[fluka-discuss]: How many terms are given to control errors?

From: <yyc2011_at_mail.ustc.edu.cn>
Date: Mon, 9 Dec 2013 16:50:56 +0800 (CST)

Hi,
   
  Everyone!Since the transport of charged particles in the Fluka uses multiple scattering theory of Molière.According to Bethe,the angular distribution can be given by a power series. But I don't know in the Fluka codes how many terms are given to control errors within 1%,3 terms,7 terms or more?

Best regards
Chen Yuan
  


> -----Original E-mail-----
> From: "Joachim Vollaire" <joachim.vollaire_at_cern.ch>
> Sent Time: 2013-12-9 5:20:23
> To: "yyc2011_at_mail.ustc.edu.cn" <yyc2011_at_mail.ustc.edu.cn>, "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>
> Cc:
> Subject: RE: [fluka-discuss]: How to get the angular distribution?
>
> Hi
> Did you consider using the USRBDX (energy / angular particle distribution across a surface) ?
> Cheers
> Joachim
>
>
> -----Original Message-----
> From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of yyc2011_at_mail.ustc.edu.cn
> Sent: 04 December 2013 02:06
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: How to get the angular distribution?
>
> Dear Fluka experts,
>
> If I want to do a statistic analysis for angles of all the particles on the detector plane, in other words, If I want to get the angular distribution for all the particles on the detector plane, how can I do this? Could you give me any suggestions?
>
> Best Regards
> Chen Yuan
>
>
> > -----Original E-mail-----
> > From: "Paola Sala" <paola.sala_at_mi.infn.it> Sent Time: 2013-11-29
> > 14:25:00
> > To: yyc2011_at_mail.ustc.edu.cn
> > Cc: fluka-discuss_at_fluka.org
> > Subject: Re: [fluka-discuss]: Why single scattering is extremely demanding in CPU time?
> >
> > Dear Chen Yuan,
> > as the words say:
> > -multiple scattering : many scatterings are cosidered all together to
> > calculate the deflection over a "step"
> > - single scattering: each scattering is considered independently, each
> > one needs a "step"
> >
> > guess what takes more time..
> >
> >
> > Please, we had already lots of discussin on this item that is a basic
> > item for all particle transport problems, there is PLENTY of
> > literature on it, starting from the Partivcle Data Book to dedicated
> > papers on the multiple scattering theory. Please refer to these unless
> > you have a fluka-specific problem Paola
> >
> > > Dear Fluka Experts,
> > > When I use MULSOPT card, setting WHAT(6)> 1000.0 with SDUM =
> > > GLOBAL, GLOBHAD or GLOBEMF, replaces systematically multiple
> > > scattering with single scattering everywhere. This choice is
> > > generally extremely demanding in CPU time.(1)But why? In other
> > > words,what causes the long computing time?(2)But,When I deal with
> > > the same problem with mutiple scattering,the computing time is
> > > greatly reduced. So,Are there any differences between single
> > > scattering and multiple scattering in the codes?And what are the differences?
> > > Thanks for any suggestions.Thanks for your time.
> > >
> > > Best Regards
> > > Chen Yuan
> > >
> > >
> > >> -----Original E-mail-----
> > >> From: "Giuseppe Battistoni" <giuseppe.battistoni_at_mi.infn.it> Sent
> > >> Time: 2013-11-25 22:56:18
> > >> To: yyc2011_at_mail.ustc.edu.cn
> > >> Cc: fluka-discuss_at_fluka.org
> > >> Subject: Re: [fluka-discuss]: some questions about charged particle
> > >> transport
> > >>
> > >> Dear Chen Yuan
> > >> you are asking something very difficult to be summarized by e-mail:
> > >> you have to refer to text books on the argument.
> > >> From your questions it seems that you have to improve your
> > >> background knowledge in the studies of interaction of radiation
> > >> with matter: this is essential for any user of general purpose
> > >> Monte Carlo codes as FLUKA.
> > >>
> > >> If I may give and advice, I strongly suggest to use always multiple
> > >> scattering for all standard problems of realistic detectors and
> > >> situation. Avoid single scattering which is to be considered only
> > >> something exceptional for very very thin layers.
> > >> (by the way, it's very CPU time consuming).
> > >>
> > >> For your study on Moli¨¨re's Theory of Multiple Scattering let me
> > >> also advice a historical paper by H. Bethe in Phys. Rev. 89,
> > >> 1256¨C1266 (1953)
> > >>
> > >> Best regards
> > >> Giuseppe Battistoni
> > >>
> > >> On 11/25/2013 11:54 AM, yyc2011_at_mail.ustc.edu.cn wrote:
> > >> > Dear Giuseppe,
> > >> >
> > >> > First,Thanks for your reply.But,I still have some questions.
