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Physics Extension > Topic 3-Radioactivity and ionising Radiation > Flashcards

Topic 3-Radioactivity and ionising Radiation Flashcards

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1
Q

Properties of beta

A

Electron
Light and fast
Moderately ionising
Stripped by thin metal

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2
Q

Properties of gamma rays

A

Electromagnetic radiation
No mass, very fast
Weakly ionising
Stopped by thick lead or thick concrete

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3
Q

What is a positron

A

Antiparticle of an electron

Exact same relative mass but different relative charge (+1)

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4
Q

What are the properties of positrons

A

Same as electrons
Light, fast moving, moderately ionising
Stopped by thin sheet of material

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5
Q

How are positrons obliterated

A

When collide with an electron at high speeds in annihilation

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6
Q

What are neutrons more penetrating than

A

Apha, beta and sometimes gamma

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7
Q

Properties of neutrons

A

Aren’t directly ionising

Absorbed by nuclei of atoms

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8
Q

What happens when an atom absorbs a neutron

A

Can make nucleus radioactive, then emits ionising radiation

Neutrons are ‘indirectly ionising’

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9
Q

What materials are used to make neutron radiation shielding

A

They are absorbed by light nuclei, lightest is hydrogen

So hydrogen rich materials water, polythene or concrete are used for radiation shielding

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10
Q

What is added to the shielding and why

A

Thick lead as neutron absorption can cause nuclei to emit gamma radiation

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11
Q

What four things cause a nucleus to be unstable

A

1) too many neutrons
2) too few neutrons
3) too many protons and neutrons
4) too much energy

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12
Q

What does a curve of stability show

A

The number of neutrons in comparison to protons for stable isotopes

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13
Q

An isotope that lies above the line of stability has

A

Too many neutrons

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14
Q

An isotope below the like of stability has

A

Too few neutrons

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15
Q

B- decay is

A

The emission of electrons from the nucleus

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16
Q

What does beta decay happen in (B-)

A

Isotopes that are “neutron rich” have more neutrons than protons
Nucleus ejects beta particle, one of neutrons changes into a proton

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17
Q

In beta (B-) decay what happens to the proton number and the nucleon number

A

The proton (atomic) number increases by one and the nucleon (mass) number stays the same

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18
Q

What is beta plus decay

A

Emission of positron from nucleus

Proton gets changed into a neutron

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19
Q

What happens to the proton number and neutron number in beta-plus decay

A

Proton number decreases by one the nucleon number stays the same

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20
Q

What does Apha decay happen in

A

Very heavy atoms e.g uranium and radium

Nuclei to massive to be stable

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21
Q

What happens to the proton number and nucleon number in Apha decay

A

Proton number decreases by two, nucleon number decreases by four.

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22
Q

Why are gamma rays emitted

A

After alpha or beta decay the nucleus has excess energy, which it loses by emitting gamma ray

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23
Q

What happens to proton and nucleon number when gamma rays are emitted

A

Nothing, no change

24
Q

What is the relative charge of up-quarks

A

2/3

25
Q

What is the relative charge of down-quarks

A

-1/3

26
Q

What is the relative mass of and up-quark

A

1/3

27
Q

What is the relative mass of a down-quark

A

1/3

28
Q

What quarks are protons made of

A

Two up-quarks and one down-quark

29
Q

What quarks are neutrons made up of

A

Two down-quarks and one up-quark

30
Q

What is the charge on a proton in quarks

A

2/3 +2/3+(-1/3)=+1

31
Q

What is the mass of a proton in quarks

A

1/3+1/3+1/3=+1

32
Q

What is the charge of a neutron in quarks

A

2/3+(-1/3)+(-1/3)=0

33
Q

What is the mass of a neutron in quarks

A

1/3+1/3+1/3=1

34
Q

When a neutron changes to a proton what quarks does it change

A

A down to an up

35
Q

If a nucleus is unstable and converts a proton to a neutron to become more stable what quarks does it change

