Particles and Radiation Flashcards
1
Q
What is the relative charge of a proton?
A
+1
2
Q
What is the relative charge of a electron?
A
-1
3
Q
Relative charge of a neutron
A
0
4
Q
Relative mass of a proton
A
1
5
Q
Relative mass of an electron
A
1/1820
6
Q
Relative mass of a neutron
A
1
7
Q
What letter is used to represent nucleon number?
A
A
8
Q
What letter is used to represent proton number?
A
Z
9
Q
What is the equation for specific charge?
A
Specific charge(C/Kg) = charge(C)/mass(Kg)
10
Q
What are isotopes?
A
Isotopes are atoms with the same number of protons but a different number of neutrons
11
Q
How does adding more neutrons affect an atom?
A
Adding more neutrons makes an atom more unstable. These unstable nuclei may be radioactive and decay to make themselves more stable
12
Q
What is the range of the strong nuclear force?
A
< 3fm
13
Q
When is the strong nuclear force repulsive?
A
When nucleon separation is less than 0.5fm
14
Q
When is the strong nuclear force attractive?
A
When nucleon separation is between 0.5fm - 3fm
15
Q
What are the forces that act within nuclei?
A
- Gravitational force
- Strong nuclear force
- Electromagnetic force
16
Q
What does the electromagnetic force do in nuclei?
A
It causes the positively charged protons to repel each other
17
Q
What is the range of the electromagnetic repulsive force?
A
Infinite
18
Q
What type of atoms does alpha decay occur for?
A
Very big atoms with greater than 82 protons
19
Q
What is an alpha particle?
A
A particle made up of 2 neutrons and two protons (A helium nucleus)
20
Q
What is beta minus decay?
A
The emission of an electron from the nucleus along with an antineutrino particle
21
Q
What type of atoms does beta minus decay from?
A
Atoms that are neutron rich (have too many neutrons)
22
Q
What happens to the nucleons of an atom that undergoes beta minus decay?
A
- One of the neutrons in the nucleus is changed into a proton
- Proton number increases by one, nucleon number stays the same
23
Q
Describe how the neutrino was theorised
A
- Scientist originally thought only an electron was emitted during beta decay
- However observations showed energy of the particles after beta decay was less than before which didn’t fit the principle of energy conservation
- It was then hypothesised that another particle was emitted and it carried away the remaining energy but it had to be neutral, and near zero mass
- This hypothesis was later accepted and this particle was named the neutrino
24
Q
What is the electromagnetic spectrum?
A
A continuous spectrum of all the possible frequencies of electromagnetic radiation
25
What are the traits of an antiparticle compared to corresponding particle?
Same mass and rest energy but opposite charge
26
Define pair production
- Energy is converted into mass in the form of a particle-antiparticle pair
- Only occurs when there is enough energy to produce the masses of the particles
27
State the equation for minimum energy needed for pair production
E(min) in MeV = 2Eo where Eo = Rest energy of particle type produced in MeV
28
Define annihilation
Matter and antimatter meet and mass is converted directly into energy in the form of two gamma ray photons which travel in opposite directions
29
State the equation for minimum energy needed for annihilation
E(min) in MeV = Eo where Eo = Rest energy of particle type annihilated in MeV
30
State an application that uses annihilation and describe how it works
- PET scanners work by putting a positron-emitting isotope into the bloodstream, and detecting the gamma rays produced by the electron-positron annihilation occurring
- A scintillator is used to detect gamma rays which are easy to distinguish as these gamma rays are always produced in pairs moving in opposite directions
31
What are hadrons?
Particles that feel the strong nuclear force
32
What are the types of hadrons?
Baryons and mesons
33
What is the most stable baryon which all particles baryons end up decaying to?
The proton
34
State the baryon numbers of baryons, antibaryons and other particles?
- Baryons = +1
- Antibaryons = -1
- Other particles = 0
35
What is neutron decay?
Beta-minus decay caused by the weak interaction where a neutron decays into a proton, an electron and an antineutrino
36
State 2 characteristics of mesons
- Mesons are all unstable
- Quark and antiquark pair
37
State 2 types of mesons
Pions and Kaons
38
Which quark is always in a kaon?
Strange quark
39
Describe pions
- Pions are the lightest mesons.
- There are 3 types: π+, π–, π0
- π– is just the antiparticle of π+
- The antiparticle of π0 is itself
- Pions are exchange particles of the strong nuclear force
40
Describe kaons
- Kaons are heavier and more unstable than pions
- There are 3 types: K+, K-, Ko
- K+ is the antiparticle of K-
- Antiparticle of Ko is itself
- Kaons have very short lifespans and decay into pions
41
Define cosmic rays
Radiation in the form of high-energy, charged particles that come from space and hit Earth
42
Define cosmic ray showers
Cosmic rays interacting with molecules in the atmosphere to produce showers of lots of high-energy particles, including pions and kaons
43
How are mesons detected?
- Cosmic ray showers can be detected with the use of two Geiger counters placed one above the other, separated by absorbing lead.
- If both counters detect radiation simultaneously, it's very likely a particle from a cosmic ray shower being detected (pions and kaons)
44
What are leptons?
