[fluka-discuss]: RE: net charge scoring

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Wed, 17 May 2017 05:43:27 +0000

Dear Tristan,

NET-CHRG gives the algebraic sum of the charges entering the URBIN volume minus the algebraic sum of charge leaving the same volume. For example, if a photon enter the volume and interact with an orbital electron of an atom to produce a recoil electron and a scattered photon (Compton interaction) both leaving the volume, in that case NET-CHRG will be equal to 1 (0 entering minus -1 leaving)...

Now for the plot, I can imagine that if your simulation, or part of it, satisfies the conditions for charged particle equilibrium (number of charged particles entering a volume equal to number of charged particles leaving it) then the bin content for NET-CHRG will fluctuate around 0 and your plots will appear noisy (while other quantities as fluence or deposited energy will look "smooth"). I would expect a better "resolution" close to region boundaries (when filled with different material) or close to the beam starting location....

Hoping this help
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of tristan.davenne_at_stfc.ac.uk
Sent: 15 May 2017 10:03
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: net charge scoring

Dear FLuka experts,

I have some questions regarding the net charge estimator which can be scored using a USRBIN.

1. Firstly, can you confirm if a positive result means that a bin has a net increase in positive charge, i.e. if there were several electrons generated in a bin which were able to escape that bin would a positive net charge be reported?

2. What are the conditions for a charge being generated in a bin containing a conductive material, i.e. for example if a proton passes through a bin containing a metal atom. How much energy must the proton pass onto an electron before it is considered that a charge has been generated?

3. Why do my net charge plots appear very noisy? I have plenty of primary particles to obtain nice smooth USRBIN contour plots of energy deposition and electron fluence or proton fluence but the net charge estimator always gives me a very noisy result? Are more statistics required or is this showing a real physical effect?

I would be grateful for any help, guidance on scoring net charge.

Kind Regards


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Received on Wed May 17 2017 - 08:51:11 CEST

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