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PHYS 5012 Radiation Physics and Dosimetry

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PHYS 5012 Radiation Physics and Dosimetry Radiation Physics Lecture 1 Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Classification of Radiation Types of Ionising Radiation PHYS 5012 Radiation Units and Properties Radiation Physics and Dosimetry Dose in Water Atomic Physics and Radiation Lecture 1 The Rutherford-Bohr Model Multi-Electron Atoms Production of Radiation Characteristic Radiation Characteristic X-rays Auger Electrons Continuous Radiation Bremsstrahlung Radiation Tuesday 5 March 2013 Synchrotron Radiation Cerenkov Radiation Particle Accelerators X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 The Discovery of Radiation Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Classification of Radiation Types of Ionising Radiation Three main discoveries of radiation made at the turn of Radiation Units and Properties the 19th century, together with several major advances in Dose in Water Atomic Physics and theoretical physics, including quantum mechanics and Radiation The Rutherford-Bohr special relativity, signalled the birth of Radiation Physics. Model Multi-Electron Atoms The subsequent realisation that radiation can be harmful Production of Radiation to humans led to the the rapid development of radiation Characteristic Radiation Characteristic X-rays dosage measurements and quantification and commonly Auger Electrons accepted standards for tolerable levels of radiation in Continuous Radiation Bremsstrahlung Radiation humans. Synchrotron Radiation Cerenkov Radiation Particle Accelerators X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 X-rays X-rays are photons (i.e. electromagnetic radiation) with Background and energies typically above 1 keV. They were discovered by Fundamentals The Discovery of Radiation Wilhelm Conrad Roentgen in 1895. X-rays Radioactivity Classification of Radiation Types of Ionising Radiation Radiation Units and Properties Dose in Water Atomic Physics and Radiation The Rutherford-Bohr Model Multi-Electron Atoms Production of Radiation Characteristic Radiation Characteristic X-rays Auger Electrons Continuous Radiation Bremsstrahlung Radiation Synchrotron Radiation Cerenkov Radiation Particle Accelerators X-ray Tubes Cyclotrons Linear Accelerators Roentgen discovered X-rays inadvertedly whilst studying fluoresence using a cathode ray tube. He explored the absorption properties of the rays in soft tissue and bone using his wife’s hand (note the ring). Radiation Physics Lecture 1 Radioactivity Natural radioactivity is the spontaneous emission of Background and radiation by a material. It was discovered by Antoine Fundamentals The Discovery of Radiation Henri Becquerel in 1896. X-rays Radioactivity Classification of Radiation Types of Ionising Radiation Radiation Units and Properties Dose in Water Atomic Physics and Radiation Whilst Roentgen’s X-rays The Rutherford-Bohr Model needed to be induced by Multi-Electron Atoms cathode rays (electrons), Production of Becquerel found that some Radiation materials, notably uranium ore, Characteristic Radiation possessed their own source of Characteristic X-rays radiation energy. He discovered Auger Electrons Continuous Radiation this after placing some uranium Bremsstrahlung Radiation mineral on a photographic plate Synchrotron Radiation wrapped in black paper into a Cerenkov Radiation dark drawer, finding afterwards Particle Accelerators X-ray Tubes that the uranium had indeed Cyclotrons left an image on the plate. Linear Accelerators Radiation Physics Lecture 1 Radioactivity Marie Curie coined the term "radioactivity" for the Background and phenomenon Becquerel found associated with uranium Fundamentals The Discovery of Radiation ore. Together with her husband Pierre, they began X-rays Radioactivity investigating radioactivity. Marie found that after Classification of Radiation Types of Ionising Radiation extracting pure uranium from ore, the residual material Radiation Units and Properties was even more radioactive than the uranium. She had Dose in Water Atomic Physics and Radiation discovered polonium and radium. The Rutherford-Bohr Model Multi-Electron Atoms Production of Radiation Characteristic Radiation Characteristic X-rays Auger Electrons Continuous Radiation Bremsstrahlung Radiation Synchrotron Radiation Cerenkov Radiation Particle Accelerators X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 Classification of Radiation Background and Fundamentals The Discovery of Radiation X-rays Radiation can be broadly classified into two main Radioactivity Classification of Radiation categories, based on its ability to ionise matter: Types of Ionising Radiation Radiation Units and Properties I Non-ionising