unit p2 - radiation lesson 01 – introduction to radiation aims: know that radiation is produced...
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Unit P2 - RadiationUnit P2 - RadiationLesson 01 – Introduction to RadiationLesson 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…1. What particles make up
atoms?
Friday 21 April 2023
It comes from…
Sources of background RadiationSources of background Radiation
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Sources of Background RadiationSources of Background Radiation
Source Amount
Radon Gas from Granite 51 %
The ground 14 %
Food & Drink (coffee & peanuts)
12 %
Cosmic Rays (outer space) 10 %
Medical (X-Rays etc.) 12 %
Other (including nuclear power stations)
1 %
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.
What happens when radiation What happens when radiation reaches atoms and cells?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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What happens when radiation What happens when radiation reaches atoms and cells?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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It is detected by…
Geiger counter Geiger counter
Demo Geiger counter
Do some work…
There are three main
types of Radiation
Radiation – a few facts…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
Alpha Decay…
• Phosphorous atom
(15 protons)
Proton
Neutron
Electron
Nucleus becomes unstable…
• Phosphorous atom
(15 protons)
Proton
Neutron
Electron
A group of 2 protons and 2 neutrons ejected…
• Phosphorous atom
(15 protons)
Proton
Neutron
ElectronThe group of 2 protons and two neutrons is called an ALPHA particle
It shoots out at high speed straight past the electrons
Alpha particle…
A group of 2 protons and 2 neutrons ejected…
Proton
Neutron
ElectronThe phosphorous atom has lost 2 protons (it now has 13)
It is now an Aluminium atom
Beta Decay…
• Phosphorous atom
(15 protons)
Proton
Neutron
Electron
Beta Decay…
• Neutrons are made from a proton and an electron (& an anti-neutrino)
Proton
Neutron
Electron
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
ProtonNeutronElectron
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
Types of RadiationTypes 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)
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.
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
Unstable nucleus
Unstable nucleus
New nucleus
New nucleus
New nucleus
Alpha particle
Beta particle
Gamma radiation Copy this bit…
IonisationIonisationWhen 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
Different Different radiation is radiation is
stopped by a stopped by a different different materialmaterial
RadioactivityRadioactivityIf 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
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
Task…Task…1. Use longman FND
book 2 – Page 2342. Produce three bubble
map showing the properties of alpha, beta and gamma radiation.
3. Then, produce a ‘double bubble’ map showing comparing and contrasting the properties of alpha and beta radiation
Alpha
BetaAlpha
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Questions…Longman FND page 234-235. Questions 1-6 & Summary
Homework…
Worksheet L15.1
1. How can concrete protect people from gamma radiation?
2. What types of radiation are stopped by a thin sheet of aluminium?
3. Polonium-210 is very radioactive, it emits alpha particles and glows blue. Explain why is safe to store 210Po in a paper bag. (http://en.wikipedia.org/wiki/Polonium)
4. What is background radiation?5. Why is an alpha particle sometimes
referred to as a helium nucleus?6. 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.
7. If alpha radiation was deflected upwards by a magnetic field, what way would beta be deflected. Explain your answer
Lesson 4Lesson 4Directing Directing RadiationRadiation
RecapRecap• 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
Radiation can Radiation can be deflected be deflected
by a by a magnetic magnetic
fieldfield
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
Things to do...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
5 / 65 / 6
Aluminium RollersAluminium Rollers
Match the radiation
Alpha
Beta
GammaHelium nuclei
High energy electron
Electromagnetic radiation
Stopped by paper or skin
Reduced by lead
Stopped by aluminium
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
Thin mica Thin aluminiumstops BETA
Thick leadreduces GAMMA
Skin or paper stops ALPHA
The penetration power of the three types of radiation.
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
Hydraulicram
detector
Thickness Control Mill
Electronic instructions to adjust rollers.
Beta Source
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.
Assessment – Aluminium Assessment – Aluminium RollersRollers
Scenario:
You need to write a sales pitch trying to sell a new Aluminium rolling machine and sensor to an Aluminium Factory
e.g.
http://www.mettradeindia.com/index.php
Assessment... (P2)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
234 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.)
234 Find out what the maximum thickness of Aluminium you could produce and measure by this method you could use
234 Find out what radioactive source you would use for (a) Paper, (b) thick card, (c) lead
234 You must describe the properties of the radiation and why it is stopped by the materials above