@Shimwell
Finally, I am able to generate the desired plot, by using the calculate_cexs method as you suggested in the beginning, it much more simple than I thought, here the example:
En1, data1 = openmc.calculate_cexs(‘Nd’, ‘element’, [’(n,gamma)’])
En2, data2 = openmc.calculate_cexs(‘Sm’, ‘element’, [’(n,gamma)’])
En3, data3 = openmc.calculate_cexs(‘Gd’, ‘element’, [’(n,gamma)’])
En4, data4 = openmc.calculate_cexs(‘B’, ‘element’, [’(n,a)’])
plt.loglog(En1, data1[0])
plt.loglog(En2, data2[0])
plt.loglog(En3, data3[0])
plt.loglog(En4, data4[0])
plt.grid(True)
plt.savefig(‘Figure00.png’, dpi=300)
Thanks lot for your help and your time