1. Unit P2 - Radiation Lesson 01 – Introduction to Radiation
Saturday, 22 April 2017
Unit P2 - Radiation Lesson 01 – Introduction to Radiation
Aims:
Know that radiation is produced from the nucleus of the atom
Know that there are three different types of nuclear radiation
Questions…
What particles make up atoms?

2. It comes from…

5. Sources of background Radiation
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6. Sources of Background Radiation
In the South West, radon gas is a major contributor to background radiation.
This is more evident in enclosed spaces e.g. caves and granite houses on Dartmoor
You are exposed to a lot more cosmic radiation on a flight.
Source
Amount
Radon Gas from Granite
51 %
The ground
14 %
Food & Drink (coffee & peanuts)
12 %
Cosmic Rays (outer space)
10 %
Medical (X-Rays etc.)
Other (including nuclear power stations)
1 %

7. What happens when radiation reaches atoms and cells?
Alpha (α) and beta (β) cause ionisation – the radiation removes electrons from atoms.
This makes the atoms very reactive
It makes atoms react uncontrollably making strange substances
It makes cells faulty – possibly causing cancer
The higher the dose of radiation – the greater chance of damage / cancer
Most gamma radiation passes through people and does not cause much damage
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8. What happens when radiation reaches atoms and cells?
Alpha (α) and beta (β) cause ionisation – the radiation removes electrons from atoms.
This makes the atoms very reactive and can…
It makes cells faulty – causing cancer
The higher the dose of radiation – the greater chance of damage / cancer
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9. It is detected by…

10. Geiger counter

11. Demo Geiger counter

13. Do some work…

15. There are three main types of Radiation

16. Radiation – a few facts…
The nucleus of atoms is made from protons and neutrons
Radiation comes from the nucleus of atoms
There are three types of radiation
Alpha α
Beta β
Gamma γ
α β γ

17. Alpha Decay…
Phosphorous atom
(15 protons)
Proton
Neutron
Electron

18. Nucleus becomes unstable…
Phosphorous atom
(15 protons)
Proton
Neutron
Electron

19. A group of 2 protons and 2 neutrons ejected…
Phosphorous atom
(15 protons)
Proton
Neutron
Electron
The group of 2 protons and two neutrons is called an ALPHA particle
It shoots out at high speed straight past the electrons
Alpha particle…

20. A group of 2 protons and 2 neutrons ejected…
Electron
The phosphorous atom has lost 2 protons (it now has 13)
It is now an Aluminium atom

21. Beta Decay…
Phosphorous atom
(15 protons)
Proton
Neutron
Electron

22. Beta Decay…
Neutrons are made from a proton and an electron (& an anti-neutrino)
Proton
Neutron
Electron

23. Beta Decay…
A neutron becomes unstable, it splits up and ejects the electron at high speed. (the anti-nutrino is ejected)
The proton stays in the nucleus
Proton
Neutron
Electron

24. Gamma Decay
When alpha or beta radiation is produced excess energy is released as a gamma ray
Gamma rays are not particles
Gamma rays are part of the electromagnetic spectrum

25. Types of Radiation
1) Alpha () – an atom decays into a new atom and emits an alpha particle (2 protons and 2 neutrons – the nucleus of a helium atom)
Unstable nucleus
New nucleus
Alpha particle
2) Beta () – an atom decays into a new atom by changing a neutron into a proton and electron. The fast moving, high energy electron is called a beta particle.
Beta particle
New nucleus
Unstable nucleus
3) Gamma – after  or  decay surplus energy is sometimes emitted. This is called gamma radiation and has a very high frequency with short wavelength. The atom is not changed.
Unstable nucleus
New nucleus
Gamma radiation
Copy this bit…

26. Ionisation
When radiation collides with neutral atoms or molecules it alters their structure by knocking off electrons. This will leave behind IONS – this is called IONISING RADIATION.
 particle
Electron

27. Different radiation is stopped by a different material

28. Words – aluminium, beta, food, radioactive
Radioactivity
If a substance is capable of ALWAYS emitting radiation under any conditions we say it is ____________. There are three types of radiation: ALPHA, _____ and GAMMA. These types of radiation are always given off by rocks, _____, building materials, air and cosmic rays around us – this is called BACKGROUND RADIATION. Each type is capable of penetrating different materials:   
Sheet of paper
Few mm of _________
Few cm of lead
Words – aluminium, beta, food, radioactive

