Re: Re: Re: [fluka-discuss]: About the single scattering set at the boundary

From: <yyc2011_at_mail.ustc.edu.cn>
Date: Tue, 29 Oct 2013 10:11:16 +0800 (CST)

Dear Professor Paola,

  I do a summary about the single scattering we have discussed last two weeks.The followings are the key points and my problem.

  In the first place,key points are as follows.
First,for 0.05 microns geometry I have defined,the Fluka can't be used for such thin layers.A minimum size of about 1 micron should be kept to get meaningful results.
Second,For micron-sized geometries, single scattering should be set for all steps.
  
  In the second place,the following is my problem.
You said in your last email"at every step yuo will be dealing with single scattering.However, as I tould you in my previous mail, this is NOT enough in ordere to have a reliable simulation in sub-micron geometries. There are other processes whose description is intrinsically built on some averaging, like the energy loss and its fluctuation.These loose their validity on very short steps."I have some difficulties to understand you.According to your idea,Even I set single scattering for all steps,it is still not enough in ordere to have a reliable simulation in sub-micron geometries.In other words,the results I got is still unreliable in sub-micron geometries.For this problem,what should I do?

  Thanks for your time.Thanks for your suggestions.I'm looking forward to receive from you.

Best Regards
YuanChen


> -----Original E-mail-----
> From: "Paola Sala" <paola.sala_at_cern.ch>
> Sent Time: 2013-10-21 16:27:39
> To: yyc2011_at_mail.ustc.edu.cn
> Cc:
> Subject: Re: Re: [fluka-discuss]: About the single scattering set at the boundary
>
> Hello
> Yes, at every step yuo will be dealing with single scattering.
> However, as I tould you in my previous mail, this is NOT enough in
> ordere to have a reliable simulation in sub-micron geometries. There are
> other processes whose description is intrinsically built on some
> averaging, like the energy loss and its fluctuation.These loose their
> validity on very short steps.
> I'm not surprised that you get differences in your geometry when going
> from multiple scattering to single scattering. The multiple scattering
> formulation is, as it name suggests, dealing with multiple scatterings
> in a single step. If the step is not long enough, the formulation looses
> its validity. Fluka takes this into account, but, again, not in extreme
> cases.
> Multiple scattering is not a Fluka invention, it dates to the original
> theory of Moliere, that you can find described in papers and textbooks.
> A description of the Fluka implementation of the Moliere multiple
> scattering is in NIM B71 (1992) 412-426.
> Regards
> Paola
>
> On Mon, 2013-10-21 at 09:21 +0800, yyc2011_at_mail.ustc.edu.cn wrote:
> > Dear Professor Paola,
> >
> > I'm very sorry to bother you again.
> > First,Last time,you said "For micron-sized geometries, single scattering should be set for all steps".In my eyes,all steps mean once the particle entered the target,we would deal with its transport in the target with single scattering until it pass through the target.In other words,for every step the particle moves in the target,we deal with the particle with single scattering.Am I right?
> > Second,When I set single scattering for all steps,the result is totally different from not setting single scattering.Now,I want to know the difference between single scattering code and mutiple scattering code in the Fluka.
> >
> > Best regards
> > YuanChen
> >
> >
> >
> >
> > > -----Original E-mail-----
> > > From: "paola sala" <paola.sala_at_cern.ch>
> > > Sent Time: 2013-10-15 21:13:09
> > > To: yyc2011_at_mail.ustc.edu.cn
> > > Cc: fluka-discuss_at_fluka.org
> > > Subject: Re: [fluka-discuss]: About the single scattering set at the boundary
> > >
> > > Dear YuanChen,
> > > the geometry you defined has layers as thin as 0.05 MICRONS. The models
> > > of the code cannot be used for such thin layers. A minimum size of about
> > > 1 micron should be kept to get meaningful results. For micron-sized
> > > geometries, single scattering should be set for all steps (see note 5 to
> > > the mulsopt description in the manual)
> > > Greetings
> > > Paola
> > >
> > >
> > > On 10/15/2013 04:34 AM, yyc2011_at_mail.ustc.edu.cn wrote:
> > > > Dear Fluka experts,
> > > >
> > > > I have a problem about the single scattering set at the boundary.I don't know when should I use the card MULSOPT.I don't know what is the influence to the result if I set the single scattering at the boundary.So,I try to explore the card MULSOPT.I find,when I use the card MULSOPT to set the single scattering at the boundary,I can get a result,and when I remove the card MULSOPT in the input file(other input parameters are the same),the result I get is total different.But why the result is so different?I'm confused this very much.Could you help me to give a reasonable explanation?The attachments contain two files,one is the input file,and the other is the comparison diagram.
> > > > Thanks for your time.Thanks for any suggestions.
> > > >
> > > > Best regards
> > > > YuanChen
> > > >
> > > >
> > > >
> > > >
> > >
> >
>
>
Received on Tue Oct 29 2013 - 04:06:27 CET

This archive was generated by hypermail 2.3.0 : Tue Oct 29 2013 - 04:06:58 CET