Re: [fluka-discuss]: the quantity scored net charge in USRBIN

From: Andrea Fontana <>
Date: Sat, 13 Jul 2019 06:41:54 +0200

Dear Joey,
    there are particles leaving your volume that are lost into VOID:
among these you can find also secondary protons generated by nuclear
interactions of the primary beam with copper (presumably in the beam
entry region). So the situation from the point of view of the net
charge is more complex.

To see this, the first step is to check at the end of the .out
file to find that energy is transported out of the system:

4.4471E-04  ( 0.6%)   0.0000E+00 ( 0.0%) GeV particles escaping the system

If you add a USRBIN for ENERGY, you see that energy is deposed
at the edges of your target, suggesting to investigate also
the surrounding region. By adding a USRBDX scorer, you can
obtain the energy spectrum of the particles leaving the target.
Finally, to inspect their charge, the best way is with the MGDRAW
user routine, in which you can add in the BXDRAW entry the
following instruction:


that will print in a text file particle ID, energy and charge.
You can then analyze the charge distribution of your leakage!
The NET-CHRGE is given in units of the elementary charge.

I send you a modified version of your input file, the
mgdraw.f routine, a couple of screenshots for the energy
deposition and spectrum plots and the text file generated
in my run.

Hopefully this reply to your questions.
Kind regards and ciao,

On 12/07/2019 18:32, 盛尹祥子 wrote:
> Dear experts,
> I am trying to understand the USRBIN scoring quantity of NET-CHRG.
> Attached is the input file and the results (ASCII), it was a simple
> input file case,
> 80MeV proton beam (point beam) incident in an 30cm*30cm*30cm copper.
> Apperently, the proton will all stop inside the copper so the charge
> that the copper collected should be around 1.
> However, when I scoring the net charge using NET-CHRG in USRBIN with
> type X-Y-Z (although in the manual it is not allow to use NET-CHRG
> when what(1)≥10, I can still run the input file), the result is around
> 0 (-7.8E-6).
> Questions are
> 1. What is the unit for this result?
> 2. Why the result is around zero instead of 1 for this case?
> 3. Any other suggestions for scoring the charge in copper for proton
> beam (main purpose: simulation of the respond of a faraday-cup in
> proton beam)?
> We appreciate for your help.
> Best regards,
> */
> /*
> */盛尹祥子/*
> */Y. Sheng(Joey)/*
> /-------------------------------------------/
> /上海市质子重离子医院/
> /Shanghai Proton and Heavy Ion Center(SPHIC)/
> /email:
> /cell: 001-86-18049876663/
> /mail: //4365 Kangxin Road, Pudong, Shanghai 201321/

Dr. Andrea Fontana                    tel: +39 0382 987991
Istituto Nazionale                    fax: +39 0382 423241
di Fisica Nucleare
Sezione di Pavia                      e-mail:
Via Bassi 6                           web   :
27100 PAVIA, Italy

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Received on Sat Jul 13 2019 - 09:03:21 CEST

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