Oscillating Isotopes: Semi-Stable/Stable Fission/Fusion?

[Physt]

Are there any semi-stable or stable isotopes that can be made to oscillate between their self and their decay products?

Specifically some kind of fission/fusion reaction where the decay is easily reversed with something like pressure (assuming the reversal is quick enough that the majority of the energy required/released by the reaction doesn't have time to get far away from the particle?)

 

[vanhees71]

Not that I know of. Oscillations occur in particle physics for, e.g., the neutral K-mesons (showing CP violation through the weak interaction as shown by Cronin and Fitch in 1964 ) or the neutrinos.

http://en.wikipedia.org/wiki/CP_violation
http://en.wikipedia.org/wiki/Neutrino_oscillation

 

[mfb]

Not in the controlled way you are probably looking for. All those processes release a lot of energy in one direction, and give two or more reaction products. The reverse direction would need those reaction products shooting together at the right energy.
Those processes are also way too fast - of the order of 10^-20 seconds. Pressure does not influence individual reactions at all. It can just increase the probability that things come close (like for fusion).

Stars during helium burning have a process that gets reversed frequently - two helium nuclei merge to beryllium which quickly decays to two helium nuclei again. Only in very rare cases the beryllium absorbs another helium to become stable carbon.

 

[Physt]

Not in the controlled way you are probably looking for. All those processes release a lot of energy in one direction, and give two or more reaction products. The reverse direction would need those reaction products shooting together at the right energy.
Those processes are also way too fast - of the order of 10^-20 seconds. Pressure does not influence individual reactions at all. It can just increase the probability that things come close (like for fusion).

Stars during helium burning have a process that gets reversed frequently - two helium nuclei merge to beryllium which quickly decays to two helium nuclei again. Only in very rare cases the beryllium absorbs another helium to become stable carbon.

What would happen if you could encase beryllium in a shell of a magnetostrictive alloy - when it decayed would the helium escape or would it be able to be squeezed back together?

 

[mfb]

There is no realistic way to force two specific helium nuclei to come together. They are just too small.

 

[Physt]

There is no realistic way to force two specific helium nuclei to come together. They are just too small.

But would they escape? If you had just split a beryllium atom inside a shell of magnetostrictive material (the force of the material squeezing down may be negligible compared to the force required to put the helium back together) the same energy levels that the beryllium had would be there if the helium couldn't escape so wouldn't it be conceivable to balance the reaction on that specific energy between decay and fusion and use the force of the shell to push it back together or pull it apart?

To put this another way, it wouldn't be an attempt to extract energy or store energy, but to have a material you could trigger into changing mass.

 

[mfb]

Escape from what?
You get two helium nuclei moving through space. What is supposed to keep them where? You can keep them in your container with a size of a few millimeters with strong magnetic fields. That is as "constrained" as two humans constrained to be somewhere in the inner solar system (12 orders of magnitude in size scale). If you don't have a good vacuum, the nuclei quickly lose their energy.

 

[Physt]

Escape from what?
You get two helium nuclei moving through space. What is supposed to keep them where? You can keep them in your container with a size of a few millimeters with strong magnetic fields. That is as "constrained" as two humans constrained to be somewhere in the inner solar system (12 orders of magnitude in size scale). If you don't have a good vacuum, the nuclei quickly lose their energy.

I was thinking of "constrained" as a shell of some metal around them ("around" meaning the single beryllium isotope would be encased in a metal lattice and be driven into an unstable state to create the two hellium isotopes).

 

[mfb]

The beryllium isotope is an unstable state - it decays within a femtosecond. Then you have two helium nuclei and you are done.
I still don't understand what is supposed to be constrained to what and why.

 

[Physt]

The beryllium isotope is an unstable state - it decays within a femtosecond. Then you have two helium nuclei and you are done.
I still don't understand what is supposed to be constrained to what and why.

Beryllium and helium were just an example set from what you said to try to relate the idea (they'd probably make a pretty bad pair in the context of the question since they are both very low mass density on the scale of the overall compound required and the fact you would have to subtract a neutron to get the unstable isotope of beryllium after initially building the compound material of beryllium surrounded by a shell [to say nothing of being such a small atom it would likely escape the containment of the shell of metal around it]).

The objective would be a material that can change inertial mass by exploiting the change in mass between isotopes.

 

[mfb]

Beryllium and helium were just an example set from what you said to try to relate the idea

They are the best thing I could find that has some sort of nuclear process that gets reversed somewhere in nature.

