1. Particle Physics Flashcards

1
Q

What makes up an atom?

A

a nucleus and electrons

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2
Q

What makes up the nucleus?

A

protons and neutrons

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3
Q

What are protons and neutrons?

A

nucleons

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4
Q

What is the relative mass of a proton?

A

1

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5
Q

What is the relative mass of a neutron?

A

1

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6
Q

What is the relative mass of an electron?

A

1/2000

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7
Q

What is the mass of a proton?

A

1.67 x 10^-27 kg

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8
Q

What is the mass of a neutron?

A

1.67 x 10^-27 kg

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9
Q

What is the mass of an electron?

A

9.11 x 10^-31 kg

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10
Q

What is the relative charge of a proton?

A

+1

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11
Q

What is the relative charge of a neutron?

A

0

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12
Q

What is the relative charge of an electron?

A

-1

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13
Q

What is the charge of a proton?

A

+1.60 x 10^-19 C

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14
Q

What is the charge of a neutron?

A

0 C

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15
Q

What is the charge of an electron?

A

-1.60 x 10^-19 C

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16
Q

What is nuclide notation?

A

how information on elements is displayed on the periodic table

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17
Q

What is an isotope?

A

at atom with the same number of protons but a different number of neutrons

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18
Q

What happens when you change the number of protons in an atom?

A

create a new element

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19
Q

What happens when you change the number of neutrons in an atom?

A

create an isotope

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20
Q

What happens when you change the number of electrons in an atom?

A

create a new ion

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21
Q

What does isotopic data mean?

A

the relative amounts of the different isotopes of an element present in a substance

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22
Q

What happens to unstable nuclei over time?

A

they decay into more stable nuclei over time

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23
Q

How can you estimate a material’s age?

A

by looking at the amount of isotopes in the material

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24
Q

What is specific charge?

A

the amount of charge an object has per kilogram

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25
Q

What three things could you be asked to find the specific charge of?

A
  • a single particle
  • a nucleus
  • an ion
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26
Q

How do you calculate the specific charge?

A

total charge/total mass

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27
Q

What is specific charge measured in?

A

Ckg^-1

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28
Q

What is meant by the relative mass of an atomic constituent?

A

relative mass is the mass relative to a proton’s mass, as opposed to the actual mass

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29
Q

In nuclide notation, what does ‘A’ represent?

A

nucleon number

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30
Q

In nuclide notation, what does ‘Z’ represent?

A

proton number

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31
Q

In nuclide notation, what does ‘X’ represent?

A

element symbol

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32
Q

What does isotopic data mean?

A

the relative amounts of the different isotopes of an element present in a substance

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33
Q

What are the four fundamental forces?

A
  • gravity
  • electromagnetic
  • strong nuclear
  • weak nuclear
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34
Q

Outline gravity

A

all objects with mass are attracted to each other

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35
Q

Outline the electromagnetic force

A

all objects with charge are either attracted to or repelled from each other

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36
Q

Outline the strong nuclear force

A

responsible for holding the nucleus of atoms together and responsible for the decay and creation of particles

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37
Q

Outline the weak nuclear force

A

responsible for the decay and creation of particles

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38
Q

What is the name of the force that holds nucleons together inside the nucleus?

A

strong nuclear force

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39
Q

Why must the strong nuclear force exist?

A

the repulsion of protons due to the electromagnetic force is much greater than the gravitational attraction, so there must be another attractive force to hold the nucleus together

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40
Q

Which particles does the strong nuclear force affect?

A

both nucleons (protons and neutrons)

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41
Q

What type of force is the SNF?

A

can either be attractive or repulsive

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42
Q

What does the type of SNF depend on?

A

distance between particles

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43
Q

What range does the SNF have?

A

very short range

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44
Q

When is the SNF repulsive?

A

if nucleons are 0-0.5fm apart

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45
Q

When is the SNF attractive?

A

if nucleons are 0.5-3fm apart

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46
Q

When does the SNF have no effect?

A

if nucleons are beyond 3fm apart

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47
Q

Why do nuclei emit alpha and beta particles?

A

because they are unstable

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48
Q

What are the three main reasons for a nucleus being unstable?

A
  • too much mass
  • imbalance of protons and neutrons
  • too much energy
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49
Q

How can a nucleus with too much mass become more stable? What is this called?