> > >> > (1)I wil study the paper so as to solve the problem.
> > >> > (2)In the Fluka course,you refer to the validity conditions of
> > >> Moliere theory more than once. But, what are the validity
> > >> conditions of Moliere theory? Could you tell me in detail?
> > >> >
> > >> > Any multiple scattering therory applies when in a given step you
> > >> > have
> > >> several coulomb scattering.Several is a qualitative word. In
> > >> practice, as a rule of thumb, you may be safe if you expect many
> > >> tens of scatterings.
> > >> >
> > >> > So,According to your view,when refer to scattering,I can only
> > >> > estimate
> > >> scattering numbers to determine whether it is appropriate to use
> > >> the mutiple scattering.And in general,how could you estimate
> > >> scattering numbers?
> > >> > (3)We advice single scattering only when you have thickness of
> > >> materials so small that the above conditions risks to be not
> > >> respected.A couple of practical examples:
> > >> > - layers of nuclear photographic emulsions.where you aim to
> > >> > measure
> > >> charged tracks with few micron accuracy
> > >> > - very thin layers of silicon trackers (order of 100 micron or
> > >> > less)
> > >> >
> > >> > According to your idea,There are no specific conditions to tell
> > >> > me
> > >> when should I use single scattering.I must judge whether I should
> > >> use single sattering as specific questions change.
> > >> >
> > >> > I don't know whether my understanding are right.Wish to
> > >> > receive
> > >> from you.
> > >> >
> > >> > Best regards
> > >> > Chen Yuan
> > >> >
> > >> >
> > >> >
> > >> >> -----Original E-mail-----
> > >> >> From: "Giuseppe Battistoni" <giuseppe.battistoni_at_mi.infn.it>
> > >> >> Sent Time: 2013-11-25 16:59:43
> > >> >> To: yyc2011_at_mail.ustc.edu.cn, fluka-discuss_at_fluka.org
> > >> >> Cc:
> > >> >> Subject: Re: [fluka-discuss]: some questions about charged
> > >> >> particle
> > >> transport
> > >> >>
> > >> >> Dear Chen Yuan
> > >> >>>
> > >> >>> When I learn charged particle transport,There are a few
> > >> >>> problems
> > >> I cannot understand.The questions are as followings.
> > >> >>> (1)The Fluka course said "Accurate PLC (not the average
> > >> >>> value
> > >> but sampled from a distribution), giving a complete independence
> > >> from step size",I cannot understand this sentence at all. What kind
> > >> of the distribution is? Could you give me a simple interpretations?
> > >> >>
> > >> >> I advice to study the paper (quoted in FLUKA references):
> > >> >> A. Ferrari et al., Nucl. Instr. Meth. in Phys. Res. B71, 412-426
> > >> (1992)
> > >> >> and references therein
> > >> >>
> > >> >>> (2)In the Fluka course,you refer to the validity conditions
> > >> >>> of
> > >> Moliere theory more
> > >> >> than once. But, what are the validity conditions of Moliere
> > >> theory? Could you tell me in detail?
> > >> >>
> > >> >> Any multiple scattering therory applies when in a given step you
> > >> >> have
> > >> several coulomb scattering.
> > >> >> Several is a qualitative word. In practice, as a rule of thumb,
> > >> >> you
> > >> may be safe
> > >> >> if you expect many tens of scatterings.
> > >> >>
> > >> >>> (3)In the Fluka course,you mentioned "full single
> > >> >>> scattering are
> > >> used to handle very low energy electron problems and very thin
> > >> layers problems. But,how much low is the electron energy? How much
> > >> thin are the layers?
> > >> >>> In a word,I want to know when I should use mutiple
> > >> >>> scattering
> > >> and when I should use the full single scattering.
> > >> >>> I'm looking forward to receive from you.Thanks for your
> > >> time.Thanks for your reply.
> > >> >>
> > >> >> We advice single scattering only when you have thickness of
> > >> >> materials
> > >> so small that the above
> > >> >> conditions risks to be not respected.
> > >> >> A couple of practical examples:
> > >> >> - layers of nuclear photographic emulsions.
> > >> >> where you aim to measure charged tracks with few micron accuracy
> > >> >> - very thin layers of silicon trackers (order of 100 micron or
> > >> >> less)
> > >> >>
> > >> >> Best regards
> > >> >> Giuseppe Battistoni
> > >> >>
> > >> >> --
> > >> >> INFN Milano
> > >> >> via Celoria 16, 20133 Milano, Italy
> > >> >> tel: +39 02 50317307
> > >> >> fax: +39 02 50317617
> > >> >>
> > >
> > >
> >
> >
> > Paola Sala
> > INFN Milano
> > tel. Milano +39-0250317374
> > tel. CERN +41-227679148
> >
>
Received on Mon Dec 09 2013 - 10:53:14 CET

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