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Physics > Particles and Radiation > Flashcards

Particles and Radiation Flashcards

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1
Q

what is the charge and mass of a proton?

A

+1.6x10^-19 and 1.67x10^-27

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2
Q

what is the charge and mass of a neutron?

A

0 and 1.67x10^-27

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3
Q

what is the charge and mass of an electron?

A

-1.6x10^-19 and 9.11x10^-31

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4
Q

what is specific charge and how do you calculate it?

A

it is the ratio of an atoms charge to its mass specific charge = charge/mass

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5
Q

What is an isotope?

A

Atoms of the same element that have different numbers of neutrons

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6
Q

what does electromagnetic force do in the nucleus?

A

causes the positively charged protons in the nucleus to repel each other

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7
Q

what does gravitational force do in the nucleus?

A

causes all the nucleons in the nucleus to attract each other due to their mass

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8
Q

what force stops the electromagnetic force tearing the nucleus apart?

A

strong nuclear force

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9
Q

what is the range of strong nuclear force?

A

it can hold nucleons together when they are separated by up to about 3fm(x10^-15)

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10
Q

why is the strong nuclear force repulsive up to about 0.5fm(x10^-15)?

A

otherwise there would be nothing to stop it crushing the nucleons to a point

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11
Q

what can you say about the size of the strong nuclear force whether it’s p-p, n-n or n-p?

A

it is the same as it works equally between all nucleons

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12
Q

how were neutrinos discovered?

A

it was observed that energy after beta decay was less than before, conservation of energy means a particle is responsible for making up the rest of the energy and momentum - the neutrino

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13
Q

what are the 7 types of EM radiation and how do wavelength and frequency change along the spectrum?

A

radiowaves, microwaves, infra-red, visible light, ultra-violet, x-rays, gamma rays. frequency increases down the spectrum, wavelength decreases

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14
Q

what is the relationship between the frequency and energy of a wave?

A

the higher the frequency the greater its energy

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15
Q

what is a photon and the equation of calculating their energy?

A

they are discrete waves (packets which carry energy) energy = (h x C)/wavelength

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16
Q

what is an anti-particle?

A

a particle which has the same mass and rest energy but opposite charge to it’s other in the particle - antiparticle pair

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17
Q

what can you assume about the rest energy of a neutrino and why?

A

that it is 0 because their mass is so small

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18
Q

what is pair production and what is required for it to happen?

A

when energy is converted into mass you get equal amounts of matter and anti-matter (this is pair production), it only happens if there is enough energy to produce the masses of the particles

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19
Q

in pair production why would the two particles produced curve away from each other in an applied magnetic field?

A

because they have opposite charges

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20
Q

what is the minimum energy needed for pair production?

A

it is the total rest energy of the particles produced (Emin=2E0)

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21
Q

what happens when a practice meets its antiparticle?

A

the annihilate, all mass is converted back to energy in the form of two gamma ray photons (2Ephotons=2E0)

22
Q

how is annihilation used in industry?

A

in PET scanners - positron emitting isotope put it into the bloodstream and gamma rays produced are detected

23
Q

what are hadrons and what are the 2 types?

A

they are non-fundamental particles which can feel the strong nuclear force. they are split into baryons and mesons

24
Q

what are baryons (with examples) and what do they all decay into and why?

A

all baryons are made up of three quarks, for example protons and neutrons. all baryons eventually decay into protons because a free proton is not unstable

25
Q

what are mesons and what are the 2 main types?

A

all mesons are made up of 2 quarks and are unstable, the two main types are pions and kaons

26
Q

what are pions and kaons and name some properties?

A

pions are the lightest mesons and are the exchange particle of strong nuclear force.
kaons are heavier and more unstable, they have a very short lifetime and decay into pions

27
Q

how can you detect mesons using cosmic rays?

A

cosmic rays interact with molecules in atmosphere and produce ‘showers’ of high-energy particles (including pions and kaons), they can be detected using 2 Geiger counters separated by absorbing lead. if both counters detect radiation simultaneously then it is likely that’s a ‘shower’

28
Q

what are leptons?

