Dear Mario,
Thanks for your reply.Thanks for your time.Wish you have a nice day!
Best Regards
Chen Yuan
> -----Original E-mail-----
> From: "Santana, Mario" <msantana_at_slac.stanford.edu>
> Sent Time: 2013-12-14 14:07:39
> To: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>
> Cc:
> Subject: Re: [fluka-discuss]: How to optimize input files?
>
> Hi
>
> Answering your ulterior questions…
> - EMF-OFF will certainly safe CPU time because EM showers will be produced
> and all the products (e-,e+,gamma) tracked up to low energies. This has a
> CPU penalty.
> - No, the result will not be altered in your case because:
> 1) you were only scoring protons, not electrons, positrons or photons
> 2) protons could not be produced from the EM cascades because a) you don't
> have photo nuclear reactions activated and b) photomuon reactions have
> much higher threshold than your proton primary energy. Thus proton fields
> are not altered in your case by not tracking EM showers.
>
> Mario
>
> On 12/13/13 8:49 PM, "yyc2011_at_mail.ustc.edu.cn" <yyc2011_at_mail.ustc.edu.cn>
> wrote:
>
> >Dear Santana,
> >
> > Thanks for your suggestions.In your reply,you said "In particular, for
> >your proton case you could save a lot of CPU with EMF-OFF." Why using
> >EMF-OFF will save a lot of CPU for protons? On the other hand,will the
> >result be changed when use EMF-OFF comparing with not using EMF-OFF?
> >
> >Best Regards
> >Chen Yuan
> >
> >
> >> -----Original E-mail-----
> >> From: "Santana, Mario" <msantana_at_slac.stanford.edu>
> >> Sent Time: 2013-12-14 3:28:40
> >> To: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>
> >> Cc:
> >> Subject: Re: [fluka-discuss]: How to optimize input files?
> >>
> >> Chen,
> >>
> >> I believe the purpose of this list is to provide guidance of specific
> >> FLUKA questions. With that spirit, I will give you some tips and
> >> recommendations, but I cannot go in-depth and perform your work.
> >>
> >> The first thing to say, is that speed of computation is not an absolute
> >> number to quantify the efficiency of your input file. It is all relative
> >> to the statistical uncertainty of the observables that you are scoring
> >>for
> >> that amount of CPU. For example, the CPU/history may be high when you
> >>have
> >> intense region biasing, but this does not necessarily mean you are
> >>wasting
> >> CPU, on the contrary, if region biasing is well tuned, you may be
> >> following many split trajectories towards your region of interest for a
> >> single history.
> >>
> >> Now, the question is whether you are wasting CPU time in processes that
> >> you don't need. In that regard I have recommend the following:
> >> 1) Reduce the number of particles per cycle and run several cycles.
> >> Analyze your results and evaluate how many particles you need in total
> >>to
> >> converge to the desired result
> >>
> >> 2) You use PRECISIO as your DEFAULT. This cards includes many options
> >>and
> >> precise settings which you may not need. I copy them at the end of the
> >> email. You should decide whether this is the DEFAULT that you want
> >>(maybe
> >> you could survive with NEW-DEFA?), or switch off those cards that are
> >>not
> >> needed for your problem. In particular, for your proton case you could
> >> save a lot of CPU with EMF-OFF. For your ELECTRON case you could play
> >>with
> >> the cut-off energies (the lower the energy the longer the simulation).
> >> 3) You are using MULSOPT. This may impact your processing speed.
> >> 4) Your USRBIN has a 2000x2000 grid. The more you write to files the
> >> slower the simulation can get. Try having a coarser grid if CPU is a
> >> concern to you. Also, the smaller the bin, the more individual
> >>statistical
> >> error you will get for a given CPU time.
> >>
> >> I hope this helps
> >>
> >>
> >> DEFAULTS=PRECISIO
> >>
> >>
> >> * EMF <http://www.fluka.org/fluka.php?id=man_onl&sub=25> on
> >>
> >> * Rayleigh scattering and inelastic form factor corrections to Compton
> >> scattering and Compton profiles activated
> >>
> >> * Detailed photoelectric edge treatment and fluorescence photons
> >>activated
> >>
> >> * Low energy neutron transport on down to thermal energies included,
> >>(high
> >> energy neutron threshold at 20 MeV)
> >>
> >> * Fully analogue absorption for low-energy neutrons
> >>
> >> * Particle transport threshold set at 100 keV, except neutrons (1E-5
> >>eV),
> >> and (anti)neutrinos (0, but they are discarded by default anyway)
> >>
> >> * Multiple scattering threshold at minimum allowed energy, for both
> >> primary and secondary charged particles
> >>
> >> * Delta ray production on with threshold 100 keV (see option DELTARAY
> >> <http://www.fluka.org/fluka.php?id=man_onl&sub=21>)
> >>
> >> * Restricted ionisation fluctuations on, for both hadrons/muons and EM
> >> particles (see option IONFLUCT
> >> <http://www.fluka.org/fluka.php?id=man_onl&sub=42>)
> >>
> >> * Tabulation ratio for hadron/muon dp/dx set at 1.04, fraction of the
> >> kinetic energy to be lost in a step set at 0.05, number of dp/dx
> >> tabulation points set at 80 (see options DELTARAY
> >> <http://www.fluka.org/fluka.php?id=man_onl&sub=21>, EMFFIX
> >> <http://www.fluka.org/fluka.php?id=man_onl&sub=28>, FLUKAFIX
> >> <http://www.fluka.org/fluka.php?id=man_onl&sub=35>)
> >>
> >> * Heavy particle e+/e- pair production activated with full explicit
> >> production (with the minimum threshold = 2m_e)
> >>
> >> * Heavy particle bremsstrahlung activated with explicit photon
> >>production
> >> above 300 keV
> >>
> >> * Muon photonuclear interactions activated with explicit generation of
> >> secondaries
> >>
> >> * Heavy fragment transport activated
> >>
> >>
> >>
> >>
> >>
> >> On 12/13/13 3:38 AM, "yyc2011_at_mail.ustc.edu.cn"
> >><yyc2011_at_mail.ustc.edu.cn>
> >> wrote:
> >>
> >> >Dear all,
> >> >
> >> > The attachmens are my input files.The first one is the input file for
> >> >protons.since I have run it for eleven days,but my computer have not
> >> >finished the first cycle.The calculation is too slow.So,I wish you
> >>could
> >> >see my input file,and optimize the input file so as to improve the
> >> >calculation speed.The second input file is about electrons.Likewise,I
> >> >wish you could see my input file and find whether there are something
> >> >wrong in my input file.I am not sure about this.So I wish you could
> >>help
> >> >me.
> >> > Thanks for any suggestion.Thanks for your help.
> >> >
> >> >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 Molière's Theory of Multiple Scattering
> >> >> let me also advice a historical paper by H. Bethe in Phys. Rev. 89,
> >> >>12561266 (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
> >> >> >>
> >> >>
> >>
> >
>
Received on Mon Dec 16 2013 - 14:12:28 CET