A

An up to a down

36
Q

When a neutron turns to a proton what has to happen and why

A

Nucleus has to produce a negatively charged particle as well to keep charge zero
Produces an electron
B- decay

37
Q

When a proton changes to a neutron what has to happen or be produced

A

Produced a positron to keep the overall charge at +1

38
Q

How are tracers in medicine used

A

Radioactive isotope injected or swallowed, external detectors followed progress around the body, computer detects image
E.g iodine-131 is absorbed by thyroid gland, gives out radiation which is detected to see if it is taking iodine as it should

39
Q

What types of isotopes are used as tracers

A

Beta or gamma as pass out of body and have short half-lives

40
Q

How does a PET scan work

A

1)Inject substance into body (glucose), containing a positron emitting radioactive isotope with short half life-tracer
2)positron meets electrons and annihilates them, emitting high energy gamma rays which are detected
Distribution of radioactivity matched up with metallic activity (more radioactive glucose is taken up by cells and used by those doing more work ) ones with increased metabolism
3)isotopes with short half lives used, made close to where used (hospitals have own cyclotrons) if travel long distance, activity too low and not useful

41
Q

Properties of alpha

A

Helium nucleus
Slow and heavy moving
Strongly ionising
Stopped by paper, skin…

42
Q

What can PET scans be used to diagnose

A

CHD-show areas of damaged tissue in heart by detecting areas of decreased bold flow —->heart attacks
EPILEPSY-blood flow and activity in brain
CANCER TUMOURS-metabolic activity in tissue, higher than in normal cells due to rate of growth

43
Q

What can ionisation from radiation lead to

A

Kill/damage cells so can’t decide—>tissue damage
Alter genetic material in cell—->Mutations
Divide and crow uncontrollably=cancer

44
Q

What is recommended for treatments to decrease the risks of radiation

A

Lowest possible dose of radiation
Short exposure time
Wear lead shielding to protect other parts of body not being treated

45
Q

What should medical personnel do to limit exposure to radiation

A

Intensity decreases with distance so stand well away or remotely control
Stand behind lead screan
Wear lead-lined clothing
Radiation closely monitored

46
Q

How is radiation used internally to treat tumours

A

Placed inside body, into or near tumour
Injecting or implanting small radioactive substance
High dose to small part of body, limit damage to normal cells

47
Q

How is radiation used externally to treat tumours

A

High energy x-Rays or gamma rays aimed at tumour

Carefully focused but damage done to healthy cells

48
Q

What are the benefits of internal sources to treat tumours rather than external

A

Shorter by up to 6 weeks
Reduces number of visits to hospital
And time to wait to undergo further planned treatment

49
Q

What is a negative of using radiation internally

A

Emit radiation after source inserted

Limit contact with people until removed (days later)

50
Q

Bonus of using external rather than internal radiation

A

Treatment lasts a few minutes and patient doesn’t emit radiation afterwards

51
Q

Effects of internal and external radiation

A

Internal, no side effects but discomfort

External, short and long term effects

52
Q

Why Aretha’s two types, internal and external

A

Used often overlap but used to treat different parts of the body

53
Q

What are some of the social and medal issues with radioactivity and medicine

A

Damage normal cells—>side effects
Radiotherapy—>hairloss, sickness, skin irritation
Serious—>long term! bowl damage and infertility
Quality of life reduced, some refuse
Rare but second cancer, but without the treatment of first life expectancy shorter
Not always cured, but reduce suffering before death (palliative care)

54
Q

What is reducing suffering before death known as

A

Palliative care

55
Q

Why is developing medical care controversial

A

New and don’t know long term side effects
Test on cells in lab, then animals, then humans
Patient should be informed of side effects but doctors don’t know them
Ill people want to get on trial but limited spaces
How long till successful treatment it shared???

Physics Extension (5 decks)

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