Physics with Neutrons WS 2012/2013 - E21 - Technische Universität ...
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Physics with Neutrons WS 2012/2013 - E21 - Technische Universität ...

2Seminar Methoden und Experimente in der NeutronenstreuungDate Topics Contact17 Oct. 12 Kick-Off Meeting7 Nov. 12 Scheduling of presentationsTime: 10:00 (st) – 11:30Place: PH 222428 Nov. 12 Larmor techniques NSE/NRSE Simone Sala, simone.sala@tum.de5 Dec. 12 Quasielastic neutron scattering:TOF-techniqueLuca Braglia, luca.braglia@tum.de12 Dec. 12 Positron Lifetime Javier Puertas Martinez, jpuertas_m@hotmail.com19 Dec. 12 Magnetic Excitations Ibrahima Diallo, dialloib@msu.edu9 Jan. 13 Flux Line Lattices in Superc. Jing Gong, happykissvicki@gmail.com16 Jan. 13 Neutron optics Tianyi Wang, Jan. 13 Strain measurements Rafael Cabello Portela, papelo72@hotmail.com30 Jan. 13 Atomic force microscopy Christina Psylla, xripsy@hotmail.com6 Feb. 13 Extreme conditions Wenbin Wu, wenbin.nj@gmail.comFeb. 2013 Visit FRM II To be arranged.

4Coherent and Incoherent Cross Sections of Some ElementsNucleus Nuclear spin coh (barn) inc (barn)1H ½ 1.76 80.27spin inc.2H = D 1 5.60 2.059Be 3/2 7.63 0.0018C 5.55 0.001excellentmonochr.N 11.01 0.50V 0.018 5.08Ni 13.3 5.2spin inc.isot. inc.After: V. F. Sears, Neutron News 3, 27 (1992).

Atomic Lattice: Real Space5ia 3n r ia 1 a 2u mnp :r i :r j :r ir ju mnplattice vectorsbasis: unit cellposition of atom i in unit cellposition of atom j in crystalu ma1 na2 pamnp 3irjumnp ρi

Reciprocal Lattice Vectors6b1 2a1a2 ( a a23 a3)b2 2a1a3 ( aa21 a3)b3 2a1a1 ( a a22 a3)aibj 2ijDefinition: reciprocal lattice vectorGhklhb kb l1 2b3

Ewald‘s Construction7Q = G k1. draw reciprocal lattice2. draw –k i3. Construct spherewith radius k i4. intersections withpoints of reciprocallattice define k f ,where maxima ofinterference occur

Bragg‘s Law8d hkl : spacing between planes of atomic latticek i k f2dhklsin nB4dhklsinB 2n4 nsin2B d2kisinBhklGhklpath difference: 2d hkl sin B

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