### Polarized SANS

This example shows how to simulate polarized SANS with BornAgain, using the Born Approximation.

The main difference between simulating GISAS and SAS in BornAgain is the presence of only a single layer in the multilayer object. This triggers the software to calculate the differential scattering cross section in the Born Approximation:

multiLayer = ba.MultiLayer()
multiLayer.addLayer(solvent_layer)

The rest of the example script hereafter contains nothing new compared to the previous examples. A sample with a magnetic core-shell particle is constructed. Beam and detector are setup to detect the spin-flip scattering channel and the result of this simulation is plotted as usual.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78  #!/usr/bin/env python3 """ Simple example demonstrating how polarized SANS experiments can be simulated with BornAgain. """ import bornagain as ba from bornagain import angstrom, deg, nm, nm2, kvector_t # Magnetization of the particle's core material (A/m) magnetization_core = kvector_t(0, 0, 1e7) def get_sample(): """ Returns a sample with a magnetic core-shell particle in a solvent. """ # Define materials magnetic_field = kvector_t(0, 0, 1e7) material_Core = ba.HomogeneousMaterial("Core", 6e-06, 2e-08, magnetic_field) material_Shell = ba.HomogeneousMaterial("Shell", 1e-07, 2e-08) material_Solvent = ba.HomogeneousMaterial("Solvent", 5e-06, 0) # Define form factors ff_1 = ba.FormFactorFullSphere(10*nm) ff_2 = ba.FormFactorFullSphere(12*nm) # Define particles particle_1 = ba.Particle(material_Core, ff_1) particle_1_position = kvector_t(0, 0, 2*nm) particle_1.setPosition(particle_1_position) particle_2 = ba.Particle(material_Shell, ff_2) # Define core shell particles particle = ba.ParticleCoreShell(particle_2, particle_1) # Define particle layouts layout = ba.ParticleLayout() layout.addParticle(particle) layout.setTotalParticleSurfaceDensity(0.01) # Define layers layer = ba.Layer(material_Solvent) layer.addLayout(layout) # Define sample sample = ba.MultiLayer() sample.addLayer(layer) return sample def get_simulation(sample): """ Returns a polarized SANS simulation """ # Beam from above (perpendicular to sample): beam = ba.Beam(1, 0.4*nm, ba.Direction(90*deg, 0)) beam.setPolarization(kvector_t(0, 0, 1)) # Detector opposite to source: detPos = 2000 # distance from sample center to detector in mm detWid = 500 # detector width in mm detPix = 200 # number of pixels per direction det = ba.RectangularDetector(detPix, detWid, detPix, detWid) det.setPerpendicularToDirectBeam(detPos, detWid/2, detWid/2) det.setAnalyzerProperties(kvector_t(0, 0, -1), 1, 0.5) return ba.GISASSimulation(beam, sample, det) if __name__ == '__main__': import ba_plot sample = get_sample() simulation = get_simulation(sample) ba_plot.run_and_plot(simulation) # TODO: restore units=ba.Axes.QSPACE) 
PolarizedSANS.py