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Henry Physics RSFC > Particles > Flashcards

Particles Flashcards

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1
Q

Which part of the atom has the largest specific charge and why?

A

The electron

(It has the same magnitude of charge as the proton but a much smaller mass)

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2
Q

Why do the proton, neutron and electron deflect differently in a magnetic field?

A

Neutron → 0 specific charge so zero deflection

Electron → Greatest specific charge so greatest deflection

Proton → Smaller deflection in opposite direction as specific charge smaller and opposite

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3
Q

How do you calculate the specific charge of a nucleus?

A

Divide the total charge of the protons by the total mass of nucleus

(Protons + Neutrons)

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4
Q

How do you calculate the specific charge of an ion?

A

Charge of the ion (Protons - Electrons) divided by total mass of ion

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5
Q

What is an isotope?

A

An atom with the

  1. same number of protons
  2. Different number of neutrons
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6
Q

When will an isotope undergo radioactive decay?

A

If the nucleus has:

  1. too many or too few protons
  2. Too many nucleons
  3. Too much vibrational energy
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7
Q

What happens in alpha (α) decay?

A

A nucleus ejects a helium nucleus (2 protons and 2 neutrons)

Decreasing its nucleon number by 4

And its proton number by 2

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8
Q

What happens in Beta Minus (β-) Decay?

A

A neutron turns into a proton

Ejecting a fast moving electron (β-) and an anti-electron neutrino

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9
Q

What happens in Beta Plus (β+) Decay?

A

A proton turns into a neutron

Ejecting a fast moving positron (β+) and an electron neutrino

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10
Q

What is wrong about this Beta Decay equation?

A

The nucleon number must not change

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11
Q

Why do the α, β-, β+ and γ deflect differently in a magnetic field?

A

α and β+ → Deflect in same direction but β+ larger (greater specific charge)

β- → Equal and opposite deflection to β+ (Equal and opposite specific charge)

γ → No deflection (no specific charge)

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12
Q

What is an antiparticle?

A

A particle with the:

  1. Same mass
  2. But equal and opposite charge
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13
Q

What happens during Annihilation?

A

A particle collides and annihilates with its correspond antiparticle

And their mass energy (E=mc2) is converted to radiation energy

Producing at least 2 gamma photons

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14
Q

Why do at least 2 photons need to be created during annihilation?

A

To conserve momentum

Before annihilation ptotal = 0

AFter annihilation ptotal = 0 (can’t be achieved with one photon)

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15
Q

What happens during pair production?

A

A gamma photon (with energy ≥ 2 × mass energy)

spontaneously creates a particle, anti-particle pair

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16
Q

What condition must pair production meet?

A

The energy of the gamma photon ≥ Mass energy of the particle anti-particle pair

(Any excess energy is used a kinetic energy for the particles produced)

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17
Q

How was the anti-electron neutrino discovered?

A

During Beta decay the emitted β- had less energy than expected so another particle carried the rest of the energy

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18
Q

What are the four fundamental forces and their approximate ranges?

A
  1. Strong
  2. Weak
  3. Electromagnetic
  4. Gravitational
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19
Q

What does the strong force do?

What is the exchange particle of the strong force?

A

Holds nucleons together in the nucleus

  • By opposing the electromagnetic repulsion of the protons
  • By attracting nucleons at small distances but repelling the, at very small distances

Gluons (between quarks), or pions (between hadrons)

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20
Q

Describe the nature of the strong force

A

Very repulsive over short distance (0-0.5fm)

Attractive over larger distances (0.5fm < d < 3fm)

Negligible beyond 3fm

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21
Q

What does the electromagnetic force act between and what is its exchange particle?

A

Acts between all particles with charge

Exchange particle is the photon

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22
Q

What does the gravitational force act between?

A

Particles or objects with mass

The exchange particle is the graviton

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23
Q

What particles does the weak force act on and what does it do?

A

Acts in any interaction leptons and hadrons (lepton-lepton or lepton-hadron) causes the decay of hadrons (by changing quark structure)

The exchange particles for the weak force are w+, w- & z bosons dependent on conservation of key values (QBLS) as z bosons have no charge whereas w bosons do

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24
Q

What are fundamental particles that make up the standard model? (that you need to know)

A

NOTE: Each of the leptons and and quarks has an corresponding anti-lepton and anti-quark

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25
Q

What is the quark structure of a proton?

A

Up, Up, Down

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26
Q

What is the quark structure of a neutron?

A

Up, down, down

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27
Q

How is a muon different from an electron?

A

Both are leptons, muon is much heavier than the electron, produced in cosmic ray showers

28
Q

What are hadrons?

