Variable radioactive decay

[montypython]

Is it conceivable to change the radioactive decay rate for a given particle by manipulating its quantum stability and/or nuclear forces? The links I've seen on Google are often linked to creationists and associated sites, so I just wanted to ask the question without that type of BS attached.

[SilverWingedSeraph]

A lot of Creationists seem to like saying that "studies have shown that radioactive decay rates can be altered in the lab by a factor of [insert stupidly large and arbitrary number here]". Near as I can tell, it's outright bullshit. If there were any known way of significantly altering radioactive decay rates, radioactive waste wouldn't be a problem, near as I can tell. But then, my skills with science are limited mostly to what I've learned off the internet, so you're probably better off waiting for one of the more scientifically savvy members of the board to comment.

[Zixinus]

Short answer: It's pure bullshit.

Long answer:

As far as I know, you radioactive decay does rate not change on its own, with either atoms or particles. Technically, I recall that particles don't decay?

The only thing that comes to mind is half-life. The only way to reduce the half-life of a given quantity of an radioactive element in by transforming it into another element with neutron bombardment. From Element XY- 245 that has a decay rate of 200 years you can turn it into Element XY - 246 that decays under 20 days. With lower decay rate, comes much more radiation though.

An example is Uranium 238. It's half-life is measured in million of years if I recall. Turn one of its neutrons into a proton right and you'll get Plutonium 238 that decays under 82 years. Pu-238's decay is so powerful that it can be used as an instant heat-source, look up RTG's.

However, this is a the process of making an unstable particle even more unstable by outside force. It's like hitting a crumbling building with a RPG: the building is already crumbling.

[montypython]

Short answer: It's pure bullshit.

Long answer:

As far as I know, you radioactive decay does rate not change on its own, with either atoms or particles. Technically, I recall that particles don't decay?

The only thing that comes to mind is half-life. The only way to reduce the half-life of a given quantity of an radioactive element in by transforming it into another element with neutron bombardment. From Element XY- 245 that has a decay rate of 200 years you can turn it into Element XY - 246 that decays under 20 days. With lower decay rate, comes much more radiation though.

An example is Uranium 238. It's half-life is measured in million of years if I recall. Turn one of its neutrons into a proton right and you'll get Plutonium 238 that decays under 82 years. Pu-238's decay is so powerful that it can be used as an instant heat-source, look up RTG's.

However, this is a the process of making an unstable particle even more unstable by outside force. It's like hitting a crumbling building with a RPG: the building is already crumbling.

I do remember in physics class about particles such as electrons and protons have the lifespan of the Universe itself, so that wouldn't be an issue of contention. The concept was regarding the rates of decay for elements in terms of energy and particle release to achieve a stable state, like U-238 decaying into lead. Now neutrons can undergo decay to transmute into a proton, electron and neutrino, but if one wanted to manipulate U-238 into conventional Pb by causing the surplus energy state to be discharged as photonic and particle energy in a single impulse, would that work?

[montypython]

Ghetto edit: Reason for asking the previous question regarding rapid energy discharge for decay stabilization was for a story idea.

[GrandMasterTerwynn]

Is it conceivable to change the radioactive decay rate for a given particle by manipulating its quantum stability and/or nuclear forces? The links I've seen on Google are often linked to creationists and associated sites, so I just wanted to ask the question without that type of BS attached.

As radioactive decay is governed by the strong and weak nuclear forces . . . which are fundamental interactions of spacetime . . . no, can't be done, not without breaking the universe.

As for the question you posed later in the thread, there is a vanishingly small probability that a given atom of U-238 will undergo the whole decay chain to Pb in very short order. Radioactive decay is a probabilistic process. To transmute U-238 into lead like that would require that you magically control probability. But that goes back to that whole breaking the universe thing.

[SpacedTeddyBear]

Now neutrons can undergo decay to transmute into a proton, electron and neutrino, but if one wanted to manipulate U-238 into conventional Pb by causing the surplus energy state to be discharged as photonic and particle energy in a single impulse, would that work?

