### Particles crossing an interface

In this example, very similar to our basic GISAS example, it is shown how to position particles in order to cross multilayer interfaces: the $z$ position of particles originally located within the air layer must be adjusted slightly downwards in order to cross the air-substrate interface.

The simulation kernel automatically detects particles crossing interfaces and adjusts the calculations accordingly, causing a drop on speed to complete each simulation.

The script below models a air-substrate bilayer in which cylindrical particles made of two materials are added to the air layer and their $z$ coordinate is shifted downwards in order to cross the air-substrate interface.

  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  #!/usr/bin/env python3 """ Scattering from particles that cross the interface between vacuum and substrate. """ import bornagain as ba from bornagain import ba_plot as bp, deg, nm, R3 def get_sample(): # Materials material_particle = ba.RefractiveMaterial("Particle", 0.0006, 2e-08) material_substrate = ba.RefractiveMaterial("Substrate", 6e-06, 2e-08) vacuum = ba.RefractiveMaterial("Vacuum", 0, 0) # Particles ff = ba.Cylinder(5*nm, 5*nm) particle = ba.Particle(material_particle, ff) particle.translate(0, 0, -3*nm) # Particle layouts layout = ba.ParticleLayout(particle) layout.setTotalParticleSurfaceDensity(0.01) # Layers layer_1 = ba.Layer(vacuum) layer_1.addLayout(layout) layer_2 = ba.Layer(material_substrate) # Sample sample = ba.MultiLayer() sample.addLayer(layer_1) sample.addLayer(layer_2) return sample def get_simulation(sample): beam = ba.Beam(1e9, 0.1*nm, 0.2*deg) detector = ba.SphericalDetector(100, 2*deg, 0, 1*deg) simulation = ba.ScatteringSimulation(beam, sample, detector) return simulation if __name__ == '__main__': sample = get_sample() simulation = get_simulation(sample) result = simulation.simulate() bp.plot_simulation_result(result) 
auto/Examples/scatter2d/ParticleAcrossInterface.py