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A Level Physics Year 1 > Particles and Radiation > Flashcards

Particles and Radiation Flashcards

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1
Q

What is a nucleon?

A

A particle in the nucleus (protons and neutrons)

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2
Q

What is the relative mass of an electron?

A

1/1840

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3
Q

What is the proton number?

A

Number of protons in the nucleus

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4
Q

What defines what an element is?

A

The number of protons

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5
Q

What do an element’s reactions and chemical behaviour depend on?

A

Number and arrangement of electrons

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6
Q

What is the mass number?

A

Number of protons and neutrons in the nucleus

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7
Q

In physics, what does ‘specific’ mean?

A

Per unit mass

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8
Q

What is the specific charge of a particle?

A

The ratio of its charge to its mass

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9
Q

What is the SI units of specific charge?

A

C kg^-1

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10
Q

What is the equation for specific charge?

A

Specific charge = Charge / Mass

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11
Q

What is a fundamental particle?

A

A particle that cannot be split up into anything smaller, such an electron

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12
Q

What is an isotope?

A

An atom of an element with the same number of protons, but a different number of neutrons

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13
Q

What does changing the number of neutrons of an atom affect?

A

The stability of the nucleus

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14
Q

In general, the greater the number of neutrons compared with the number of protons…?

A

The more unstable the nucleus is

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15
Q

What do unstable nuclei do?

A

Decay to make themselves more stable

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16
Q

What isotopic data?

A

The relative amounts of isotopes in a substance

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17
Q

What is the electromagnetic force?

A

A fundamental force that causes interactions between charged particles

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18
Q

What does the electromagnetic force cause in the nucleus?

A

The positively charged protons to repel each other

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19
Q

What does the gravitational force in the nucleus cause?

A

All the nucleons in the nucleus to attract each other due to their mass

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20
Q

Which is a bigger force in the nucleus, the repulsion from the electromagnetic force or attraction from the gravitational force?

A

The repulsion from the electromagnetic force

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21
Q

What is the strong nuclear force?

A

A fundamental force with a short range which is attractive at short separations, but repulsive at very small separations

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22
Q

What is the strong nuclear force responsible for?

A

The stability of the atom

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23
Q

What are interactions that use the strong nuclear force called?

A

Strong interactions

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24
Q

What separation of nucleons is the strong nuclear force repulsive for?

A

Less than 0.5 fm (5x10^-16 m)

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25
Q

Describe the strong nuclear force once the nucleon separation has increased past 0.5 fm?

A

The strong nuclear force becomes attractive, reaching a maximum attractive value, the falling rapidly to zero after about 3 fm (3x10^-15)

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26
Q

What is nuclear decay?

A

When unstable nuclei will emit particles to become more stable

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27
Q

What is an alpha particle?

A

The nucleus of a helium atom

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28
Q

Alpha decay can only happen in…?

A

Very large atoms with more than 82 protons

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29
Q

Why are very large atoms, such as uranium, very unstable?

A

Because they’re so big that the strong nuclear charge can’t keep them stable

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30
Q

How do very large atoms become more stable?

A

They release an alpha particle from their nucleus

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31
Q

What happens to the proton number when an alpha particle is released from the nucleus?

A

The proton number decreases by 2

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32
Q

What happens to the mass number when an alpha particle is released from the nucleus?

A

The mass number decreases by 4

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33
Q

Describe the range of an alpha particle in air

A

Only a few cm

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34
Q

What does a Geiger Counter do?

A

Measure the amount of ionising radiation

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35
Q

How does a Geiger counter work?

A

The counter consists of a tube filled with an inert gas that becomes conductive of electricity when it is impacted by a high-energy particle. When a Geiger counter is exposed to ionizing radiation, the particles penetrate the tube and collide with the gas, releasing more electrons

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36
Q

What is beta-minus decay?

A

The emission of an electron from the nucleus along with an antineutrino particle

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37
Q

What does beta decay normally occur with?

A

Isotopes that are ‘neutron rich’ (have to many neutrons compared to protons)

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38
Q

What happens when the nucleus ejects a beta particle?

A

One of the neutrons in the nucleus turns into a proton

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39
Q

Which has a greater range, alpha or beta particles?

A

Beta particles can travel a few metres in air

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40
Q

What is the evidence that the electron wasn’t the only particle to be emitted in beta-minus decay?

A

The energy of the particles before the beta decay was less than the energy before, which goes against the principle of the conservation of energy

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41
Q

What did Wolfgang Pauli suggest about beta decay in 1930?

A

That another particle was being emitted that carried away the missing energy

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42
Q

What would have to be 2 characteristics of the other particle that Pauli suggested was emitted in beta decay?

