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Physics > 2.1 & 2.2 Particles and Radiation > Flashcards

2.1 & 2.2 Particles and Radiation Flashcards

2.1 atomic structure & decay equations 2.2 classification of particles

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1
Q

What are the 3 constituents of an atom?

A

protons
neutrons
electrons

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2
Q

what is the structure of an atom?

A
  • at the centre of an atom is a nucleus
  • the nucleus is formed of protons and neutrons
  • they’re known as nucleons
  • electrons orbit the nucleus in shells
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3
Q

What are the properties shown in the constituents of the atom?5

A
  • charge
  • relative charge
  • mass
  • relative mass
  • specific charge
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4
Q

What is the charge of a proton?

A

1.6 x 10^-19

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5
Q

What is the relative charge of a proton?

A

+1

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6
Q

What is the mass of a proton?

A

1.67 x 10^-27

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7
Q

What is the relative mass of a proton?

A

1

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8
Q

What is the specific charge of a proton?

A

9.58 x^7

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9
Q

What is the charge and relative charge and specific charge of a neutron?

A

0

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10
Q

What is the mass of a neutron?

A

1.67 x 10^-27

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11
Q

What is the relative mass of a neutron?

A

1

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12
Q

What is the charge of an electron

A

-1.6 x 10^-19

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13
Q

What is the relative charge of an electron?

A

-1

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14
Q

What is the specific charge of electrons?

A

1.76 x 10^11

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15
Q

what is the mass of electrons?

A

9.11 x 10-31

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16
Q

What is the relative mass of an electron?

A

0.0005

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17
Q

What is the specific charge of a particle?

A

The charge to mass ratio
- calculated by dividing a particles charge by its mass

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18
Q

What is an isotope?

A

atoms with the same number of protons but different numbers of neutrons

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19
Q

What is the proton number denoted by?

A

Z

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20
Q

What is the nucleon number and what is it denoted by?

A
  • number of protons and neutrons
  • A
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21
Q

How do strong nuclear forces keep nuclei stable?

A
  • by contracting the electrostatic force of repulsion between protons in the nucleus
  • only acts on nucleons and has a very short range, - - —– where it is attractive up to separations of 3fm, and below separations of 0.5fm
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22
Q

What are unstable nuclei? 4

A
  • those which have too many either protons, neutrons or both
  • causing the strong nuclear forces to not be enough to keep them stable
  • thus the nuclei will decay in order to become stable
  • the type of decay experienced depends on the amount of each nucleon in them
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23
Q

What are the different types of decay?

A
  • alpha decay
  • beta-minus decay
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24
Q

What is alpha decay?

A
  • occurs in large nuclei with too many both protons and neutrons
  • proton number decreases by 2
  • nucleon number decreases by 4
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25
Q

What is Beta-minus decay?

A
  • occurs when nuclei which are neutron rich have too many neutrons
  • the proton number increases by one
  • nucleon number stays the same
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26
Q

What are antiparticles?

A

particles that have the same rest energy and mass but all its other properties are opposite the particles

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27
Q

What are photons?

A
  • electromagnetic radiation travel in packets called photons
  • they transfer energy
  • have no mass
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28
Q

What is the relationship between photon energy and frequency of the electromagnetic radiation?

A

energy of photons is directly proportional to the frequency of electromagnetic radiation

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29
Q

What is the Planck constant?

A
  • h
  • 6.63 x 10^(-34)
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30
Q

What is beta-plus decay?

A
  • high energy positron emitted from the nucleus
  • when a proton turns into a neutron emitting a positron and an electron neutrino
  • proton number decreases by one
  • nucleon number remains the same
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31
Q

What is an electron neutrino?

A
  • type of subatomic particle - - with no charge
  • negligible - mass
  • which is also emitted from the nucleus
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32
Q

What is an anti-neutrino?

A
  • anti particle of a neutrino
  • produced during beta minus decay
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33
Q

What is annihilation?

A
  • when a particle meets its equivalent anti-particle they both are destroyed
  • their mass is converted into energy in the form of two gamma ray photons
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34
Q

What happens when an electron and positron collide?

