Particles definitions Flashcards
alpha radiation
particles that each consist of two protons and two neutrons
annihilation
When a particle and its antiparticle meet, they destroy each other and become radiation.
antibaryon
A hadron consisting of three antiquarks.
antiparticle
There is an antiparticle for every type of particle. A particle and its corresponding antiparticle have equal rest mass and, if charged, equal and opposite charge.
atomic number Z
The number of protons in the nucleus of an atom.
baryon
A hadron consisting of three quarks.
beta radiation
Fast moving electrons emitted by unstable neutron-rich nuclei fast moving positrons emitted by unstable proton-rich nuclei.
electromagnetic interaction (or force)
interaction (or force) between two charged objects
electron capture
Process in which an inner-shell electron of an atom is captured by the nucleus.
gamma radiation
High-energy photons emitted by unstable nuclei or produced in particle annihilations.
hadron
particles and antiparticles that can interact through the strong interaction and are made up of quarks
isotopes
atoms of the same element with different numbers of neutrons and the same number of protons
kaon (or K meson)
a meson that consists of a strange quark or antiquark and another quark or antiquark
lepton
Particles that cannot interact via the strong interaction e.g. electrons, muons, neutrinos.
lepton number
A lepton number is assigned to every lepton (+1) and antilepton (-1), on the basis that the total lepton number for each branch of the lepton family is always conserved.
meson
A hadron consisting of a quark and an antiquark.
nucleon
A neutron or proton in the nucleus.
nucleon number
A the number of neutrons and protons in a nucleus; also referred to as mass number.
nuclide
A type of nucleus with a particular number of protons and neutrons.
pair production
When a gamma photon changes into a particle and an antiparticle.
pion (or π meson)
A meson that consists of an up or down quark and an up or down antiquark.
positron
antiparticle of the electron
rest energy
Energy due to rest mass. E = mc^2, where c is the speed of light in free space.
specific charge
charge to mass ratio
strangeness number
Strangeness of a strange quark = -1, strangeness of an anti-strange quark = +1. Strangeness is always conserved in the strong interaction, but not in a weak interaction or a weak decay involving a strange quark or antiquark.
strong interaction
Interactions that only hadrons can undergo.
strong nuclear force
Attractive force between nucleons that holds the nucleons in the nucleus.
virtual photon
Exchange particle of the electromagnetic force; a photon exchanged between two charged particles when they interact.
W boson
Exchange particle of the weak nuclear force; W bosons have non-zero rest mass and may be positive or negative.
weak nuclear force
Force responsible for beta decay.