A

Neutral (or charge won’t be conserved)

Almost zero mass (as it had never been detected)

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43
Q

What is the other particle that is emitted in beta decay called?

A

Electron Antineutrino ( ̅νe)

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44
Q

What is the electromagnetic (EM) spectrum?

A

A continuous spectrum of all the possible frequencies of EM radiation

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45
Q

What are the 7 different types of EM radiation (in order of increasing wavelength)

A 
Gamma
X-Ray
UV
Visible Light
Infrared 
Microwave
Radio
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46
Q

Which has a bigger wavelength, gamma rays or radio waves?

A

Radio waves

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47
Q

Which has a bigger frequency, UV or visible light?

A

UV

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48
Q

Which has a bigger frequency, gamma rays or radio waves?

A

Gamma rays

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49
Q

The higher the frequency of the EM radiation, the…?

A

Greater its energy

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50
Q

What are photons?

A

Packets of EM radiation

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51
Q

How suggested that EM waves only existed in discrete packets called photons?

A

Einstein

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52
Q

What is the equation for the energy of a photon (in J)?

A

E = hf

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53
Q

In the equation for the energy of a photo, what does the h mean?

A

Planck’s constant (6.63x10^-34 Js)

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54
Q

In the equation for the energy of a photo, what does the f mean?

A

Frequency of light, Hz

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55
Q

What equation links the energy of a photon, Planck’s constant, wavelength and speed of light in a vacuum?

A

E = (hc) / λ

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56
Q

What is an antiparticle?

A

A particle with the same rest mass and energy as its corresponding particle, but an equal and opposite charge

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57
Q

What is an antiproton?

A

A negatively charged particle with the same mass as a proton

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58
Q

What is matter?

A

Name given to all particles

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59
Q

What is antimatter?

A

Name given to all antiparticles

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60
Q

What is pair production?

A

A process of converting energy to mass in which a gamma ray photon has enough energy to produce a particle-antiparticle pair

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61
Q

What do you get when energy is converted into mass?

A

Equal amounts of matter and antimatter

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62
Q

Pair production can only happen if there is enough of what?

A

If there is enough energy to produce the masses of the particles

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63
Q

Why do you need a large amount of energy to fire 2 protons at each other to make them collide?

A

Because they’re both positively charged, so they repel each other

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64
Q

If a photon has enough energy, what can be produced from 2 photons being fired into each other?

A

An electron-positron pair

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65
Q

When does an electron-positron pair most commonly get produced?

A

When a photon passes near a nucleus

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66
Q

What is the minimum amount of energy needed for pair production?

A

The total of the rest energy of the particles that are produced

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67
Q

What is rest energy?

A

The amount of energy that would be produced if all the particle’s mass was converted to energy

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68
Q

What is the minimum amount of energy need for pair production equal to?

A

2 x rest energy of particle (Emin = 2Eo)

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69
Q

How do you convert MeV to J?

A

Multiply by 1.60 x10^-13

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70
Q

Why do you normally get electron-positron pairs produced, rather than any other pair?

A

Because they have a relatively low mass, so less energy is need for pair production to happen

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71
Q

What is it called when a particle meets its antiparticle?

A

Annihilation

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72
Q

What is annihilation?

A

The process when a particle and antiparticle meet and their mass gets converted to energy in the form of a pair of gamma ray photons

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73
Q

What happens in annihilation to conserve momentum?

A

The 2 gamma ray photons travel in opposite directions

74
Q

What is the equation for the minimum energy of photon produced during annihilation?

A

Emin = Rest energy of particle produced

75
Q

What does PET scanner stand for?

A

Positron Emission Tomography scanner

76
Q

How does a PET scanner work?

A

In hospitals they’ll put a positron-emitting isotope into the bloodstream, then detect the gamma rays that are produced by the annihilation that occurs

77
Q

In a PET scanner, what detects the radiation?

A

A scintillator

78
Q

How does a scintillator work?

A

Contains scintillation crystals which produce a flash of light when a gamma ray hits them. These flashes of light can be detected and used to form an image

79
Q

What are hadrons?

A

Particle made up of quarks that is affected by the strong nuclear force

80
Q

Are hadrons fundamental particles or not?

A

They’re not fundamental, because they’re made up of smaller particles called quarks

81
Q

What are the 2 types of hadron?

A

Baryons

Mesons

82
Q

Give 2 examples of a baryon

A

Proton

Neutron

83
Q

What can be said about the stability of baryons?

A

All baryons except a free proton, can be unstable meaning they decay to become other particles

84
Q

What baryon doesn’t decay, and therefore is stable?

A

Proton (and anti-proton)

85
Q

What do all baryons, except a proton, decay into?

