Radioactivity Flashcards
What sort of radiation is always present in the environment around us
Background radiation
Sources of background radiation
Food Cosmic rays Radon gas Rocks and building materials
How do radiation detectors work
When radiation passes close to an atom it knocks out electrons and ionises the atom Radiation detectors work by detecting these charged atoms
What does radiation consist of?
High energy particles or waves emitted from the nucleus of an unstable atom
What can be concluded by the fact that radiation is emitted randomly
It is impossible to predict when a nucleus will emit radiation
Alpha particles characteristics
high energy particles made up of 2 protons and 2 neutrons Usually emitted from nuclei that are too large Highly ionising Travel around 10cm and are stopped by paper Leave a dense trail of ions behind it which affects virtually every atom they meet Due to their dense trails of ions they lose energy quickly and can’t travel far Harmless if handled carefully; dangerous if alpha emitters enter the body
Beta particle characteristics
High energy electrons emitted from the nucleus Emitted if the nucleus has too many neutrons Few of 10’s cm range in air Stopped by 5mm of aluminium Medium ionisation Create a less dense path of ions than alpha which gives it a longer range to travel More dangerous than alpha as they can penetrate skin, travel further, ionising enough to cause serious damage
Gamma particle characteristics
Emitted by nuclei that need to lose energy Its an electromagnetic wave Infinite range of travel as its low ionising Stopped by a few mm of lead Because they have no ions they are more penetrating which can be dangerous in large amounts
What can ionisation do
Cause genetic mutation Kill or damage living cells
Why can alpha and beta but not gamma particles be deflected by electric and magnetic fields
Because alpha and beta have charges but gamma is neutral
Why are beta particles deflected more than alpha
Because beta particles have a smaller mass
How is radioactivity used in thickness application
As a material moves above a beta source, the particles able to penetrate it are detected using a monitor If the material gets thicker, more particles are absorbed meaning that less will get through; vice versa This allows the monitor to make adjustments to keep the thickness constant
How is radioactivity used in tracers
Radioactive isotopes that are added to fluid so that its flow can be monitored In medicine they are used for flow blood and to detect blood clots In industry they are used for oil pipelines to check for leakages To minimise harm, gamma radiation with a short half life is used to minimise radiation exposure time and is low ionising which wont harm the body
How is radioactivity used in radiation therapy
Radiation is used to kill cancer cells beams of gamma rays are directed at tumours, as they can penetrate the body reaching the tumour The beams are moved around to minimise harm but still kill the tumour
How is radioactivity used in sterilization
Medical instruments are sterilized by gamma ray exposure Gamma rays kill bacteria and virus Gamma rays can penetrate all areas making it completely sterilized
