Hi Amanda, sorry for the late response.
I have checked your input script, and I think your mesh tally definition is good, but the interpretations are quite complicated.
in your case, when you use 1D mesh while using the same domain (space) definition, then you are tallying a larger mesh which is then averaged with the larger volume. that’s why your flux value is lower in 1D z-axis plot in comparison to 2D xz plot because of the mesh region (volume) in your 2D xz is 96.8748 cc while in your 1D z is 19374.96 cc, larger but most of it has a low neutron population.
If you use the same volume by indicating a smaller domain, i.e. near your neutron source but with a proper x width to make sure that it covers the same region as your 2D XZ plot, then you will get the proper average neutron flux.
Also, I hope you noticed that your 2D xz plot itself is just reporting the average neutron flux along the y-axis from -14 to 165 when you see it from the xz plane. so the actual neutron flux locally at some point near your source could be higher.
I am troubleshooting your problem with eigenvalue mode but I think it still works with fixed source. here is the 2D xz plot in fixed source
and here is the 1D z-axis plot, sorry that I can’t get the x position as close as the peak neutron flux shown in xz plot (on the left). but you can change it later as you want.
while this is the result when I use the eigenvalue problem with 100k particles, 50 inactive, and 150 total batches. 2D xz plot
and here is the 1D z-axis plot,
I hope you can get my point since I am not good at English, sorry.