Hi,
The publication "An improved multiple scattering model for charged
particle transport" in NIMB Volume 71, Issue 4
<
http://www.sciencedirect.com/science/journal/0168583X/71/4>, 2 September
1992, Pages 412426, describes the model in depth, including discussions
of the approximations and resulting errors. Coming to your specific
question, I see that fourth power serial approximations to the scattering
angle are mentioned, but I am not sure if those are in the same context as
what you are asking.
In any case, through MULSOPT cards you can evaluate for your specific
problem, what the effect is of switching ON/OFF multiple scattering as
well as other related parameters.
Mario
On 12/9/13 12:50 AM, "yyc2011_at_mail.ustc.edu.cn" <yyc2011_at_mail.ustc.edu.cn>
wrote:
>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 - 21:41:47 CET