The objective would be a material that can change inertial mass by exploiting the change in mass between isotopes.

Light isotopes are better then, as they have a larger relative mass difference. But even then the differences will be very small.

Controlling nuclear reactions is problematic, especially for radioactive decays.
⁷Be is an interesting case. It can only decay via electron capture with a half-life of 53 days. If you fully ionize it, it is stable as there is no electron it could capture.

 

[rootone]

There is the CNO cycle.
http://en.wikipedia.org/wiki/CNO_cycle

 

[Physt]

Light isotopes are better then, as they have a larger relative mass difference. But even then the differences will be very small.

It seems if you were trying to construct a metamaterial (kind of a bastardization there - since it seems it would be somewhere between a bunch of nanoparticles and a metamaterial) to have variable inertial mass exploiting the differences in different isotopes the bulk of the mass of the material would likely be in the support structure (the shell holding the whole reaction together) - so the mass density differences of the reactive isotopes seem to weigh in more than the mass differences of the reaction itself and you'd still need something large enough to be contained (I'm guessing the distance between atoms in a Terfenol-D [the highest magnetostrictive alloy] for instance are going to be far enough apart to let something as small as helium slip through [especially when the helium is imparted with a high kinetic energy]). The best option might actually end up being something like Terfenol-D with the terbium replaced by an unstable isotope of holmium since both would be contained within the material and the lower-energy terbium state of the cycle would add excess forces to force it back into holmium - but I'm just guessing here.

 

[mfb]

I don't get the point of the magnetostrictive material. Everything solid will stop helium nuclei within a millimeter or less, the type of material does not matter.

and the lower-energy terbium state of the cycle would add excess forces to force it back into holmium

No.

You seem to have some misconceptions about radioactivity. It has no similarity to chemical reactions, where things like the molecule or crystal structure would be relevant.

 

[Physt]

I don't get the point of the magnetostrictive material. Everything solid will stop helium nuclei within a millimeter or less, the type of material does not matter.

The goal would be a bunch of individual reactionary isotopes with shells (1-atom or 1-molecule thick all around - nowhere near 1mm all around) that can contain the reaction.

You seem to have some misconceptions about radioactivity. It has no similarity to chemical reactions, where things like the molecule or crystal structure would be relevant.

At some point the forces exerted by the surrounding material has to play into it - even if it is a very very finite amount if you are keeping a two-way reaction balanced at the point between the two cycles of the reaction you'd only need a nudge.

 

[mfb]

The goal would be a bunch of individual reactionary isotopes with shells (1-atom or 1-molecule thick all around - nowhere near 1mm all around) that can contain the reaction.

That does not exist.

At some point the forces exerted by the surrounding material has to play into it

No. Influences from other atoms are completely irrelevant for radioactive decays (something like 15 orders of magnitude too weak to be relevant). They just determine the position of the atoms.

 

[Physt]

That does not exist.

You can actually build structures like that by combining two different materials in the form of plasma and carefully controlling the ratio of the two along with the exposure time.

No. Influences from other atoms are completely irrelevant for radioactive decays (something like 15 orders of magnitude too weak to be relevant). They just determine the position of the atoms.

Right. But if you can trigger decay and fusion so logically you can combine those two controls into a single package and you would need to contain them - whether that is with ionization or externally generated magnetic fields, RF or the pressure induced from surrounding matter are the details I'm looking for with this question. Specifically: are there two isotopes that are relatively easy to get to fuse or decay into each other?

 

[mfb]

You can actually build structures like that by combining two different materials in the form of plasma and carefully controlling the ratio of the two along with the exposure time.

Containing products of nuclear decays? Do you have a reference for that?

But if you can trigger decay and fusion so logically you can combine those two controls into a single package

No. We can induce fission or radioactive decays via neutrons for some nuclei, and we can do fusion with other nuclei. Those are not reverse processes.

You can use particle accelerators to smash all sorts of different nuclei together, but then you get a huge mess of many different nuclei as result.

whether that is with ionization or externally generated magnetic fields, RF or the pressure induced from surrounding matter are the details I'm looking for with this question

Nothing like this would help at all.

Specifically: are there two isotopes that are relatively easy to get to fuse or decay into each other?

No.

 

[rootone]

Even if were possible to get a reversable nuclear reaction, what would be the use of it?
The total mass - energy involved is unchanged by the time you have converted A to B then back to A again.
You will have acheived exactly nothing.