A

A proton

86
Q

Give 2 examples of anti-baryons

A

Anti-proton

Anti-neutron

87
Q

Why don’t you find anti-baryons in normal matter?

A

Because they’re annihilated by their corresponding particle

88
Q

What is the baryon number?

A

The number of baryons

89
Q

What can be said about the baryon number?

A

It is a quantum number that is conserved

90
Q

What is a quantum number?

A

A number that represents a property of a particle that must be conserved in all interactions

91
Q

What is the baryon number of protons and neutrons?

A

+1 (because they’re both baryons)

92
Q

What is the baryon number of anti-baryons?

A

-1

93
Q

What baryon number is given to particles that aren’t baryons?

A

0

94
Q

The total baryon number in any particle interaction…?

A

Never changes

95
Q

What is formed when a neutron decays?

A

Proton + electron + antineutrino

96
Q

How do mesons interact with the baryons?

A

Via the strong force

97
Q

What can be said about the stability of mesons?

A

All of them are unstable

98
Q

What is the baryon number of all mesons?

A

0 (because they’re not baryons)

99
Q

Which is the lightest type of meson?

A

Pion (π+, π0, π-)

100
Q

What is the antiparticle of π+?

A

π-

101
Q

What is the antiparticle of π0?

A

Itself

102
Q

Which force are pions the exchange particle for?

A

Strong nuclear force

103
Q

Compare Kaons (K+, K0, K-) with the pions?

A

Kaons are heavier and more unstable

104
Q

What do kaons decay into?

A

Pions

105
Q

What are cosmic rays?

A

Radiation in the form of charged particles that come from Space and hit Earth

106
Q

What are cosmic ray showers?

A

Lots of high-energy particles that are produced from cosmic rays interacting with molecules in the atmosphere

107
Q

What are leptons?

A

Fundamental particles that don’t feel a strong nuclear force

108
Q

Name a stable lepton

A

The electron

109
Q

Give 2 examples of leptons

A

Electrons

Muons

110
Q

How do leptons interact with other particles?

A

Via the weak interaction (as well as gravitational potential and electromagnetic if they’re charged)

111
Q

What is a muon?

A

A heavier electron that is very unstable

112
Q

What do muons decay into?

A

Electrons

113
Q

What is the neutrino of the electron?

A

Electron neutrino (ν e)

114
Q

What is the neutrino of the muon?

A

Muon neutrino (ν μ)

115
Q

What is the mass and charge of neutrinos?

A

Almost zero mass and zero charge

116
Q

What is the antiparticle of the electron?

A

Positron

117
Q

What is the antiparticle of the muon?

A

Antimuon

118
Q

What is the lepton number?

A

A quantum number that is the number of leptons

119
Q

What is the lepton number of the leptons?

A

+1

120
Q

What is different about the lepton number of the electron compared to the muon?

A

They have to be counted separately as L e for electron lepton number and L μ for muon lepton number

121
Q

What is the lepton number of the corresponding anti-particles of the leptons?

A

-1

122
Q

In all particle interactions, what must be conserved?

A

Lepton number and Baryon number

123
Q

How do you check to see if a particle interaction can occur?

A

See if baryon number and lepton number are conserved

124
Q

How are strange particles created?

A

Via the strong interaction, in which strangeness is conserved

125
Q

What is strangeness?

A

A property which particles that contain strange quarks have. Strange particles are always produced in pairs

126
Q

Why are strange particles always produced in pairs?

A

Because of the conservation of strangeness

127
Q

Describe the stability of the strange quark (and antiquark)

A

Very unstable

128
Q

What do strange quarks decay into?

A

An up quark, electron and an electron antineutrino

129
Q

What is the strangeness value of leptons?

A

0

130
Q

In a strong interaction, what 4 things are conserved?

A

Baryon number
Strangeness
Total number of quarks
Type of quark

131
Q

In a weak interaction, what 2 things are conserved?

A

Total number of quarks

Baryon number

132
Q

In a weak interaction, what 2 things are not conserved?

A

Strangeness

Type of quark

133
Q

If strangeness is conserved, which type of interaction will it always be?

A

Strong interaction

134
Q

In any particle interaction, the total charge after the interaction must equal what?

A

The total charge before the interaction

135
Q

How is the conservation of charge shown in the pair production of a photon?

A

A photon with enough energy will produce an electron-positron pair. It couldn’t produce just one of them, because the charge before the interaction is 0, so the charges need to cancel out (+1 -1)

136
Q

In any particle interaction, the baryon number after the interaction must equal what?

A

The baryon number before the interaction

137
Q

When a proton is produced in pair production, how is the conservation of baryon number shown?

A

Proton has a baryon number of +1, so an anti-proton is produced as well, with a baryon number of -1

138
Q

What are baryons made of?

