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Forum: Physics List
Re: None Secondaries from heavy-ion projectiles with different physics lists (Mark Looper)
Re: Idea Re: Secondaries from heavy-ion projectiles with different physics lists (Vladimir Ivanchenko)
Date: 20 Aug, 2013
From: Mark Looper <Mark Looper>

On Tue, 16 Jul 2013 12:16:24 GMT, Vladimir Ivanchenko wrote:
> Hello,
> 
> would it be possible to repeat the study using Geant4 10.beta recently available?
>  The reason is that FTF ion/ion interaction in previous version of Geant4 was very preliminary (not all features were in). Now this model is released in desired form, so some differences with previous results are expected. If we speak about Binary cascade for ion/ion interaction E>2 GeV/u is away of model assumptions, the model should not properly forhigher energies.
> 
> VI
> 

Sorry to have sat on this for a month; other projects intervened, and I had some problems getting runtime on our cluster. I finally finished running the same simulation, as detailed in the original message:

http://hypernews.slac.stanford.edu/HyperNews/geant4/get/phys-list/772.html

but under the beta of version 10 of Geant4. I used the QBBC_EMZ reference physics list, and it does show some differences compared to 9.6.p01; however, it still has alarming "jumps" at high projectile energies, just past the galactic cosmic ray peak. I attach two plots; one is for direct comparison with the plots I sent with the original message, showing the spectra of protons coming backwards out of the side of the aluminum slab struck by the Fe56 beam, as a function of Fe56 energy. The "step" around 2 GeV/u incident energy is still there, but now there is another one around 4 GeV/u. The second plot shows alphas coming out the frontside; the strong "band" that asymptotically turns into a diagonal is from alphas that cleave off the incident Fe56 and continue forward with nearly its full velocity, but you can also see strong "steps" in the more diffuse secondary production around 2 and 4 GeV/nuc incident energy.

So -- given this situation, what is your recommendation for a physics list to study secondary production by heavy ions around hundreds of MeV/u to a few GeV/u striking matter? Again, my application is "albedo" from cosmic rays striking the surface of the moon and the atmosphere of the Earth, plus breakup of cosmic rays striking space radiation sensors (or shielding).

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/08/20/17.23-98877-qbbc_emz_beta.png
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/08/20/17.23-42204-qbbc_emz_beta_alphas.png

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1 Idea: Re: Secondaries from heavy-ion projectiles with different physics lists   (Mark Looper - 21 Aug, 2013)
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