ONLINE COURSE, PART I : AN INTRODUCTION TO RADIATION

ONLINE COURSE, PART I : AN INTRODUCTION TO RADIATION

DESCRIPTION ATOMS ATOMS RADIOACTIVITY RADIOACTIVITY TYPES OF RADIOACTIVE DECAYS TYPES OF RADIOACTIVE DECAYS IONIZATION IONIZATION IONIZING AND NON-IONIZING RADIATION IONIZING AND NON-IONIZING RADIATION QUIZ ?

protons, neutrons, and electrons. ATOMS All matter is made up of atoms. The different elements are simply made up of atoms with different numbers of protons, neutrons, and electrons. Click on the different particles to learn more about them! Nucleus

protons, + + neutrons, and electrons. + - ATOMS Back • Protons : • Electrical charge : + 1 •  Interacts with other charged particles • Mass : 1.6726  10-27 kg ~ 1 unit of mass u •  About the same mass as a neutron • Size : 10-15 meters •  100 000 times smaller than the atom! All matter is made up of atoms. The different elements are simply made up of atoms with different numbers of protons, neutrons, and electrons. Click on the different particles to learn more about them! Nucleus

protons, neutrons, and electrons. ATOMS Back All matter is made up of atoms. The different elements are simply made up of atoms with different numbers of protons, neutrons, and electrons. Click on the different particles to learn more about them! • Neutrons : • Electrical charge : 0 •  Does not interacts with other charged particles • Mass : 1.6726  10-27 kg ~ 1 unit of mass u •  About the same mass as a proton • Size : 10-15 meters •  100 000 times smaller than the atom! Nucleus

protons, neutrons, and electrons. + - ATOMS Back • Electrons : • Electrical charge : - 1 •  Interacts with other charged particles • Mass : 9.1 x 10-31 kg •  2000 times less massive than protons and neutrons • Size : 10-18 meters •  1000 times smaller than protons and neutrons All matter is made up of atoms. The different elements are simply made up of atoms with different numbers of protons, neutrons, and electrons. Click on the different particles to learn more about them! Nucleus - -

protons, neutrons, and electrons. ATOMS Back • Nucleus : • Electrical charge : Z (Atomic Number, number of protons) • Mass : A (Mass Number, number of protons and neutrons) • Size : 10-14 meters •  10 000 times smaller than the atom! All matter is made up of atoms. The different elements are simply made up of atoms with different numbers of protons, neutrons, and electrons. Click on the different particles to learn more about them! Nucleus

RADIOACTIVITY ... • Nuclear Forceskeep the nucleus together. • Weak nuclear forces  unstable nucleus, needs to release energy • Radiation anything emitted from an unstable nucleus • Unstable atoms are called a radioactive atom, a radioisotope, or a radionuclide Stable! Unstable Atom Radiation Radioactive atom, radioisotope, radionuclide

RADIOACTIVITY • Nuclear Forceskeep the nucleus together. • Weak nuclear forces  unstable nucleus, needs to release energy • Radiation anything emitted from an unstable nucleus • Unstable atoms are called a radioactive atom, a radioisotope, or a radionuclide • Nuclear force: makes nucleons (protons and neutrons) attract • Only acts on a very short scale, but powerful on that scale • Large nuclei or nuclei with too few neutrons: electromagnetic force greater than the nuclear force, and the nucleus is unstable Unstable Atom Radiation Stable! Close

TYPES OF RADIOACTIVE DECAY A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! Alpha Decay Beta Decay Radioactive Decay Gamma Decay Neutron Radiation

TYPES OF RADIOACTIVE DECAY Back • Alpha Decays : • 2 protons and 2 neutrons • They are heavy and doubly charged • They interact strongly with other charged particles • A sheet of paper can stop them • If they are ingested, inhaled or absorbed by the skin, they can be very damaging • Alpha decays only occur in elements heavier than lead (Z > 82) A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! Alpha Decay Beta Decay Radioactive Decay Gamma Decay Neutron Radiation Examples of alpha decays

EXAMPLES OF ALPHA DECAY ... ... Uranium-238 Thorium-234 4.18 MeVAlpha + Radium-226 Radon-222 4.77 MeVAlpha +

EXAMPLES OF ALPHA DECAY ... Uranium-238 Thorium-234 4.18 MeVAlpha • This is the isotope of Uranium which contains 238 nucleons (protons and neutrons) • Uranium has 92 protons, but can have between 140 and 146 neutrons • Atoms with different numbers of neutrons are called isotopes • Uranium-238 has 92 protons and 146 neutrons, for a total of 238 nucleons. + 4.77 MeVAlpha Radium-226 Radon-222 + Close

EXAMPLES OF ALPHA DECAY ... Uranium-238 Thorium-234 4.18 MeVAlpha This is the kinetic energy, or energy of motion, of the alpha particle. It is indicative of how much energy this particle can deposit in matter. 1 MeV = 1 000 000 eV 1 eV = 1.6 x 10-19 J + Radium-226 Radon-222 4.77 MeVAlpha + Close