A

their mass is converted into energy in the form of 2 photons emitted in opposite directions

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35
Q

What is the minimum energy of 1 photon after annihilation?

A

the total rest mass energy of one particle is:
E=hf

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36
Q

What is the rest mass energy of one of the particles in annihilation?

A

E = hf = hc/gamma

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37
Q

what is pair production?

A
  • opposite of annihilation
  • when a photon interacts with a nucleus or atom and the energy of the photon is used to create a particle - antiparticle pair
38
Q

What occurs when a photon with enough energy reacts with a nucleus?

A

produces an electron - positron pair

39
Q

Why must the photon react with enough energy in pair production?

A

the energy of the photon must be above a certain value to provide the total rest mass energy of the particle-antiparticle pair

40
Q

What is the minimum energy for a phone to undergo pair production?

A

the total rest mass energy of the particles produced

41
Q

What direction do the particle and anti - particle move in pair production?

A

opposite directions due to the conservation of momentum

42
Q

What are the two categories matter and antimatter are split into?

A

Hadrons and leptons

43
Q

What are hadrons?

A
  • groups of subatomic particles that are made up of quarks
  • hadrons can feel the strong nuclear force
44
Q

What are the 2 classes of hadrons?

A

Baryons (3 quarks)
Mesons (quark and anti-quark pair)

45
Q

What are the common baryons?

A

protons, neutrons and their anti-particles

46
Q

What are the common mesons?

A

pions and kaons and their anti particles

47
Q

What is the quark structure of baryons?

A

3 quarks

48
Q

What is the quark structure of mesons?

A

quark and anti-quark

49
Q

What is a baryon number?

A
  • depends on whether the particle is a baryon, anti-baryon or neither
    • baryons have +1
    • anti-baryons have -1
    • particles not baryons have 0
  • quantum number and is conserved in all interactions
50
Q

What is the baryon number of up down and strange quarks?

A
  • 1/3
  • anti quarks have -1/3
51
Q

What properties does the proton have as a baryon?

A
  • most stable baryon
  • longest half life of any baryons
  • most baryons eventually decay to be a proton
  • most stable as it is the lightest baryon
    • radioactive decay occurs when heavier particles decay into lighter particles
    • decay of the proton would therefore violate the conservation of baryon number
52
Q

What are the most common mesons?

A
  • pions
  • kaons
53
Q

What are properties of pions?

A
  • lightest mesons
  • more stable than most mesons
  • originally discovered in cosmic rays
  • can be observed in a cloud chamber
54
Q

What are strong nuclear forces?

A

forces that keep protons and neutrons bound together in a nucleus and is one of the four fundamental interactions
- each of these interactions is caused by a particle exchange

55
Q

What are pions?

A
  • the exchange particle of the strong nuclear force
  • strong force is transmitted between a proton and neutron bay the exchange of a piano
  • pions mediate the strong nuclear forces
56
Q

What is a gluon?

A
  • an exchange particle of the strong force
57
Q

What’s the difference between a pion and a gluon?

A
  • gluons are responsible for binding quarks together
  • referred to as the strong interaction
  • pions are responsible for binding nucleons together
  • referred to as the strong nuclear force
58
Q

How are kaons produced?

A

by the strong interaction between pions and protons

59
Q

Why do Kaons decay?

A
  • they’re heavy and unstable this decay into pions normally
60
Q

What is the lifetime of kaons and why?

A
  • usually have long lifetimes
  • because kaons contain a strange quark and longer lifetimes are characteristic of particles containing strange quarks
61
Q

What is neutral kaon decay?

A

neutral kaon -> positive pion + negative pion

62
Q

What are leptons?

A
  • fundamental particles
  • interact with other particles via the weak, gravitational or electromagnetic interactions
    • not via the strong nuclear force
63
Q

What makes a particle a fundamental particle?

A

not made up of any other particles
- i.e. no quarks

64
Q

What are the most common lepton?

A
  • electrons
  • electron neutrino
  • muon
  • muon neutrino
    and their anti-particles
65
Q

How do positive pions decay?

