Re: [fluka-discuss]: Mgdraw.f to study processes

From: Paola Sala <paola.sala_at_mi.infn.it>
Date: Tue, 8 Sep 2020 10:22:41 +0200

Dear Julien,
no, one cannot separate the various subprocesses at the end of the
reaction. The variable that you are using, namely ICESTR, IBESTR, and the
existence of an alpha particle in the genstk common, are only flagging
events where there has b=been particle emission in the fast stages of the
reaction, in this case in the preequilibrium stage. They do not mean that
there has been the formation of a Boron nucleus, only that at a certain
stage there was a bag of 8 nucleons , maybe highly excited, on the way to
break-up (not evaporation, for light nuclei we use fermi break-up). There
is no "exported" variable reporting the chain of produced fragments.

I am a bit puzzled by your sentence "t seems that reaction 3 contributes
in reality for less than 5%", which would mean that in the remaining 95%
an alpha is emitted in the preequilibrium stage. I would expect rather the
opposite in the 0-5 MeV range.

How to identify then the subprocess? For the channel involving Be in the
ground state, one could reconstruct the invariant mass of the system
composed by the two alphas in genstk or the last two in fheavy. Foir the
Be excited state this procedure is less effective because the excited
state is broad. Maybe the best thing to do is to use the same procedure as
in the experimental papers.

Hope this helps
Paola

> Dear fluka experts,
>
> I am studying the proton Boron 11 fusion and I would like to discriminate
> ways to produce alphas particles between:
> 1) p + 11B --> 12C* --> 8Be* + alpha0 --> alpha1 + alpha2 +alpha0
> 2) p + 11B --> 12C* --> 8Be + alpha00 --> alpha01 + alpha02 +alpha00
> 3) p + 11B --> 12C* --> alpha11 + alpha22 +alpha20
>
> To achieve that, i use mgdraw.f routine:
> ENTRY SODRAW
> RETURN
> *
> ENTRY USDRAW ( ICODE, MREG, XSCO, YSCO, ZSCO )
> IF ( UDFIRST ) THEN
> UDFIRST = .FALSE.
> ENDIF
> do 20 ip = 1, NP
> IF (KPART(ip) .EQ. -6 .OR. KPART(ip) .EQ. 7 .OR.
> & KPART(ip) .EQ. 8) THEN
> WRITE(IODRAW,*)'2NDY ',NCASE,JTRACK,ZSCO,
> & KPART(ip),ZPART,APART,TKI(ip)
> ENDIF
> 20 continue
> do 30 ip=1,NPHEAV
> WRITE (IODRAW,*) 'Heav', NCASE, JTRACK,ZSCO,
> & ICODE,KHEAVY(ip),ICHEAV(KHEAVY(ip)),IBHEAV(KHEAVY(ip)),
> & TKHEAV(ip)
> 30 continue
> IF (ICODE.NE.100) THEN
> WRITE(IODRAW,*) 'nuc', NCASE,JTRACK,ICODE,ICHTAR,
> & IBTAR, ICESTR, IBESTR,ICRES,IBRES
> ENDIF
> RETURN
>
> I obtain these kind of informations:
> 2NDY 1882 1 0.13088856811273053 -6 0.0000000000000000 0.0000000000000000
> 2.2024593427923289E-002
> Heav 1882 1 0.13088856811273053 101 6 2 4 5.8379209697727672E-003
> Heav 1882 1 0.13088856811273053 101 6 2 4 7.9018346964389828E-003
> nuc 1882 1 101 5 11 4 8 0 0
>
> Here for the Ncase=1882, it seems we have 1 alpha as secondary and 2
> alphas as heavy secondaries from 8Be evaporation (produced at the same
> place in the simulation). OK. But how can i make difference between
> reactions 1) and 2) : Be8 is in an excited state before evaporation or
> not?
>
> For reaction 3):
> Heav 5523 1 8.4310820700689224E-002 101 6 2 4 6.5847353447588833E-003
> Heav 5523 1 8.4310820700689224E-002 101 6 2 4 6.6214411305522847E-003
> Heav 5523 1 8.4310820700689224E-002 101 6 2 4 9.2596922984330380E-004
> nuc 5523 1 101 5 11 6 12 0 0
>
> Here it seems that correspond to equation 3. 12C directly break up into 3
> alphas (3 heavy secondaries).
> Whhen I count the cases for each type of reaction, I obtain the
> proportions in the attached picture pB11.png
>
> It seems that reaction 3 contributes in reality for less than 5% with
> protons from 0 to 5MeV (it is this kind of spectrum I use in FLUKA). So
> this reaction with direct break up of C12 in 3 alphas particles seems to
> be overestimated in FLUKA. Is it possible or did I make a mistake in my
> routine mgdraw?
>
> Thanks in advance
>
> Julien
> CELIA FRANCE
>
>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148

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Received on Tue Sep 08 2020 - 12:26:41 CEST

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