
Beta decay
The emission of a beta particle when a proton turns into a neutron
(or vice versa) in an unstable nucleus. Beta minus radiation is weakly ionising.
Beta plus radiation is immediately annihilated by electrons.
Binding energy
The amount of energy required to split a nucleus into all its
separate constituent nucleons. It is equivalent to the mass defect.
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 a alpha
particle at it. It involves calculating the distance at which all the alpha particle’s
kinetic energy is converted to electric potential energy.
Combination
The introduction of radioactive material to another object. The
object is consequently radioactive.
Control rods
Rods found in nuclear reactors to absorb neutrons and control the
rate of reaction. They can be raised or lowered depending on the rate required.
Coolant
A substance that passes through nuclear reactors and is responsible for
removing heat from the core. This heat is then used to generate energy.
What is Critical Mass?
The smallest mass of fissile material required in a fission reactor for a chain reaction to be sustained.
Critical mass is essential for maintaining nuclear reactions in reactors.
Define 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. An electron neutrino is also produced.
Electron capture is a form of beta decay.
What is Fission?
The splitting a nucleus, to form two smaller daughter nuclei, neutrons and energy.
Fission is the primary reaction used in nuclear power plants.
What is Fusion?
The joining of two smaller nuclei to form a larger nucleus and to release energy.
Fusion is the process that powers the sun.
What occurs during Gamma Decay?
The emission of gamma rays from an unstable nucleus that has too much energy.
Gamma radiation requires several centimetres of lead to be stopped.
What is Half-Life?
The average time it takes for the number of radioactive nuclei in a sample to halve.
Half-life is a critical concept in understanding radioactive decay.
Explain the Inverse Square-Law in relation to radiation.
A law that governs the intensity of gamma radiation, meaning that the intensity of radiation at any point is inversely proportional to the square of the distance from its source.
This law is crucial for radiation safety and shielding.
What is Irradiation?
The exposure of an object to radiation. The exposed object does not become radioactive.
Irradiation is different from contamination.
Define Mass Defect.
The difference in mass between a nucleus and the sum of the masses of its constituent nucleons.
Mass defect is related to the binding energy of the nucleus.
What is the role of a Moderator in nuclear reactors?
A material that absorbs energy from fast moving neutrons, to slow them down to speeds that can be absorbed by fissile neutrons to induce fission.
Common moderators include water and graphite.
What is Radioactive Dating?
The use of radioactive isotopes with known half-lives to date objects, commonly using Carbon-14.
Radioactive dating is widely used in archaeology.
What is Radioactive Waste?
The waste produced from the products of fission reactions, which must be stored and handled carefully due to its instability and radioactivity.
Proper disposal methods are critical for environmental safety.
Radiation
Where an unstable nucleus emits energy in the form of EM waves or subatomic particles in order to become more stable
