Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA PARTICLES AND RADIATION > 1.6 - HADRONS AND LEPTONS > Flashcards

1.6 - HADRONS AND LEPTONS Flashcards

1
Q

What particles are affected by the strong nuclear force?

A

Hadrons only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the exchange particle of gravity?

A

Graviton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What particles are affected by gravity?

A

All types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is particle physics concerned with gravity?

A

Not really - it is usually ignored because it is very feeble unless large masses are involved.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the mass of a W boson?

A

About 100 times that of a proton.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Compare and explain the ranges of a W boson and a photon.

A
  • W boson - Very short range because it has a large mass. This means it requires a lot of energy to create and can’t travel very far.
  • Photon - Infinite range because it has zero mass.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are hadrons?

A

Particles that feel the strong nuclear force. They are not fundamental.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are hadrons made of?

A

Quarks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Are hadrons fundamental particles?

A

No, they are made of quarks.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two types of hadrons?

A
  • Baryons

* Mesons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the difference between baryons and mesons?

2 REASONS

A
  • Baryons - Made of 3 quarks and decay into a proton directly or indirectly
  • Mesons - Made of a quark and antiquark and do NOT decay into a proton
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Name some baryons.

A
  • Protons
  • Neutrons
  • Other particles (e.g. Sigmas)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the only stable baryon?

A

Proton - this means all baryons will decay in sequence and eventually form a proton.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Are antibaryons found in ordinary matter?

A

No, because they annihilate with baryons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What values are particles given in baryon number conservation?

A
  • Baryons = +1
  • Antibaryons = -1
  • Other particles = 0
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some examples of antibaryons?

A
  • Antiprotons

* Antineutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does beta decay happen?

A

Neutrons are not stable baryons, but protons are, so a neutron will decay into a proton.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Are mesons stable?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the different types of meson?

A

Pions and kaons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is another name for a pion?

A

Pi-meson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is another name for a kaon?

A

K-meson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the difference between pions and kaons?

A
  • Pions - Lighter, less unstable, not strange

* Kaons - Heavier, more unstable, strange, very short lifetime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the antiparticle for π+

A

π-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the antiparticle for π0

A

Itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens to kaons?

A

They decay into pions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where were pions and kaons seen?

A

Cosmic rays interact with molecules in the atmosphere and produce “showers” of lots of high-energy particles, including pions and kaons. = cosmic ray showers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How did scientists find pions and kaons?

How are they seen now?

A

Cloud chamber used to observe the tracks of the particles.

Now:
Two Geiger counters on top of each other with absorbing lead between them. If both counters detect radiation simultaneously it is likely to be a particle from a cosmic ray shower (rather than just random noise like background radiation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do mesons interact with baryons?

A

Through the strong force.

29
Q

What are the general rules for determining the type of interaction in a reaction?

A
  • If any leptons involved at all -> Weak interaction
  • If strangeness isn’t conserved -> Weak interaction
  • All others -> Strong interaction
30
Q

What are leptons?

A

Particles that do not feel the strong interaction. They are fundamental.

31
Q

What are the different leptons?

A
  • Electrons
  • Muons
  • Neutrinos
  • Tau
32
Q

What happens to muons?

A

The eventually decay into electrons. This is because muons are unstable.

33
Q

What can muons be described as?

A

Heavy electrons.

34
Q

What is the mass and charge of neutrinos?

A
  • Mass - Almost zero

* Charge - Zero

35
Q

How does lepton conservation work?

A
  • There are 3 generations of lepton number - electron, muon and tau
  • Each lepton number must be conserved separately
  • Each normal lepton and its respective neutrino is given a lepton number of +1
  • Each anti-lepton and its respective antineutrino is given a lepton number of -1
36
Q

What are the symbols for each lepton number?

A
  • Electron lepton number = Le
  • Muon lepton number = Lmuon
  • Tau lepton number = Lt
37
Q

What are antiparticles of hadrons made from?

A

Antiquarks

38
Q

How do strange particles (e.g. kaons) interact?

A
  • Created by the strong interaction

* Decay via the weak interaction

39
Q

Strange particles are always produced in pairs (e.g. K+ and K-). Why?

A

The strangeness cancels out to become 0, so that strangeness is conserved. Therefore, the reaction is a strong interaction.

40
Q

What are the types of quark?

A
  • Up
  • Down
  • Strange
41
Q

What is the charge of an up quark?

A

+2/3

42
Q

What is the charge of a down quark?

A

-1/3

43
Q

What is the charge of a strange quark?

A

-1/3

44
Q

What is the charge of an anti-up antiquark?

A

-2/3

45
Q

What is the charge of an anti-down antiquark?

A

+1/3

46
Q

What is the charge of an anti-strange antiquark?

A

+1/3

47
Q

What is the strangeness of a strange quark?

A

-1

48
Q

What is the strangeness of an anti-strange antiquark?

A

+1

49
Q

What is unusual about strangeness?

A
  • It is not ALWAYS conserved
  • Strange quarks are given a strangeness of -1 and anti-strange antiquarks are given a strangeness of +1.

In weak force: it is not usually conserved and can change by +1, -1, or 0

50
Q

What quarks make up a proton?

A

uud

51
Q

What quarks make up an antiproton?

A

anti-u, anti-u, anti-d

52
Q

What quarks make up a neutron?

A

udd

53
Q

What quarks make up an antineutron?

A

anti-u, anti-d, anti-d

54
Q

What are baryons made of?

A

3 quarks

55
Q

What are mesons made of?

A

A quark and an antiquark

56
Q

What is the antiparticle of a pi-plus meson?

A

A pi-minus meson.

57
Q

Remember to revise the diagram on mesons.

A

Pg 14 of the revision guide

58
Q

What is a weak interaction in terms of quarks?

A

A weak interaction is something that changes the quark type (e.g. A neutron (udd) turning into a proton (uud))

59
Q

What properties are conserved in an interaction?

A
  • Charge
  • Baryon number
  • Strangeness (only in strong interactions)
  • Lepton number (all 3 generations separately)
60
Q

How is baryon number conserved in pair production?

A
61
Q

How is charge conserved in pair production and neutron decay (e.g. beta minus)?

A
62
Q

Why is strangeness only conserved in strong interaction?

A

You can change the type of quark in weak interactions.

In strong interactions the strange quarks have to be conserved throughout.

63
Q

Can a quark exist on its own?

A

No.

64
Q

What is quark confinement?

A

The idea that quarks cannot exist not their own.

65
Q

Through which interaction do hadrons tend to decay?

A

Weak

66
Q

Describe the mass, range and charge of a W boson.

A
  • Non-zero rest mass
  • 0.001fm range
  • Can be positively or negatively charged
67
Q

What are the quarks in a K0 meson?

A
  • Anti-s

* d

68
Q

What are the quarks in an anti-K0 meson?

A
  • s

* Anti-d

AQA PARTICLES AND RADIATION (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions