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Forum: Biasing and Scoring
Re: Question Hadr01 Can't count secondaries at a few hundred keV (Robert Nnaemeka)
Date: 27 Feb, 2015
From: Daren Sawkey <Daren Sawkey>

The electrons are below the default production threshold energy. Lower it by e.g. adding these lines to your macro:

/testhadr/CutsAll 1 nm

/cuts/setLowEdge 2 eV

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Feedback Re: Hadr01 Can't count secondaries at a few hundred keV  by Robert Nnaemeka <Robert Nnaemeka>,   27 Feb, 2015
Re: None Re: Hadr01 Can't count secondaries at a few hundred keV (Daren Sawkey)
Also, the computation is interminable.I had to issue abort instruction for it to display the computation. Is this due to infrared divergence? I am guessing I may need to increase the production threshold energy. What do you think? On Fri, 27 Feb 2015 19:15:45 GMT, Daren Sawkey wrote:
> The electrons are below the default production threshold energy. Lower
> it by e.g. adding these lines to your macro:
> 
> /testhadr/CutsAll 1 nm
> 
> /cuts/setLowEdge 2 eV
> 

None Re: Hadr01 Can't count secondaries at a few hundred keV  by Daren Sawkey <Daren Sawkey>,   27 Feb, 2015
Re: Feedback Re: Hadr01 Can't count secondaries at a few hundred keV (Robert Nnaemeka)
Yes, that's the reason for the cut in the first place.

Many of the electrons are produced by electron ionization, rather than proton. If you turn off electron ionization the code runs much faster (although with dubious physics): /process/inactivate eIoni

The DNA physics group is interested in this type of interaction, although maybe not Ti. You could try that forum. Also try hadronics forum.

Feedback Re: Hadr01 Can't count secondaries at a few hundred keV  by Robert Nnaemeka <Robert Nnaemeka>,   27 Feb, 2015
Re: None Re: Hadr01 Can't count secondaries at a few hundred keV (Daren Sawkey)
Thanks. The simulation is a part of D-D fusion, a novel High Flux Neutron Generator under construction. The target is inside a high vacuum ~10^-5 torr and I think if I choose the production threshold accordingly, electron ionization would be reduced. So far, simulation of residual gas ionization shows it is very small. So, switching of electron ionization might not affect the result. I will post it in any of the forum. You saved me much hassle. Many thanks. On Fri, 27 Feb 2015 20:28:17 GMT, Daren Sawkey wrote:
> Yes, that's the reason for the cut in the first place.
> 
> Many of the electrons are produced by electron ionization, rather than
> proton. If you turn off electron ionization the code runs much faster
> (although with dubious physics): /process/inactivate eIoni
> 
> The DNA physics group is interested in this type of interaction,
> although maybe not Ti. You could try that forum. Also try hadronics
> forum.
> 

None Re: Hadr01 Can't count secondaries at a few hundred keV  by Daren Sawkey <Daren Sawkey>,   27 Feb, 2015
Re: Feedback Re: Hadr01 Can't count secondaries at a few hundred keV (Robert Nnaemeka)
> So far, simulation of
> residual gas ionization shows it is very small.

Just to be clear, the ionization occurs in the metal as well. I don't recommend turning off the eIoni process, except as a means to study the problem. You'll have to determine what is physically realistic.

Ok Re: Hadr01 Can't count secondaries at a few hundred keV  by Robert Nnaemeka <Robert Nnaemeka>,   28 Feb, 2015
Re: None Re: Hadr01 Can't count secondaries at a few hundred keV (Daren Sawkey)
Good. Your replies helped me understand the whole process and be ready to apply it to the physical situation at hands. Many thanks.On Sat, 28 Feb 2015 00:58:30 GMT, Daren Sawkey wrote:
> > So far, simulation of
> > residual gas ionization shows it is very small.
> 
> Just to be clear, the ionization occurs in the metal as well. I don't
> recommend turning off the eIoni process, except as a means to study the
> problem. You'll have to determine what is physically realistic.
> 

Feedback Re: Hadr01 Can't count secondaries at a few hundred keV  by Robert Nnaemeka <Robert Nnaemeka>,   01 Mar, 2015
Re: Ok Re: Hadr01 Can't count secondaries at a few hundred keV (Robert Nnaemeka)
Hi Darren, This is the result so far after setting minimum energy threshold to ~ 50eV and selecting setting the proton cut to about 1keV. Simulation is indicating secondary production in Molybdenum cannot start at proton energy less than ~ 83keV. However, published experimental data indicates significant electron production at proton energy as low as 25keV. Again, as the energy is increased, the average electron produced increased in exponential form to ~44 at 120keV. But experimental data from published works indicated that electron liberation in Molybdenum is about 0.2 at proton energy of 25keV and levels 0ff to ~1.5 at about 120keV. What could be wrong with my simulation? I added the check volume as a sensitive detector in addition to the target, so as to ensure all liberated electrons were detected. Many thanks.

Feedback Re: Hadr01 Can't count secondaries at a few hundred keV  by Robert Nnaemeka <Robert Nnaemeka>,   27 Feb, 2015
Re: None Re: Hadr01 Can't count secondaries at a few hundred keV (Daren Sawkey)
Thanks Daren. I did it and it is working as expected. However, the computation time increased in a quantum amount. Is there any way I could speed up the computation? I am using intel i7 core laptop with 8GB RAM.On Fri, 27 Feb 2015 19:15:45 GMT, Daren Sawkey wrote:
> The electrons are below the default production threshold energy. Lower
> it by e.g. adding these lines to your macro:
> 
> /testhadr/CutsAll 1 nm
> 
> /cuts/setLowEdge 2 eV
> 

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