Radioactive Emissions 70-71 Flashcards
What is the symbol, constituent, relative charge and mass(u) for the radiation alpha.
Symbol : alpha
Constituent : A helium nucleus - 2 protons and 2 neutrons.
Relative charge: +2
Mass(u) : 4
What is the symbol, constituent, relative charge and mass(u) for the radiation Beta-minus?
Symbol: ß or ß-
Consituent: Electron
Relative Charge: -1
Mass(u) : (negligeable)
What is the symbol, consituent, reltive charge and mass(u) of the radiation Beta-plus?
Symbol: ß+
Constituent: Positron
Relative charge: +1
Mass(u) : (negligeable)
What is the symbol, constituent, relative charge and mass(u) for the gamma radiation?
Symbol: gamma
Constituent: Short-wave, high-frequency electromagnetic wave.
Relative charge: 0
Mass(u) 0
Why are radioactive emissions also known as ionising radiation?
When a radioactive particle hits an atom it can knock off electrons, creating an ion.
For the radiation alpha, how strong is the ionising radiation. What is the speed of the radiation. What is the penetrating power and is it affected by magnetic fields?
Ionising: Strongly
speed: Slow
Penetrating power: Absorbed by paper or a few cm of air.
Affected by magnetic field: Yes
How strong is the ionising radiation of Beta minus. What is the speed of the radiation? What is the penetrating power of Beta-minus? Is it affected by magnetic fields?
Ionising: Weakly
Speed: Fast
Penetrating power: Absorbed by 3mm of aluminium
Affected by magnetic field: Yes
Why does the Beta-plus not travel very far and not affect many things?
It is annihilated by an electron - so virtually zero range.
How ionising is Gamma radiation, what is its speed and what is its penetrating power. And is it affected by a magnetic field?
Ionising: Very weakly
Speed: Speed of light
Penetrating Power: Absorbed by many cm of lead, or several m of concrete.
Not affected by a magnetic field.
How does the intensity of gamma radion decrease with distance when travelling through an absorbing material.
Its intensity decreases exponentially.
How can the absorbed does be calculated?
absorbed dose = energy/mass
Absorbed dose is measured in grays (Gy)
What is the effective dose?
What are its units
How is it calculated?
The effective dose is a measure that lets you compare the amount of damage to body tissues that have been exposed to different types of radiation.
Effective dose = absorbed dose x radiation quality
The unit of effective dose is the siervert ( v)
What is the typical radiation quality factor of alpha, beta and gamma?
Alpha: 20
Beta: 1
Gamma: 1
If you exposed a sample of body tissue to 1 Gy of alpha radiation, how much gamma radiation would be required to do the same amount of damage.
If you exposed a sample of body tissue to 1Gy of alpha radiation, it could do the same damage as an exposure of 20Gy of gamma radiation on the body tissue.
Why is the radiation quality factor for alpha particles really high?
Alpha particles are strongly positive so they can easily pull electrons off atoms, ionising them.
The alpha particle quickly ionises many atoms and loses all it’s energy.
Why does beta-minus particle have a lower radiation quality factor?
The beta-minus particle has lower mass and charge than the alpha particle, but a higher speed. This means it can still knock electrons off atoms. Each beta particle will ionise about 100 atoms, loosing energy at each interaction.
This lower number of interactions means that beta radiation causes much less damage to body tissue than alpha radiation - explaining the lower radiation quality factor.
Explain some uses of radioactive materials.
They are used to generate power, in medecine for diagnosis and treatment, and to kill harmful microorganisms that might contaminate our food.
What harmful problems can radioactive materials cause?
Cancerous tumours, skin burns, radiation sickness, hair loss and even death.
What are the two things considered when looking at the risk of using radioactive materials?
How likely it is that the radiation will cause a problem and how bad the problem would be if it did happen.
Give two examples of uses of radioactive materials where the risks outweigh the benefits.
1) A nuclear reactor melting down would be catastrophic,but it’s also very unlikely, so the risk might be acceptable.
2) Ionising radiation can cause cancer, but it can also be used in cancer treatments to destroy tumours. The risk of serious damage caused by the treatment is considered acceptable if the treatment is likely to prolong or improve a patient’s life.
