[fluka-discuss]: fluka simulation with Pb beam hitting silicon planes

From: Gianluca Usai <gianluca.usai_at_ca.infn.it>
Date: Mon, 4 Feb 2019 10:32:44 +0100

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

+39 070 675 4906
+41 22 767 5740 (CERN)

Strada prov.le per Sestu, km 1.00
09042 Monserrato (CA)


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Received on Mon Feb 04 2019 - 11:50:33 CET

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