TYPES OF RADIOACTIVE DECAY Back • Beta Decays: • Small, charged particles emitted from the nucleus • Negative beta : electron • Positive beta : positron • They interact electrically with other charged particles • A layer of plastic or aluminum can stop beta particles • Beta radiation occurs when a nucleus changes a neutron into a proton or a proton into a neutron • Positive Beta Decay (β+ decay) : • Negative Beta Decay (β- decay) : A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! Alpha Decay Beta Decay Proton p+ Radioactive Decay p+ n0 + Gamma Decay Neutron Radiation Neutron n0 + Electron - n0 p+ - Positron Examples of Beta Decay

EXAMPLES OF BETA DECAY Beta particle (electron) Phosphorus-32 Sulfur-32 + Beta particle (positron) Sodium-22 Neon-22 +

TYPES OF RADIOACTIVE DECAY • Gamma decay: • Energetic photon liberated from a nucleus • No mass or charge, so don’t change the nature of the nuclei they are emitted from • Typically follow alpha or beta decays • Electrically neutral, don’t interact as readily with matter • Only slowed down or stopped in direct collisions with electrons • Thick layers of lead are required to reduce their intensity Back A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! ... Alpha Decay Beta Decay Radioactive Decay Gamma Decay Neutron Radiation Example of gamma decays

TYPES OF RADIOACTIVE DECAY • Gamma decay: • Energetic photon liberated from a nucleus • No mass or charge, so don’t change the nature of the nuclei they are emitted from • Typically follow alpha or beta decays • Electrically neutral, don’t interact as readily with matter • Only slowed down or stopped in direct collisions with electrons • Thick layers of lead are required to reduce their intensity Back A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! • A photon is an electromagnetic wave • It has a frequency and a wavelength, which dictate its characteristics • Visible light is photons with a certain range of wavelengths • Less energetic photons (longer wavelengths) compose radio frequencies, microwaves and infrared light • Higher energy photons comprise UV light, X-rays, and gamma rays. Alpha Decay Beta Decay Radioactive Decay Gamma Decay Neutron Radiation Close Example of gamma decays

Neon-22 EXAMPLE OF GAMMA DECAY Sodium-22 Beta particle Neon-22* Unstable Gamma ray Stable!

TYPES OF RADIOACTIVE DECAY Back • Neutron radiation : • Neutrons are not emitted on their own from an unstable nucleus • During nuclear fission, several neutrons can be ejected • They only interact with particles through direct collisions • They deposit a lot of energy in collisions with single protons • There are many single protons in water (hydrogen) • The tissue in our body is made of 60% water • Neutrons therefore deposit a lot of energy in our body • Good shields : • Thick layers of water, preferably heavy water • Other materials heavy in hydrogen (e.g. concrete, paraffin) A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! Alpha Decay Beta Decay Radioactive Decay Gamma Decay Neutron Radiation ... Example of neutron radiation

TYPES OF RADIOACTIVE DECAY Back • Neutron radiation : • Neutrons are not emitted on their own from an unstable nucleus • During nuclear fission, several neutrons can be ejected • They only interact with particles through direct collisions • They deposit a lot of energy in collisions with single protons • There are many single protons in water (hydrogen) • The tissue in our body is made of 60% water • Neutrons therefore deposit a lot of energy in our body • Good shields : • Thick layers of water, preferably heavy water • Other materials heavy in hydrogen (e.g. concrete, paraffin) Heavy water is water in which the hydrogen atoms are made up of a proton and a neutron, instead of simply a proton. This hydrogen isotope is called deuterium. Heavy water is used in CANDU reactors. A radioactive decay is a process in which the unstable nucleus releases energy. There are several types of radioactive decays. Click on each to lean more about them! Alpha Decay Beta Decay Close Radioactive Decay Gamma Decay Neutron Radiation Example of neutron radiation

EXAMPLE OF NEUTRON RADIATION Photon Fission fragment Neutron Photon Neutron Neutron Fission fragment Photon

IONIZATION • Radiation with enough energy can knock electrons out of their orbits • Alpha and beta particles strip electrons from their orbit through electric interactions • Photons can give all or a fraction of their energy to electrons, liberating them from their orbit • Both types of interactions result in a positive and negative piece of atom : ions Replay! Negative Ion Positive Ion Neutral Atom

IONIZATION • Radiation with enough energy can knock electrons out of their orbits • Alpha and beta particles strip electrons from their orbit through electric interactions • Photons can give all or a fraction of their energy to electrons, liberating them from their orbit • Both types of interactions result in a positive and negative piece of atom : ions Negative Ion Positive Ion Neutral Atom

IONIZING AND NON-IONIZING RADIATION ... • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. Radio waves Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Visible Light Microwaves

IONIZING AND NON-IONIZING RADIATION • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. • X-rays are photons • Very energetic • Produced when electrons lose energy, e.g. when electrons interact with matter, notably with other electrons. Close Radio waves Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Visible Light Microwaves

IONIZING AND NON-IONIZING RADIATION Back • Microwaves : • Less energetic than visible light • Optimal wavelength (size) to transfer energy to water • Analogous to pushing a kid on a swing • If you are not at the right place, you are wasting a lot of energy • Placing yourself at the end of the natural motion of the swing will allow for a maximal push • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. H H O Radio waves Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Visible Light Microwaves

