# Cylinders in Distorted Wave Born Approximation

Scattering from a monodisperse distribution of cylindrical particles using the Distorted Wave Born Approxiamtion (DWBA).

This example is similar to the simulation in Born Approximation, CylindersInBA, but now the particles sit on top of a substrate. Therefore incoming and scattered waves are distorted by reflections from the substrate surface, as described by the DWBA.

• The distribution of cylinders is monodisperse with heights and radii of 5 nm.
• The wavelength is equal to 1 Å.
• The incident angles are equal to αi = 0.2°, Φi = 0°.
• No interference effects from inter-particle correlations (dilute-particles approximation).
Real-space model:
Intensity Image:
Python Script:
```"""
Cylinder formfactor in DWBA
"""
import bornagain as ba
from bornagain import deg, angstrom, nm

def get_sample():
"""
Returns a sample with cylinders on a substrate.
"""
# 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)
particle_layout = ba.ParticleLayout()

air_layer = ba.Layer(m_ambience)
substrate_layer = ba.Layer(m_substrate)

multi_layer = ba.MultiLayer()
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.getIntensityData()

if __name__ == '__main__':
result = run_simulation()
ba.plot_intensity_data(result)
```