Cylinders in Born Approximation

Scattering from a monodisperse distribution of cylinders using the Born approximation.

  • The cylinders are all identical with radii and heights equal to $5$ nanometers.
  • The wavelength is equal to $1$ $\unicode{x212B}$.
  • The incident angles are equal to $\alpha_i = 0.2 ^{\circ}$ and $\phi_i = 0^{\circ}$.
  • There is no substrate (particles are embedded in the air layer), hence no refraction, hence no distorted waves, hence DWBA boils down to regular Born approximation.
  • Scattering is not affected by inter-particle correlations (dilute-particles approximation).

Real-space model

Intensity image

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"""
Cylinder formfactor in Born approximation
"""
import bornagain as ba
from bornagain import deg, angstrom, nm


def get_sample():
    """
    Returns a sample with cylinders in a homogeneous environment ("air"),
    implying a simulation in plain Born approximation.
    """
    # defining materials
    m_ambience = ba.HomogeneousMaterial("Air", 0.0, 0.0)
    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)
    particle_layout = ba.ParticleLayout()
    particle_layout.addParticle(cylinder, 1.0)

    air_layer = ba.Layer(m_ambience)
    air_layer.addLayout(particle_layout)

    multi_layer = ba.MultiLayer()
    multi_layer.addLayer(air_layer)
    return multi_layer


def get_simulation():
    """
    Returns a 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, cmap='jet', aspect='auto')
CylindersInBA.py