RE: [fluka-discuss]: How to get the angular distribution?

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Sun, 8 Dec 2013 21:20:23 +0000

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 Sun Dec 08 2013 - 23:08:23 CET

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