Particles Flashcards
(120 cards)
1
Q
What is the force which overcomes the repulsive force within the nucleus ?
A
The strong nuclear force
2
Q
What types of particles does the strong nuclear force impact ?
A
Hadrons ( neutrons and protons )
3
Q
What is the purpose of the strong nuclear force ?
A
To overcome the repulsive electrostatic forces holding the nucleus together
4
Q
At what distances is the strong nuclear force repulsive ?
A
Under 0.5 fm
5
Q
What is the range of the strong nuclear force ?
A
3-4 fm (10^-15)
6
Q
Why is the strong nuclear force repulsive at certain distances ?
A
To prevent the protons and neutrons from colliding into each other
7
Q
Why does alpha decay occur ?
A
The atom is too large for the strong nuclear force to keep stable
8
Q
What is an alpha particle ?
A
A helium nucleus consisting the nucleon number 4 and proton number 2
9
Q
What happens to the nucleon number as the particle undergoes alpha decay ?
A
Decreases by 4
10
Q
What happens to the proton number as the particle undergoes alpha decay ?
A
Decreases by 2
11
Q
What is the range of an alpha particle ?
A
A few centimetres (short range )
12
Q
Why does beta minus decay occur ?
A
Due to the high ratio of neutrons to protons , converting a neutron to a proton
13
Q
What is ionisation ?
A
The removal or addition of electrons from an atom or molecule
14
Q
Which beta decay converts a neutron to a proton ?
A
Beta minus decay
15
Q
What does a beta minus decay emit ?
A
A beta particle along with an antineutrino
16
Q
What happens to the the nucleon number during the emission of a beta particle ?
A
The nucleon number remains the same
17
Q
What happens to the proton number as a beta minus particle is emitted ?
A
The proton number increases by one
18
Q
Explain why alpha dust is hazardous to an unprotected human
A
- can enter the body through ingesting or breathing in the particles which can kill cells as the human cells and tissues become damaged
19
Q
How had neutrinos been discovered ?
A
- the energy after the decay had been lower than the initial energy (not following the conservation of energy principle )
This lead to the suggestion that another particle is also emitted with almost no mass and charge
20
Q
What is a gamma radiation ?
A
An electromagnetic radiation emitted by an unstable nucleus
21
Q
Why is gamma radiated ?
A
Particles with too much energy following an alpha or a beta emission
22
Q
What does every particle have ?
A
An antiparticle with the same mass and rest energy but an apposite charge
23
Q
When does annihilation occur ?
A
When a particle comes into contact with its antiparticle
24
Q
What occurs when a particle is annihilated?
A
The mass is converted into energy producing two gamma photons in opposite directions
25
Why are 2 photons produced in opposite directions when a particle and an antiparticle come into contact ?
To conserve momentum
26
What is the minimum energy of a single photon produced during annihilation ?
hfmin - rest energy of one particle
27
What is the minimum energy produced during annihilation ?
The rest energy of the particle and its antiparticle combined
28
What is pair production ?
When a discrete photon creates a particle and its corresponding antiparticle
29
What is the minimum energy of the photon required for pair production to occur ?
The sum of the rest energy of the particle and its corresponding antiparticle
30
What are photons ?
Packets of electromagnetic waves
31
What is the electromagnetic spectrum ?
Radio , micro, infrared, visible, ultraviolet, X-rays, gamma rays
32
Why must the frequency be a certain value for pair production to occur ?
If the frequency is below a certain value there is not enough energy to provide the rest energy of the particle and its antiparticle as e is directly proportional to f
33
What speed do electromagnetic waves travel in a vacuum?
3 *10^8 m/s
34
What has a greater wavelength gamma or radio ?
Radio has a greater wavelength
35
What has a greater frequency gamma or radio waves ?
Gamma has a greater frequency
36
What is the energy of a photon equal to ?
Planks constant * frequency or (speed/ wavelength)
37
Properties that are conserved in pair production ?
Energy, momentum , charge , lepton , baryon , strangeness
38
What is planks constant ?
6.63*10^-34
39
What are forces a result of ?
Particle exchange
40
Why do two like charges repel each other ?
One of the particle passes an exchange particle to the other transferring momentum, resulting in them moving away from each other ( a guy throwing a ball on a skateboard)
41
What do oppositely charged particles attract each other ?
One of the particle passes an exchange particle to the other particle transferring momentum resulting in the particles moving towards each other
42
What is the exchange particle of the electromagnetic force ?
Virtual photon
43
What particles are affected by the electromagnetic force ?
All charged particles
44
What force is responsible for the repulsion of two like charges ?
The electromagnetic force
45
What is the exchange particle of the weak force ?
W+ and w- and z0 bosons
46
What force is affects by all particles?
Weak force
47
What force and exchange particle is responsible for the emission of beta plus and minus particles ?
Weak - w bosons
48
What is produced when a neutron and neutrino interact ?
A proton and a beta minus is emitted
49
What is produced when proton and antineutrino interact?
A beta plus and a neutron is emitted
50
Which interaction emits a neutron and a beta plus particle ?
- proton and an antineutrino
51
What interaction produces a proton and a beta minus particle ?
Neutrino and a neutron
52
What is the bosson when a beta minus particle is an antineutrino is emitted ?
W -
53
What is the bosson when a beta plus particle is a neutrino is emitted ?
W + bosson
54
What are the two classifications of particles ?
