I Radioactive decay question for K --> Ca

[ProjectFringe]

As I understand ⁴⁰K decays into ⁴⁰Ca over a period of $1.248(3)×10^9$ yrs. Assuming this is the natural rate of decay, is there any way to shorten the period of decay (increase the rate of decay), for example, under extreme pressure or heat?

Thanks

 

[Vanadium 50]

Not measurably.

 

[Kolmo]

The quantum Zeno or Anti-Zeno effects?

 

[snorkack]

As I understand ⁴⁰K decays into ⁴⁰Ca over a period of 1.248(3)×109 yrs.

No, that´ s the total half-life.

Assuming this is the natural rate of decay, is there any way to shorten the period of decay (increase the rate of decay), for example, under extreme pressure or heat?

Thanks

Increasing pressure would speed up decay into ⁴⁰Ar by electron capture, because density of electrons to be captured is affected by pressure and chemical environment. But electron emission would be less affected, and increase of pressure would slow it down as electron states are taken.
Extreme heat would promote beta decay as the electrons, especially inner electrons of K are ionized away, opening decays into bound states.

 

[mathman]

Not 109, should be $10^9$.

 

[berkeman]

Not 109, should be $10^9$.

Fixed with in-line LaTeX. Thanks for the catch!

As I understand 40K decays into 40Ca over a period of $1.248(3)×10^9$ yrs.

 

[mfb]

Shooting electrons beams at K-40 could speed up electron capture to argon, too.

Shooting positrons could lead to positron capture.

 

[ProjectFringe]

Thanks for your replies and sorry for the mistakes!

One last question related to this (I hope)...

I understand ⁴⁰K can decay into ⁴⁰Ca, but where does ⁴⁰K come from? Is it decaying from something else?

For example, is it possible, under certain conditions, that ⁴¹Ca decays to ⁴⁰K+H(or a neutron), instead of ⁴¹K through electron capture?

 

[mfb]

K-40 is produced in heavy stars late in their life together with other potassium and the surrounding elements. Neutron capture of K-39 or one of the many other reactions that can happen under these conditions.

 

[snorkack]

K-40 is produced in heavy stars late in their life together with other potassium and the surrounding elements. Neutron capture of K-39 or one of the many other reactions that can happen under these conditions.

I find that the cross sections of K isotopes for neutron capture are, from
https://www.ncnr.nist.gov/resources/n-lengths/elements/k.html
K-39 2,1 barns
K-41 1,46 barns
Does this mean that the abundances of K isotopes should relate as inverse of their neutron cross-section - about 40 % K-39 and 60 % K-41?

 

[mfb]

No, it's far more complex. You didn't consider the source of these two nuclei, you didn't consider the energy-dependence of the cross section, and you didn't consider the neutron flux. Apart from the cross section all these depend on time, too.

 

[ProjectFringe]

Thanks again everyone for your help!

I've been working for 8 years on creating a compound and I think I'm finally to the point where I can post the basic steps in the creation process, along with what I think could happen at each step. I'll post it soon as a separate posting to get some much needed feedback!