RE: [fluka-discuss]: USRBDX Neutron-Energy

From: Joachim Vollaire <>
Date: Sat, 16 Dec 2017 11:23:40 +0000

Hello Konstantin
A few things looking at your input. As you are using an electron beam and you want to see neutrons from photonuclear reactions it is recommended to add a LAM-BIAS card to increase the probability of nuclear reactions (FLUKA will correct the weight of generated particles accordingly). See the corresponding part of the manual.
Concerning the scoring, USRBDX is a surface crossing estimator (shared surface between adjacent regions), so it does not make sense to use the generalized particle ENERGY which corresponds to energy deposited along tracks not at surface crossing. The filtering with AMB74 does not make sense either as this is usually used for dose equivalent scoring (generalized particle DOSE-EQ) to select the desired dose equivalent conversion factor (folded with the fluence from track length estimators -> USRTRACK/USRBIN…).
So the first card is the correct approach. Note that the binning structure below 20 MeV will not be linear as you request but it will correspond to the boundaries of the 260 energy groups used for neutron transport below 20 MeV. It is suggested to manually set the binning structure (upper limit in that case) and use logarithmic bins for neutrons spectra scoring.
Hoping this help

From: [] On Behalf Of Konstantin Rönsch
Sent: 15 December 2017 20:33
Subject: [fluka-discuss]: USRBDX Neutron-Energy

Dear Fluka experts,
with Fluka i simulate an elektron beam on a tungsten target and i want to detect the energy spectrum of the neutron radiation between the materials tungsten and air.
I use the Card USRBDX to detect the spectrum, but i am not shure which settings are correct for my example. I simulate USRBDX for Neutrons and in an other card USRBDX with energy and a AUXSCORE card to filter the neutron part of the energy. So which way is the correct, or what are the differents, because the results are not exactly the same.
Thanks for help

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Received on Sat Dec 16 2017 - 13:44:30 CET

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