Fundamental particles which don't feel the strong nuclear force
45
State 4 types of leptons
- Electron
- Electron neutrino
- Muon
- Muon neutrino
46
State the properties of neutrinos
- Almost zero mass
- Zero electric charge
47
What are the two types of lepton numbers?
Le and Lμ
48
State the symbol, relative charge and lepton numbers of each lepton
Electron: symbol = e- ; relative charge = -1 ; Le number = +1 ; Lμ number = 0
Electron neutrino: symbol = νe ; relative charge = 0 ; Le number = +1 ; Lμ number = 0
Muon: symbol = μ ; relative charge = -1 ; Le number = 0 ; Lμ number = +1
Muon neutrino: symbol = vμ ; relative charge = 0 ; Le number = 0 ; Lμ number = +1
49
What must be conserved in particles interactions?
Baryon number, lepton number, charge, energy and momentum
50
State the properties of strange particles
- Quantum number, like baryon and lepton number
- Created by the strong interaction, in which strangeness is conserved
- Conservation means strange particles can only be created in pairs
- All leptons have a strangeness of 0
- Strange particles decay through the weak interaction
- Strangeness is not conserved in the weak interaction
51
When is strangeness conserved?
For strong interactions and in some weak interactions, such as beta-decay
52
State the properties of quarks
Up: symbol = u ; charge = +2/3 ; baryon number = +1/3 ; strangeness = 0
Down: symbol = d ; charge = -1/3 ; baryon number = +1/3 ; strangeness = 0
Strange: symbol = s ; charge = -1/3 ; baryon number = +1/3 ; strangeness = -1
Antiquarks have opposite properties, up quark charge = -2/3
53
What is the quark composition of a baryon?
3 quarks
54
What is the quark composition of an antibaryon?
3 antiquarks
55
What is the quark composition of a meson?
1 quark and 1 antiquark
56
What is the quark composition of a proton?
uud
57
What is the quark composition of a neutron?
udd
58
What is the quark composition of a pion?
Combinations of up, down and anti-up, anti-down quarks
59
What is the quark composition of a kaon?
Kaons have strangeness, so an up or down or anti-up or anti-down with a strange quark
60
What is quark confinement?
- It's impossible to get a quark by itself
- The energy used trying to remove a quark only creates a quark antiquark pair in a pair production
61
State how the quark composition changes in beta-minus decay
A d quark turns into a u quark
62
State how the quark composition changes in beta-plus decay
A u quark turns into a d quark
63
Define exchange particle
A virtual particle which allows forces to act in a particle interaction. Also known as gauge bosons
64
State the type of interactions
Strong nuclear
Electromagnetic
Weak nuclear
Gravitational
65
State the exchange particle of the strong nuclear force interaction
Pions: Gluons, mesons
66
State the exchange particle of the electromagnetic force interaction
Virtual photons(γ)
67
State the exchange particle of the weak nuclear force interaction
W+, W- bosons
68
State the exchange particle of the gravitational force interaction
Graviton
69
State the range of the gravitational force interaction
Infinite
70
State the range of the weak nuclear force interaction
10^-3fm
71
State the symbol form of beta-minus decay
n -> p + e- + ̅Ve
72
What should be the layout for a particle interaction diagram?
Baryons on the left, leptons on the right, exchange particle in the middle
73
State the symbol form of beta-plus decay
p -> n + e+ + Ve
74
What is electron capture?
When proton rich nuclei capture an electron capture an electron from inside the atom and change into a neutron and electron neutrino
75
State the symbol form of electron capture
p + e- -> n + Ve
76
What happens in electromagnetic repulsion?
Two particles with equal charge interact, causing them to repel. The exchange particle is the virtual photon
77
What is the difference between electron capture and electron-proton collisions?
In electron-proton collisions, it is the electron that's acting as it's being fired at the proton. The W boson then comes from the electron, making it W-
78
What does the word "specific" refer to in "Specific Charge" or "Specific heat capacity"?
Per unit mass
79
Define relative mass
The mass of a particle relative to the mass of a proton
80
Define relative charge
The charge of a particle relative to the charge of a proton
81
State the letter used to represent the neutron number
N
82
What is a gamma particle?
A high energy photon
83
How is an excited nucleus denoted in an equation?
By an asterisk
84
What is the difference between an electron and a beta particle?
Beta particles have much more energy than electrons (Beta particles eject from the nucleus at 98% of the speed of light)
85
State the particles acted upon by the gravitational force interaction
Particles with a mass
86
State the particles acted upon by the weak nuclear force interaction
All particles
87
State the particles acted upon by the strong nuclear force interaction
Quarks, baryons
88
State the particles acted upon by the electromagnetic force interaction
Particles with a charge
89
Which quark has the most energy?
Strange quark
90
What is the exchange particle in beta-minus decay?
W- boson
91
What is the exchange particle in beta-plus decay?
W+ boson
92
What is the exchange particle in electron capture?
W+ boson
93
What is the exchange particle in electron-proton collisions?
W- boson
94
What is the exchange particle of electromagnetic repulsion?
Virtual photon
95
State the 6 leptons
- Electron
- Muon
- Tauon
- Electron neutrino
- Muon neutrino
- Tauon neutrino