A

eject some particles (alpha decay)

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50
Q

How can a nucleus with an imbalance of nucleons become more stable? What is this called?

A

weak nuclear force can change the particle type (beta +/- decay)

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51
Q

How can a nucleus with too much energy become more stable? What is this called?

A

release some energy (gamma decay)

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52
Q

What is an alpha particle?

A

2 protons and 2 neutrons (helium nucleus)

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53
Q

When is an alpha particle emitted?

A

when a particle undergoes alpha decay

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54
Q

In what type of nucleus does alpha decay usually occur?

A

very heavy nuclei

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55
Q

What is the proton number of an alpha particle?

A

2

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56
Q

What is the nucleon number of an alpha particle?

A

4

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57
Q

In what type of nucleus does beta-minus decay usually occur?

A

neutron-rich

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58
Q

What happens during beta-minus decay?

A

a neutron turns into a proton via the weak nuclear force, emitting a beta-minus particle and an anti-neutrino

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59
Q

Which particle is a beta-minus particle identical to?

A

electron

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60
Q

Name three pieces of equipment which could be used to detect alpha and beta radiation

A
  • geiger counter
  • spark counter
  • cloud chamber
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61
Q

How did observations of beta-minus decay lead to the prediction of the neutrino?

A
  • the total energy of the particles emitted in beta-minus decay was less than the energy before
  • this energy couldn’t be accounted for by the recoil of the nucleus
  • therefore there must be another particle carrying away the missing energy
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62
Q

What are photons?

A

described as ‘packets’ of electromagnetic waves

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63
Q

What are the similarities and differences between photons?

A

they can have different frequencies, wavelengths and energies, but they all travel at the speed of light

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64
Q

What is the speed of light?

A

3.00 x 10^8 m/s

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65
Q

How is the energy of a photon related to its frequency?

A

directly proportional

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66
Q

What is the value of Planck’s constant?

A

6.63 x 10^-34 (m^2kg/s)

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67
Q

State the equation linking energy of photons (E), Planck’s constant (h) and frequency (f)?

A

E = hf

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68
Q

State the equation linking the energy of photons (E), Planck’s constant (h), speed of light (c) and wavelength (λ)?

A

E = (hc)/λ

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69
Q

What is annihilation?

A

when a particle and its corresponding antiparticle meet and their mass (and kinetic energy) is converted into two photons, travelling in opposite directions to conserve momentum

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70
Q

What is pair production?

A

when a photon with enough energy converts its energy into a particle and its corresponding antiparticle pair

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71
Q

What is anti-matter?

A

particles which have identical mass as their corresponding matter particle, but every other property is opposite

72
Q

What is the charge and mass of a proton?

A
  • charge: +1.60 x 10^-19 C

- mass: 1.67 x 10^-27 kg

73
Q

What is the charge and mass of an anti-proton?

A
  • charge: -1.60 x 10^-19 C

- mass: 1.67 x 10^-27 kg

74
Q

What is the charge and mass of a neutron?

A
  • charge: 0 C

- mass: 1.67 x 10^-27 kg

75
Q

What is the charge and mass of an anti-neutron?

A
  • charge: 0 C

- mass: 1.67 x 10^-27 kg

76
Q

What is the charge and mass of an electron?

A
  • charge: -1.60 x 10^-19 C

- mass: 9.11 x 10^-31 kg

77
Q

What is the charge and mass of a positron?

A
  • charge: +1.60 x 10^-19 C

- mass: 9.11 x 10^-31 kg

78
Q

What unit is used to measure energy at this scale?

A

electron volt (eV)

79
Q

What is an electron volt?

A

the kinetic energy gained by an electron if it passes through a potential difference of 1V

80
Q

What is 1 eV in Joules?

A

1.60 x 10^-19 J

81
Q

What is 1 MeV in Joules?

A

1.60 x 10^-13 J

82
Q

What is rest energy?

A

the energy stored in an objects mass

83
Q

What is the rest energy of a proton and an anti-proton?

A

938.257 MeV

84
Q

What is the rest energy of a neutron and an anti-neutron?

A

939.511 MeV

85
Q

What is the rest energy of an electron and a positron?

A

0.511 MeV

86
Q

What is energy released as during annihilation?

A

two identical photons

87
Q

Why are the photons emitted in opposite directions during annihilation?

A

to conserve momentum

88
Q

What does E0 stand for?

A

rest energy

89
Q

What does Emin stand for?