Hadrons and leptons
55
What are hadrons ?
Particles made up of quarks that experience the strong nuclear force
56
What can hadrons be further classified as ?
Baryons and mesons
57
What is the difference between baryons and mesons ?
Baryons are made up three quarks whereas mesons are made from two a quark and an antiquark
58
What are baryons ?
Protons and neutrons ( they all decay to become other particles ,always including a proton within the decay as a proton is the most stable
59
What is the baryon number of a proton ?
1
60
What type of number is the baryon number ?
A quantum number
61
What reaction is the baryon number conserved in ?
All interactions
62
What are mesons ?
Pions , kaons
63
What is a pion ?
The lightest mesons
64
What is a kaon ?
A heavier more unstable meson which have a short life time and decay into pions
65
What is a lepton ?
Electron and muons
66
What is a muon ?
A heavier more unstable version of an electron therefore it decays into an electron
67
What type of interactions do neutrinos take part in ?
W bozzons
68
What are lepton rules ?
-leptons can convert into other leptons as well as be produced or ambulated within a particle antiparticle interaction
69
What is an isotope?
Atoms with the same proton number but a different nucleon number - different number of neutrons
70
What are the three isotopes of hydrogen ?
Protium - deuterium - tritium
71
What is the radius of an atom ?
10^-10m
72
What is the radius of a nucleus ?
10^-15m
73
Mass of a proton ?
1.63 * 10^-27
74
Mass of a neutron?
1.675 *10^-27
75
Mass of an electron?
9.11*10^-31
76
Charge of an electron ?
-1.6*10^-19
77
What is the specific charge ?
The ratio of its charge to mass
78
How would you work out the specific charge of a nucleus ?
Proton number * charge of a proton / ( mass of all proton and neutron )
79
What is the nucleon number ?
The mass number , number of protons and neutrons in the nucleus ( total number of nucleons)
80
What is the proton number ?
Atomic number, the number of protons in the nucleus
81
What determines the chemical properties of an atom?
The electrons
82
What would be different for the isotopes ?
The stability as the nucleus defines the stability
83
What constituent particle has a zero charge per mass ratio ?
Neutron
84
What constituent particle has the largest charge per unit mass ratio ?
The electron
85
What is a beta minus particle ?
A high speed electron emitted from the nucleus
86
What is a beta plus decay ?
A high speed positron that is emitted from the nucleus
87
What must be done to validate the predictions of an unconfirmed scientific theory ?
- produce an experiment that proves the hypothesis that is repeatable if not reject hypothesis
88
Explain why the alpha particle , once outside the nucleus is unaffected by the strong nuclear force ?
- strong nuclear force has a short range - no effect at distances greater than 3fm
89
Why do photons from the annihilation of an electron- positron pair not go on to creating new electron - positron pairs ?
During annihilation, energy of a single photon is half the energy required to produce an electron positron pair.
90
What are the four fundamental forces ?
- strong nuclear
- electromagnetic
- weak nuclear
- gravitational
91
What is the range if the gravitational force ?
Infinite range
92
What is the range of the weak force ?
Short
93
What is the range of the electromagnetic force ?
Infinite range
94
What is the range if the strong nuclear force ?
Short - few fm
95
What is the purpose of the gravitational force ?
To hold objects together - weak on sub nuclear levels
96
What is the weak force responsible for ?
Fusion and beta decay interactions
97
What is the electromagnetic force responsible for ?
The repulsion of protons
98
When drawing a Feynman diagram, which side must baryons stay on ?
The left
99
When drawing a Feynman diagram, which side must the leptons be on ?
On the right side
100
How are particles represented on a Feynman diagram ?
Through a straight line
101
How are bosons represented on a Feynman diagram ?
Through wiggly lines
102
What bosson can carry charge from one side to the other side on a diagram ?
W bosons
103
How would you use w bosons when drawing a Feynman diagram ?
Treat like kirchoffs law - entering a junction = exiting a junction
104
What is electron capture ?
When an proton rich nucleus absorbs an electron from the inner shell producing a neutron and an electron neutrino
105
What is an electron proton collision ?
When a high speed proton collides with an electron emitting a neutron and a neutrino
106
What is the bosson for electron capture ?
W+ going to the right
107
What is the boson for an electron proton collision ( and the direction ) and why ?
The electron initiates the interaction so the there is a w- bosson carried from the right to the left
108
How can mesons interact with the baryons ?
The strong interaction
109
What is a neutrino ?
Leptons , with negligible mass , no charge and only interact via the weak interaction
110
What are gen 1 quarks ?
Up and down quarks
111
What are gen 1 leptons ?
Electron , electron neutrino
112
What are gen 2 quarks ?
Strange ( charm )
113
What are gen 2 leptons ?
Muon , muon neutrino
114
What are strange particles ?
Particles that have a s quark and display a property called strangeness.
115
Quark composition of a proton ?
Two up quarks and a down quark
116
Quark composition of a neutron ?
Two down quarks and one up quark
117
What happens to the quarks during a beta minus decay ?
A down quark turns into an up quark
118
What is conserved in strong interactions ?
-baryon number
- lepton number
- charge
- strangeness
- energy / mass
- momentum
119
What is conserved in weak interactions ?
-baryon number
- lepton number
- charge
- energy / mass
- momentum
120
What is conserved in the Em interaction ?
- energy
- momentum
- charge