A

fundamental particles which don’t feel the strong nuclear force, mainly interact through weak interaction but also a little through gravitational and electromagnetic

29
Q

what are the 4 main types of lepton?

A

electrons, muons, electron neutrinos and muon neutrinos (muons are like heavier, unstable, electrons and decay eventually into electrons)

30
Q

what 2 lepton quantities need to be conserved in reactions?

A

Le - electron lepton number
Lu - muon lepton number

31
Q

how is strangeness created?

A

via the strong interaction and strange particles are created in pairs (to conserve strangeness)

32
Q

how do strange particles decay and what happens to strangeness?

A

through the weak interaction and strangeness in not conserved

33
Q

what properties are conserved in an interaction excluding the quantum numbers?

A

energy, momentum and charge

34
Q

what are the properties on an up and anti-up quark?

A

up: charge = +2/3 baryon number = +1/3 strangeness = 0
anti-up: charge = -2/3 baryon number = -1/3 strangeness = 0

35
Q

what are the properties of a down and anti-down quark?

A

down: charge = -1/3 baryon number = +1/3 strangeness = 0
anti-down: charge = +1/3 baryon number = -1/3 strangeness = 0

36
Q

what are the properties of a strange and anti-strange quark?

A

strange: charge = -1/3 baryon number = +1/3 strangeness = -1
anti-strange: charge = +1/3 baryon number = -1/3 strangeness = 1

37
Q

what are the quark compositions of the 4 types of kaon?

A

K+ = us-, K- = su-, K0 = ds-, K0- = sd-

38
Q

what are the quark compositions of the 3 types of pion?

A

pi+ = ud-, pi- = du-, pi0 = uu-, dd- or ss-

39
Q

what are the quark compositions of a proton or a neutron?

A

proton = uud, neutron = udd

40
Q

why can you not get a quark by itself?

A

its just not possible, if you fire lots of energy at a proton the energy builds up until there is enough to make an u and u- couple and make a pi0

41
Q

in decay what is the only interaction which can make quarks change type?

A

weak interaction

42
Q

what are exchange particles?

A

virtual particles which are responsible for how forces act between two particles

43
Q

what is the exchange particle of the strong nuclear force and what does it affect?

A

gluon/pions (all types) and they only effect hadrons

44
Q

what is the exchange particle for the electromagnetic interaction and what does it affect?

A

virtual photon and it only effects charged particles only

45
Q

what is the exchange particle or the weak interaction and what does it affect?

A

W+ and W- bosons and they affect everything

46
Q

what 2 interactions do you need to do Feynman diagrams for?

A

weak and electromagnetic

47
Q

what are the 4 things you need to know about Feynman diagrams?

A

incoming particles start at the bottom
baryons stay on one side, leptons on the other
W bosons carry charge between sides (to balance charge)
a W- going left is the same as a W+ going right

48
Q

what is the Feynman diagram for beta-minus decay?

A

Vertical line with n below and p above

Squiggly line coming off diagonal (W-)

Above line departing off (v with minus above)

Below is e-

49
Q

what is the Feynman diagram for beta-plus decay?

A

vertical line with p below and n above

Squiggly line coming off diagonal (W+)

Above line departing off (v)

Below is e+

50
Q

what is the Feynman diagram for electron capture?

A

P going diagonal, n breaking off that

Squiggly line in middle (w+) Arrow above going right.

V breaking off above

e- breaking off below

51
Q

what is the Feynman diagram for an electron - proton collision?

A

P going diagonal, n breaking off that

Squiggly line in middle (w-) Arrow above going left

V breaking off above

e- breaking off below

52
Q

what is the Feynman diagram for electromagnetic repulsion?

A

e- going diagonal, e- breaking off that

Super Squiggly line in middle with fancy Y

e- breaking off above

e- breaking off below

Physics (6 decks)

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