A

energy of photon

90
Q

In pair production, what can be produced when you have a more energetic photon?

A
  • heavier particles
  • particles with extra kinetic energy
  • lots of smaller particles
91
Q

What formula is used to calculate the energy released in annihilation?

A

E0 = Emin

92
Q

What formula is used to calculate the energy needed for pair production?

A

2E0 = Emin

93
Q

What are the four main groups of particles?

A
  • hadrons
  • leptons
  • baryons
  • mesons
94
Q

What are the two main groups of all matter and anti-matter?

A

hadrons and leptons

95
Q

What is a hadron?

A

a particle which experiences the strong nuclear force and can be broken up into smaller particles (quarks)

96
Q

What is a lepton?

A

a type of fundamental particle which does not experience the strong nuclear force

97
Q

What are the two types of hadrons?

A

baryons and mesons

98
Q

What is the difference between a baryon and a meson?

A

a baryon is made up of 3 quarks whereas a meson is made up of 2 quarks

99
Q

Which is the most stable baryon?

A

proton

100
Q

Which baryon will all baryons eventually decay into?

A

proton

101
Q

State three examples of baryons

A
  • protons
  • neutrons
  • sigmas
102
Q

State two examples of anti-baryons

A
  • anti-protons

- anti-neutrons

103
Q

What are quantum numbers?

A

fundamental properties that must always be conserved

104
Q

What are the typical values of quantum numbers?

A

+1, 0, -1

105
Q

State the four quantum numbers

A
  • relative charge
  • baryon number
  • lepton electron number
  • lepton muon number
106
Q

What is the baryon number of a baryon?

A

+1

107
Q

What is the baryon number of an anti-baryon?

A

-1

108
Q

What is the baryon number of leptons and mesons?

A

0

109
Q

Are mesons stable or unstable?

A

unstable

110
Q

What are the two main groups of mesons?

A

pions and kaons

111
Q

What three types of mesons are there?

A

positive, neutral and negative

112
Q

Which forces are felt by leptons?

A
  • gravity
  • electromagnetism (if charged)
  • the weak nuclear force
113
Q

What is the criteria for a lepton to feel electromagnetism?

A

the lepton must be charged

114
Q

What is a muon?

A

a big unstable electron, which will eventually decay into an electron

115
Q

What is a neutrino?

A

a very low mass particle that interacts very weakly with other matter

116
Q

What are the two types of quantum number that a lepton may have?

A
  • lepton electron number

- lepton muon number

117
Q

What are the only values of both types of lepton number?

A

+1, 0, -1

118
Q

What is the lepton electron number and lepton muon number of an electron?

A
  • lepton electron = +1

- lepton muon = 0

119
Q

What is the lepton electron number and lepton muon number of a positron?

A
  • lepton electron = -1

- lepton muon = 0

120
Q

What are the 6 mesons on the spec?

A
  • pion plus
  • pion zero
  • pion minus
  • kaon plus
  • kaon zero
  • kaon minus
121
Q

What gives baryons and mesons their overall properties?

A

quarks and anti-quarks

122
Q

What is the quark composition of a baryon?

A

3 quarks (qqq)

123
Q

What is the quark composition of a meson?

A

1 quark and 1 antiquark

124
Q

What is the baryon number of a quark?

A

+1/3

125
Q

What is the baryon number of an antiquark?

A

-1/3

126
Q

What are the 6 quarks and antiquarks on the spec?

A
  • up
  • down
  • strange
  • anti-up
  • anti-down
  • anti-strange
127
Q

What is the charge of an up quark?

A

+2/3

128
Q

What is the charge of a down quark?

A

-1/3

129
Q

What is the charge of a strange quark?

A

-1/3

130
Q

What is the charge of an anti-up quark?

A

-2/3

131
Q

What is the charge of an anti-down quark?

A

+1/3

132
Q

What is the charge of an anti-strange quark?

A

+1/3

133
Q

What is the structure of a proton?

A

up, up, down

134
Q

What is the structure of an anti-proton?

A

anti-up, anti-up, anti-down

135
Q

What is the structure of a neutron?

A

up, down, down

136
Q

What is the structure of an anti-neutron?

A

anti-up, anti-down, anti-down

137
Q

What are the four meson rules?