29. Properties of alpha, beta and gamma radiation…
Name of radiation
Symbol
Passes through:
Is absorbed by:
Alpha α
5cm air only
A few cm of air
Beta β
Air & paper
A thin sheet of paper
Gamma γ
Most things except thick lead and concrete
A thick sheet of lead
A very thick wall of concrete

30. Task… Use longman FND book 2 – Page 234
Produce three bubble map showing the properties of alpha, beta and gamma radiation.
Then, produce a ‘double bubble’ map showing comparing and contrasting the properties of alpha and beta radiation
Alpha
Beta
Alpha

31. Longman FND page 234-235. Questions 1-6 & Summary
Homework…
Worksheet L15.1
Saturday, 22 April 2017

32. How can concrete protect people from gamma radiation?
What types of radiation are stopped by a thin sheet of aluminium?
Polonium-210 is very radioactive, it emits alpha particles and glows blue. Explain why is safe to store 210Po in a paper bag. (
What is background radiation?
Why is an alpha particle sometimes referred to as a helium nucleus?
Alpha and beta radiation can be deflected by a magnetic or electric field. Gamma radiation cannot be deflected by electric or magnetic fields – explain why.
If alpha radiation was deflected upwards by a magnetic field, what way would beta be deflected. Explain your answer

33. Lesson 4 Directing Radiation

34. Recap Alpha An energy beam Beta Two protons and two neutrons Gamma
What are the three types of radiation?
Match the radiation with its properties...
Where does radiation come from?
Name some sources of radiation?
Why do we [in Plymouth] get more radiation than people in other parts of the country?
Describe the process that makes beta radiation.
Alpha
An energy beam
Beta
Two protons and two neutrons
Gamma
A fast moving electron

35. Radiation can be deflected by a magnetic field

38. Properties of alpha, beta and gamma radiation…
Name of radiation
Symbol
Passes through:
Is absorbed by:
Alpha α
5cm air only
A few cm of air
Beta β
Air & paper
A thin sheet of paper
Gamma γ
Most things except thick lead and concrete
A thick sheet of lead
A very thick wall of concrete

39. Things to do...
Complete the handout with the properties of alpha, beta and gamma radiation
Use Longman FND book2, Btec Science book or the AQA book to help

40. 5 / 6

41. Aluminium Rollers

42. Match the radiation Electromagnetic radiation Stopped by paper or skin
Alpha
High energy electron
Reduced by lead
Beta
Helium nuclei
Gamma
Stopped by aluminium

43. Background radiation
Background radiation is the radiation all around us. Working in pairs try to think of five possible sources of background radiation.
You have FIVE minutes!!
Rocks
Air
Building materials
Outer space
Food

44. The penetration power of the three types of radiation.  
Skin or paper
stops ALPHA
Thin aluminium
stops BETA
Thick lead
reduces GAMMA
Thin mica

45. Using your results from the previous three investigations, fill in the table below:
Alpha
Beta
Gamma
Penetrating power
Range of radiation
Most dangerous outside of body
Most dangerous inside of body
Affected by a magnetic field
least
medium
most
shortest
medium
longest
least
medium
most
most
medium
least
yes
yes no

46. Thickness Control Mill
A radioactive source is on one side of the material and a detector on the other.
If too much radioactivity is getting through, then the material is too thin and the rollers open up a bit to make the material thicker.
If not enough radioactivity is detected then the rollers compress to make the material thinner.
This method is used in the manufacture of lots of sheet materials: plastics, paper, sheet steel.
Beta Source
detector
Hydraulic
ram
Electronic instructions to adjust rollers.

47. Assessment – Aluminium Rollers
Scenario:
You need to write a sales pitch trying to sell a new Aluminium rolling machine and sensor to an Aluminium Factory
e.g.

48. Assessment... (P2) AQA Lng 2 Btec
What you must do to Pass this assignment...
378
(240)
Explain how a Aluminium Roller works (AQA page 378 may help)
234
Work out which would be the most appropriate radiation to use to work out the thickness of the Aluminium (explain what alpha, beta and gamma are, which you would choose and why)
374,
383 42
Write down everything you have found out from the theory about alpha, beta and gamma. (What they are, their range, their levels of ionisation, what you need to stop them etc.)
Find out what the maximum thickness of Aluminium you could produce and measure by this method you could use
Find out what radioactive source you would use for (a) Paper, (b) thick card, (c) lead
You must describe the properties of the radiation and why it is stopped by the materials above