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

From: Giorgi Kharashvili <giorgi.kharashvili_at_daes.pro>
Date: Mon, 25 Apr 2022 10:20:04 +0200

Dear Sebastiano,

The Cu-66 that you observe 50000s after the EOB is coming from beta-
decay of Ni-66.

If you compare these two isotopes in your tab.lis files, you will
notice that after some decay time Cu-66 is in equilibrium with Ni-66.

Best regards,

-- 

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Giorgi
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On 2022-04-22T17:14:03.000+02:00, SEBASTIANO PAOLUCCI
<sebastiano.paolucci_at_studenti.unicam.it> wrote:

> 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 Mon Apr 25 2022 - 11:34:57 CEST

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