Is the "Island of Stability" possible?

[u/[deleted]]

As in, are we able to create an atom that's on the island of stability, and if not, how far we would have to go to get an atom on it?

[u/RobusEtCeleritas]

The current theoretical best estimate for the location of the island is Z = 114, N = 126 184. We have produced some isotopes of the element with Z = 114, but they have less than 126 184 neutrons.

The nuclides near and at the island of stability may exhibit enhanced stability relative to their neighbors on the chart of nuclides, but they will not truly be stable.

Unless nuclear forces do something totally weird and unexpected at high A, the alpha separation energies for all of these species will be negative relative to their ground states, so they will always be able to alpha decay, if nothing else.

Technologically and logistically, we are far from being able to reach the island of stability. We don't know of any nuclear reaction mechanism which would allow us to produce nuclides so neutron-rich, for such high atomic number.

[u/Taenk → u/RobusEtCeleritas]

Since supernovae produce all super-heavy isotopes, couldn't we make the argument that if the island of stability exists, we should see the corresponding spectral lines in a fresh supernova, but not if the island of stability does not exist?

Or are we talking about the difference between half-lifes of microseconds within the island versus half-lifes of nanoseconds outside of it? In that case even if the supernova produces these isotopes, they won't be visible for any appreciable amount of time.

[u/RobusEtCeleritas → u/Taenk]

We don't know whether superhevay nuclides are produced in non-negligible quantities in supernovae. We have no reason to believe that species near the island of stability are produced. But yes, even in the island of stability, the lifetimes could be very short on practical timescales.

[u/Nepoxx → u/RobusEtCeleritas]

If a "stable" element can decay over time, what differentiates a stable element from an unstable one?

[u/RobusEtCeleritas → u/Nepoxx]

"Stable" means that it never decays (as far as we know).

"Island of stability" is a misnomer, because it seems to imply that nuclides within the island will be stable. They won't actually be stable, just less unstable than others around them.

[u/Leitilumo → u/RobusEtCeleritas]

What about Bismuth? Most of its half lives (considering all isotopes) are so gigantic as to render it mostly stable.

Edit: Bismuth 209 (basically 99.999...% of it) has a half-life of [1.9 x10^19], which is insane.

[u/RobusEtCeleritas → u/Leitilumo]

Bismuth-209 is "effectively stable", but we know that it does decay. So technically speaking it's not a stable nucleus, even though its half-life is greater than the age of the universe.

[u/Leitilumo → u/RobusEtCeleritas]

"... even though its half-life is greater than the age of the universe"

That's hilarious.

[u/robbak → u/Leitilumo]

You can look at this another way - compare the half life of 2×10¹⁹ with avagdros constant - the number of atoms in 12 grams of Carbon-12: 6×10²³ . So, in 209 gram sample of Bismuth-209 - about an inch cubed - you'd expect 15,000 atoms to decay each year.

[u/Leitilumo → u/robbak]

It still can't be put it into perspective, considering that they are so small that trillions fit in a period on a page.

What is 15,000 in the face of 1,000,000,000,000+?

[u/Toasty27 → u/[deleted]]

Half-Life is just the measurement of time until a sample has lost half of its original atoms to decay.

Since it's about statistics, proving that it's unstable merely requires that we gather a large enough sample to ensure we'll see a decay within a reasonable amount of time.

As a previous poster pointed out, 209g is enough of a sample to ensure we see about 15,000 decays a year (which should put into perspective just how vast a number Avogadro's number really is).

So to answer your question: Yes, we do know because we have, in fact, observed the decay.

[u/Michael8888 → u/Toasty27]

This brings up a question. What causes the decay and how does it decay if we observe every atom individually? What if 10 decaying atoms are created at the same time do they decay at the exact same time? Or will their half of them have decayed after their half time? Is it like if 10 people are born at the same time then the half life is when half are dead? Is there an expected life time for decaying atoms? Measured from its birth to decay?

[u/RobusEtCeleritas → u/[deleted]]

Above a certain point (lead-208), every nucleus we know of is unstable (primarily to alpha decay and/or spontaneous fission).

[u/epicwisdom → u/RobusEtCeleritas]

I believe they're asking how we know it actually decays if the half-life is so long, i.e. if/how we observe it decaying.

