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Forum: Hadronic Processes
Re: None Photonuclear with Bertini in g4.10.00.p01 (Dario Lattuada)
Re: None Re: Photonuclear with Bertini in g4.10.00.p01 (Dennis H. Wright)
Re: None Re: Photonuclear with Bertini in g4.10.00.p01 (Dario Lattuada)
Re: None Re: Photonuclear with Bertini in g4.10.00.p01 (Dario Lattuada)
Date: 25 Jul, 2014
From: Michael H. Kelsey <Michael H. Kelsey>

On Fri, 25 Jul 2014 16:56:54 GMT, Dario Lattuada wrote:
> UPDATE
> 
> There's still something really strange.
> 
> Thresholds for 24Mg(g,a)20Ne and 12C(g,3alfa) are respectively about
> 9.32 MeV and 7.37 MeV.
> 
> With 11MeV gamma beam on carbon (and Mg) target with
> PreCompoundDeexcitation I get a lot of alphas from C->3alpha reaction
> (and it works down to 7.4 MeV also decreasing the # of output particles)
> but it's the only source of alphas up to 11MeV or above, so I can't find
> any alpha from 24Mg(g,a)20Ne until around 15 MeV.

I ran our internal unit test of BERT with gamma on 24Mg, and I don't see any alpha production below 17 MeV. This is the same for both PreCompound and for BERT's internal de-excitation modules. Below that threshold I see multiple gammas, and often a proton, but that's all.

BERT doesn't have any explicit "threshold" for different nuclei or different final states. Rather, the threshold appears as a consequence of the cascade: the gamma enters the nucleus and interacts with one nucleon, which then starts "travelling" in the nucleus, either exiting or having secondary collisions.

At this low energy, you'll either get the nucleon ejected or the nucleus put into an excited state which the de-excitation code will then process down to a ground state. The issue here may be with the order of operations in PreCompound: if it tries to reduce the energy by throwing off gammas first, that could be more favorable, and leave the system with too little energy for an alpha.

  -- Michael Kelsey

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1 None: Re: Photonuclear with Bertini in g4.10.00.p01   (Dario Lattuada - 29 Jul, 2014)
1 None: Re: Photonuclear with Bertini in g4.10.00.p01 (ERRATA CORRIGE)   (Dario Lattuada - 29 Jul, 2014)
2 None: Re: Photonuclear with Bertini in g4.10.00.p01   (Dennis H. Wright - 31 Jul, 2014)
1 None: Re: Photonuclear with Bertini in g4.10.00.p01   (Dario Lattuada - 01 Aug, 2014)
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