Particles Flashcards
Atom
An electrically neutral collection of electrons, protons and neutrons. The number of electrons is equal to the number of protons.
Element
A substance that can’t be broken down by chemical means into simpler substances.
Nucleon
A particle that makes up the nucleus- either a proton or a neutron.
Nucleon number (A)
The total number of nucleons in the nucleus (protons + neutrons) - mass number
Ion
An atom that has gained or lost one or more outer electrons leaving its charge unbalanced
Nuclide
The nucleus of a unique atom that is one with a specific number of protons and neutrons
Isotope
Elements with different numbers of neutrons but the same number of protons. Have similar properties to the element but are normally radioactive
Proton number (Z)
The total number of protons present in the nucleus - atomic number
Specific charge formula
Actual charge / actual mass
Total protons) x (charge of proton)/(number of nucleons)x(mass of nucleon
Specific charge of an atom
0
What has the biggest specific charge? A proton or an electron?
Electron.
They have a smaller mass than a proton (sc=charge/mass)
Strong nuclear force
Force which holds the nucleus together and stops protons from repelling
What is alpha decay?
A helium nucleus of +2 charge and mass of 4AMU
(2 protons 2 neutrons)
Happens in atom with very large mass number
What is beta minus decay?
A fast moving electron of single negative charge and mass 1/1860 AMU.
(n > p + e)
Happens in a neutron rich nucleus
What is beta plus decay?
p > n + e(+)
Happens in a proton rich nucleus
What is gamma decay?
A photon of energy (wave) with no charge or mass. Released to channel away energy (get rid of excess energy).
What is a neutrino?
Has no charge and a very small mass. Millions pass through your body every second but don’t interact
How does light travel?
As photons (packets of energy)
Formula for energy of a photon
E = hf
or
E=hc/wavelength
What is an antiparticle?
Every particle has an antiparticle which has the same mass but the opposite charge
1MeV in joules?
1.6x10-13 J
What is rest energy?
The amount of energy needed to make one of these particles/ the amount of energy released is the particle is destroyed
What is annihilation?
If a particle and its antiparticle meet they destroy each other and produce photons of energy
What is pair production?
Making a particle and its antiparticle with enough energy (normally from a gamma photon)
What is the electromagnetic force?
Force between 2 charged objects due to the exchange of virtual photons (attraction and repulsion). One particle emits and the other absorbs it (exchanging momentum).
What does the electromagnetic force act on?
Quarks, charged leptons, W+ W-
What is the weak nuclear force?
Force created in radioactive decay of subatomic particles. Mediated by W+ or W- bosons
What does the weak nuclear force act on?
Quarks and leptons
What is the strong nuclear force?
It holds the nucleus together, stops protons from repelling and stops protons and neutrons from squashing into each other.
What is the strong nuclear force carried by?
Gluons
What does the strong nuclear force act on?
Quarks and gluons
Feynman diagram for B- decay
n -> p + e- + Ve_
Occurs via weak interaction
Mediated by W- boson
B+ decay
P -> n + e+ + Ve
Occurs via weak interaction
Mediated by W+ boson
Electron capture
P + e- -> n + Ve
Occurs qua weak interaction
Mediated by W+ boson
Neutrino-neutron collision
N + Ve -> p + e-
Occurs via weak interaction
W- boson
Antineutrino-proton collision
P + Ve_ -> n + e+
Weak interaction
W+ boson
Electron-proton collision
e- + p -> n + Ve
Weak
W- boson
Quark
A fundamental and subatomic particle that combines with other quarks to form hadrons
Lepton
A subatomic particle which doesn’t take part in strong interactions (electron, muon, tau or neutrino)
Light and fundamental
Experience weak force
If charged interact via weak/electromagnetic
Gauge bosons
Force carriers. Elementary particle interact by exchange of gauge bosons.
What are the quark flavours?
Up + down
Charm + strange
Top + bottom
What is the quark structure of a proton?
uud
What is the quark structure of a neutron?
udd
What is the general quark structure of Baryons?
3 quarks
What is he general quark structure of anti-baryons?
3 anti-quarks
What is the general quark structure of mesons?
Quark- antiquark pair
What is a hadron?
Have quarks inside
Heavy, not fundamental
Experience strong force but decay via weak force
What is a baryon?
Bigger hadron (proton or neutron)
What is a meson?
Medium hadron (pi mesons, k mesons)
What is the conservation of charge?
Q before = Q after
What is the conservation of lepton number?
L before = L after
What is the conservation of baryon number?
B before = B after
What is the conservation of strangeness?
Strangeness is conserved in strong and electromagnetic interactions.
Not conserved in weak interactions (increases/decreases by 1)
1fm in m?
X10-15 m
Formula for total energy
Total energy = number of photons x energy of one photon
What quantity changes continuously in moving from the bottom to the top of a Feynman diagram?
Time
