[fluka-discuss]: RE: Secondaries from low energy neutron interactions

From: Stefan Roesler <Stefan.Roesler_at_cern.ch>
Date: Mon, 30 Oct 2017 14:04:02 +0000

Dear Guanying

Sorry for the late reply.

Actually, for pointwise cross section and correlated generation of secondaries from neutron capture reactions on 40Ar you would need an additional data-file that is not included in the official distribution and only available on request from the authors. See also the following post
http://www.fluka.org/web_archive/earchive/new-fluka-discuss/5231.html

Thus, for all reactions below 20MeV the neutron scattering probability on Ar and production of residual nuclei is meaningful only on average over a large number of interactions but not at the level of individual interactions.

Cheers
Stefan


From: Zhu, Guanying [mailto:zhu.1475_at_buckeyemail.osu.edu]
Sent: 20 October 2017 21:53
To: Stefan Roesler <Stefan.Roesler_at_cern.ch>
Cc: fluka-discuss_at_fluka.org
Subject: Re: Secondaries from low energy neutron interactions

Dear Stefan,

Thank you for your reply! I checked the manual and some online resources on low energy neutron transports, but I’m still a bit confused.

Let’s say I switch on point-wise neutron scattering in 40Ar.
(1) If there is a neutron capture, then from fluka outputs, I should see 41Ar as residual nuclei, and all the secondaries are gammas?
(2) For all the other interactions, the output secondaries are actually meaningless, or not physical, because of the group transport thing?
      What about residual nuclei information? If I see ICRES=17, and IBRES=41, can I say the residual is a 41Cl?
(3) Are we saying that there is no way to distinguish between ES, (n, n’), (n, np), (n, p), etc.?


Thank you!
Guanying



On Oct 20, 2017, at 11:09 AM, Stefan Roesler <Stefan.Roesler_at_cern.ch<mailto:Stefan.Roesler_at_cern.ch>> wrote:

Dear Guanying Zhu

Neutron interactions below 20MeV are based on a multigroup algorithm with uncorrolated production of secondaries, see for example
https://indico.cern.ch/event/604018/contributions/2435695/attachments/1395458/2242762/10_Low_Energy_Neutrons_2017.pdf

In a very few specific materials point-wise neutron scattering can be switched on but in case of 40Ar this is limited to physical gammas from n capture. Please see the manual entry for the LOW-NEUT card, in particular Notes 4 and 5

Cheers
Stefan


From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Zhu, Guanying
Sent: 20 October 2017 04:29
To: fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>
Subject: [fluka-discuss]: Secondaries from low energy neutron interactions

Dear fluka users,

I’m simulating 10 MeV neutron interactions in liquid 40Ar. The goal is to count how many 40Ar(n, g)41Ar and how many 40Ar(n, n+g)40Ar.

I try to separate these two types of interactions by looking at the secondaries produced in each interaction. Below are two examples:
Example 1:
      mgdraw.f:
      IF (NCASE .EQ. 56 .AND. JTRACK .EQ. 8) THEN
   ETNEW = ETRACK-Am(JTRACK)
           do ip = 1, NP
              WRITE(82,600) NCASE, JTRACK, ETNEW,
     & ip, Kpart(ip), Tki(ip), NP,
     &
ICHTAR, IBTAR, ICRES, IBRES
           end do
      END IF
      Output:
        56 8 0.10000E-01 1 7 0.60471E-03 3 18 40 18 40
        56 8 0.10000E-01 2 7 0.29167E-02 3 18 40 18 40
        56 8 0.10000E-01 3 7 0.57545E-02 3 18 40 18 40
Example 2:
      mgdraw.f:
      IF (NCASE .EQ. 12060 .AND. JTRACK .EQ. 8) THEN
   ETNEW = ETRACK-Am(JTRACK)
           do ip = 1, NP
              WRITE(83,600) NCASE, JTRACK, ETNEW,
     & ip, Kpart(ip), Tki(ip), NP,
     &
ICHTAR, IBTAR, ICRES, IBRES
           end do
      END IF
      Output:
     12060 8 0.10000E-01 1 7 0.27595E-02 5 18 40 18 40
     12060 8 0.10000E-01 2 7 0.14334E-02 5 18 40 18 40
     12060 8 0.10000E-01 3 7 0.64536E-02 5 18 40 18 40
     12060 8 0.10000E-01 4 8 0.10126E-01 5 18 40 18 40
     12060 8 0.10000E-01 5 8 0.26580E-02 5 18 40 18 40

So the output shows two interactions: n + 40Ar -> 40Ar + gamma ; n + 40Ar -> 2n + 40Ar + gamma. However, they are not physical.

Does anyone know how to interpret the outputs shown here?




Thank you!
Guanying Zhu


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Received on Mon Oct 30 2017 - 16:37:10 CET

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