Calculate response with USRTRACK and RESNUCLEi

Dear experts,

I want to simulate the response of Bonner sphere neutron spectrometer of monoenergetic neutrons with ^{3}He(n, p)T reaction. To get the response, I should know the reaction counts [cm^{2}] and neutron flux [neutrons/cm^{2}] in the ^{3}He sphere region.

  1. I read from a paper that the author used USRTRACK to get neutron flux, and RESNUCLEi to score proton and triton nuclei as the reaction numbers (assuming that every (n,p) reaction was recorded). I am wandering whether this methord is reasonable, or is there any other way to get the response?

  2. Besides, I also tried to run a simple condition of ^{3}He(n, p)T reaction, a point neutron source shot on a cubic ^{3}He region (the atmoic density n_{3He} was 10^{20}atoms/cm^{3}​). And I scored with USRTRACK and RESNUCLEi (normalized by the cube volume). The results as below:

    I find that the \text{USRTRACK} * \Sigma \approx \text{RESNUCLEi} numerically. So it is right to regard RESNUCLEi as the reaction count?
    t-track.inp (2.2 KB)

  3. In part 2, I also used USRBIN to score proton and triton, but no proton or triton has been recorded. I am confused about this.

Thank you very much for your help,

Dear @Jungle,

Thanks for the clearly stated questions. Let’s tackle them:

1 and 2: This is an indirect way of looking at the number of reactions, which should be ok assuming that you do not expect protons and/or tritons to appear as a result of any other reaction.
Probably the most direct way is to count the number of reactions using the mgdraw.f routine. But in this case you will need to code the logic yourself. This post may help you to do so: (p.n) reaction position-MGDRAW - #5 by qding

3: The reason why you don’t see them in the USRBIN is because these secondaries are not transported but their energy is deposited at the point of interaction. This is the general approach for charged secondaries produced in low energy neutron reactions, although there are some exceptions. This is why your USRBINs, which are trying to score track-length of protons and tritons see nothing.

Kind regards,

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Dear Francisco,

Thank you very much for your fast and detailed answer. I will try the mgdraw.f and will come back if something exceeds me.

Thank you for your help.


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