Re: [fluka-discuss]: [fluka-discuss] neutron fluence spectrum

From: George Kharashvili <>
Date: Sat, 8 Dec 2018 14:57:26 -0500 (EST)

Hello Angel,

You can use either in this case. The difference is that USRBDX scores double differential (energy and angle) particle distributions across a boundary surface which gives
results per cm2, per GeV, per steradian, per primary, while USRTRACK calculates differential fluence as a function of energy by scoring track-length in a given region and gives results per cm2, per GeV, per primary. The scoring lecture from FLUKA beginners courses provides summary descriptions of the two

One thing to keep in mind when scoring low energy (<20 MeV) neutron spectra: the transport of low energy neutrons in FLUKA is performed through a multigroup treatment, for which the neutron energy is not exactly defined but belongs to one of the 260 predefined intervals of the cross section library. Because of this, whether you use USRBDX or USRTRACK to score energy spectrum, energy binning is forced to match the 260 energy intervals regardless of what was requested by the user.

For very helpful information regarding scoring neutron spectra I would also recommend reading the replies to the following thread:

Best regards,

----- Original Message -----
From: "Angel" <>
To: "FLUKA Discussion List" <>
Sent: Saturday, December 8, 2018 6:17:31 PM
Subject: [fluka-discuss]: [fluka-discuss] neutron fluence spectrum

Dear FLUKA experts and users,

I need to obtain the neutron fluence spectrum at different depths inside a
concrete wall. The manual points that I can use the USRBDX or USRTRACK
card for the purpose. What is the difference between the two cards? Using
the first one I can choose to score the neutron fluence on a surface
passing in both directions or just in one. The second gives me neutron
fluence in a given volume. Which one would you advise me to use? Are these
cards the right ones to use?

Best regards,

You can manage unsubscription from this mailing list at
Received on Sat Dec 08 2018 - 22:17:08 CET

This archive was generated by hypermail 2.3.0 : Sat Dec 08 2018 - 22:17:16 CET