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#!/usr/bin/env python3
# /// script
# requires-python = ">=3.10"
# dependencies = ["bornagain>=25,<26"]
# ///
"""
Coordinate-dependent custom background in a GISAS simulation.
"""
import bornagain as ba
import numpy as np
ba.require_versions("bornagain>=25,<26")
from bornagain import deg, nm
def get_sample():
"""
A dilute random assembly of cylinders on a substrate.
"""
substrate_color = (0.28, 0.57, 0.82)
substrate_mat = ba.RefractiveMaterial("Substrate", substrate_color, 6e-6, 2e-8)
particle_color = (0.86, 0.24, 0.18)
particle_mat = ba.RefractiveMaterial("Particle", particle_color, 6e-4, 2e-8)
particle = ba.Particle(particle_mat, ba.Cylinder(5*nm, 5*nm))
particle_layer = ba.Layer(ba.Vacuum())
particle_layer.deposit2D(ba.Dilute2D(0.001, particle))
substrate_layer = ba.Layer(substrate_mat)
sample = ba.Sample()
sample.addLayer(particle_layer)
sample.addLayer(substrate_layer)
return sample
class DetectorRegionBackground:
"""
Different background models for four detector regions.
"""
def __init__(self, phi_boundary, alpha_boundary, seed=0):
self.phi_boundary = phi_boundary
self.alpha_boundary = alpha_boundary
self.rng = np.random.default_rng(seed)
def background(self, field):
"""
Use two constant backgrounds, Poisson noise, and no background in the
four quadrants.
"""
values = field.intensities().copy()
phi_axis = field.xCenters()
alpha_axis = field.yCenters()
for i_alpha, i_phi in np.ndindex(values.shape):
alpha = alpha_axis[i_alpha]
phi = phi_axis[i_phi]
# No background in the lower-left quadrant.
if alpha < self.alpha_boundary and phi < self.phi_boundary:
values[i_alpha, i_phi] += 0.
# Small constant background in the lower-right quadrant.
elif alpha < self.alpha_boundary and phi >= self.phi_boundary:
values[i_alpha, i_phi] += 0.03
# Poisson noise in the upper-left quadrant.
elif alpha >= self.alpha_boundary and phi < self.phi_boundary:
intensity = values[i_alpha, i_phi]
if np.isfinite(intensity):
values[i_alpha, i_phi] = self.rng.poisson(intensity)
# Large constant background in the upper-right quadrant.
else:
values[i_alpha, i_phi] += 0.3
return ba.Datafield(field.title(), field.frame(), values.ravel().tolist())
def get_simulation(sample, background=None):
beam = ba.Beam(1e6, 0.1*nm, 0.2*deg)
n = 100
detector = ba.SphericalDetector(n, 0., 2*deg, n, 0., 2*deg)
simulation = ba.ScatteringSimulation(beam, sample, detector)
if background is not None:
simulation.setBackground(background)
return simulation
def simulate(sample, background, title):
simulation = get_simulation(sample, background)
result = simulation.simulate()
result.setTitle(title)
return result
if __name__ == '__main__':
sample = get_sample()
background = DetectorRegionBackground(1*deg, 0.63*deg)
results = [
simulate(sample, None, "No background"),
simulate(sample, background, "Custom background"),
]
ba.showSample3D(sample, sample_size=120*nm, seed=0)
ba.plot2d_to_row(results, log_range=5, unit_aspect=1)
ba.plt.show()
|
BornAgain
≻ git-develop
≻ Documentation ≻ Examples ≻ GISAS ≻ Simulation setup and instrument ≻ Custom background