A
  1. must contain a quark and an anti-quark
  2. the charge must add up to either +1, 0 or -1
  3. if the strangeness = 0, it is a pion
  4. if the strangeness does not = 0, it is a kaon
138
Q

What is meant by the term “quark confinement”?

A

it is not possible to get a quark by itself

139
Q

What would happen if you tried to split a meson in two? What is this called?

A

the amount of energy needed actually creates a quark and an anti-quark (pair production)

140
Q

What three things happen when a nucleus undergoes beta minus decay?

A
  1. an electron is emitted
  2. an anti-electron neutrino is emitted
  3. a neutron turns into a proton
141
Q

In a nucleus, what is responsible for a neutron turning into a proton? What is this called?

A

the weak nuclear force, weak interaction

142
Q

What is the key difference between beta MINUS decay and beta PLUS decay?

A

in beta PLUS decay, a positron and a normal neutrino are produced whereas in beta MINUS decay, an electron and an anti-electron neutrino is produced

143
Q

What does it mean when a property is conserved throughout an interaction?

A

the value of that property before is the same as the value of that property after

144
Q

State six properties that are always conserved

A
  • energy
  • momentum
  • charge
  • baryon number
  • lepton electron number
  • lepton muon number
145
Q

Is strangeness always, sometimes or never conserved?

A

sometimes

146
Q

What property is never conserved?

A

mass

147
Q

What property do particles such as kaons have?

A

strangeness

148
Q

What are the values of strangeness?

A

+1, 0, -1

149
Q

In which interaction is strangeness always conserved?

A

the strong interaction (when SNF acts between baryons and mesons

150
Q

In which interaction is strangers not always conserved?

A

the weak interaction (when WNF acts)

151
Q

What is the strangeness of a kaon plus?

A

+1

152
Q

What is the strangeness of a kaon zero?

A

+1

153
Q

What is the strangeness of an anti-kaon zero?

A

-1

154
Q

What is the strangest of a kaon minus?

A

-1

155
Q

How do we know an interaction is strong? What does this mean for strangeness?

A
  • can’t involve leptons
  • only involves hadrons
  • strangeness is conserved
156
Q

How do we know an interaction is weak? What does this mean for strangeness?

A
  • will probably involve leptons
  • usually 1 particle decaying into 2
  • strangeness is probably not conserved
157
Q

Via which interaction are strange particles created?

A

strong interaction

158
Q

Via which interaction do strange particles decay?

A

weak interaction

159
Q

By what amount(s) can strangeness change in the strong interaction?

A

0

160
Q

By what amount(s) can strangeness change in the weak interaction?

A

+1, 0, -1

161
Q

What special property do strange particles have?

A

strangeness

162
Q

What is the role of an exchange particle in an interaction?

A

exchange particles transmit forces between particles by exchanging momentum and energy

163
Q

What are exchange particles sometimes called?

A

gauge bosons

164
Q

What is the exchange particle of the electromagnetic force?

A

virtual photon

165
Q

Why is the virtual photon virtual?

A

because ‘seeing’ it would stop the force transmitting

166
Q

What are the exchange particles of the weak nuclear force?

A

W+ and W- bosons

167
Q

What is the exchange particle of the strong nuclear force?

A

pions - force between nucleons

& gluons - force between quarks

168
Q

What is the exchange particle of gravity?

A

graviton (not yet observed)

169
Q

What is the mass, charge and range of a virtual photon?

A

0 mass, 0 charge, infinite range

170
Q

What is the mass, charge and range of W+ and W- bosons?

A

has mass, has charge, very short range

171
Q

What is the mass, charge and range of pions (& gluons)?

A

has mass, has charge, very short range

172
Q

What is the mass, charge and range of a graviton?

A

0 mass, 0 charge, infinite range

173
Q

What diagram did Richard Feynman develop?

A

a simple and elegant system called Feynman diagrams

174
Q

What are the rules for a Feynman diagram?

A
  • before interaction at the bottom
  • after interaction at the top
  • baryons on the left
  • leptons on the right
175
Q

What is the relationship between the mass of an exchange particle and its range?

A

inversely proportional - the heavier the exchange particle, the shorter the range

176
Q

What are the five Feynman diagrams you need to know?

A
  1. beta MINUS decay
  2. beta PLUS decay
  3. electromagnetic repulsion
  4. electron capture
  5. electron proton collision
177
Q

What is the only difference between electron capture and electron proton collision?

A

the type and direction of the exchange particle