IONIZING AND NON-IONIZING RADIATION Back • Radiowaves : • Radiofrequencies are not ionizing • They therefore do not break DNA strands and cells in our bodies • Regardless, many research projects have investigated if there is a link between cell phone use and brain cancer. • So far, the results have NOT shown a link • For more information on these topics, consult the following pages : • Health Canada : www.hc-sc.gc.ca/hl-vs/iyh-vsv/prod/cell-eng.php • World Health Organization : www.who.int/mediacentre/factsheets/fs193/en/ • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. Radio waves Radio waves Infrared light Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Non-Ionizing Rad. Visible Light Visible Light Microwaves Microwaves

IONIZING AND NON-IONIZING RADIATION Back Visible Light : Did you know your eyes are sensitive to as few as 5 to 9 photons? Here’s some literature if you are interested : http://www.desy.de/user/projects/Physics/Quantum/see_a_photon.html • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. Radio waves Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Visible Light Microwaves

IONIZING AND NON-IONIZING RADIATION Back • Infrared Light: • Our eyes cannot see infrared photons, but our body can still sense them • Infrared light is essentially heat • Slightly less energetic than red light • Reason why oven elements glow red • Ionizing Radiation : radiation which can create ions • Alpha, beta, gamma and X-rays are always ionizing • Ions travelling through your body can break DNA and cells • Poor repairs of the DNA and cells can lead to cancer. • Non-ionizing radiation : photons not energetic enough to create ions • Will not produce breaks in your cells and DNA, and should not lead to cancers related to radiation exposure. Electromagnetic Spectrum Energy Increasing Radio waves Radio waves Infrared light Infrared light Click on the types of non-ionizing radiation to learn more! Non-Ionizing Rad. Non-Ionizing Rad. Visible Light Visible Light Microwaves Microwaves Courtesy NASA/JPL-Caltech

SUMMARY • The atom is made up of a small nucleus at its centre, with electrons orbiting around it. The nucleus, in turn, is made up of protons and neutrons. • An unstable nucleus will try to become stable by undergoing radioactive decay. During this process, different types of particles can be emitted: alpha, beta or gamma. • During fission, neutrons can also be emitted • X-rays are not produced by unstable particles, but by electrons losing energy. • Ionization is the process of creating ions, in other words breaking up an electrically neutral atom or molecule into a positive component and a negative one. • Alpha, beta, gamma and X-ray radiation are always ionizing. Examples of non-ionizing radiation are radiowaves, microwaves, visible light, and infrared light.

QUIZ 1. All types of radiation are dangerous and exposure to them can lead to cancer. True False

QUIZ 1. All types of radiation are dangerous and exposure to them can lead to cancer. Wrong . The minimum energy required for ionization is 34 eV. Any radiation from photons with energies below that cannot ionize matter, therefore cannot break atoms in your body, kill cells, or induce mutations. Examples of radiation which do not cause damage are visible light, infrared light, microwaves and radiofrequencies. True False Try again!

QUIZ 1. All types of radiation are dangerous and exposure to them can lead to cancer. Good ! The minimum energy required for ionization is 34 eV. Any radiation from photons with energies below that cannot ionize matter, therefore cannot break atoms in your body, kill cells, or induce mutations. Examples of unharmful radiation are visible light, infrared light, microwaves and radiofrequencies. True False Continue

QUIZ 2. Beta particles are : Bundles of energy, also known as photons Made up of two protons and two neutrons, in other words the nucleus of Helium Small, charged particles. Examples are electrons and positrons. Neutral hadrons, the most common being neutrons

QUIZ 2. Beta particles are : Wrong . Gamma rays are photon. Beta particles aren’t. Bundles of energy, also known as photons Try again! Made up of two protons and two neutrons, in other words the nucleus of Helium Small, charged particles. Examples are electrons and positrons. Neutral hadrons, the most common being neutrons

QUIZ 2. Beta particles are : Bundles of energy, also known as photons Wrong . Those are alpha particles. Made up of two protons and two neutrons, in other words the nucleus of Helium Try again! Small, charged particles. Examples are electrons and positrons. Neutral hadrons, the most common being neutrons

QUIZ 2. Beta particles are : Bundles of energy, also known as photons Good ! Remember, electrons have a negative charge, and positrons are the electrons’ anti-particle. In other words, they have the same mass and size than electrons, but they have an opposite charge. They are positive. Made up of two protons and two neutrons, in other words the nucleus of Helium Small, charged particles. Examples are electrons and positrons. Neutral hadrons, the most common being neutrons Continue

QUIZ 2. Beta particles are : Bundles of energy, also known as photons Made up of two protons and two neutrons, in other words the nucleus of Helium Small, charged particles. Examples are electrons and positrons. Wrong . Neutral hadrons, the most common being neutrons Try again!

QUIZ 3. Ionization : Can be produced by alpha and beta particles Results in two ions, ions being charged particles or molecules Is not produced by visible light and microwaves All of the above

ONLINE COURSE, PART I : AN INTRODUCTION TO RADIATION