Nuclear Physics Flashcards
What is beta decay?
The emissions of a beta particle when a proton turns into a neutron in an unstable nucleus. Beta- radiation is weakly ionising. Beta+ radiation is immediately annihilated by electrons.
What are 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.
What is the Rutherford scattering experiment?
An experiment involving firing alpha particles at a thin gold foil and observing their deflections. It showed the existence and nature of the nucleus.
What is binding energy?
The amount of energy required to split a nucleus into all its separate constituent nucleons. Equivalent to the mass defect.
What is fission?
The splitting of a nucleus, to form to smaller daughter nuclei, neutrons and energy.
What is contamination?
The introduction of radioactive material to another object. The object is consequently radioactive.
What is background radiation?
Radiation that is found in small quantities. It originates from natural sources such as rocks and cosmic rays and man-made sources such as nuclear accidents and medical sources.
What is half life?
The average time it takes for the number of radioactive nuclei in a sample to halve.
What is fusion?
The joining of two smaller daughter nuclei to form a larger nucleus and release energy.
What is alpha decay?
The emission of an alpha particle (2 protons, 2 neutrons) from an unstable nucleus to make it more stable. Alpha radiation is strongly ionising and is stopped by a few cm of air or a sheet of paper.
What is radioactive dating?
The use of radioactive isotopes with known half lives to date objects. The isotope that is usually used is carbon-14.
What is a moderator?
A material in nuclear reactors that absorb energy from fast moving neutrons to slow them down to speed that can be absorbed by fissile neutrons to induce fission.
What is mass defect?
The difference in mass between a nucleus and the sum of the masses of the constituent nucleons.
What is a chain reaction?
The process of the neutrons released by a fission reaction inducing further fissile nuclei it undergo fission.
What is critical mass?
The smallest mass of fissile material required in a fission reactor for a chain reaction to be sustained.