Gamma,Alpha,Beta

• Whats an alpha particle?

  its a helium nucleus - mass of 4 and charge of +2
• What is a beta particle?

  Its an electron with no mass and a charge of -1
• What is the decay process of gamma?

  After an alpha or beta emission, the nucleus sometimes needs to get rid of extra energy. It does this by emitting a gamma emission.
• What is a gamma ray?

  Its a photon with no charge
• Alpha - 2 neutrons and 2 protons ( Helium, nuclei )
• Beta - high energy/speed electron
• Gamma - high energy electromagnetic radiation
• What is the penetrating power of the alpha?

  Stopped by paper or a few cm of air
• What is the penetrating power of the beta?

  Stopped by a few mm of aluminium
• What is the penetrating power of the gamma?

  Reduced by several cm's of lead or several metres of concrete
• What was the ionising power of the alpha?

  Strongly ionising
• What was the ionising power of the beta?

  strongly deflected
• What was the ionising power of the gamma?

  Very weakly ionising
• What was the deflection of the alpha by the magnetic field?

  Weakly deflected
• What was the deflection of the beta by the magnetic field?

  Strongly deflected
• What was the deflection of the gamma by the magnetic field?

  No deflection
• What is the use of the alpha?

  Smoke alarms
• What is the use of the beta?

  Thickness of paper and metal sheets
• What is the use of the gamma?

  Medical tracers, radiotherapy, sterilising medical equipment.
• How do smoke alarms work with the radiation, Alpha?

  • They emit alpha particles that ionise the air
  • The ionised air is attracted to oppositely to charged electrodes causing a current to flow in the circuit
• What happens if there is smoke in the air with smoke alarms? (Alpha)

  It binds to the ions, this means the current is weaker or stops flowing and the alarm sounds
• How does the thickness of paper or thin sheets of metal work - beta?

  Beta particles are emitted through paper/metal sheet and detected
• What happens if too much beta particles go through the paper/metal sheet?

  The sheet is too thin so a signal is sent to the rollers to move apart, if not enough goes through then the rollers move closer
• Why can’t we use Alpha to emit through paper sheets?

  As it is weakly penetrating but gamma is very penetrating
• What happens when all gamma particles go through metal sheets/paper?

  variations in thickness so cannot be detected
• How do tracers work with gamma particles?

  Radioactive isotopes can be injected into the body. An external detector tracks it progress around the body and a computer converts the reading
• What is an advantage of radioactive isotope?

  They are normally gamma emitters so the radiation can pass out the body without causing much ionisation
• What is an disadvantage of radioactive isotope?

  They have short life’s so they quickly disappear
• how does radiotherapy work ?

  high dose of radiation kills all living cells so it can be used to treat cancer
• How do gamma rays work in radiotherapy?

  They are directed carefully with the correct dosage to kill cancer cells without damaging too many normal cells. They can also be implanted into tumours