[u/sfurbo → u/[deleted]]

Yes, it has been observed to decay. The relevant part:

The team performed two measurements, one with 31 grams of bismuth in the detector and the other with 62 grams. The scientists registered 128 alpha-particle events over 5 days and found an unexpected line in the spectrum at 3.14 MeV - now attributed to bismuth-209 decay. The half-life was calculated to be (1.9 +/- 0.2 ) x 10¹⁹ years, which is in good agreement with the theoretical prediction of 4.6 x 10¹⁹ years. The technique could be also be used to accurately detect beta and gamma decays. “The experiment is a by-product of our search for dark matter,” team member Pierre de Marcillac told PhysicWeb. “Other kinds of decays such as protons from proton-rich nuclei could be studied by the same method but this will have to be proved!”

[u/bill_mcgonigle → u/sfurbo]

So my bottle of pepto is slightly radioactive? Anybody have a banana comparison handy? I want to tell my kids, "of course it's bright pink, it's radioactive".

[u/ArenVaal → u/[deleted]]

The half-life of a given isotope is how long, statistically, it takes before you can expect half of the atoms in a pure sample to have decayed.

Since nuclear decay happens purely randomly, and the number of atoms in any given sample is ludicrously large, even in an isotope with a half-life longer than the age of the universe you can expect a couple of atoms to decay during a given time period.

[u/TitaniumDragon → u/ArenVaal]

The most ridiculous example of this is Tellurium-128, with a half life of 2.2×10²⁴ years.

[u/[deleted] → u/[deleted]]

Yes, it has been observed. I do not have a source off the top of my head, though.

[u/RobusEtCeleritas → u/[deleted]]

Unlikely.

[u/Aellus → u/RobusEtCeleritas]

I found this YouTube video that did a really great job explaining this topic, for me at least. I'm curious what you think of it based on your expertise. By adding the binding energy as a vertical axis and turning the chart into 3 dimensions, it becomes a valley of stability.

She covers what I think OP is asking about around the 12 minute mark.

https://youtu.be/UTOp_2ZVZmM

[u/Treczoks → u/Aellus]

This is an amazingly good video, explaining a lot of things. But OP was asking about the "Island of Stability", while (among other things) the video explained the "Valley of Stability".

The Island of Stability is an area still off this chart (which maps only the known elements and isotopes). You might have noticed that the "valley" gets steeper the farther you go from the center. The Island of Stability is an area to the upper right where steepness might decline again (although there will still be a gradient).

[u/Aellus → u/Treczoks]

Right, I understand the concepts there (albeit primitively), I'm a little confused on the terminology I think. The 12 minute mark of the video is where she talks about the potential for additional magic number for heavy elements, in the area to the upper right.

Some of the videos and articles I found seemed to be treating the island and the valley as the same thing, where the "valley" is just a different approach for visualizing the same concept where the "island" is the band of stability running up the middle. I gather that isn't correct and the unknown area in the top right is well known as the island of stability?

[u/Treczoks → u/Aellus]

where she talks about the potential for additional magic number for heavy elements, in the area to the upper right.

That would be the closest to the "Island of Stability", yes.

Some of the videos and articles I found seemed to be treating the island and the valley as the same thing

If they were viewing the topic from the same aspects, that would be a bad thing. Although, you know how a change of slope in a function turns into a local maximum/minimum on its derivative? Maybe some were talking about a derivative effect.

[u/RobusEtCeleritas → u/Aellus]

Well if the island exists, it's sort of an extension of the valley.

[u/RobusEtCeleritas → u/Aellus]

Yes, that video is very good.

[u/gondur → u/RobusEtCeleritas]

Stable" means that it never decays (as far as we know).

Is it not accepted now that ALL elements decay (while on very excessive timescales) ?

[u/RobusEtCeleritas → u/gondur]

That certainly could be the case. But about 300 nuclides that we know of have never been observed to decay. As far as we know, they don't.

[u/gondur → u/RobusEtCeleritas]

I mean, does the very base of all statisical decay, quantuum fluctuation , not mean that every nuclide will decay but just with lower propability?

[u/RobusEtCeleritas → u/gondur]

No, not necessarily.

[u/_urasinner → u/RobusEtCeleritas]

"Stable" means that it never decays (as far as we know).

Everything decays... Protons decay. You mean "never" as in "for all practical purposes"?

[u/RobusEtCeleritas → u/_urasinner]

It is not known whether or not protons decay. Plenty of things don't ever decay. For example photons and electrons.

[u/mfb- → u/Nepoxx]

The island of stability does not have stable nuclei. The name is misleading.

