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Introduction to Radiation: Radiation Types

Introduction to Radiation: Radiation Types. Types of Ionizing Radiation. Alpha Particles Stopped by a sheet of paper. Radiation Source. Beta Particles Stopped by a layer of clothing or less than an inch of a substance (e.g. plastic). Gamma Rays Stopped by inches to feet of concrete

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Introduction to Radiation: Radiation Types

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  1. Introduction to Radiation: Radiation Types

  2. Types of Ionizing Radiation Alpha Particles Stopped by a sheet of paper Radiation Source Beta Particles Stopped by a layer of clothing or less than an inch of a substance (e.g. plastic) Gamma Rays Stopped by inches to feet of concrete or less than an inch of lead

  3. Radiation Types - Alpha • An alpha particle consists of two protons and two neutrons • Very large on an atomic scale • Positively charged • Penetration in materials • Outside the body, an alpha emitter is not a hazard unless it is on the skin • Inside the body, an alpha emitter is a bigger hazard if it deposits its energy in sensitive tissue

  4. Radiation Types - Alpha • Common alpha-particle emitters • Radon-222 gas in the environment • Uranium-234 and -238 in the environment • Polonium-210 in tobacco • Common alpha-particle emitter uses • Smoke detectors • Cigarettes/cigars • Static eliminators

  5. Radiation Types - Beta • A beta particle is a charged electron • Has the size and weight of an electron • Can be positively or negatively charged • Penetration in materials • At low energies, a beta particle is not very penetrating – stopped by the outer layer of skin or a piece of paper • At higher energies, a beta particle may penetrate to the live layer of skin and may need 0.5” of plexiglass to be stopped

  6. Radiation Types - Beta • Penetration in materials, continued • Inside the body, a beta particle is not as hazardous as an alpha particle because it is not as big • Because it is not as big, it travels farther, interacting with more tissue (but each small piece of tissue gets less energy deposited)

  7. Radiation Types - Beta • Common beta-particle emitters • Tritium (hydrogen-3) in the environment • Carbon (14) in the environment • Phosphorus (32) used in research and medicine • Common beta-particle emitter uses • Carbon dating • Basic research • Cancer treatment

  8. Radiation Types - Gamma • A photon is an x or gamma ray • Has no weight • Has no charge • Penetration in materials • At low energies, a photon can be stopped by a very thin (almost flexible) layer of lead or several centimeters of tissue • At higher energies, inches of lead might be necessary to stop a photon and they can pass right through a human

  9. Radiation Types - Gamma • Common photon emitters • Cesium (137) • Technetium (99m) used in medicine • Iodine (131) used in medicine • Common photon emitter uses • Determining the density of soil • Diagnosing disease • Cancer treatment

  10. Gamma Decay

  11. Examples of Radioactive Materials Physical RadioactiveHalf-LifeUse Cesium-137 30 yrs Food Irradiator Cobalt-60 5 yrs Cancer Therapy Plutonium-239 24,000 yrs Nuclear Weapon Iridium-192 74 days Industrial Radiography Hydrogen-3 12 yrs Exit Signs Strontium-90 29 yrs Eye Therapy Device Iodine-131 8 days Therapy Technetium-99m 6 hrs Imaging Americium-241 432 yrs Smoke Detectors Radon-222 4 days Environmental

  12. Rates of radioactive decay • All things do not decay at the same rate some decay faster than others do. • We use this time to gauge how old something is. • Based on how much of a parent element is present compared to the daughter element we can make a guess at how the object was when it started decaying

  13. Half-life • Half-Life is the amount of time it takes for one half of a sample of a radioactive element to decay into its daughter element. • Nuclear decay rates are constant and do not change. • After one half life how much of the substance would you have? • After 2 half lifes? • After 3 half lifes? • Increments of half life for what remains of the original amount is 1. 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256

  14. Fission • Splitting an atomic nucleus into two smaller atoms. • Nuclear Bombs • Lots of energy from Fission • Energy released from one kg of uranium-235 is equivalent to burning 17,000 kg of coal!

  15. Fission

  16. Fusion • Process in which the nuclei of 2 atoms combine to form a larger nucleus. • Happens in all stars • Two hydrogens combine to form a helium but part of the mass turns into pure energy. • If we could harness that energy there is enough energy to fuel new york city for about a month in a tiny piece of chalk.

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