Slide 1RadiationHistoryHistoryHistoryTerminologySlide 7Alpha ParticlesAlpha decayBeta DecayGamma RaysSlide 12X-raysRadiation doseEnergy TermsUraniumUranium Decay ChainRadonIodineRadiation protectionSlide 21TermsMeasure of RadioactivityInteraction with MatterExposureHistorical Health EffectsLocal AreasRadiationDavid Shubert [email protected] Sherman AnnexRadiation•On cell phone picHistory•Wilhelm Conrad Rontgen (1845-1923)•1901 Awarded the first Nobel Prize in Physics•Produced and detected the first X-rays•Considered the father of diagnostic radiology•“In 1815 Wilhelm made experiments with cathode rays- radiation emitted in a low pressure glass tube when a voltage is applied between two metal plates. He discovered weak light appearing on a screen a bit away although the glass tube was shielded. Subsequent experiments showed that the radiation was previously unknown and penetrating.”History•Henri Becquerel (1852 – 1908)•1903 Nobel Prize in Physics for discovering radioactivity•Discovered spontaneous radioactivity. •One wraps a Lumière photographic plate with a bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative. … One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduces silver saltsHistory•Marie Sklodowka Curie (1867-1934)•Born in Poland•Physicist and Chemist•Discovered •Polonium (1898) •Radium (1910)•1903 Nobel Prize in Physics along with Pierre Curie and Henri Becquerel•1911 Nobel Prize in Chemistry (discovery of radium and polonium)•Died 1934 from aplastic anemia•Curie (Ci), a measure of radioactivity is named in her and her husband’s (Pierre) honor•Pitchblende (Uraninite) – mineralTerminology•Ionizing radiation – electromagnetic waves strong enough to detach electrons from atoms •Types •Alpha particles – two protons and two neutrons•Radium radon uranium thorium•Beta particles – electrons or positrons•Strontium 90, carbon 14, tritium, sulfur 35•Gamma Rays – electromagnetic rays from the nucleus •Iodine 131 cesium 137, cobalt 60, radium 226•X-rays – electromagnetic rays emitted from electrons.Alpha Particles•Decay –•Helium nuclei - two protons and two neutrons with a charge of +2•226Ra -> 222Rn + 4He•Loses energy, slows velocity, acquires 2 electrons from media becomes helium.•Low velocity compared with the speed of light•Alpha particle heavy charged particle with a mass that is 7300 times that of electrons, what it interacts with•High energy loss per unit path length•Energy of 4-8 MeV.Alpha decayBeta Decay•Neutons transformed into a proton and electron, ejection of electrons (light weight, fast particle)•Loss of negativity or poistively charged electron•C  N + e + v•25Al -> 25Mg + électron + anti-neutrino•Carbon 14- emits electron and electron antineutrino to become nitrogen 14 ( non- radioactive) half-life 5730 years•Shielding low density materials (plastic, plexiglass, wood)•P32•T1/2 = 14.29 daysGamma Rays•Originate from the nucleus as photon emission •Occurs in combination with alpha, beta, or positron emission•No mass & no charge pure electromagnetic energy•Travel at the speed of light•Easily pass through material•Cobalt 60, Cesium 137 and Technetium 99m•Very dense material needed for shielding•leadBremsstrahlung means:” braking Radiation” electrons deceleratedWhen fired ta a metal targetX-rays•X-rays and gamma rays have essentially the same properties but differ in origin•X-rays originiate from outside the nucleus•Lead can stop x-rays•Single largest man-made source of radiation exposure •Examinations (medical)•Inspections (industry)Radiation dose•Absorbed dose – amount of energy deposited per unit mass in an object or person (rad or gray (gy)) •Equivalent dose – energy transfer from alpha and beta particles is much greater than gamma rays – absorbed dose adjusted for the relative biological effect (roentgen equivalent man (rem) and Sievert (sv) •Committed dose – internal emitters irreversible dose – dose that accounts for continuing exposures over long periods of time (50 years for adult, 70 years for children)Energy Terms•eV –It is the change in energy of an electron, when it is moved through a difference of potential of 1 volt•eV = 1.602 x 10-19 joules•100 watt light bulb burning for 1 hr = 2.2x1024 eV•KeV- kilo electron volts 1KeV = 1000 eV•MeV – mega electron volts 1MeV= 100,000 eVUranium •Naturally occurring element in rock, soil, and water•Oxide form used to add color to ceramic glazes•First isolated as a metal in 1841•Discovered to be radioactive in 1896 Henri Becquerel•65% more dense than lead, all uranium isotopes are radioactive •Uses•Military shielding, bullets, missiles, nuclear reactorsIsotope Natural Abundance Half-lifeU-238 99.27 4.47 billionU-235 0.72 700 millionU-234 0.0055 246,000Uranium Decay ChainRadon•Radioactive gas•Radon-222 product of radium-226 and uranium-238 decay•Found everywhere since uranium is essentailly ubiguitous in the earth’s crust•Radon-222 has a half-life of 3.8 days, and emits an alpha particle as it decays to polonium-218, and eventually to stable lead •Radon-220, is the decay product of thorium – it is sometimes called thoron, has a half-life of 54.5 seconds and emits an alpha particle in its decay to polonium-216•EPA estimate national average indoor level is 1.3 pCi/L of air•Action level 4 pCi/LIodine•Iodine-129 & 131 are radioactive isotopes found in the environment•produced by the fission of uranium atoms during operation of nuclear reactors and by plutonium (or uranium) in the detonation of nuclear weapons.•Iodine-129 has a half-life of 15.7 million years• Iodine-131 has a half-life of about 8 days used for thyroid cancer•Both emit beta