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## Re: Unexpected results for fluence and TID using Spenvis/GRAS

Forum: Space Applications
Re: Unexpected results for fluence and TID using Spenvis/GRAS (Svetlana Shasharina)
Date: 08 Mar, 2016
From: Svetlana Shasharina <Svetlana Shasharina>

 ```One more data point, when I switch from FLUX to CURRENT normalization, the TID becomes 4 times larger, while fluences become 4 times smaller. Sveta On 3/8/16 11:07 AM, Svetlana Shasharina wrote: > *** Discussion title: Space Applications > > I did the following calculations using Spenvis/GRAS(gdml): > > 1. Independent runs for two vacuum spheres with r = 19cm and r = 15 cm. > Source: Monoenergetic (100MeV) electrons with fluence 100 (1/cm^2 s), > sphere with r = 20cm. > > SPENVIS calculated fluences 28390 and 17644 for the first and the second > spheres. The ratio of fluences/surface_area is constant for these cases > (6.24 and 6.26) and is very close to 2pi :-) but is very different from > the incident fluence (100). > > First confusion: I thought the calculated fluence is normalized to the > target's areas. But looks like it is not. Second confusion: after > dividing by the surface areas I still have a number very different to > the incident environment number (100). > > Maybe I do not understand what the incident fluence really mean? How do > I get a number that would relate to it? > > 2. Ta sphere r = 15cm, calculating TID in MeV with the source described. > I get 1.6564e+06MeV/s. > > If all e were to absorb, I would expect 100(1/cm^2 s)*100MeV*SurfaceArea > = 1e+4 MeV/s *2826cm^2 = 2.8e+7 MeV/s. > > So about 1/16 of the electrons gets absorbed, I guess? If I change > normalization to CURRENT instead of FLUX, I will get 1/4 difference, I > assume. Still a big difference. Any intuitive reaction to this > difference? > > Best regards, Sveta > > ------------------------------------------------------------- > Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at: > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/space_app/120.html > ```

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1 Re: Unexpected results for fluence and TID using Spenvis/GRAS   (Svetlana Shasharina - 10 Mar, 2016)
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