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Question Re: Non Ionizing Energy Loss (NIEL) and Displacement Damage 

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Re: Question Non Ionizing Energy Loss (NIEL) and Displacement Damage
Re: Feedback Re: Non Ionizing Energy Loss (NIEL) and Displacement Damage (Michael H. Kelsey)
Date: Jun 06, 17:48
From: <jeonyboy@gmail.com>

First, thank you very much for your response. I am curious though, even though Geant4 isn't built to simulate diplacement damage, it still does produce secondary particles through inelastic scattering (nuclear reactions) for neutrons. This is what I found as definition of displacement damage mechanism:

Displacement damage occurs through interaction of incident particles with Si atoms by any of the following three processes: 1) Rutherford (i.e., Coulomb) scattering, 2) nuclear elastic scattering, and 3) nuclear inelastic scattering.

So couldn't the secondaries created by neutron via Hadr07 example be a indirect way of estimating displacement damage? Maybe not the whole picture, but a part of it.

On Wed, 23 May 2018 04:27:32 GMT, Michael H. Kelsey wrote:

> On Mon, 21 May 2018 16:01:08 GMT, jeonyboy wrote:
> 
> > Hello, I am trying to gather information of NIEL and displacement damage
> > from Geant4 simulations. I am trying to shoot neutron particles on a
> > variety of materials such as Hafnium Dioxide and silicon dioxide.
> 
> Geant4 does not include simulation of solids as crystalline structures,
> per se. In particular, there is no direct simulation of "displacement
> damage." If you were dealing with atomic beams, I would point you in the
> direction of SRIM/TRIM as a "better" simulation (one which more directly
> addresses your question). I don't know if something similar to SRIM
> exists for neutron beams.
> 
> One of the Geant4 examples, extended/electromagnetic/TestEm7 (which you
> already know about), does include physics processes and calculations,
> such as Lindhard partitioning, relevant to nuclear recoil and
> non-ionizing energy loss effects. But again, this example is aimed at
> heavy-ion interactions, and does not include neutrons as relevant
> particles for those processes.
> 
> > From what I've discovered, there is a GetNonIonizingEnergy function
> > which I tried to use in TestEm7. However, for neutrons, I am getting 0
> > value returned for nonionizing energy deposit. How do I remedy this?
> 
> The special processes in TestEm7 are only applied for GenericIon, not
> for neutrons. I suspect that even if you tried to simply add the
> processes to the neutron ProcessManager (and modified them so that
> IsApplicable() returned true for neutrons) you would not get physically
> correct results.
> 
> > Also, when I run example such as Hadr07, I can get a list of secondary
> > particle created along with their min and max energies. Can I understand
> > the secondaries as result of displacement damage? (See attached file).
> 
> Not really. Neutrons interact internally with individual nuclei, which
> (or some other transmuted species) will be produced as a recoiling
> secondary. However, Geant4 treats all materials as simple, uniform
> volumes of non-interacting particles, essentially an ideal gas with a
> suspiciously high density :-) Each atom is available for an interaction,
> but there is no "crystal potential", just as there is no valence or
> conduction band, or band gap, for electrons in a Geant4 "solid."
> 
> There are efforts, both within and outside Geant4, to develop additional
> physics processes, and in some cases, additional particles (non-scalar
> charge carriers in a crystal, for example), to model some of this very
> low-energy physics. But even these efforts don't include issues such as
> displacement damage due to neutrons.
> 
>   -- Michael Kelsey
> 

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1 Idea: Re: Non Ionizing Energy Loss (NIEL) and Displacement Damage   (Vladimir Ivanchenko - Jul 04, 05:45)
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