Date: Wed, 6 Feb 2019 23:09:49 +0530
Dear Cesc,
Thanks for highlighting the distinct feature of "trajectory plot" in
FLAIR. I am a just beginner in FLUKA but trying to learn from
fluka-discussions as in your valuable reply to Gianluca's problem. I am
just working with simple example of photon attenuation in some material.
The transmission values are been obtained using USRBDX score card. I tried
to plot a trajectory plot in mine case by following the procedure you
explored to Gianluca. But I did not find any USERDUMP output file to
upload, you can see the screenshot for the same. Could i make a trajectory
in my simple geometry? please help to plot the same by correcting my input.
Regards,
A. Sharma
On Wed, Feb 6, 2019 at 9:36 PM Francesc Salvat-Pujol <
francesc.salvat.pujol_at_cern.ch> wrote:
> Dear Gianluca,
>
> Indeed, the trajectory plot is one of the many distinctly practical
> features of Flair.
>
> Once you have your USERDUMP output file visible, you:
>
> - click on "Layers"
> - click on the little arrow with the hover text "Add layer to project"
> - enter some name for the layer, e.g. "Layer"
> - click on <Add>
> - click on Userdump
> - select userdump file
> - select for which particle you want to see trajectories
> - click Apply
> - go to some viewport and select the newly created "Layer" instead of
> the usual Media/Borders/3D/Lattice.
>
> With kind regards,
>
> Cesc
>
> On Wed, Feb 06 2019, at 14:31 +0100, Gianluca Usai wrote:
> >
> >Dear Cesc,
> >thanks a lot for the very nice and instructive account. I think this
> clarified essentially everything.
> >I was not aware about the possibility to visualize particle tracks in
> flair superimposed to the geometry. May I profit a little bit more to ask
> how can I do that?
> >Thanks again,
> >Cheers,
> > Gianluca
> >
> >> PS3: I understand that you linked with ldpmqmd.
> >yes
> >
> >
> >Il giorno 06/feb/2019, alle ore 13:02, Francesc Salvat-Pujol <
> francesc.salvat.pujol_at_cern.ch> ha scritto:
> >
> >> Dear Gianluca,
> >>
> >> In the attachment is a Flair screenshot from a quick run showing a few
> >> electron trajectories in the XZ plane (upper right-hand viewport) and
> >> the YZ plane (lower left-hand viewport). One sees the trajectories
> >> nicely spiraling under the action of your B field along the X axis
> >> (viewport XZ) and one can examine the various radii in the YZ viewport.
> >> For screenshot clarity I killed electrons below 10 MeV.
> >>
> >> Looking at the XZ projection one sees that the delta rays cross your
> >> first disk many times as the electrons progress along X, however, in the
> >> YZ projection one realizes it's basically at two well defined spots
> >> along the Y axis: at Y~0 (disk axis, where most delta rays initiate) and
> >> at a second Y=spiral radius. This explains why you see the fluence
> >> decrease along Y: whereas "all" spirals cross Y~0, at finite Y>0 only
> >> those with energy matching such a curving radius will.
> >>
> >> Another aspect which contributes to the more intense fluence you observe
> >> at small Y is that delta rays with lower energy (smaller spiral radius)
> >> are much more likely to be produced: the "delta ray production" cross
> >> section goes like 1/T^2, where T is the energy loss of the passing
> >> charged particle which sets the delta ray in motion.
> >>
> >> In order to try to account for the structure along the X axis, and to
> >> see which electrons contribute where, in the lower panels of the
> >> screenshot I scored the electron fluence (your unit 27) for various
> >> values of the delta-ray production threshold, Tdelta: 100 keV, 1 MeV,
> >> 10 MeV, 50 MeV, and 100 MeV.
> >>
> >> The rightmost panel (Tdelta=100 MeV) shows the expected spot around Y~0,
> >> one at Y~20 cm (the expected 2*radius for electrons in B=3 T as per the
> >> cheatsheet in the PS below) and some minor hits in between, which should
> >> correspond to energetic delta rays originating in the other disks (one
> >> can spot such situations in the YZ viewport).
> >>
> >> Similar story for the Tdelta=50 MeV and 10 MeV plots, but at the
> diameters
> >> exceeding the expected ~10 cm and ~2 cm, respectively.