I believe that process is called fission. While lead may not be the immediate byproduct, it's what the fragments would eventually decay into.

[Lord of the Abyss]

Is it conceivable to change the radioactive decay rate for a given particle by manipulating its quantum stability and/or nuclear forces?

Yes, it's been done. I think that this article mentions it, but don't want to buy it to find out.

G. C. Baldwin and S. A. Wender
Los Alamos National Laboratory, Los Alamos, New Mexico 87545

Received 15 March 1982

Optical excitation of an atom containing an isomeric nucleus should affect its internal conversion coefficient through modification of its bound-state electronic wave functions as well as by interaction with the outgoing electron. The extreme case of 235mU, which decays entirely by internal conversion and for which pronounced environmental effects on the half-life have been observed, is considered. Resonant (bound-state) effects on the lifetime and electron emission spectrum are predicted to occur with moderate-power cw laser irradiation.



©1982 The American Physical Society

I read an article on the subject long ago, but can't find a link. As I recall, the idea is that you use a laser to "interrogate" the radioactive atoms in question; this collapses their quantum state and prevents them from having the quantum certainty that at least some atoms need to decay. Note that this can only work on gases and surfaces, since the laser has to hit the atoms.

[Lord of the Abyss]

this collapses their quantum state and prevents them from having the quantum certainty

Gah; make that UNcertainty.

[Zixinus]

I do remember in physics class about particles such as electrons and protons have the lifespan of the Universe itself, so that wouldn't be an issue of contention. The concept was regarding the rates of decay for elements in terms of energy and particle release to achieve a stable state, like U-238 decaying into lead. Now neutrons can undergo decay to transmute into a proton, electron and neutrino, but if one wanted to manipulate U-238 into conventional Pb by causing the surplus energy state to be discharged as photonic and particle energy in a single impulse, would that work?

Radioactive decay IS discharging energy in the form of photonic and particle energy.

As in a single impulse? Ermm, the only nuclear reaction I know of that could do that would anti-matter - matter reactions. Otherwise the only other reaction that I know where you get from a high energy state to a small one is called fission. Even then, its gradual somewhat, U-235 will not turn into pure H+ ions but into two, still heavy and radioactive atoms.

[Ariphaos]

I recall reading something about 'a watched particle doesn't decay' and ever since I've been trying to -find- that article again...

[Steel]

I recall reading something about 'a watched particle doesn't decay' and ever since I've been trying to -find- that article again...

I did a question on that is my QM undergrad course. I cant remember the exact details, and i dont have my notes here unfortunately, but the gist of it was that with a 2 state quantum system if you keep prodding it then the wavefunction gets reset to the original state rather than jumping/evolving to the next one as it would if you didnt interfere. The conclusion was that a watched quantum kettle never boils.

[Steel]

Actually the question is still on the web, its Question 8 on this sheet. This is the easy introductory QM course, so the examples are generally pretty easy to follow and guide you to the necessary steps.

[Ariphaos]

Awesome, thanks!

I've occasionally had mental images of several trillion atoms of some volatile isotope getting trapped and preserved for testing.

[Gil Hamilton]

Typed up in Mathematica. Radioactive decay is a constant for a substance. Booyah.

[Surlethe]

Gil, aren't you assuming to start with that k is constant? That's the decay rate, and since the question at hand is whether the decay rate can change, you're begging the question.

[Gil Hamilton]

Gil, aren't you assuming to start with that k is constant? That's the decay rate, and since the question at hand is whether the decay rate can change, you're begging the question.

k has to be constant in order for it to be first order kinetics in the first place. It's a rate constant, it doesn't change by definition. The point is that when you solve the differential equation, any references to variables disappear. Thus, the decay rate can't change for a given substance.

I suppose you could question whether or not radioactivity follows first order kinetics or not, though.

