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RADIATION
Radiation is an energy in the formof electro-magnetic waves orparticulate matter, traveling in theair.”
HISTORY1895 - Wilhem Conrad Roentgen discovered X-raysand in 1901 he received the first Nobel Prize forphysics.1903 - Marie Curie and Pierre Curie, along withHenri Becquerel were awarded the Nobel Prize inphysics for their contributions to understandingradioactivity, including the properties of uranium.1942 - Enrico Fermi and others started the firstsustained nuclear chain reaction in a laboratorybeneath the University of Chicago football stadium.1945 – Nuclear bombs dropped on Japan.
RADIATIONSOURCES
Sources of radiation can be dividedinto two categories:Natural Background RadiationMan-Made Radiation
NATURALBACKGROUNDRADIATIONCosmic RadiationTerrestrial RadiationInternal Radiation
COSMICRADIATIONThe earth, and all living things on it, areconstantly bombarded byradiationfromouter spaceCharged particles from the sun and stars interact withthe earth’s atmosphere and magnetic field to producea shower of radiation.The amount of cosmic radiation varies in differentparts of the world due to differences in elevation andto the effects of the earth’s magnetic field.35 mrad / yr normal altitudeJet pilots – 300 mrad / yr
ATMOSPHERICRADIATIONTerrestrialRadioactive materialis also found throughoutnature in soil, water, and vegetation.Important radioactive elements include uranium,thorium, radium & isotopes of potassium(K40)Some radioactive material is ingested with food andwater.The amount of terrestrial radiationaprox. 50 mrad/yrAtmosphericGases like Radon & thorum – 2 mrad/yr
INTERNALRADIATIONPeople are exposed to radiation from radioactivematerial inside their bodies. Besides radon, the mostimportant internal radioactive element is naturallyoccurring potassium-40. Others -uranium, thorium,strontium & carbon.25 mrad / yr.May go up to 70 or 80.Total natural radiation -0.1 rad / yr.
MAN-MADERADIATIONSOURCESExamples of man-made sources of radiation tomembers of the public:Lantern mantlesMedical diagnosisBuilding materialsNuclear power plantsCoal power plantsTobaccoPhosphate fertilizersT V setsRadium watches
ANNUALAVERAGEDOSE(MREM/YEAR)MAN-MADE SOURCE706050403020100Smoking(perWeek)MedicalBuildingMaterialPhosphateFertilizerNatural GasNuclear PlantLanternMantlesCoal Plant60257420.40.20.15

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Term
Fall
Professor
NoProfessor
Tags
Ionizing radiation, Nonionizing Radiation, Wilhem Conrad Roentgen

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