> >>
> >> Note also that when including lower energy delta rays, the pitch or step
> >> of the spiral they fly on decreases (it should scale with the velocity
> >> along the field axis), which could explain the occasional empty pixel
> >> along X for Y~0 at the larger Tdelta plots. Of course, this applies only
> >> for the presently poor statistics: with a more serious/long run you'd
> >> eventually get a smooth picture, but the origin would be clear.
> >>
> >> The CSDA range for 1 MeV electrons in Si (just a coarse estimate from a
> >> quick read of the ESTAR plot and dividing by rho=2.32 g/cm^3) should be
> >> something like ~0.24 cm and for 100 keV it's something around .008 cm
> >> (80 micron already). The latter is comparable to your disk's 50 micron
> >> thickness.
> >>
> >> Thus, delta rays with, say, 100 keV - 1 MeV may manage to spiral a few
> >> times in and out of the disk, losing a bit of energy at every crossing,
> >> but dropping below (transport) threshold quite soon and not making to
> >> the edge of your disk. Indeed, for the Tdelta=1 MeV and 100 keV plots
> >> you see a quite intense maximum "blob" at X=Y=0 in the fluence (many
> >> such slow delta rays produced as per 1/Tdelta^2), with a finite extent
> >> along X as expected, and quite intense (there are a lot of such slow
> >> delta rays).
> >>
> >> Considering the above, unless I am missing something essential, the
> >> overall structure and sizeable intensity of your fluence plots could
> >> well be reasonable.
> >>
> >> Your initial expectation (to just see electrons close to the axis) is
> >> indeed what one would expect in the absence of a magnetic field.
> >>
> >> I hope the above is reasonably accurate/helpful!
> >>
> >> Cheers,
> >>
> >> Cesc
> >>
> >> PS: the cheatsheet/table. In m, the rule of thumb for the (electron)
> >> radius was something like r = p / (0.3 B), with p in GeV/c and B in T.
> >> For electrons in your B=3 T, we have 0.3B~1, so
> >>
> >> Edelta = 1 MeV ---> r ~ 0.14 cm
> >> Edelta = 10 MeV ---> r ~ 1 cm
> >> Edelta = 50 MeV ---> r ~ 5 cm
> >> Edelta = 100 MeV ---> r ~ 10 cm
> >>
> >> PS2: seems like your source is precisely on the boundary between two
> >> regions (the black hole region and vacuum). Advance it a bit into vacuum
> >> to be on the safe side with respect to numerical hiccups.
> >>
> >> PS3: I understand that you linked with ldpmqmd.
> >>
> >>> Dear Fluka users,
> >>> I would like to study the charged particle fluence produced by a 40
> GeV Pb beam shooted across silicon disks of radius 20 cm and thickness 50
> micron. These mimics silicon tracking stations based on a possible very
> large area monolithic active pixel sensor which is being discussed for
> future heavy ion fixed target experiments. There is no central hole in the
> silicon disk in this simulation. The disks are immersed in a 3 T dipole
> field along x. Since I would like to see the fluence along x-y at the z of
> the different disks, I thought to use usrbin with -30<x,y<30 (60 bins in
> x,y), abs(z-zdisk)<50 micron (1 bin in z).
> >>> I attach the .inp file (there is the possibility to simulate also a Pb
> target system, but the target volume is filled with vacuum in this
> simulation).
> >>> The scoring of the electron fluence in the first disk is puzzling me
> (usrbin card with output unit 27). I attach a fluence plot from a
> simulation of 1000 primary ions. The fluence seems rather large and there
> is a very long horizontal band along x extending even beyond abs(x)>20 cm
> which I cannot explain. I would have thought naively to see electrons more
> or less close around the ion crossing point. I would appreciate if you
> could give me some clue about what I am observing and in particular if
> there is something wrong in the scoring or in the settings in the .inp file.
