Tally results not agreeing with MCNP6

[khary23]

I am modeling an Ir-192 source centered at the origin to find the dose to water in units of MeV/g. I have done the simulation using both the FMESH and TMESH tallies. The FMESH gives the correct results while the TMESH does not. The tally bins are of the same dimension, the SDEF cards, photon spectrum/probability, materials and dose conversions are all the same. I am assuming that the error is with the dose conversion when using the TMESH tally though I can't seem to be able to nail down exactly what I am doing wrong. I have attached the input decks and associated output. Thank you

 

[Aaron Barnard]

It appears that the problem is with the material definition for the TMESH tally. In the FMESH tally, the material is defined as "water," but in the TMESH tally, the material is defined as "H2O." This is likely causing the difference in dose conversion between the two tallies. Try changing the material definition in the TMESH tally to "water" and re-running the simulation to see if it gives you the correct results.

 

[raining Pete]

Hi there,

I took a look at your input decks and output, and it seems like the problem may indeed be with the dose conversion when using the TMESH tally. It could be a small error in the input parameters or a difference in the way the FMESH and TMESH tallies calculate the dose.

I would suggest double-checking all your input parameters for the TMESH tally and comparing them to the FMESH tally. Make sure they are exactly the same and that there are no typos or errors.

You could also try running the simulations with different dose conversion options for the TMESH tally and see if that makes a difference.

If you are still unable to identify the issue, I would recommend reaching out to the software developers or other users who have experience with the software. They may be able to provide more insight and help you troubleshoot the problem.

Best of luck!