Radioactivity Flashcards
3 types of radiation
Alpha
Beta
Gamma
What is irradiation
Being exposed to ionising radiation
What is contamination
Unwanted presence of radioactive nuclei on/ inside body
What does radiation dose measure
The health risk of exposure to radiation. Depends on type and amount of radiation
What does radiation dose depend on
Amount and type of radiation
Facts about alpha radiation
2 protons, 2 neutrons
Charge of +2
High ionising power
Can be blocked/ absorbed by paper and dead skin cells
Can travel a few cm in air
Away from you isn’t dangerous (doesn’t travel far and can be blocked by skin)
Inside you is dangerous due to high ionising power
Alpha decay occurs when a particle with 2 protons and 2 neutrons (helium nucleus) is released from the nucleus
Facts about beta radiation
1 electron
Charge of -1
Can travel a few metres in air
Blocked/ absorbed by a few mm of aluminium
Medium ionising power
Beta decay occurs when a neutron turns into a proton which creates an electron that’s emitted from the nucleus
Facts about gamma radiation
It is an electromagnetic wave
It has no charge
It can travel a few km in the air
It can be blocked/ absorbed by a few cm of lead
It has a low ionising power
It is the most dangerous radiation outside of your body because it can travel the furthest and takes a few cm of lead to be blocked but inside of you it’s the least dangerous as it has the lowest ionising power
Gamma decay occurs when the nucleus releases energy in the form of an electromagnetic wave (photon) e.g during nuclear fission process
What is alpha decay
Particle with 2 protons and 2 neutrons released from the nucleus
(What’s released is the same as a helium nucleus)
What is beta decay
Neutron turns into proton which creates an electron that’s emitted from the nucleus
What is gamma decay
Nucleus releases energy in form of electromagnetic wave (photon)
What is the type of electromagnetic wave called in gamma radiation
Photon
Which type of radiation is most dangerous inside body
Gamma- has highest ionising power
Why is alpha radiation the most dangerous when in the body
Has highest ionising power
Why is alpha radiation not very dangerous outside of the body
Can only travel a few cm in air
Is blocked by dead skin cells
Which type of radiation is most dangerous outside of body
Gamma
Travels a few km in air
Requires a few cm of lead to be blocked
Which type of radiation is least dangerous inside the body
Gamma- has lowest ionising power
What can each type of radiation be blocked/ absorbed by
Alpha- paper/ dead skin cells
Beta- a few mm of aluminium
Gamma- a few cm of lead
What is meant by activity
Rate at which source of unstable nuclei decays
(Measured in Bq)
What is meant by Count rate
Number of decays recorded each second by a detector
(Measured in a Bq)
Example of detector used to measure count rate
Geiger-Muller tube
3 uses of radioactivity
Medical traces, automatic thickness monitoring, radiotherapy
What is meant by hale life of radioactive isotope
Average time for half of unstable nuclei to decay/ for activity of source to half