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Question Alphas cutting off at 1.77 MeV 

Forum: Hadronic Processes
Date: 20 Jun, 2011
From: Kareem Kazkaz <Kareem Kazkaz>

Hello all.

I am tracking alphas in a volume of liquid xenon, and for some reason the tracking is cutting off at just below 1.8 MeV. That is to say, the last step is depositing the remaining energy all in one go. I have the secondaries cut length set to 1 nm, so the alpha should be tracked to energy much lower than this.

I started with 5-MeV alphas, turned tracking verbosity to 1, and attached the output. As you can see from the attachment, there is a very large jump in dE/dx at 1.79 MeV. Sometimes the cutoff is at 1.37 MeV, sometimes at 1.77 MeV, but it's always in that range.

I am using GEANT4.9.4.p01, and invoking the QGSP_BIC_HP list from the physics factory. I have also tried substituting in the Livermore list for the standard EM list, with similar results.

Any ideas on what's going on? Why would the alpha energy bottom out?

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2011/06/20/17.08-89793-IonizationOutput.txt

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1 Idea: Re: Alphas cutting off at 1.77 MeV   (Vladimir Ivanchenko - 22 Jun, 2011)
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