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

Topic 3-Radioactivity and ionising Radiation Flashcards

(55 cards)

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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

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A

Nothing, no change

24
Q

What is the relative charge of up-quarks

25
What is the relative charge of down-quarks
-1/3
26
What is the relative mass of and up-quark
1/3
27
What is the relative mass of a down-quark
1/3
28
What quarks are protons made of
Two up-quarks and one down-quark
29
What quarks are neutrons made up of
Two down-quarks and one up-quark
30
What is the charge on a proton in quarks
2/3 +2/3+(-1/3)=+1
31
What is the mass of a proton in quarks
1/3+1/3+1/3=+1
32
What is the charge of a neutron in quarks
2/3+(-1/3)+(-1/3)=0
33
What is the mass of a neutron in quarks
1/3+1/3+1/3=1
34
When a neutron changes to a proton what quarks does it change
A down to an up
35
If a nucleus is unstable and converts a proton to a neutron to become more stable what quarks does it change
An up to a down
36
When a neutron turns to a proton what has to happen and why
Nucleus has to produce a negatively charged particle as well to keep charge zero Produces an electron B- decay
37
When a proton changes to a neutron what has to happen or be produced
Produced a positron to keep the overall charge at +1
38
How are tracers in medicine used
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
What types of isotopes are used as tracers
Beta or gamma as pass out of body and have short half-lives
40
How does a PET scan work
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
Properties of alpha
Helium nucleus Slow and heavy moving Strongly ionising Stopped by paper, skin...
42
What can PET scans be used to diagnose
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
What can ionisation from radiation lead to
Kill/damage cells so can't decide--->tissue damage Alter genetic material in cell---->Mutations Divide and crow uncontrollably=cancer
44
What is recommended for treatments to decrease the risks of radiation
Lowest possible dose of radiation Short exposure time Wear lead shielding to protect other parts of body not being treated
45
What should medical personnel do to limit exposure to radiation
Intensity decreases with distance so stand well away or remotely control Stand behind lead screan Wear lead-lined clothing Radiation closely monitored
46
How is radiation used internally to treat tumours
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
How is radiation used externally to treat tumours
High energy x-Rays or gamma rays aimed at tumour | Carefully focused but damage done to healthy cells
48
What are the benefits of internal sources to treat tumours rather than external
Shorter by up to 6 weeks Reduces number of visits to hospital And time to wait to undergo further planned treatment
49
What is a negative of using radiation internally
Emit radiation after source inserted | Limit contact with people until removed (days later)
50
Bonus of using external rather than internal radiation
Treatment lasts a few minutes and patient doesn't emit radiation afterwards
51
Effects of internal and external radiation
Internal, no side effects but discomfort | External, short and long term effects
52
Why Aretha's two types, internal and external
Used often overlap but used to treat different parts of the body
53
What are some of the social and medal issues with radioactivity and medicine
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
What is reducing suffering before death known as
Palliative care
55
Why is developing medical care controversial
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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