section 1 - particles and radiation. Flashcards

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1
Q

what is an isotope?

A

an atom with the same atomic number, but different nucleon number - same no. protons, different no. neutrons.

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2
Q

equation for specific charge?

A

specific charge (of a nucleus) = charge / mass.

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3
Q

proton: (p)

A

charge (C) : 1.60 x 10^-19

mass (kg) : 1.67(3) x 10^-27

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4
Q

neutron: (n)

A

charge (C) : 0

mass (kg) : 1.67(5) x 10^-27

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5
Q

electron: (e-)

A

charge (C) : -1.60 x 10^-19

mass : 9.11 x 10^-31

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6
Q

antimatter?

A

same: REST MASS + REST ENERGY.
different: CHARGE. (-> exception neutrons + neutrinos (+ antimatter))

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7
Q

neutrino/antineutrino: (v, v^_)

A

rest mass: 0

charge: 0

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8
Q

is the strong nuclear force attractive or repulsive?

A

attractive up to 0.5 fm, then repulsive.

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9
Q

what is the max. range of the strong nuclear force?

A

3-4 fm.

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10
Q

the theory behind strong nuclear force?

A

in stable atoms, atoms are neither expanding or shrinking. electrostatic repulsion between similar charged nucleons occurs. therefore there must be an attractive force that is short range.

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11
Q

how does alpha decay cause an nucleus to change?

A

NUCLEON NUMBER: -4

ATOMIC NUMBER: -2

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12
Q

what is the alternate name for an alpha particle?

A

helium nucleus.

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13
Q

how ionizing is alpha radiation? how penetrating is alpha radiation?

A
highly ionizing.
lowly penetrating (paper stops)
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14
Q

wave speed of the electromagnetic spectrum?

A

3 x 10^8 m/s

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15
Q

electromagnetic spectrum from longest wavelength to shortest wavelength?

A

radio, microwaves, infrared, visible, UV, x-rays, gamma rays.

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16
Q

photon energy equation:

A

photon energy = hf (E = hf)

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17
Q

what is annihilation?

A

when a particle and its antiparticle collide and their masses are converted into energy (x2 photons).

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18
Q

ANNIHILATION: min. photon energy equation:

A

2hf (min) = 2E –> hf = E
E = rest energy.
hf = energy of one photon.

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19
Q

ANNIHILATION: NON-min. photon energy equation:

A
2hf = 2E + 2KE --> hf = E + KE
hf = energy of one photon.
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20
Q

what is pair production?

A

when a photon with SUFFICIENT ENERGY creates a particle and its corresponding antiparticle, and vanishes.

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21
Q

PP: min. energy of photon req. equation:

A
hf(min) = 2E
E = rest energy
hf = photon energy
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22
Q

what is the eV –> J conversion?

A

1eV = 1.60 x 10^-19 J

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23
Q

what types of particles does the strong nuclear force act between?

A

hadrons - protons and neutrons –> EQUALLY.

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24
Q

what is the weak nuclear force?

A

force responsible for beta decay.

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25
Q

properties of weak nuclear force?

A

weak - doesn’t affect stable nuclei.

short range.

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26
Q

what types of particles does the weak nuclear force act between?

A

all.

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27
Q

what are the four fundamental forces?

A

1) strong nuclear force.
2) weak nuclear force.
3) gravity.
4) electromagnetic.

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28
Q

what is the exchange particle for electromagnetic force?

A

virtual photon.

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29
Q

what is the exchange particle for the strong nuclear force?

A

gluon/pion.

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30
Q

what is the exchange particle for the weak nuclear force?

A

W bosons (W+ / W- ).

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31
Q

describe what happens to the participants of electromagnetic repulsion?

A
particles of the same charge come close to each other.
exchange a virtual photon.
move off it opposite directions.
no change to particle.
(often e-)
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32
Q

describe what happened to the participants of beta minus decay?

A

NEUTRON –> PROTON.

emits a BETA MINUS particle (e-) + ELECTRON ANTINEUTRINO.

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33
Q

during beta minus decay, how does the quark composition of the nucleons involved change?

A

DOWN quark to UP quark.

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34
Q

what force is involved in electromagnetic repulsion?

A

electromagnetic force.

35
Q

what force is involved in beta minus decay?

A

weak nuclear force.

36
Q

describe what happens to the participants of beta plus decay?

A

PROTON –> NEUTRON.

emits a BETA PLUS particle (e+) + ELECTRON NEUTRINO.

37
Q

what is the exchange particle of electromagnetic repulsion?

A

virtual photon.

38
Q

what is the exchange particle for beta minus decay?

A

W- boson.

39
Q

what is the exchange particle for beta plus decay?

A

W+ boson.

40
Q

what force is involved with beta plus decay?

A

weak nuclear force.

41
Q

what particles are involved with electron capture?

A

PROTON interacts with ELECTRON.

–> NEUTRON + ELECTRON NEUTRINO.

42
Q

what particle interactions are similar? what is the difference between them?