[Steel]

Gil, aren't you assuming to start with that k is constant? That's the decay rate, and since the question at hand is whether the decay rate can change, you're begging the question.

k has to be constant in order for it to be first order kinetics in the first place. It's a rate constant, it doesn't change by definition. The point is that when you solve the differential equation, any references to variables disappear. Thus, the decay rate can't change for a given substance.

I suppose you could question whether or not radioactivity follows first order kinetics or not, though.

I think the point is that while there are also chemical reactions that follow first order kinetics, when you dump a catalyst into the mix the rate changes significantly. While the new rate may still be following the first order structure (although possibly not with the different mechanism), the rate has changed significantly. (I seem to recall you can catalyse the decomposition of hydrogen peroxide with something, but that might not be a first order rates thing to begin with, and might not be after the catalysation... not terribly convincing, but that might be an example of what i'm talking about, and i'm sure there are others that someone who likes chemistry can trot out)

What you actually want to do is assume k=k(t) and then keep the right hand side in integral form, and then you dont just get everything to cancel, you have an integral equation which has determined [in this case just the time till half the stuff is gone] t_1/2 [as long as k(t) doesnt do anything silly] and wont have a proper half life.

I mean for the example of a catalysed reaction where catalyst is added at time T you would have k defined as

k= k1 t<T
k2 t>=T

[Gil Hamilton]

I think the point is that while there are also chemical reactions that follow first order kinetics, when you dump a catalyst into the mix the rate changes significantly. While the new rate may still be following the first order structure (although possibly not with the different mechanism), the rate has changed significantly. (I seem to recall you can catalyse the decomposition of hydrogen peroxide with something, but that might not be a first order rates thing to begin with, and might not be after the catalysation... not terribly convincing, but that might be an example of what i'm talking about, and i'm sure there are others that someone who likes chemistry can trot out)

Except I would turn around and trot out that catalysts work by lowering the activation energy of a reaction by providing a different path than the original reaction. It's not actually speeding up a reaction, that's a misconception based on the layman definition of what a catalyst does, but provides a more energy efficient different means for A to get to B.

However, more to the point, catalysts are somewhat irrelevant to radioactive decay, aren't they?

[Gil Hamilton]

I suppose in hindsight I should stop, since I automatically in my brain pencilled in "constant, given specific conditions" in the case of chemical reactions. The rate constant for a chemical reaction has a temperature dependance baked into it, for example, so I suppose if you only cared about [A] -> , without pencilling in any conditions (which seems a very odd thing to do from my perspective), then rates of reaction can be variable.

However, I still don't see what this has to do with radioactive decay.

[Kuroneko]

You're missing the point. By assuming first-order kinetics in the first place, you beg the question, because the form has a constant rate by definition. Besides, it's not even true across the board for radioactive decay. A half-life that varies with concentration is the backbone of nuclear fission, for instance.

[Vehrec]

The only reason chain-reaction half-lives are variable is because they destabilize isotopes by shooting neutrons into them and changing the mass, thereby disrupting the nucleus. 18% of all Neutron-U235 reactions withing nuclear reactors result in U236, so even that isn't totally reliable.

It isn't true that the half-life varies with concentration-the odds of spontaneous decay remain the same in all situations.

[Starglider]

This sounds like a misunderstanding of a real problem with radiocarbon dating, which is that the concentration of carbon 14 in the atmosphere varies over time (mostly in response to solar & cosmic radiation levels). Amusingly enough the various techniques used to correct for this would also correct for a non-logarithmic decay rate, if such a thing existed (which of course it doesn't).

[Kuroneko]

It isn't true that the half-life varies with concentration...

Under those conditions, it does. The context of the disputed statement made it clear that the claim was about the bulk half-life of a substance, which admittedly is different from the question in the OP.

-the odds of spontaneous decay remain the same in all situations.

That translates to constant bulk half-life only under the assumption that the individual atomic decays are independent, which can be false.

[defanatic]

Wouldn't increasing the decay rates (were it possible) increase the amount of heat generated? Given numbers quoted like a million times, that could be a lot of heat.