• The sample is made of cylinders with radii and heights equal to $5$ nm, deposited on a substrate.
• The distribution of particles follows a radial paracrystal, characterized by a peak distance of $20$ nm and a damping length of $1$ $\mu$m.
• The wavelength is equal to $1$ $\unicode{x212B}$.
• The incident angles are $\alpha_i = 0.2 ^{\circ}$ and $\phi_i = 0^{\circ}$.
• A damping length is used to introduce finite size effects by applying a multiplicative coefficient equal to $exp \left(-\frac{peak\_distance}{damping\_length}\right)$ to the Fourier transform of the probability densities.
  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  """ radial paracrystal """ import bornagain as ba from bornagain import deg, angstrom, nm phi_min, phi_max = -2.0, 2.0 alpha_min, alpha_max = 0.0, 2.0 def get_sample(): """ Returns a sample with cylinders on a substrate that form a radial paracrystal. """ # defining materials m_ambience = ba.HomogeneousMaterial("Air", 0.0, 0.0) m_substrate = ba.HomogeneousMaterial("Substrate", 6e-6, 2e-8) m_particle = ba.HomogeneousMaterial("Particle", 6e-4, 2e-8) # collection of particles cylinder_ff = ba.FormFactorCylinder(5*nm, 5*nm) cylinder = ba.Particle(m_particle, cylinder_ff) interference = ba.InterferenceFunctionRadialParaCrystal( 20.0*nm, 1e3*nm) pdf = ba.FTDistribution1DGauss(7 * nm) interference.setProbabilityDistribution(pdf) particle_layout = ba.ParticleLayout() particle_layout.addParticle(cylinder, 1.0) particle_layout.setInterferenceFunction(interference) # assembling the sample air_layer = ba.Layer(m_ambience) air_layer.addLayout(particle_layout) substrate_layer = ba.Layer(m_substrate) multi_layer = ba.MultiLayer() multi_layer.addLayer(air_layer) multi_layer.addLayer(substrate_layer) # print(multi_layer.treeToString()) return multi_layer def get_simulation(): """ Create and return GISAXS simulation with beam and detector defined """ simulation = ba.GISASSimulation() simulation.setDetectorParameters(200, -2.0*deg, 2.0*deg, 200, 0.0*deg, 2.0*deg) simulation.setBeamParameters(1.0*angstrom, 0.2*deg, 0.0*deg) return simulation def run_simulation(): """ Runs simulation and returns intensity map. """ simulation = get_simulation() simulation.setSample(get_sample()) simulation.runSimulation() return simulation.result() if __name__ == '__main__': result = run_simulation() ba.plot_simulation_result(result)