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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?
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It comes from…
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Sources of background Radiation
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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 %
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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 copy
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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 copy
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It is detected by…
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Geiger counter
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Demo Geiger counter
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Do some work…
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There are three main types of Radiation
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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
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Alpha Decay… Phosphorous atom (15 protons) Proton Neutron Electron
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Nucleus becomes unstable…
Phosphorous atom (15 protons) Proton Neutron Electron
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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…
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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
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Beta Decay… Phosphorous atom (15 protons) Proton Neutron Electron
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Beta Decay… Neutrons are made from a proton and an electron (& an anti-neutrino) Proton Neutron Electron
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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
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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
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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…
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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
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Different radiation is stopped by a different material
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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
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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
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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
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Longman FND page 234-235. Questions 1-6 & Summary
Homework… Worksheet L15.1 Saturday, 22 April 2017
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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
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Lesson 4 Directing Radiation
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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
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Radiation can be deflected by a magnetic field
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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
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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
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5 / 6
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Aluminium Rollers
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Match the radiation Electromagnetic radiation Stopped by paper or skin
Alpha High energy electron Reduced by lead Beta Helium nuclei Gamma Stopped by aluminium
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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
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The penetration power of the three types of radiation.
Skin or paper stops ALPHA Thin aluminium stops BETA Thick lead reduces GAMMA Thin mica
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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
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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.
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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.
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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
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