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Physics 452 Quantum mechanics II Winter 2012 Karine Chesnel Phys 452 Homework Friday Mar 30: assignment # 20 11.1, 11.2, 11.4 Tuesday Apr 3: assignment #21 11.5, 11.6, 11.7 Sign up for the QM & Research presentations On Friday April 6 or Monday April 9 Phys 452 Homework Fri April 6 & Mon April 9 assignment # 24 Research &QM presentations • Briefly describe your research project and how Quantum Mechanics can help you or can be connected to your research field • If no direct connection between your research and QM, mention one topic of QM that could potentially be useful or that you particularly liked • 2-3 minutes / student (suggested 2-3 transparencies) Phys 452 Scattering A classical geometrical view Scattering solid angle d Scattering angle d b Incident cross-section Differential cross-section d D d Impact parameter Phys 452 Scattering Scattering solid angle A classical geometrical view Scattering angle d b Incident cross-section Impact parameter To be determined in specific situations b db D sin d tot d D d Example: Hard-sphere scattering b R cos / 2 tot R 2 Phys 452 Scattering Pb 11.1 Rutherford scattering 1. Conservation of energy 2. Conservation of angular momentum 3. Change of variable to express r(f) 4. Integration: to find fmax in terms of b etc 5 Relationship between fmax and 6 Final relationship b b q1q2 cot / 2 8 0 E q1 r f q2 Phys 452 Scattering Quantum treatment Plane wave plane Aeikz Spherical wave sph eikr Af r Scattering amplitude Phys 452 Quiz 33 Which one of these statements describes best the quantum treatment of scattering? A. The incident wave is described by the initial state of the wave function B. The scattered wave is described by the final state of the wave function C. Only the scattered wave is the solution to the Schrödinger equation D. The global solution for the wave function includes the sum of the incident and scattered waves E. The quantum theory of scattering has no physical analogy with the classical theory of scattering Phys 452 Scattering Quantum treatment Elastic process Spherical wave Plane wave In 3D ikz eikr A e f r 2 sph dV cst 2 Pb 11.2 In 2D sph dS cst 2 In 1D sph dz cst Phys 452 Scattering Quantum treatment Plane wave Spherical wave ikz eikr A e f r Differential cross-section 2 d D f d Phys 452 X-ray Resonant Magnetic Scattering q=k’-k Interaction photon spin / magnetic moment ’ e’ ’ e Sphoton M I (q ) iq rn fe 2 n f f non.res f res Electric dipolar transition E1 ( L2,3 : 2p 3d) edges) f E1 (e' e) F (0) i(e'e) MF (1) (e' M )(e M ) F ( 2) charge magnetism Phys 452 Scattering Partial wave analysis Develop the solution in terms of spherical harmonics, solution to a spherically symmetrical potential r, ,f R r Yl m ,f kr 1 2 d 2u l (l 1) V r u Eu 2 2 2m dr 2m r 2 V 0 Radiation zone V 0 intermediate zone Scattering zone Phys 452 Scattering Partial wave analysis kr V 0 V 0 V 0 1 Radiation zone Intermediate zone Physical Solution General Solution Scattering zone kr 1 d 2u 2 k u 2 dr R r eikr / r d 2u l (l 1) 2 u k u 2 2 dr r R(r ) hl1 kr Hankel functions ikz 1 m r , , f A e cl ,m hl kr Yl , f l .m Geometrical considerations Solve the Schrödinger equation with potential V r , , f A eikz k i l 1 2l 1 al hl1 kr Pl cos l Partial wave amplitude Phys 452 Scattering Partial wave analysis kr 1 V 0 V 0 Connecting intermediate and radiation zone ikz eikr r , , f A e f r with when kr 1 f 2l 1 al Pl cos l Differential cross-section Total cross-section D f 2 l' * 2 l 1 2 l ' 1 a l ' al Pl ' cos Pl cos l D d 4 2l 1 al l 2 Orthogonality of Legendre polynomials Phys 452 Scattering Partial wave analysis kr 1 Connecting all three regions and expressing the Global wave function in spherical coordinates ikz eikr r , A e f r V 0 V 0 Rayleigh’s formula e i l 2l 1 jl kr Pl cos ikz l 0 Jl Bessel functions r , A i l 2l 1 jl kr ikal hl1 kr Pl cos l Total cross-section D d 4 2l 1 al l 2 To be determined by solving the Schrödinger equation in the scattering region + boundary conditions Phys 452 Scattering Partial wave analysis r , A i l 2l 1 jl kr ikal hl1 kr Pl cos l Bessel function Hankel function h1(1) ( x) jl ( x) inl ( x) Legendre polynomial Phys 452 Scattering Partial wave analysis V 0 Boundary conditions V a, 0 A il 2l 1 jl kr ikal hl1 kr Pl cos 0 l Exploiting Pn Pl nl Total cross-section (Pb 11.3) Example: Hard-sphere scattering 4 2l 1 al al i jl ka khl1 ka 2 l ka 1 4 a 2 Phys 452 Scattering- Partial wave analysis Pb 11.4 Spherical delta function shell Assumption ka V 0 Outside: (low energy scattering) f 2l 1 al Pl cos a0 P0 cos a0 l sin kr eikr A a0 kr r V 0 Inside: r B Continuity of Boundary conditions 1 sin kr kr Discontinuity of Find a relationship between a0 and (a,... ' f ' 2m 2 D a