> >>> Thanks in advance,
> >>> best regards,
> >>> Gianluca Usai
> >>>
> >>>
> >>> ______________________________
> >>> Gianluca Usai
> >>>
> >>> Professor of physics
> >>> Department of Physics and INFN
> >>> Cagliari - Italy
> >>>
> >>> Phone:
> >>> +39 070 675 4906
> >>> +41 22 767 5740 (CERN)
> >>>
> >>> Address:
> >>> Strada prov.le per Sestu, km 1.00
> >>> 09042 Monserrato (CA)
> >>> Italy
> >>>
> >>> web:
> >>> http://gruppo3.ca.infn.it/usai
> >>> http://people.unica.it/gianlucausai
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>> <html><body style="word-wrap: break-word; -webkit-nbsp-mode: space;
> -webkit-line-break: after-white-space;"><head><meta
> http-equiv="Content-Type" content="text/html
> charset=us-ascii"></head><div></div></body></html>
> >>
> >>> <html><body style="word-wrap: break-word; -webkit-nbsp-mode: space;
> -webkit-line-break: after-white-space;"><head><meta
> http-equiv="Content-Type" content="text/html
> charset=us-ascii"></head><div></div></body></html>
> >>
> >>> <html><head><meta http-equiv="Content-Type" content="text/html
> charset=us-ascii"></head><body style="word-wrap: break-word;
> -webkit-nbsp-mode: space; -webkit-line-break:
> after-white-space;"><div></div><div apple-content-edited="true">
> >>> <span class="Apple-style-span" style="border-collapse: separate;
> border-spacing: 0px;"><div style="word-wrap: break-word; -webkit-nbsp-mode:
> space; -webkit-line-break: after-white-space;"><span
> class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0,
> 0); font-family: Helvetica; font-style: normal; font-variant: normal;
> font-weight: normal; letter-spacing: normal; line-height: normal; orphans:
> 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2;
> word-spacing: 0px; border-spacing: 0px; -webkit-text-decorations-in-effect:
> none; -webkit-text-stroke-width: 0px;"><div style="word-wrap: break-word;
> -webkit-nbsp-mode: space; -webkit-line-break:
> after-white-space;"><div>______________________________<br><font
> class="Apple-style-span" size="4"><span class="Apple-style-span"
> style="font-size: 14px;">Gianluca Usai</span></font><div><font
> class="Apple-style-span" size="4"><span class="Apple-style-span"
> style="font-size: 14px;"><br></span></fon!
> t><div><font class="Apple-style-span" size="4"><span
> class="Apple-style-span" style="font-size: 14px;">Professor of
> physics<br>Department of Physics and INFN<br>Cagliari -
> Italy<br><br>Phone:<br>+39 070 675 4906<br>+41 22 767 5740
> (CERN)<br><br>Address:<br>Strada prov.le per Sestu, km 1.00<br>09042
> Monserrato (CA)<br>Italy<br><br>web:<br><a href="
> http://gruppo3.ca.infn.it/usai">http://gruppo3.ca.infn.it/usai</a></span></font></div></div></div><div><font
> class="Apple-style-span" size="4"><span class="Apple-style-span"
> style="font-size: 14px;"><a href="http://people.unica.it/gianlucausai">
> http://people.unica.it/gianlucausai</a></span></font></div><div><font
> class="Apple-style-span" size="4"><span class="Apple-style-span"
> style="font-size: 14px;"><br></span></font></div></div></span><br
> class="Apple-interchange-newline"></div></span><br
> class="Apple-interchange-newline"><br class="Apple-interchange-newline">
> >>> </div>
> >>> <br></body></html>
> >>
> >> --
> >> Francesc Salvat Pujol
> >> CERN-EN/STI
> >> CH-1211 Geneva 23
> >> Switzerland
> >> Tel: +41 22 76 64011
> >> Fax: +41 22 76 69474
> >> <sshot.png>
> >
> >______________________________
> >Gianluca Usai
> >
> >Professor of physics
> >Department of Physics and INFN
> >Cagliari - Italy
> >
> >Phone:
> >+39 070 675 4906
> >+41 22 767 5740 (CERN)
> >
> >Address:
> >Strada prov.le per Sestu, km 1.00
> >09042 Monserrato (CA)
> >Italy
> >
> >web:
> >http://gruppo3.ca.infn.it/usai
> >http://people.unica.it/gianlucausai
> >
> >
> >
> >
> >
>
> --
> Francesc Salvat Pujol
> CERN-EN/STI
> CH-1211 Geneva 23
> Switzerland
> Tel: +41 22 76 64011
> Fax: +41 22 76 69474
>
>
> __________________________________________________________________________
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(image/png attachment: Screenshot_2019-02-07_04-14-52.png)
- application/octet-stream attachment: attenuation1.inp