A

Particles that are made up of quarks

29
Q

How are baryons and mesons different?

A

Both are hadrons (made up of quarks)

But Baryons are made up of 3 quarks

And Mesons are made up of 1 quark 1 anti-quark

30
Q

What are the similarities and differences between W bosons and photons?

A

Both are exchange particles

But W bosons mediate the weak force, Photons mediate electromagnetic

W bosons carry charge of +1 or -1, Photons have no charge

W bosons have mass, Photons are massless

31
Q

What are the similarities and differences between gluons and pions?

A

Both mediate the strong force

But gluons act between quarks, Pions act between hadrons (to keep the nucleus together)

Gluons have no mass, Pions have mass

32
Q

What does the Higgs Boson do?

A

It creates the Higgs field

Which gives mass to particles

33
Q

What quantities are always conserved in every interaction?

A
  • Total momentum
  • Total energy
  • Charge
  • Baryon
  • Lepton number

NOTE 1: Kinetic energy is conserved in elastic collisions

NOTE 2: Strangeness is conserved in all interactions apart from weak

34
Q

What must you know about k-mesons? (kaons)

A

They are made of 1 quark and 1 anti-quark (mesons)

They have non-zero strangeness

Produced by strong interactions, Decay (into pions) by weak interactions

35
Q

What must you know about π-mesons? (pions)

A

They are made up of 1 quark and 1 anti-quark (mesons)

They have strangeness = 0

36
Q

What is the most stable lepton and what is the most stable hadron?

(That other isolated particle will eventually decay into)

A

The electron and the proton

37
Q

Why can’t this muon decay happen like this?

(What’s the mistake with the logic in the table?)

A

When electron and muon type particles are involved each lepton number must be considered separately

38
Q

What is the formula for a muon decaying into an electron?

A
39
Q

What is the feynman diagram for an electron-electron collision?

A
40
Q

What is the feynman diagram for β- Decay?

A
41
Q

What is the feynman diagram for β+ Decay?

A
42
Q

What is the quark feynman diagram for β- Decay?

A
43
Q

What is the quark feynman diagram for β+ Decay?

A
44
Q

Identify the unknown particles in this feynman diagram for electron capture

A
45
Q

Identify the unknown particle in this feynman diagram for the electron proton collision

A
46
Q

Identify the unknown quark in the feynman diagram for electron capture

A
47
Q

Identify the unknown exchange particle in the quark feynman diagram of electron proton collision

A
48
Q

Which particles have a baryon number = +1?

Which have a B = -1?

Which have a B = 0

A

Baryons = +1

Anti-Baryons = -1

All other particles (including mesons) = 0

49
Q

Which particles have a Lepton number = +1?

Which have a L = -1?

Which have a L = 0

A

Leptons = +1

Anti-Leptons = -1

All other particles = 0

50
Q

What is the muon lepton number of an electron?

A

0! Only muons and muon neutrinos have Lmuon = +1

51
Q

What is the electron lepton number of a muon?

A

0! Only electrons and electron neutrinos have Lelectron = +1

52
Q

What is the formula for electron capture?

A

AZX + 0-1e-1 → A Z-1Y+ ve

proton turns into a neutron

You do not need to know this

53
Q

What is the formula for neutron emission?

A

AZX → A-1ZY + 10n

You do not need to know this

54
Q

What is the formula for proton emission?

A

AZX → A-1Z-1Y+ 11P

You do not need to know this

55
Q

Why was the Antiproton not discovered until 1955?

A

It was only then that large enough particle accelerators were built in order to form large enough particles

56
Q

Why can’t particles such as muons or leptons decay into baryons?

A

Particles can’t decay into bigger particles than themselves

57
Q

Why are quarks only found in baryons and mesons?

A

Quarks cannot exist on their own

58
Q

Why did it take so long for the Higgs boson to be discovered?

A

Was not discovered until 2012 as there was not a particle accelerator big enough to form the particle until CERN

59
Q

Which exchange particles have mass?

A

W+, W-, Z0

60
Q

Which exchange particles have charge?

A

W+, W-

61
Q

What is the case at junctions of Feynman diagrams?

A

All conservation laws apply

62
Q

How are particles and exchange particles represented on Feynman diagrams?

A

Exchange particles - wiggly lines
Particles - straight lines

63
Q

What is on the y-axis for feynman diagrams?

A

Time

64
Q

Which other quark can strange quarks decay into?

A

Up quarks

65
Q

Which quark is the heaviest

A

Strange quark

Henry Physics RSFC (27 decks)

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