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Warning Bug in dnaphysics example 

Forum: DNA/Very Low Energy
Date: Jun 15, 08:07
From: Ivan Konobeev <Ivan Konobeev>

Hello

I would like to report a bug in

examples -> extended -> medical -> dna -> dnaphysics

example of Geant4 10.04.p01. I would appreciate if one of devs would confirm that it is a bug and reply to this message.

To reproduce this bug one should make these changes in "dnaphysics.in" control file:

/tracking/verbose 0 -> /tracking/verbose 1

/gun/particle proton -> /gun/particle e-

/gun/energy 100 keV -> /gun/energy 10 keV

Then run example with "dnaphysics.in" file as argument. For example:

Debug\dnaphysics dnaphysics.in

You will see that electrons with kinetic energy of EXACTLY 10 keV can only suffer elastic scattering and cannot ionise other electrons or deposit any energy in water medium at all. The only process that occurs is "e-_G4DNAElastic". If one changes energy of electrons to 9.9 keV or 10.1 keV this problem dissapears.

Activating physics with

RegisterPhysics(new G4EmDNAPhysics());

in PhysicsList instead of using mixed standard and DNA physics with G4EmDNAPhysicsActivator also solves the problem.

The source of the problem is likely in G4EmDNAPhysicsActivator who attaches two models for e-_G4DNAIonisation process: DNAEmfietzoglouIonisationModel (from 0 eV to 10 keV) and DNABornIonisationModel (from 10 keV to 1 MeV). So these models probably do not cover energy of exactly 10 keV so that e-_G4DNAIonisation process does not occur in simulation process at all.

This bug probably will not affect results of any simulations unless user sets energy of source to exactly 10 keV. But if he does he will obtain wrong results.

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1 None: Re: Bug in dnaphysics example   (Sebastien INCERTI - Jun 18, 02:07)
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