[fluka-discuss]: Re: 1MeV pions energy loss in water - branching ratio discrepancy in two versions of FLUKA

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Thu, 27 Oct 2016 18:22:14 +0200

Hi Guanying,

the Z law means branching proportional to the nucleus charge, yielding for
a molecule of water the 80-20 sharing you observed with the previous
version.

On the new approach, perhaps Niels himself would like to comment.

Kind regards

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Mon, 24 Oct 2016, Zhu, Guanying wrote:

> Dear Francesco,
>
> Thanks for the reply!  
> Can you explain a little bit more on what “Z law” is and what the current
> approach is?
>
>
>
> Thank you!
>
> Guanying
>
>
>
>
> On Oct 24, 2016, at 12:44, Francesco Cerutti
> <Francesco.Cerutti_at_cern.ch> wrote:
>
>
> Dear Guanying Zhu, 
>
> indeed the discrepancy is due to a physics improvement, see 
> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/7275.html
> in particular:
>
> When treating anti-nucleon annihilation, *negative pion* and negative 
>    muon absorptions on mixtures, the evaluation of the relative 
>    probability of annihilation/capture on different target 
>    components has been switched from a naïve “Z law” to more sound 
>    approaches (following a suggestion by N. Bassler) 
>
> Kind regards
>
> Francesco
>
> ____________________________________________________________________________
> From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it]
> on behalf of Zhu, Guanying [zhu.1475_at_buckeyemail.osu.edu]
> Sent: 24 October 2016 17:32
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: 1MeV pions energy loss in water - branching
> ratio discrepancy in two versions of FLUKA
>
> Dear fluka users,
> I’m studying negative pions (kinetic energy = 1.0 MeV) energy loss in
> water.
>
> My fluka version is FLUKA 2011 2c.3.  
> And I got the branching ratio of pions interacting with proton was
> 0.5%, and the ratio of interacting with oxygen was 99.5%. 
> I used mgdraw.f to record the interactions.
>    IF (MREG .EQ. 3. .AND. JTRACK .EQ. 14 ) THEN
>       do ip = 1, NP
>         WRITE(82, *) NCASE, JTRACK, ICODE, PTRACK, IBTAR, ICHTAR, 
>      &       IBRES, ICRES, NPHEAV, ip, KPART(ip), NP, TKI(ip)
>       end do
>    END IF
> Please find attached the related files. 
>
> However, according to the result from an early run with FLUKA 2011
> 2b.5, the ratio of pions interacting with proton was 20.5%, and with
> oxygen was 79.5%.
>
>
> Does anyone know if the discrepancy is due to fluka update? 
>
>
> Thanks!
> Guanying Zhu
>
>
>
>

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Received on Thu Oct 27 2016 - 19:52:43 CEST

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