Re: [fluka-discuss]: 66Cu half life problem

From: <alfredo.ferrari_at_mi.infn.it>
Date: Sun, 24 Apr 2022 05:56:54 +0200

Dear Sebastiano

The half-life of 66Cu in the Fluka database is 307 s, hence in agreement
with what you expect.

Are you sure 66Cu in your case is not fed by other decays, eg if you have
66Ni produced as well it will decay into 66Cu with a much longer
half-life, 1.97E5 s, and therefore 66Cu will be in equilibrium with 66Ni.

Please let me know if this is the case

Alfredo

> Dear Fluka expert,
>
> I’ve tried to calculate the activity of copper isotopes after a proton
> irradiation onto a 70Zn enriched target. (see the entire details in the
> file .inp attached)
>
> After the EOB (End of bombardment), the activity of all isotopes decays
> exponentially, following the respective decay constants. I’ve verified
> this, scoring the activities at 2 different times after the EOB
> (t=EOB+50000s and t=EOB+200000s).
>
> The problem appears for the 66Cu isotope: this should decay with a half
> life of 5 minutes, and so after only 50000 seconds after the EOB, the
> activity should goes to zero. This does not happen. It seems like the half
> life of 66Copper is different from 5 minutes. (see _sum.lis file attached)
>
> Furthermore, If you try calculate the decays constants for all the other
> copper isotopes involved (only using the activity a t=EOB and one between
> the 2 instant t=EOB+50000s or t=EOB+200000s), you obtain a coherent and
> correct values of the half lives. Instead, if you try to achieve the half
> life of 66Cu through this method, you obtain different results if you use
> t=EOB+50000s or t=EOB+200000s: respectively 2 hours and 7.5 hours of half
> life. (that are however wrong values)
>
> I do not understand how to solve this problem.
>
> Thanks.
>
> Sebastiano
>
> --
>
>


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Received on Sun Apr 24 2022 - 07:36:18 CEST

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