Dear OpenMC experts,
I created a compound in OpenMC so that I can view the inelastic and elastic contributions to its macroscopic cross section. You can see the plot produced with OpenMC and script which I used below. What’s striking is the inelastic cross section - it has two sharp dips which drop precipitously in magnitude at energies just above and below 1e7 eV. The macroscopic inelastic cross section also does not appear to have any value on the y-scale presented for energies below ~5e6 eV.
I did the same exercise using XS Plotter. But XS Plotter gives me a different/more sensible solution (see last plot) for the inelastic macroscopic cross section. Conversely, the total and elastic macroscopic cross sections seem to agree. I think there is something wrong with the inelastic plotting function in OpenMC. Please let me know what might be awry. Thanks very much!
Plot from OpenMC
Python Script
import os
from pprint import pprint
import shutil
import subprocess
import urllib.request
import h5py
import os
import numpy as np
import matplotlib.pyplot as plt
import openmc.data
from matplotlib.patches import Rectangle
import matplotlib.cm
mesi = openmc.Material()
mesi.add_nuclide('H1', 12.0,'ao')
mesi.add_nuclide('C0', 9.0,'ao')
mesi.set_density('g/cm3', 0.87)
openmc.plot_xs(mesi,['total','elastic','inelastic'],temperature=20)
plt.xlim([1E-5,1.5E8])
plt.ylim([1e-6,100])
plt.title('Macroscopic Cross Sections for Mesitylene at 20K')
plt.show()
Plot Obtained with XS Plotter
Best,
Dalini
I think this might be down to the cross section library used instead of anything else.