Section 1 - Particles Flashcards
(104 cards)
1
Q
What are atoms made up of?
A
Protons, neutrons, electrons
2
Q
What is a nucleus made up of?
A
Protons and neutrons
3
Q
What is the collective name for protons and neutrons?
A
Nucleons
4
Q
What is the relative charge for a proton, neutron and electron?
A
Proton = +1 Neutron = 0 Electron = -1
5
Q
What is the relative mass for a proton, neutron and electron?
A
Proton = 1 Neutron = 1 Electron = 0.0005
6
Q
What is the proton number?
A
The number of protons in the nucleus
7
Q
What is the atomic number, and what is its symbol?
A
The number of protons. Symbol Z
8
Q
What defines an element?
A
The proton number
9
Q
What condition must be satisfied for an element to be neutral?
A
Proton number must equal the neutron number
10
Q
What does an element’s chemical behaviour depend on?
A
The number of electrons
11
Q
What is the nucleon number and what is its symbol?
A
The total amount of protons and neutrons in an atom, symbol A
12
Q
What is the mass number?
A
Total number of protons and neutrons
13
Q
What are isotopes?
A
Atoms with the same number of protons but different numbers of neutrons
14
Q
What does changing the number of neutrons in an atom do?
A
Does not effect chemical properties, but changes stability
15
Q
What happens to unstable nuclei?
A
They may be radioactive and decay into different nuclei
16
Q
What is a use for radioactive isotopes?
A
Find out how old stuff is
17
Q
How do you find out how old stuff is with radioactive isotopes?
A
- All living things have the same number of carbon-14
- After they die, the carbon-14 decreases over time as it decays into stable elements
- Can calc age by using isotopic data to find the % of radioactive carbon-14 left in an object
18
Q
What is specific charge?
A
The ratio of its charge to its mass
19
Q
What is the unit of specific charge?
A
C/kg
20
Q
What does the strong nuclear force do?
A
Binds nucleons together
21
Q
What is the range of the strong nuclear force when holding nucleons together?
A
A few femtometeres
22
Q
Describe the graph of the strong nuclear force
A
- Repulsive for very small separations (up to 1/2 femtometer)
- After 1/2 femtometer, SNF becomes attractive
- Reaches a maximum value, then falls rapidly towards 0 after 3 femtometer
23
Q
Why does the SNF have to be repulsive at very small distances?
A
To stop the nucleus crushing to a point
24
Q
Where does alpha emission happen?
A
In very big nuclei
25
Why does alpha emission happen in big nuclei?
Because the nuclei are too massive for the SNF to keep them stable
26
What happens when an alpha particle is emitted?
The proton number decreases by 2, the nucleon number decreases by 4
27
What is the range of an alpha particle?
A few cm in air
28
How can you observe alpha particles?
Using a cloud chamber or a Geiger counter
29
How can you use a Geiger counter to measure alpha particles?
Bring it close to the source and move it away slowly. Then count how the count rate drops
30
When does beta-minus emission happen?
In neutron rich nuclei
31
What is emitted in beta-minus emission?
An electron and an antineutrino
32
What happens when a nucleus emits a beta particle?
A neutron is changed into a proton
33
What happens in beta minus emission?
The proton number increases by one, the nucleon number stays the same
34
Why do you get an antineutrino in beta minus decay?
To carry away some energy and momentum
35
List the spectrum in order of increasing frequency
Radio, micro, infra, visible, ultraviolet, x-ray, gamma
36
What is an anti particle?
A particle with the same mass and rest energy, but opposite charge to the particle
37
What is the anti particles for a proton, neutron, electron and neutrino?
Proton, anti-proton
Neutron- anti-neutron
Electron, positron
Neutrino, anti-neutrino
38
What is the rest energy of particle?
The energy equivalent of the particle's mass
39
What happens when energy is converted to mass?
You get equal amounts of matter and antimatter
40
What produces a particle, antiparticle pair?
A single photon
41
When does pair production occur?
When one photon has enough energy to produce that much mass
42
What photons have enough energy to produce mass, and where does this usually occur?
Gamma ray photons, near the nucleus
43
What is the minimum energy needed for a photon to undergo pair production?
The total rest energy of the particles produced
44
When energy is converted to matter, what is this called?
Pair production
45
When mass is converted to energy, what is this called?
Annihilation
46
What happens when a particle meets its corresponding antiparticle?
Annihilation
47
What happens in annihilation?