radiation cannot ionise matter because Dose in Water Atomic Physics and its energy is lower than the ionisation potential of the Radiation The Rutherford-Bohr Model matter. Multi-Electron Atoms I Ionising radiation has sufficient energy to ionise Production of Radiation matter either directly or indirectly. Characteristic Radiation Characteristic X-rays Auger Electrons Although non-ionising radiation can transfer some of its Continuous Radiation Bremsstrahlung Radiation energy to matter, the low energies involved result in Synchrotron Radiation Cerenkov Radiation negligible effects compared to those of ionising radiation. Particle Accelerators X-ray Tubes Henceforth, only ionising radiation will be considered. Cyclotrons Linear Accelerators Radiation Physics Lecture 1 Types of Ionising Radiation Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Ionising radiation can be further subdivided into two Classification of Radiation Types of Ionising Radiation classes: Radiation Units and Properties I Directly ionising - charged particles (electrons, Dose in Water Atomic Physics and protons, α particles, heavy ions); deposits energy in Radiation The Rutherford-Bohr Model matter directly through Coulomb collisions with Multi-Electron Atoms orbital electrons. Production of Radiation I Indirectly ionising - neutral particles (photons, Characteristic Radiation Characteristic X-rays neutrons); deposit energy indiectly through a Auger Electrons Continuous Radiation two-step process: 1. release of charged particles Bremsstrahlung Radiation Synchrotron Radiation and 2. charged particle energy deposition through Cerenkov Radiation Particle Accelerators Coloumb interactions. X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 Types of Directly Ionising Radiation Background and Fundamentals The Discovery of Radiation Charged particles are described as light (electrons and X-rays Radioactivity positrons), heavy (protons, deutrons, α particles) or Classification of Radiation Types of Ionising Radiation heavier (e.g. carbon-12). Some of the common Radiation Units and Properties nomenclature is as follows: Dose in Water Atomic Physics and Radiation Light charged particles The Rutherford-Bohr Model Multi-Electron Atoms I photoelectrons – produced by photoelectric effect Production of Radiation I recoil electrons – produced by Compton effect Characteristic Radiation Characteristic X-rays I delta rays – electrons produced by charged particle Auger Electrons Continuous Radiation collisions Bremsstrahlung Radiation Synchrotron Radiation I beta particles – electrons or positrons emitted from Cerenkov Radiation − + Particle Accelerators nuclei by β or β decay: X-ray Tubes 1 1 0 1 1 0 Cyclotrons n −! p + e or p −! n + e + ν Linear Accelerators 0 1 −1 1 0 +1 Radiation Physics Lecture 1 Types of Directly Ionising Radiation Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Heavy charged particles Classification of Radiation Types of Ionising Radiation 1 I protons – nucleus of hydrogen-1 ( H) atom Radiation Units and 1 Properties 2 Dose in Water I deuteron – nucleus of deuterium ( H) atom Atomic Physics and 1 Radiation 3 The Rutherford-Bohr I triton – nucleus of tritium ( H) atom Model 1 Multi-Electron Atoms 3 I helium-3 – nucleus of helium-3 (2He) atom Production of 4 Radiation I α particle – nucleus of helium-4 ( He) atom Characteristic Radiation 2 Characteristic X-rays Auger Electrons Heavier charged particles include nuclei or ions of Continuous Radiation 12 14 Bremsstrahlung Radiation heavier atoms such as carbon-12 ( C), nitrogen-14 ( N), Synchrotron Radiation 6 7 20 Cerenkov Radiation or neon-20 ( Ne). Particle Accelerators 10 X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 Types of Indirectly Ionising Radiation Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Classification of Radiation Ionising photons can be classified into four groups: Types of Ionising Radiation Radiation Units and Properties I characteristic X-rays – due to electronic transitions Dose in Water Atomic Physics and between discrete atomic energy levels Radiation The Rutherford-Bohr Model I bremsstrahlung emission – due to electron-nucleus Multi-Electron Atoms Coulomb interactions Production of Radiation Characteristic Radiation I gamma rays – resulting from nuclear decays Characteristic X-rays Auger Electrons I annihilation radiation – resulting from Continuous Radiation Bremsstrahlung Radiation electron-positron pair annihilation Synchrotron Radiation Cerenkov Radiation Particle Accelerators X-ray Tubes Cyclotrons Linear Accelerators Radiation Physics Lecture 1 Radiation Units and Properties Background and Fundamentals The Discovery of Radiation X-rays Radioactivity Classification of Radiation Types of Ionising Radiation Radiation
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