Particle Physics Flashcards
What are the two groups of fundamental particles?
Hardons and leptons
What are the two sub groups within hadrons?
Baryons and mesons
What is a baryon made of?
Its made up of three quarks
What are two common baryons?
Protons and neutrons
What is a proton made up of?
UUD quarks
What is a neutron made up of?
DDU quarks
What is a meson made up of?
A quark and an antiquark
What are two common mesons?
Pions and Kaons
What is special about Kaons?
They always have a strange quark
What are the three groups found in Leptons?
Electrons, Muons and Taus
Which is the massive lepton particle?
Tau
Which is the lepton particle of least mass?
Electron
What is alpha radiation made up of?
2 neutrons and 2 protons
What is an alpha particle also?
A helium nucleus
What sort of elements release alpha particles?
Heavy elements
What stops an alpha particle?
Paper
How far do alpha particles travel?
A few cm’s
How ionising are alpha particles?
Very strongly
What is a beta particle?
An electron
How is a beta particle released?
When a neutron becomes a proton
How far can beta particles travel?
A few metres
What stops beta particles?
Aluminium
How ionising are beta particles?
Weakly
What is beta plus particles?
A positron
How are beta plus particles released?
When a proton decays to a neutron and a positron
How far can a beta plus particle travel?
Nowhere as it is antimatter so it annihilates
What is gamma radiation?
A form of electromagnetic wave
How ionising is gamma radiation?
Very weak
What is gamma radiation stopped by?
stopped by thick concrete and lead
How far can gamma radiation travel?
Its range is virtually unlimited
What is gamma radiation?
excess energy
What is binding energy?
The energy required to break the potential energy bonds between particles in a nucleus
How do you work out the binding energy?
Binding energy = mass defect x c^2
What is plasma?
A gas with no electrons
How does nuclear fission occur?
- When a neutron is fired at a large element nucleus
- Nucleus oscillates
- Then nucleus breaks into two new nuclei and two more neutrons are released
Under what conditions does nuclear fission happen?
Extremely high temperature and extremely high pressures
What is a moderator used for in nuclear fission?
Used to get the right speeds for thermal absorption
What are the conservation rules for fundamental particles?
- Mass is conserved
- Electric charge is conserved
- Baryon number is conserved
- Lepton number is conserved
- Strangeness can be conserved
What is the formula for rest energy?
E=mc^2
What is pair production?
The formation of a positron and an electron when a gamma wave (EM pulse) goes near a nucleus
What is the equation for pair production?
E=hf
What is annihilation?
When an electron and positron collide producing two gamma ray photons
What is 1U?
1/12 the mass of Carbon 12
What does 1eV equal?
1.6x10^-19
What is the definition of 1 electron volt?
The amount of work done to move an electron through a potential difference of 1V
What is the relative mass of an electron?
1/2000
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
Which number is the atomic number?
The number on the bottom that signifies the number of protons in the nucleus
Which is the atomic mass?
The number on the top that signifies the number of protons and neutrons
What is an isotope?
An element with the same number of protons but different neutrons
What is an Ion?
A charged atom due to the loss of a proton or electron
What is thermionic emission?
The emission of electrons due to the heating of a metal in a vacuum
What is the equation for thermionic emission?
eV=1/2mv^2, e = electron charge V = Voltage m = mass of electron v = velocity of electron