A

3 quarks

139
Q

What are mesons made of?

A

1 quark and 1 anti-quark

140
Q

What is the symbol equation for proton-antiproton pair production?

A

p + p —> p + p + p̄ + p

141
Q

Are the electron and muon lepton numbers conserved?

A

Yes

142
Q

What type of interaction is the only interaction where strangeness is conserved?

A

Strong interaction

143
Q

What is the only way to change the type of quark?

A

Via a weak interaction

144
Q

What are the 3 types of quark?

A 
Up quark (u)
Down quark (d)
Strange quark (s)
145
Q

What are the 2 types of quark you need to make a nucleon?

A

Up and down quark

146
Q

What is the quark composition of a proton?

A

duu

147
Q

What is the quark composition of a neutron?

A

ddu

148
Q

What do the properties of a particle depend on?

A

Properties of the quark that make it up

149
Q

What are the 3 types of anti-quark?

A

anti-proton
anti-neutron
anti-strange

150
Q

What are the properties of anti-quarks compared to quarks?

A

Opposite

151
Q

What are anti-baryons made of?

A

3 anti-quarks

152
Q

What is the quark composition of leptons?

A

Leptons aren’t made of quarks as they’re fundamental particles

153
Q

What is the quark composition of π 0?

A

ŪU, d̅ d or SŠ (all 1 quark and 1 anti-quark)

154
Q

What is quark confinement?

A

The idea that quarks can’t be isolated

155
Q

What is the equation for beta-plus decay?

A

p —> n + e+ + Ve

156
Q

What type of interaction is beta-minus decay?

A

Weak interaction

157
Q

How do we know that beta-minus decay is a weak interaction?

A

Because of the quark composition

n —> p

u —> u
d —> u type of quark is not conserved so weak
d —> d

158
Q

What is a quark changing into another quark known as?

A

Changing the quark’s character

159
Q

What are all forces caused by?

A

Particle exchange

160
Q

What are gauge bosons?

A

A virtual particle which allows forces to act in a particle interaction. They’re known as exchange particles

161
Q

What is an exchange particle?

A

A virtual particle which allows forces to act in a particle interaction. They’re also known as gauge bosons

162
Q

What is a virtual particle?

A

A particle that only exists for a small amount of time

163
Q

What is the electrostatic force of repulsion between 2 protons caused by?

A

By the exchange of virtual photons (the exchange particles of the electromagnetic force)

164
Q

What is the gauge boson of the strong nuclear interaction?

A

Pions

165
Q

What particles are affected by the strong nuclear interaction?

A

Hadrons only

166
Q

What is the gauge boson of the electromagnetic force?

A

Virtual photon

167
Q

What particles are affected by the electromagnetic force?

A

Charged particles only

168
Q

What is the gauge boson of the weak nuclear interaction?

A

W+, W- bosons

169
Q

What particles are affected by the weak nuclear force?

A

All types of particle

170
Q

What are the 4 fundamental types of interaction?

A

Strong
Weak
Electromagnetic
Gravity

171
Q

What determines the range of a force?

A

The size of the exchange particle

172
Q

Describe the range, and therefore the range of the force, of a heavier exchange particle

A

Heavier exchange particles have a shorter range, so the force has a shorter range

173
Q

Why does the weak interaction have a very short range?

A

Because W bosons are around 100 times as heavy as a virtual photon, and they use so much energy they can’t exist for very short time and can’t travel far. All this means that the weak interaction has a short range

174
Q

Why does the electromagnetic force have an infinite range?

A

Because virtual photons have almost zero mass, so it doesn’t use much energy and can travel further

175
Q

In Feynman Diagrams, what do squiggly lines represent?

A

Exchange particles

176
Q

In Feynman Diagrams, what do straight lines represent?

A

Particles (not exchange particles)

177
Q

What are the 4 rules for drawing Feynman diagrams?

A
  • Time starts at the bottom and works up (so incoming particles start at bottom)
  • Baryons stay on one side of diagram and leptons stay on other side
  • The W bosons carry charge from one side of diagram to the other
  • A W- particle travelling left is the same as a W+ particle travelling right
178
Q

What is beta-minus decay?

A

When a neutron decays into a proton, electron and antineutrino

179
Q

What is electron capture?

A

The process of a proton-rich nucleus capturing an electron to turn a proton into a neutron, emitting a neutrino

180
Q

What is the formula for electron capture?

A

p + e- —> n + Ve

181
Q

How is an electron-proton collision Feynman diagram different to that of electron capture?

A

Has a W- boson coming from the electron, because the electron is acting on the proton, whereas in electron capture it’s a W+ boson from the proton because the proton is acting on the electron

A Level Physics Year 1 (7 decks)

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