Particles Definitions Flashcards
Isotope
atoms of the same element with the same number of protons (atomic number) but a different number of neutrons (mass number)
Specific Charge Equation
charge / mass
Specific Charge Units
Ckg^-1
Particle with the greatest specific charge
electron (mass is extremely small Q/m)
Alpha Radiation
Helium nucleus - 2 protons 2 neutrons
largest particle, slow-moving
can be stopped by paper - least penetrating a few cm in air
strongly ionising
Beta Radiation
fast-moving electron
relative mass 0 relative charge -1
smallest particle
can be stopped by aluminium - relatively penetrating
less ionising than alpha
Gamma Radiation
short wavelength, high frequency electromagnetic radiation
high energy photon, fast moving
has no mass, uncharged
most penetrating - long distances
can be stopped by lead
less ionising than alpha radiation
Axes of a Feynmann Diagram
vertical - time
horizontal - space
Funamental Forces and their Corresponding Exchange Particles
Strong force - pion
Weak force - W particle (boson)
Electromagnetic force - virtual photon
Gravitational force - graviton
Pair Production
when a gamma photon changes into a particle and its corresponding antiparticle
Annihilation
when a particle and its antiparticle meet, they destroy each other and releases 2 gamma photons
Antimatter
particles with the same rest mass but equal and opposite charge as corresponding particle
Exchange Particles Transfer…
momentum
energy
force
charge (only in weak interactions)
Difference between Hadrons and Leptons
Hadrons feel the strong force
Leptons do not feel the strong force
Baryon (protons, neutrons) Quark Composition
baryon qqq
protons uud neutrons dud
Anti-Baryon (anti-proton, anti-neutron) Quark Composition
anti-baryon qqq
Meson Quark Composition
meson qq (one antiquark one quark)
What Baryons decay into
Protons
Most stable Baryon
Proton
What is conserved in strong and weak interactions?
All interactions : energy, momentum, charge, baryon number, lepton number
Strong force only : strangeness
What is a Strange Particle
a particle that contains at least one strange quark or anti-quark
Characteristics of a Strange Quark
has a strangeness of -1
Size of Nucleus
x10^-15
Size of Atom
x10^-10
Properties of Strong Nuclear Force
Very short range force
Repulsive: 0.5fm
Attractive: between 0.5fm and 3fm
Non existent: above 3fm
Decay Modes of Unstable Nuclei
very large nuclei - alpha
neutron rich nuclei - beta-
proton rich nuclei - beta+
proton rich nuclei - electron capture
Similarities between Hadrons and Leptons
They both feel the weak force and electromagnetic force (if they are charged).
What do Kaons decay into
Pions
What do Muons decay into
Electrons
Properties of a Strange Particle
Strange particles are produced via strong interaction but decay via the weak interaction
What is strangeness?
A quantum number to reflect the fact that strange particles are always created in pairs.
In weak interactions, how does strangeness change?
Can change by -1, 0 or +1 in weak interactions.
Conservation Rules for Weak Interaction
Baryon number, Charge and Lepton Number (by family) must all be conserved.
Conservation Rules for Strong Interaction
Baryon number, Charge, Lepton Number (by family) and strangeness must all be conserved.
