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A2 Physics > G485 - Nuclear Physics > Flashcards

G485 - Nuclear Physics Flashcards

1
Q

Describe Rutherford’s alpha particle scattering experiment

A

A beam of alpha particles (helium nuclei) was directed at a thin sheet of gold leaf
The leaf was surrounded by a ring of detectors to pick up where the alpha particles went after passing through the gold leaf

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2
Q

What were the observations from Rutherford’s alpha particle scattering experiment?

A

Most alpha particles passed straight through the gold leaf with little or no deflection
A few alpha particles were deflected through large angles

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3
Q

What conclusions can be drawn from Rutherford’s alpha particle scattering experiment?

A

Atoms are mostly empty space
Mass is concentrated at a single point, the nucleus
The nucleus is positively charged as it repelled the positively charged alpha particles

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4
Q

Nucleus Diameter

A

10^-15

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5
Q

Atom Diameter

A

10^-10

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6
Q

Relative mass of a neutron

A

1

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7
Q

Relative mass of a proton

A

1

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8
Q

Relative mass of an electron

A

1/1840

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9
Q

Nucleon / Mass Number Definition

A

The number of nucleons in the nucleus

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10
Q

Proton / Atomic Number Definition

A

The number of protons in the nucleus

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11
Q

Isotope Definition

A

Different form of the same element containing the same number of protons in the nucleus but a different number of neutrons

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12
Q

What quantities are conserved in nuclear decay?

A 
charge
momentum
lepton number 
baryon number
mass / energy
spin
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13
Q

List the four forces in the universe from strongest to weakest

A

Strong Nuclear Force
Electromagnetic Force
Weak Nuclear Force
Gravitational Force

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14
Q

Properties of the Strong Nuclear Force

A

Short ranging
Attractive at longer distances
Repulsive at very short distances
Acts on quarks

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15
Q

Properties of the Electromagnetic Force

A 
Only acts between objects with charge
Attractive between opposite charges
Repulsive between like charges
Long ranging
Obeys the inverse square law
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16
Q

Properties of the Weak Nuclear Force

A

Can effect any particle

Governs nuclear decay

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17
Q

Properties of the Gravitational Force

A

Acts between objects with mass
Always attractive
Long ranging
Obeys the inverse square law

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18
Q

Fundamental Particle Definition

A

A particle which cannot be broken down any further

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19
Q

What is the exchange particle for the Strong Nuclear Force?

A

gluon

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20
Q

What is the exchange particle for the Electromagnetic Force?

A

photon

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21
Q

What is the exchange particle for the Weak Nuclear Force?

A

W and Z bosons

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22
Q

What is the exchange particle for the Gravitational Force?

A

graviton

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23
Q

Hadron Definition

A

a particle which is made up of quarks

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24
Q

Baryon Definition

A

a hadron which is made up of three quarks

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25
Meson Definition
a hadron which is made up of a quark and an anitquark
26
Lepton Definition
fundamental particles which are not effected by the strong nuclear force
27
Examples of Mesons
pion | kaon
28
Examples of Baryons
``` proton neutron lambda sigma omega ```
29
Examples of Leptons
electron muon tau neutrino
30
Antimatter Defintion
the opposite of matter in every way
31
What happens when a particle collides with its antiparticle?
They annihilate | The equivalent of their mass is released as two photons in opposite directions
32
What is a β- particle?
electron
33
What is a β+ particle?
positron
34
Beta Minus Decay
neutron -> proton + electron + antielectronneutrino ExchangeParticle = W- Boson
35
Beta Plus Decay
proton -> neutron + positron + electronneutrino ExchangeParticle = W+ Boson
36
Alpha Decay
(X,Y)^A -> (X-4,Y-2)B + (4,2)He
37
Gamma Decay
(X,Y)A -> (X,Y)A + gammaphoton
38
What is the quark composition of a proton?
uud
39
What is the quark composition of a neutron?
udd
40
What are the 6 types of quark?
``` up down strange top bottom charm ```
41
Binding Energy Definition
minimum energy required to separate all of the nucleons in a nucleus
42
Binding Energy per Nucleon Definition
energy required to remove a nucleon from the nucleus of an atom
43
Mass Defect Definition
during nuclear decay the mass of particles before the decay is always greater than the total mass after the decay, the difference in mass is the mass defect and is equivalent to the energy released in the decay, E=mc²
44
What is the most stable nucleus?
Iron, has the greatest binding energy per nucleon Nuclei smaller than iron fuse to make iron which releases energy Elements larger than iron fission to release energy
45
Describe Nuclear Fission
U-235 nucleus absorbs a slow moving neutron The new nucleus is very unstable, it decays to form two daughter nuclei which are roughly equal in size Three neutrons are also released as well as energy
46
Describe how a chain reaction can start
When an unstable nucleus decays it releases three neutrons which can go on to cause a further three nuclei to decay and release another three neutrons each Reaction rate will increase exponentially if uncontrolled
47
Describe the role of fuel rods in a nuclear reactor
Contain unstable nuclei which will decay when bombarded with slow moving neutrons
48
Spontaneous Fission
some radioactive isotopes contain nuclei that are highly unstable at some point they will naturally decay
49
Induced Fission
fisson can be induced by bombarding atoms with neutroms
50
Describe the role of control rods in a nuclear reactor
Control rods can be lowered to absorb neutrons and slow down the rate of the chain reaction Control rods can be raised so that more neutrons can collide with nuclei and cause decay to increase the reaction rate
51
Describe the role of the moderator in a nuclear reactor
the moderator (made of graphite) slows down neutrons so the they can be absorbed by the uranium nuclei this process generates heat coolant absorbs heat
52
Advantages of Nuclear Fission to Produce Energy
high energy yield efficient doesn't produce greenhouse gases
53
Disadvantages of Nuclear Fission to Produce Energy
radioactive waste nuclear meltdown radiation initially very expensive and expensive to decommission
54
Why is nuclear fusion possible inside stars?
Extremely high pressure and temperature
55
Radioactive Decay
spontaneous and random | it is impossible to predict when an individual nucleus will decay
56
Alpha Radiation | Nature
helium nucleus (2 protons, 2 neutrons)
57
Beta Radiation | Nature
electron
58
Gamma Radiation | Nature
electromagnetic radiation
59
Alpha Radiation | Range
short
60
Beta Radiation | Range
medium
61
Gamma Radiation | Range
long
62
Alpha Radiation | Penetration
absorbed by thin paper
63
Beta Radiation | Penetration
absorbed by a few mm of aluminium
64
Gamma Radiation | Penetration
absorbed by a few cm of lead
65
Activity Definition
A, the number of radioactive decays per unit time (Bq)
66
Decay Constant Definition
λ, the probability that an individual nucleus will decay n a unit time (s^-1)
67
Half Life Definition
the time taken for the number of radioactive nuclei to decrease by half
68
Radiocarbon Dating
Living things take in carbon, after death this stops, carbon-14 in the organism decays to carbon-12 The ratio of carbon-14 to carbon-12 in the sample can be determined Compared with the ratio of carbon-14 to carbon-12 in a loving organism Age of sample found using X = X0e^(-λt)

A2 Physics (8 decks)

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