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Question Re: unstable ion lifetimes wildly wrong 

Forum: Hadronic Processes
Re: Question unstable ion lifetimes wildly wrong (Tom Roberts)
Re: None Re: unstable ion lifetimes wildly wrong (Dennis H. Wright)
Date: 19 Dec, 2016
From: Tom Roberts <Tom Roberts>

I put that test code into BeginOfEventAction, but G4IonTable still thinks Pu238 is stable.

What changed? This used to work as recently as geant4-10-01-patch-01.

Note the actual code has a loop over the geometry, looking for unstable isotopes in all volumes, so it only looks up the lifetimes of isotopes that have been used in some G4Material. Playing with that test code shows that the ion table claims Pu238 is stable regardless of whether it is used in the geometry or not. (This particular example is trying to simulate a radioisotope thermal generator.)

Note the file z94.a238 in RadioactiveDecay5.1 gives the correct half-life for Pu238 of 2.767602e+09 seconds.

Note also that MANY ions/isotopes have incorrect lifetimes, not just Pu238.

I also noticed another change: previously GetIonLifeTime() would return -1001 for very short-lived particles; it now returns 0 for them. This makes more sense, as a negative lifetime is used to flag stable isotopes.

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1 Ok: Re: unstable ion lifetimes wildly wrong   (Tom Roberts - 20 Dec, 2016)
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