Particles Flashcards
What is the ‘specific charge’?
The value of charge (in coulombs) divided by mass (in kilograms). Units are coulombs per kg
What is an ion?
An atom with has gainer or lost electrons
What is the strong nuclear force?
Acts between nucleons
Works at very short distances - attractive at 3fm
Repulsive at 0.5fm so the nucleus doesn’t collapse on itself
What is given off during alpha radiation?
An alpha particle (a helium nucleus)
What is beta minus radiation?
A neutron decays into a proton, emitting an electron (beta- particle) and an electron anti-neutrino.
Occurs via the weak interaction and a W- boson is exchanged
What is beta plus decay?
A proton decays into a neutron, emitting an electron neutrino and a positron (beta+ particle)
Occurs via weak interaction and a W+ boson is exchanged
What is electron capture?
An electron is absorbed by a proton in the nucleus, which produces a neutron and an electron neutrino.
Occurs via weak interaction and a W+ boson is exchanged
What is electron-proton collision?
An electron collides with a proton outside the nucleus, emitting a neutron and an electron neutrino.
Occurs via weak interaction and a W- boson is exchanged
Describe the properties of hadrons
Subject to the strong interaction
Divided into baryons (+antibaryons) and mesons
Baryon number as a quantum number. Conserved
Proton is only stable baryon winto which other baryons eventually decay
Pion is exchange particle of the strong nuclear force
Describe the properties of leptons
Subject to weak interaction
Lepton number as a quantum number. Conservation of lepton number for muon leptons and for electron leptons
What is a fundamental particle?
A particle which can’t be divided into anything smaller
Describe strangeness
Must be the same before and after in strong and electromagnetic but not weak interactions
In weak interactions the strangeness can change by 0, +1 or -1
Describe electromagnetic interaction
Experienced by all particles.
Infinite range
Photon is exchange particle
Describe gravitational interaction
Experienced by all particles with mass.
Infinite range
Exchanged particle is graviton
Describe gravitational interaction
Experienced by hadrons.
Range about 3x 10^-38m
Exchange particle is gluon
Describe weak interaction
Experienced by all fundamental particles.
Range about 10^-18m
Exchange particle is W+, W-, Z boson
Describe leptons
Fundamental particle
Cannot take part in strong interactions
All interact by way of weak interaction
Charged leptons can also interact through electromagnetic interactions
Describe hadrons
Particles which are made up or quarks and/or antiquarks
Only tupe of particle which can interact via the strong nuclear force.
Divided into baryons, antibaryons and mesons
Baryons are made of 3 quarks.
Mesons are made of a qyak and an antiquark
Describe annihilation
When an antiparticle and particle collide they annihilate and form new particles (often photons)
Describe pair-production
If a gamma photon with enough energy interacts with a nucleus or an atomic electron, it can disappear and form a particle and antiparticle.
