Brainscape's Knowledge GenomeTM

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


See full index

PHYS3001: Atoms, Photons and Fundamental Particles > 1. Radioactivity > Flashcards

1. Radioactivity Flashcards

1
Q

What is the typical order of nuclear sizes?

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

Nuclear time scales have a _____ range.

A

Vast

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

What are nuclear energies typically measured in?

A

MeV

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

State the conversion between eV and J

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

What are nuclear masses typically measured in?

A

Unified atomic mass units (u)

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

State the conversion between u and MeV/c²

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Convert the following constant to MeV fm

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

Convert the following constant to MeV fm

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

A nucleus consists of _______ (positively charged) and ________ (neutral).

A

Protons
Neutrons

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

Isotopes have different numbers of ________.

A

Neutrons

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

What is the mass number, A?

A

Number of protons + number of neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the atomic number, Z?

A

Number of protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is alpha decay?

A

Decay in which a helium nucleus (alpha particle) containing 2 protons and 2 neutrons is emitted.

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

State 5 properties of an alpha particle (He nucleus)

A
  • Strongly ionising
  • Heavy
  • Large charge
  • Very damaging inside the body
  • Stopped by skin/paper
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is beta decay?

A

Decay in which a high energy electron (or positron) and an anti-neutrino (or neutrino) are emitted from the nucleus.

In the case of an electron, a neutron in the parent nucleus decays into a proton, an electron, and an anti-neutrino. The proton remains in the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State 4 properties of a beta particle (electron/positron)

A
  • Less ionising than alpha
  • Much faster speed
  • Lower charge
  • Stopped by a sheet of aluminium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is gamma decay?

A

Decay in which a nucleus de-excites and emits a gamma ray photon (like electron transitions leading to photons in atoms).

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

State 4 properties of a gamma ray photon

A
  • Very energetic
  • Interacts weakly with matter
  • Uncharged
  • Stopped by a thick sheet of lead
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why do larger nuclei have more neutrons?

A

Because neutrons have no repulsive forces so this is how they keep themselves together.

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

Describe the graph of the number of neutrons, N, against the number of protons, Z, in nuclides

A

Stability valley = line of stable nuclides
Stability valley moves away from N=Z for large Z.

Alpha emitters are heavy nuclides.
Beta- emitters are above the line of stability.
Beta+ emitters are below the line of stability.

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

There are no stable nuclei with an atomic number, Z, above __.

A

83

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

Give the equation for the rate of decay

A

dN/dt = rate of decay
N = number of atoms which can decay
λ = decay constant

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

State the decay law

A

N = number of atoms which can decay
N_0 = initial number of atoms
λ = decay constant
t = time

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

Describe the shape of a linear decay plot

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

Define half-life

A

The time taken for half the atoms in a sample to decay.

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

Give the equation for half-life

A

N_0 = initial number of atoms
λ = decay constant
t_1/2 = half-life

27
Q

Define activity

A

The rate at which decays occur.

28
Q

Give the equation for activity

A

A = activity
λ = decay constant
N = number of atoms which can decay

29
Q

What are the SI units for activity?

A

The Becquerel, Bq

1 Bq = 1 decay/second

29
Q

How does carbon dating work?

A

Cosmic radiation converts N-14 in the atmosphere to C-14 (with a half-life of 5730 years). It combines with oxygen to form carbon dioxide which plants take up. When the plant dies, the decay of C-14 can be used to determine the age of the artefact.

30
Q

How do decay sequences impact the rate of decay/production of materials?

A

In a chain of nuclide production, the rate of decay of an atom determines how quickly it is depleted and the rate of decay of the atom ahead of it in the sequence determines how quickly it is produced.

The first atom in the chain only decays.
The final atom in the chain is only produced.

31
Q

Describe the differential equations for the decay sequence of 3 nuclei: A, B, and C

A
32
Q

State the decay equation for alpha decay

A
33
Q

Alpha decay results in a nuclei of a _________ ___________ as Z has changed.

A

Different element

34
Q

How much energy is released by one alpha decay?

A

~5 MeV

35
Q

How is the energy release due to a decay calculated?

A

By comparing the difference in mass between reactants and products.

36
Q

Give the equation for the energy release due to a decay

A

Q = energy release
M_reactants = nuclear mass of reactants
M_products = nuclear mass of products
c = speed of light

37
Q

Energy release must be ________ for decay to be possible.

A

Positive

38
Q

State the conversion between nuclear mass and atomic mass

A

M_N = nuclear mass
M_A = atomic mass
Z = atomic number
m_e = electron mass

39
Q

What is the Geiger-Nuttall rule?

A

The relationship between the half-life and energy release for alpha decay, explained by quantum tunneling. It assumes that the alpha particle is pre-formed inside the nucleus and moves in the spherical potential well.

40
Q

Describe the shape of the potential for alpha decay

A

r = distance between the alpha particle and the daughter nucleus
Q = alpha particle energy

Region 1 (r < a): the alpha particle is classically confined to this region
Region 2 (a < r < b): the barrier region where the potential is greater than Q
Region (b < r): classically permitted region

41
Q

Give the equation for the Coulomb potential energy between two nuclei

A

V = potential energy
Q = charge
ε0 = vacuum permittivity
r = separation distance
Z = atomic number
e = electron charge

42
Q

State the time-independent Schrodinger equation

A
43
Q

What are the solutions to the time-independent Schrodinger equation when E > V_c?

A

Oscillatory solutions

44
Q

What are the solutions to the time-independent Schrodinger equation when E < V_c?

A

Exponential solutions

45
Q

What is the coulomb potential for alpha decay approximated as?

A

A step potential

46
Q

What is the transmission probability?

A

The probability of a particle tunnelling through a barrier.

47
Q

The decay constant is the product of the transmission _________ and the _________ at which a particle of velocity, v, hits the barrier

A

Probability
Frequency

λ = fP

48
Q

State the decay equation for beta- decay

A
49
Q

State the decay equation for beta+ decay

A
50
Q

State the decay equation for orbital electron capture

A
51
Q

A positron is the ____________ of an electron.

A

Anti-particle

52
Q

An anti-particle has the same ____ but equal and opposite ______.

A

Mass
Charge

53
Q

Is beta decay a strong or weak interaction?

A

Weak interaction

54
Q

What does the electron neutrino/electron anti-neutrino add to beta decay?

A

They conserve lepton numbers

55
Q

Where does beta decay occur?

A

Inside the nucleus

56
Q

Give the nuclear equation for beta- decay

A
57
Q

Give the nuclear equation for beta+ decay

A
58
Q

Give the nuclear equation for orbital electron capture

A
59
Q

Why do electrons/positrons have a range of energies in beta decay?

A

Because the neutrinos also carry some of the energy released.

60
Q

What is the other name for orbital electron capture?

A

Inverse beta decay

61
Q

Where does orbital electron capture occur?

A

In proton-rich nuclei

62
Q

Briefly describe the process of orbital electron capture

A

The nucleus captures an orbiting inner electron so the outer shell electron replaces this, causing one of the protons to be converted into a neutron and a photon to be emitted.

PHYS3001: Atoms, Photons and Fundamental Particles (11 decks)

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