![]() Warning: We will use this many times to calculate s but derivation not required for exams, given here for completeness. , G=FWHM Tony Weidberg Nuclear Physics Lecturesįermi Golden Rule Want to be able to calculate reaction rates in terms of matrix elements of H. Uncertainty relationship Determine lifetimes of states from width. Important in atomic, nuclear and particle physics. Normalised Breit-Wigner line shape Q: where have you seen this shape before? We will see this many times in NP and PP. Start with NR Schrödinger equation: X by f*n and integrate Start in state m exponential decay Tony Weidberg Nuclear Physics Lecturesįor Tony Weidberg Nuclear Physics Lectures dR(a+bc+d)/dE=(NbT) F ds(a+bc+d) /dE Tony Weidberg Nuclear Physics Lectures ![]() Can also define differential cross sections, as a function of reaction product, energy, transverse momentum, angle etc. Reaction Rates Na beam particles/unit volume, speed v Flux F= Na v Rate/target b atom R=Fs Thin target x<<l: R=(NbT) F sTotal This is total cross section. ![]() #Nuclear physics lectures ppt how to#Experimental Definition How to calculate s Fermi Golden Rule Breit-Wigner Resonances QM calculation of Rutherford Scattering Tony Weidberg Nuclear Physics Lecturesĭefinition of s a+bx Effective area for reaction to occur is s Na(0) particles type a/unit time hit target b Nb atoms b/unit volume Number /unit area= Nb dx Probability interaction = s Nbdx dNa=-Na Nb dx s Na(x)=Na(0) exp(-x/l) l=1/(Nb s) Beam a Na dx Tony Weidberg Nuclear Physics Lectures Fermi Golden rule recipe to calculate cross section BW cross section formula QM Rutherford Scattering Cross section calculation Tony Weidberg Nuclear Physics LecturesĬross-Sections Why concept is important Learn about dynamics of interaction and/or constituents (cf Feynman’s watches). Breit-Wigner Resonances Rutherford Scattering Outline Experimental definition of cross section Theory of how to calculate cross sections: QM BW line shape. Presentation on theme: "Nuclear Physics Lectures"- Presentation transcript:Ĭross Sections Definition of Cross Section Why its useful. ![]()
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