/**
* Generates a new instance of material with given characteristics
*
* @param name is material identifier
* @param density is material density
* @param composition is atomic composition by weight of material
* @return null if material cannot be created
*/
public static Material newMaterial(
String name, double density, WeightedAtomicComposition composition) {
Material material = new Material();
material.setName(name);
material.setDensity(density);
material.setWeightedAtomicComposition(composition);
return material;
}
public SingleMaterialMonteCarlo() {
double energyEV = 1000000;
System.out.println("energy " + energyEV / 1000000 + " MeV");
double photo =
material.getAttenuation(energyEV / 1000, AttenuationType.PHOTOELECTRIC_ABSORPTION);
double compton =
material.getAttenuation(energyEV / 1000, AttenuationType.INCOHERENT_ATTENUATION);
System.out.println("cross section photo: " + photo + "cm" + " compton " + compton + "cm");
System.out.println("mean free path compton " + 1 / compton + "cm");
System.out.println("mean free path photo " + 1 / photo + "cm");
double totalCrossSection =
material.getAttenuation(
energyEV / 1000, AttenuationType.TOTAL_WITHOUT_COHERENT_ATTENUATION);
System.out.println("total attenuation " + 1 / totalCrossSection + "cm");
System.out.println("total attenuation sum " + 1 / (photo + compton) + "cm");
raytrace(energyEV, numRays);
double mean = XRayTracer.computeMean(pathlengths);
double stddev = XRayTracer.computeStddev(pathlengths, mean);
System.out.println("pathlength = " + mean + " +- " + stddev);
mean = XRayTracer.computeMean(xs);
stddev = XRayTracer.computeStddev(xs, mean);
System.out.println("x = " + mean + " +- " + stddev);
mean = XRayTracer.computeMean(ys);
stddev = XRayTracer.computeStddev(ys, mean);
System.out.println("y = " + mean + " +- " + stddev);
mean = XRayTracer.computeMean(zs);
stddev = XRayTracer.computeStddev(zs, mean);
System.out.println("z = " + mean + " +- " + stddev);
// rayTrace(800000, numRays);
// visualize the klein-nishina angle distribution and the rejection
// sampling for different energies
// visualizeKleinNishina(10000000*eV);
visualizeKleinNishina(140000 * eV);
// visualizeKleinNishina(2.75*eV);
//
// visualizeKleinNishina(55000*eV);
}
private void raytrace(double energyEV, int numRays) {
Grid2D grid = new Grid2D(600, 500);
FloatProcessor imp;
imp = new FloatProcessor(grid.getWidth(), grid.getHeight());
imp.setPixels(grid.getBuffer());
// SimpleVector startPosition = new SimpleVector(40,grid.getHeight()/2/scale, 0);
SimpleVector startPosition = new SimpleVector(0, 0, 0);
for (int i = 0; i < numRays; ++i) {
followRay(startPosition.clone(), new SimpleVector(1, 0, 0), energyEV, imp, 0, 0);
}
imp.drawString(
grid.getWidth() / scale + "cm",
grid.getWidth() / 2 - 20,
grid.getHeight() - 10,
Color.WHITE);
grid.show("Energy: " + energyEV + "eV, Material: " + material.getName());
System.out.println(
"Rejection sampling: average misses per draw: " + (float) sumMisses / (float) numDraws);
numDraws = 0;
sumMisses = 0;
}
private void followRay(
SimpleVector pos,
SimpleVector dir,
double energyEV,
FloatProcessor imp,
int scatterCount,
double totalDistance) {
if (energyEV <= 1 || scatterCount > 20000) {
System.out.println("energy low, times scattered: " + scatterCount);
return;
}
// follow ray until next interaction point
SimpleVector oldPos = pos.clone();
double dist = sampler.getDistanceUntilNextInteractionCm(material, energyEV);
pos.add(dir.multipliedBy(dist));
pathlengths.add(dist);
// draw the entire path
// imp.drawLine((int)(scale*oldPos.getElement(0)), (int)(scale*oldPos.getElement(1)),
// (int)(scale*pos.getElement(0)), (int)(scale*pos.getElement(1)));
// draw interaction points only
imp.drawDot((int) (scale * pos.getElement(0)), (int) (scale * pos.getElement(1)));
// choose compton or photoelectric effect
double photo =
material.getAttenuation(energyEV / 1000, AttenuationType.PHOTOELECTRIC_ABSORPTION);
double compton =
material.getAttenuation(energyEV / 1000, AttenuationType.INCOHERENT_ATTENUATION);
if (sampler.random() * (photo + compton) <= photo) {
// photoelectric absorption
energyEV = 0;
// System.out.println("absorbed after " + scatterCount + " collisions");
xs.add(pos.getElement(0));
ys.add(pos.getElement(1));
zs.add(pos.getElement(2));
return;
} else {
// compton scattering
energyEV = sampler.sampleComptonScattering(energyEV, dir);
// send new ray
followRay(pos, dir, energyEV, imp, scatterCount + 1, totalDistance + dist);
}
}
public static synchronized void updateAttenuationCoefficientsMap(
HashMap<Material, double[]> attenuationCoefficientsMap,
double[] energies,
Material mat,
AttenuationType att) {
double[] attenuation = new double[energies.length];
try {
for (int j = 0; j < attenuation.length; j++) {
attenuation[j] = mat.getAttenuation(energies[j], att);
}
attenuationCoefficientsMap.put(mat, attenuation);
} catch (NoSuchElementException e) {
System.out.println(
"Skipping " + mat + " as attenuation data is incomplete for the configured energies.");
} catch (NullPointerException e2) {
System.out.println("Skipping " + mat + " as attenuation data is incomplete.");
}
}