A

electron capture and proton-electron collision. difference is proton-electron collision take places at VERY HIGH SPEEDS.

43
Q

what is the exchange particle for electron capture?

A

W+ boson.

44
Q

what particles are involved in proton-electron collision?

A

PROTON collides with ELECTRON (at HIGH SPEEDS ++) –> NEUTRON + ELECTRON NEUTRINO.

45
Q

what is the exchange particle for proton-electron collision?

A

W- boson.

46
Q

** what particles are involved in neutron and neutrino interaction? **

A

neutron + neutrino –> proton + beta minus.

47
Q

**what is the exchange particle for neutron and neutrino interaction? **

A

W- boson.

48
Q

what particles are formed when a proton and an antineutrino interact?

A

proton + antineutrino –> neutron + positron.

49
Q

what is the exchange particle for the proton - antineutrino interaction?

A

W+

50
Q

what is another name for a beta minus particle?

A

electron.

51
Q

after annihilation occurs, why do the photons produce move off in opposite directions?

A

to conserve linear momentum.

52
Q

how many photons are required to pair produce?

A

ONE.

53
Q

definition of an eV?

A

equal to the KE gained by an e- when accelerated by a PD of 1V.

54
Q

rest energy equation?

A

E = mc^2

55
Q

describe what happens when a positron and its antiparticle meet? (2 marks)

A

positron and electron annihilate, producing x2 photons of equal energy (that move off in opposite directions).

56
Q

why do a particle and its antiparticle move off in opposite directions after pair production?

A

the have opposite charges.

57
Q

what is the fundamental force responsible for proton-electron collision?

A

weak nuclear force (weak interaction).

58
Q

state why the total energy after the annihilation collision is greater than the KE before the collision.

A

total energy must include KE and rest energy.

59
Q

do photons have rest mass?

A

no.

60
Q

how does the nucleon composition of the nucleus change after beta minus decay?

A

number of protons decreases increases by ONE.

nucleon number remains the same.

61
Q

how does the nucleon composition of the nucleus change after beta minus decay?

A

number of protons decreases by ONE.

nucleon number does not change.

62
Q

what is 1MeV equal to?

A

1 x 10^6 eV.

63
Q

power of the laser beam equation?

A

power = n x h x f.

n: no. photons passing a fixed point each second.

64
Q

order the pion, muon and kaon from largest to smallest rest mass.

A

kaon, pion, muon.

65
Q

what is the charge of an up quark? why does it have this charge?

A

+2/3.

a baryon is made up of three quarks. baryon charge is +1/-1/0 (integer), quark composition makes up total charge.

66
Q

what is the charge of a down quark? why does it have this charge?

A

-1/3.

a baryon is made up of three quarks. baryon charge is an integer, charges of quark composition make up total charge.

67
Q

what is the quark combination of a neutron?

A

udd

68
Q

what is the quark composition of a proton?

A

uud.

69
Q

show that charge is conserved in beta decay.

A

udd -> uud + e- + (anti) Ve.

+2/3 + (-1/3) + (-1/3) –> + 2/3 +2/3 + (-1/3) + (-1)

70
Q

why are protons and kaons in different categories of particles?

A

protons are made of 3 quarks whereas kaons are made of a quark and its anti-quark.

71
Q

what are the two subgroups of hadrons? give examples of s.a particles in each group.

A

baryons: proton/neutron.
mesons: electron/pion/kaon.

72
Q

how are leptons different to hadrons?

A

leptons do not interact via the strong force whereas hadrons interact by all fundamental forces. leptons are fundamental particles so cannot be broken down whereas hadrons can.

73
Q

what are the five aspects of a decay equation that must be conserved?

A

baryon number; lepton (e-) number; lepton (muon) number; charge; momentum.

74
Q

why must lepton (e-) number and lepton (muon) number be counted separately?

A

muons cannot decay into electrons or electron neutrinos (and vise versa) so decay equation may obey lepton conservation but may not be possible.

75
Q

how do the rules regarding the conservation of strangeness change for weak vs strong interaction?

A

strangeness is always conserved in the strong interaction. strangeness can change in the weak interaction.

76
Q

are protons involved in meson decay?

A

no, only baryon decay.

77
Q

true/false: a baryon number is always an integer.

A

true.

78
Q

where can mesons be found?

A

cosmic rays; particle accelerators.

79
Q

is a muon a lepton or a meson?

A

lepton - it is a fundamental particle so cannot be broken down into quarks.

80
Q

true/false: up, down and strange quarks have the same baryon number?

A

true.

81
Q

what is the baryon number of an up quark?

A

+1/3.

82
Q

what changes about baryon number, lepton number, charge and strangeness in a corresponding antiparticle.

A

change in sign - (+)ve to (-)ve and vise versa.

83
Q

give one characteristic of a strange particle that makes it different from a non strange particle.
(1 mark)

A

contains a strange quark.
longer half life than expected.
decays via weak interaction.

84
Q

what proves that light is not a wave?

A

max. kinetic energy did not increase with intensity.

changing intensity had no effect below the threshold frequency.