All of the mass of the particle gets converted back to energy
48
What are forces caused by?
Particle exhcnage
49
What are exchange particles called?
Gauge bosons
50
What is the repulsion between 2 protons caused by?
Exchange of virtual photons
51
State the 4 fundamental forces
SNF, WNF, Gravity, Electromagnetic
52
In electromagnetic interaction, what is the gauge boson and the particles effected?
Virtual photon, charged particles
53
In weak interaction, what is the gauge boson and the particles effected?
W+, W-, all types of particles
54
In strong interaction, what is the gauge boson and the particles effected?
pions (pi+, pi-, pi0), hadrons only
55
What happens when the mass of the gauge boson is larger?
The force has a shorter range
56
What is the mass of a W boson?
100x the proton
57
Describe the feyman diagram for electromagnetic repulsion
e- and e- go in, virtual photon exchanged, e- and e- go out. Same for positron
58
Describe the feyman diagram for electron-proton/ electron capture collisons
p and e- go in, W+ exchanged, neutron and neutrino out
59
What is the equation for electron capture
p + e- -> n + ve
60
Describe the feyman diagram for beta-minus decay
neutron in, W- exchanged, proton, electron and antineutrino
61
Describe the feyman diagram for beta-plus decay
proton in, W+ exchanged, neutron, positron and neutrino out
62
What is the equation for beta-minus decay
n -> p + e- + anti ve
63
What is the equation for beta-plus decay
p -> n + e+ + ve
64
What are hadrons?
Partciles that feel SNF
65
Are hadrons fundamental partciles?
No, they are made up of quarks
66
What are the 2 types of hadrons?
Baryons and mesons
67
What baryons are there?
Protons and neutrons
68
Which baryon is stable?
Protons, all others are unstable
69
What do all baryons decay into?
A proton (Apart from protons hehe)
70
Which family do antiprotons and antineutrons belong to?
Anti-baryons
71
What is the baryon number?
The number of baryons in an interaction
72
What is the baryon number for baryons, antibaryons, and non baryons?
```
Baryon = +1
Antibaryon = -1
Non-baryon = 0
```
73
Does the baryon number have to be conserved in an interaction?
Yes, the total baryon number in any particle interaction never changes
74
What do neutron decay into?
Protons
75
Are electrons and antineutrinos baryons?
No, they're leptons
76
What mesons are there?
Pions and kaons
77
Are all mesons stable?
No
78
Which meson is the lightest?
Pions, which have 3 charges
79
Are kaons more unstable and heavier than pions?
Yes, they come in K+ and K0
80
What do kaons decay into?
Pions
81
What force do mesons and baryons interact through?
SNF
82
Do leptons feel the SNF?
No
83
Are leptons fundamental particles?
Yes
84
What force do leptons interact by?
WNF
85
Are electrons stable?
Yes
86
Are muons leptons, and how stable are they?
Yes, they are unstable
87
What do muons decay into?
Electrons
88
What is the neutrino for electrons and muons?
Electron neutrtino, muon neutrino
89
What is the mass and charge of a neutrino?
Basically 0 mass, no charge
90
What are the 2 types of lepton number?
Lepton electron number, lepton muon number
91
What is the Le number for an electron, electron-neutrino, muon and muon neutrino?
Electron = +1
Electron-neutrino = +1
muon and muon-neutrino = 0
92
What is the Lmu number for an electron, electron-neutrino, muon and muon neutrino?
Electron = 0
Electron-neutrino = 0
muon and muon-neutrino = +1
93
What are quarks?
Fundamental particles - building blocks for hadrons
94
Is strangeness always conserved?
No
95
When is strangeness conserved?
In strong interaction, not weak interaction
96
How are strange particles produced?
In pairs
97
State the quark composition for:
Proton, antiproton
Neutron, antineutron
```
Proton = uud
Antiproton = antiU antiU antiD
Neutron = udd
Antineutron = antiU antiD antiD
```
98
What are mesons?
A quark and an anti quark
99
What are pions made up of
Combinations of up, anti-up, down, anti-down quarks
100
Out of Pions, mesons and kaons, which ones are strange?
Kaons
101
What is the relation between the pi- and pi+, K- and K+?
pi- is the antiparticle of pi+, K- is the anti particle of K+
102
How can you change the quark type?
Via weak interaction
103
What 6 properties are conserved in particle interactions?
Charge, baryon number, strangeness (in strong), energy, momentum, lepton (both)
104
Can you separate quarks?
No
