MCNP PTRAC card help

[MadGander]

TL;DR

Need help setting up and interpreting my PTRAC output.

Hi all,

I'm attempting to simulate a very specific setup in MCNP. I want to know the fraction of particles contributing to a surface tally that previously interacted (scattered) with a specified cell. I'm currently doing this via the PTRAC card as well as FILTER. Currently, my PTRAC is outputting gibberish. I'm also curious what the number is at the bottom of my regular output... "binary file ptrac written with 10000 events from 9111 histories." Does this mean 9111 simulated particles fit the requirements of the PTRAC card? I've attached my input deck below. Any help is appreciated.

 

[DEvens]

OK, a year old post with no answer. Probably it is too late to do anybody any good.

PTRAC files can be text or binary depending on the options you choose. Check the manual entry for the card that produces the PTRAC file. The message you quote says "binary file" so probably you have chosen the wrong one.

PTRAC files are often HUGE. By default, they produce many lines of output for the history of every particle produced. You want to put careful limits on what is produced and how many histories are included. Otherwise you are likely to get many gigabytes of data.

Depending on what you select to be output, you should see things like the x,y,z coords of every event on a particle's history, the momentum px, py, pz, the type of interaction, and some other stuff I don't recall without looking in the manual.

I have used PTRAC to debug complicated source terms by limiting the output to just the particle's origin, then listing only the first 1000 histories or such. Also, when MCNP loses a particle, it will produce some PTRAC-like info for the particle that gets lost.