Particles & Nuclear Physics Flashcards
Proton number (or atomic number)
The number of protons in the nucleus of an atom
Neutron number
The number of neutrons in the nucleus of an atom
Nucleon number (or mass number)
The number of protons and neutrons in the nucleus of an atom
Plum Pudding model
A model of the atom in which negative charges are distributed throughout a sphere of positive charge
Isotope
An atom with the same number of protons in the nucleus but a different number of neutrons
Conservation of ___
The total ___ before a nuclear change will equal the total ___ after.
Quantities conserved in nuclear decay
Nucleon number, mass-energy, lepton number, baryon number, charge
Atomic mass unit
A 1/12th the mass of a C-12 nucleus
Thermal neutron
These are slow-moving neutrons
Control rods
Rods of a neutron-absorbing material used to reduce the rate of a nuclear chain reaction
Coolant
A substance used to transfer thermal energy from the core of a nuclear reactor
Induced nuclear fission
A fission reaction started when a neutron is absorbed by a nucleus
Mass defect
The difference between the total mass of the individual, separate nucleons and the mass of the nucleus
Moderator
A material used in a nuclear reactor to slow down fast-moving neutrons so that they have a greater change of interacting with the fissile nuclei
Activity
The rate of decay or disintegration of nuclei in a radioactive sample
Decay constant
The probability of a nucleus decaying per unit time
N as in A = λN
The number of undecayed nuclei in a sample
Half-life
The mean time taken for half the number of active nuclei in a radioactive sample to decay
Chain reaction
An exponential growth of a fission reaction caused by the increasing flux of neutrons causing fission
Spontaneous
Occurs without external influence
Random
Cannot be predicted
Binding energy
The minimum external energy required (per nucleon) to separate all the protons and neutrons in a nucleus
Binding energy per nucleon
The minimum external energy required (per nucleon) to separate all the protons and neutrons in a nucleus
Antimatter
Particles with the same mass but opposite charge and properties
Annihilation
When matter and antimatter collide to produce gamma ray photons only
Electro-magnetic intensity
Electromagnetic power per unit cross-sectional area
Photon
A quantum of electromagnetic energy
