Dear Vasilis
thanks a lot for your help !
I never thought that I had to use current for
USRBDX card to get total number of neutrons !
It is great surprise for me !
So, the flow for USRBDX card has the weight 1/cosTET
Ok.
Another puzzle for me was - why for the USRYIELD card
I see different results for the SAME distributions :
I mean the variant :
dN2 / d x1 d x2
where a) x1 - linTHETA , x2 = lnE
b) x1 = lnE, x2 = linTHETA
I used the example from the Scoring lecture, where they used
the degree interval:
0 - 180.0
But according to advise of Ivan Gordeev
today I replaced degree to radians : 0 - pi
...and I got the RIGHT result !
So, I know today , that using degree in FLUKA is very dangerous thing !
thank Vasilis and Ivan.
Vladimir
18.01.2019 13:17, Vasilis Vlachoudis пишет:
> Dear Vladimir,
>
> you want to get the total outgoing yield of neutrons from the target
> but in the USRBDX you are scoring Fluence and not Current.
> Fluence will be normalized with the cosine of the direction vs surface normal
> and this is not what you want.
>
> USRYIELD with the proper normalization should give you identical results
> with USRBDX
>
> Making a fast test with your input and using current I get a value of 80
> close to your measured one.
>
> Vasilis
>
>
> ________________________________________
> From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of babintsev [babintsev_at_ihep.ru]
> Sent: Tuesday, January 15, 2019 13:35
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: Neutron output - big difference in results
>
> Dear experts,
>
> I need to get total number of neutrons from the body (lead)
> to compare FLUKA results with those published in articles.
>
> For this I use 2 cards : USRBDX and USRYIELD
>
> I observed that output of N total is very different
> and depends on the size of taget !
> I have got the following results for the "small" geometry:
> Tuto-lead-3.5.inp
>
> Lead, R= 5 cm, L = 9 cm, beam - P , E= 3.5 GeV
> -----------------------------------------------
>
> *) USRBDX: N Fl from Pb into Air : Area: 1 cmq,
>
> Tot. resp. (Part/cmq/pr) 27.26922 +/- 0.5661705 %
> ( --> (Part/pr) 27.26922 +/- 0.5661705 % )
>
> *) USRYIELD: Fl from Pb into Air : linOmega LogE (0-5)
>
> Tot. response (integrated over x1) 3.654836 +/- 0.7171366 %
> ( --> Tot. response without normaliz. 3.654836 +/-
> 0.7171366 % )
>
> Ntot= 3.654836 * 5 = 18.27418
>
> *) USRYIELD: Fl from Pb into Air : LogE LinOmega (0-4pi)
>
> Tot. response (integrated over x1) 1.819517 +/- 0.7171366 %
> ( --> Tot. response without normaliz. 1.819517 +/- 0.7171366 % )
>
> Ntot= 1.819517 *4*3.14156 = 22.864487
>
> ------------------------------------------------------
>
> Then I use bigger volume :
> accoring to the article: N.SOBOLEVSKY :
>
> "Monte Carlo Calculation of Neutron Yield from Extended
> Iron and Lead Targets Irradiated by 1 and 3.65 GeV/u Ion Beams"
>
> where for Ep = 3.5 GeV Ntotal = 65 - 77 neutrons
> ----------------
> So, I use :
>
> Lead, R= 10 cm, L = 60 cm, beam - P , E= 3.5 GeV --
> Tuto-lead-3.5-Big.inp
> -----------------------------------------------
>
> Results:
>
> *) USRBDX: N Fl from Pb into Air : area = 1
>
> Tot. resp. (Part/cmq/pr) 125.0001 +/- 0.2880751 %
> ( --> (Part/pr) 125.0001 +/- 0.2880751 % )
>
>
> *) USRYIELD: N Fl from Pb into Air : linOmega LogE (0-5)
> ------------------
> Tot. response (integrated over x1) 16.10910 +/-
> 0.2112415 %
> ( --> Tot. response without normaliz. 16.10910 +/- 0.2112415
>
> Ntot = 16.10910 * 5 = 80.545
>
>
> *) USRYIELD: N Fl from Pb into Air : LogE LinOmega (0-4pi)
>
> Tot. response (integrated over x1) 8.019730 +/-
> 0.2112417 %
> ( --> Tot. response without normaliz. 8.019730 +/- 0.2112417
>
> Ntot = 8.019730 *4*3.14156 = 100.777
>
> ---------------------------------------
>
> Questions:
>
> - are there large leakage from "small" target even for this
> small energy ?
> - the presented results are very different from the published ones.
> How to get "right" number of the output neutrons from a body
> with FLUKA ?
>
> Summary: measured N : 70 +- 7
>
> simulated : a) 125
> b) 80
> c) 100
>
>
> thank you
> Vladimir
>
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Received on Fri Jan 18 2019 - 13:37:23 CET