[fluka-discuss]: Unexpected behaviour of WW-THRES card for low-neutrons

From: Rodion Kolevatov <Rodion.Kolevatov_at_ife.no>
Date: Wed, 14 Mar 2018 10:51:24 +0000

Dear FLUKA experts,

While doing simulation of detector shielding against neutrons I have found that to set up weight windows for low-energy neutrons requires setting both WHAT(4) (from particle) and WHAT(5) (to particle) in WW-THRES card to "WWLOWNEU":
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
WW-THRES 200. 261. 1. WWLOWNEU WWLOWNEU PRIMARY

Omitting "WWLOWNEU" at WHAT(5) position
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
WW-THRES 200. 261. 1. WWLOWNEU PRIMARY
results in no splitting/RR in the regions set by WW-FACTOR, though, according to documentation, this should have the same effect as the line above.

I have checked that setting weight windows for photons requires just setting WHAT(4) in WW-THRES while WHAT(5) may be left blank. This behavior of the WW-TRES card with respect to low energy neutrons is not described in the documentation, neither in fluka-discuss, and it took me a while to find out what was the reason for no splitting/RR for neutrons in my simulation.

Could you please confirm whether this behavior is a generic input feature or is it platform specific?
I am using FLUKA 2011.2x compiled with gfortran 7.3.0 under Ubuntu 16.04.

With best regards,
Rodion Kolevatov.

Dr. Rodion Kolevatov
Postdoctoral researcher
NMAT Department,
Institute for Energy Technology,
P.B. 40, NO-2027 Kjeller, Norway
Mobile: +47 41394217
E-mail: Rodion.Kolevatov_at_ife.no



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Received on Wed Mar 14 2018 - 13:37:57 CET

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