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A.GammaRaysFollowingBetaDecayGammaradiationisemittedbyexcitednucleiintheirtransitiontolowerlyingnuclearlevels.Notes:1)Forcommonexampleswidelyusedasgammaraycalibrationsources.Ineachcase,aformofbetadecayleadstothepopulationofexcitedstateinthedaughternucleus.2)Thegammaraysfromanyonetransitionarenearlymonoenergetic.3)Thecommongammaraysourcebasedinbetadecayaregenerallylimitedtoenergiesbelowabout2.8MeV.Whentheparentnucleusundergoesbeta-plusdecay,additionalelectromagneticradiationisgenerated.Theoriginlieinthefateofthepositronsemittedintheprimarydecayprocess.AnnihilationRadiation:Theoriginalpositronandelectrondisappearandarereplacedbytwooppositelydirected0.511MeVelectromagneticphotonsknownasannihilationradiation.Example:thedecayof22Na:C.GammaRayFollowingNuclearReactionsIfgammarayswithenergieshigherthanthoseavailablefrombeta-activeisotopesareneeded,someotherprocessmustleadtothepopulationofhigher-lyingnuclearstates.Example1:Notes:1)Formonoenergeticelectronthatslowdownandstopinagivenmaterial,theBremsstrahlungenergyspectrumisacontinuumwithphotonenergiesthatextendashighastheelectronenergyitself.2)Theshapeoftheenergyspectrumfromanx-raytubecanbebeneficiallyalterbyfiltrationorpassagethroughappropriateabsorbermaterials.3)Bremsstrahlungisalsoproducedbyothersourceoffastelectrons,includingbetaparticles.I4)InadditiontoBremsstrahlung,characteristicx-raysarealsoproducedwhenfastelectronpassthroughanabsober.Therefore,thespectrafromx-raytubesorotherBremsstrahlungsourcesalsoshowcharacteristicx-rayemissionlinessuperimposedonthecontinuousBremsstrahlungspectrum.Iftheorbitalelectronsinanatomaredisruptedfromtheirnormalconfigurationbysomeexcitationprocess,theatommaybeexistinanexcitedstateforashortperiodoftime.Thereisanaturetendencyfortheelectronstorearrangethemselvestoreturntheatomtoitslowestenergystateorgroundstatewithinatimethatischaracteristicallyananosecondorlessinasolidmaterial.Theenergylibratedinthetransitionfromtheexcitedtothegroundstatetakestheformofacharacteristicx-rayphot
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