Large uncertainty in low energy neutron simulation

From: keep <>
Date: Wed Jun 11 2008 - 14:48:35 CEST

Dear all,


I am simulating the response of a tissue equivalent chamber in neutron


I setup a parallel beam with mono-energetic neutron, and a chamber at 10 cm
away from source.

The incident neutron energy is changed from 10 MeV to 0.1 eV,
and I use USRBIN to tally the "energy deposition" in the chamber gas which
is about 0.1 cm3.


When the incident neutron energy is above 100 eV, the USRBIN results have
errors about 3 % for 2x109 primary particles.

When the neutron energy is 10 eV or below 10 eV, the USRBIN results have
large error up to 60 %.



Could anyone tell me what cause the large error? How can I solve it??



Thanks in advance,


Keith Wang

Received on Thu Jun 12 18:06:14 2008

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