A

positive pions -> anti-muon + muon neutrino

66
Q

What is a lepton number?

A
  • number of leptons in an interactions
  • depends on whether the particle is a lepton, anti-lepton or neither
    • lepton have +1
    • anti-leptons have -1
    • particles not leptons have 0
  • quantum number that is conserved in all interactions
67
Q

What is muon decay?

A
  • muons decay into an electron
  • anti muons decay into positrons
  • muon decay occurs through the weak interaction
68
Q

What is the Feynman diagram of muon decay?

A
  • muon goes to muon neutrino
  • then through W- boson it goes to
  • anti electron neutrino and electron
69
Q

What are the 3 quark flavours?

A

up
down
strange

70
Q

What do all quarks have?

A
  • charge
  • baryon number
  • strangeness
71
Q

How is the charge of quarks relevant

A

the sum of them determine the charge of a hadron

72
Q

What is the quark combination of baryons?

A

they’re not fundamental thus made up of 3 quarks

73
Q

What is the quark combination of protons?

A

uud

74
Q

What is the quark combination of neutrons?

A

udd

75
Q

What is the quark combination of mesons?

A

pions and kaons are made up of a quark and anti-quark pair

76
Q

What is the quark structure of pions?

A

positive pions - up, anti-down
negative pions - anti up, down
neutral pions - up, anti up or down, anti down

77
Q

What is the quark combination of kaons?

A

positive kaons - up, anti-strange
negative kaons - anti-up, strange
neutral kaon - down, anti-strange or anti-down, strange

78
Q

What are the properties of strange particles?

A
  • produced through the strong interaction
  • decay through weak interaction
  • produced in quark - antiquark pairs
79
Q

What is strangeness?

A
  • quantum number, like baryon and lepton number
  • conserved in every interaction except the weak interaction
  • strange particles are produced in pairs (e.g. K+ and K-)
  • particles with strange quark have -1
  • with anti strange have +1
  • with no quark have 0
80
Q

What is the process of particle physics?

A
  • a new theory is developed; may be hypothesis the existence of a new particle and its properties
  • experiments carried out to find this new particle
  • different experiments are combined to suggest a new discovery
  • if confirmed usually repeated to reduce experimental uncertainty, the theory is then validated
  • if validated the scientific community will accept it as the theory is more likely to be correct
81
Q

What are particle accelerators used for?

A

to collide particles at very high speeds in order to
- produce new particles
- reveal the inner structure of particles

82
Q

what happens in a particle accelerator?

A

particles collide at very high energies meaning they travel close to the speed of light

83
Q

What are the 2 types of particle accelerators?

A
  • linear
  • circular
84
Q

What is required in a circular particle accelerator and why?

A
  • require extremely powerful superconducting magnets
  • to keep high speed particles in a circular orbit
85
Q

When experiments using particle accelerators occur why is it important it is done collaboratively?

A
  • they’re expensive
  • complicated pieces of equipment required to make a particle accelerator
  • provides funding
  • expertise to design
  • construct and operate experiments successfully
86
Q

What does LHC stand for?

A

large hadron colider

87
Q

What is a large hadron collider?

A
  • works largest and highest energy particle collider
  • based at CERN in Geneva on the France, Swiss botder
  • 2500 scientists work there, comprising of 110 nationalitiees
88
Q

What are the 4 main detectors that the LHC Is made of?

A
  • CMS
  • LH Cb
  • ATLAS
  • ALICE
89
Q

What occurs in the CMS portion of the LHS?

A
  • confirmed existence of the Higgs Boson
  • same scientific goals as ATLAS but a different magnetic system
90
Q

What occurs in the LH Cb portion of the LHS?

A
  • study of matter - antimatter asymmetry in particles containing the bottom quark
  • discovery of the tetra - quark
91
Q

What occurs in the ATLAS portion of the LHS?

A
  • discovery of the Higgs boson
  • search for dark matter
  • search for physics beyond the standard model
92
Q

What occurs in the ALICE portion of the LHS?

A
  • proton beams collide head on at each detector
  • study of quark-gluon plasma

Physics (18 decks)

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