Stopping Neutron in a defined region

Dear FLUKA experts,

Thanks for being so much helpful.
I wanted to add few things in my previous email.

I am calculating dose equivalent from neutrons produced in the snout and in
the phantom. In order to calculate the dose equivalent from internal
neutrons (neutrons produced inside the phantom), I need to dump the
neutrons which are produced in the snout so that they can not reach the
phantom. How can I do that?

Is it possible to place a thin region of low dense material in front of the
snout where all the neutrons produced in the upstream will be stopped (like
a Bremsstrahlung electron problem described fluka website FAQ). I have
absolutely no idea what card to use and how to do that. Please help me with
any suggestions .

Attached is my input and user routine used for Dose equivalent.

Sincerely
Mohammad Rafiqul Islam
PhD student Oklahoma state University
USA