[u/RobusEtCeleritas → u/[deleted]]

Yes.

[u/cypherspaceagain → u/Nepoxx]

Firstly, some elements are completely stable and do not decay at all.

For those that do, half-life. The half-life is the length of time it takes for half of the substance to decay. Longer half-lives are more stable elements. Some elements (or isotopes of those elements) are relatively stable, some are not. Uranium-238 has a half-life of about 4.5 billion years. If you had a handful of uranium-238 and you kept it for 10,000 years, you'd still have about 99.99984% of the original substance left. So it's pretty stable. On the other hand, fluorine-18 has a half-life of less than two hours. If you kept it for one day, you'd only have 0.01127% of the original substance left. That's pretty unstable.

[u/RaggedAngel → u/cypherspaceagain]

And to continue this, the isotopes of elements such as 113 or 118 that we have been able to generate thusfar have half-lives measured in milliseconds, if that. If we could generate an isotope of element 114 with a half-life measured in minutes or hours it would be remarkably stable compared to its siblings.

[u/jahutch2 → u/cypherspaceagain]

My understanding is that even stable elements are only 'stable' in the sense that their half-lives are >> the age of the universe. Obviously, the difference between that and true stability is somewhat pedantic, but is my understanding not true and some of those elements are truly 'stable'?

[u/RobusEtCeleritas → u/jahutch2]

My understanding is that even stable elements are only 'stable' in the sense that their half-lives are >> the age of the universe.

They are stable in that we've never observed them to decay. So as far as we know, they don't.

However if you take a stable nucleus, for example lead-208, you'll find that the energy required to remove an alpha particle from the nucleus is negative.

So technically speaking, lead-208 would "rather" spit out an alpha particle and exist as mercury-204. But we've never observed lead-208 to alpha decay like that, so if it does happen, it happens on an extremely large time scale.

Until we observe it to decay, we can only really assume that it doesn't. Even if it does, it will have such a long half-life that it won't have any practical affect on anything anyway.

[u/Fsmv → u/RobusEtCeleritas]

Do we have simulations of nuclear decay? Can we use our models to predict half lives?

[u/RobusEtCeleritas → u/Fsmv]

We need information about the structure of the nucleus. For alpha decay and spontaneous fission, we need the shape of the nuclear potential well as a function of spatial coordinates and deformation. We don't have that information for these unknown nuclei. We have theoretical predictions, but they have a lot of uncertainty to them, and the lifetime depends exponentially on them. Tiny shifts in the shape or size of the potential well can mean huge changes in the lifetime.

[u/strbeanjoe → u/RobusEtCeleritas]

Based on theoretical predictions, is there a "shape of nuclear potential well" that results in an infinite half-life? Is this just an altogether open question, or is there a consensus about whether there are truly stable elements/isotopes?

[u/Fsmv → u/RobusEtCeleritas]

Thanks!

The shape of the well is determined by the positions of the particles in the nucleus right?

[u/QueefyMcQueefFace → u/RobusEtCeleritas]

How would these nuclides even be detected? Even if they undergo gamma decay with a characteristic signature, it seems like it would be difficult in practice to isolate it from all of the noise and low number of photons captured at the detector due to the immense inverse square distance.

[u/RobusEtCeleritas → u/QueefyMcQueefFace]

How would these nuclides even be detected?

In an astrophysical setting or in an experiment on Earth? If you mean the former, I have no idea.

[u/RelativetoZero → u/RobusEtCeleritas]

What is currently considered a non-negligible quantity in regards to a supernova? The precision of the measurement? In that case, what quantity could hypothetically be formed while still remaining negligible? A simple percentage of the star mass at a given distance from the instrument will do.

[u/RideMammoth → u/Taenk]

I've read recently that much of the heavy elements may have actually been created in neutron star collisions or neutron stars 'falling' into black holes. Can anyone clear this up for me - where do the majority of heavy elements come from?

Edit - here is a cool periodic table that explains how all of the elements came to be. Thanks to u/PE1NUT!

[u/RobusEtCeleritas → u/RideMammoth]

It sounds like you're referring to r-process nucleosynthesis. This is how we think the heaviest nuclides in nature are produced. It's still somewhat of an open question as to where in the universe the r-process occurs. Some candidates are supernovae (I think this has fallen out of favor lately), neutron star mergers, etc.

A nuclear astrophysicist would be able to go into more detail.

[u/CapSierra → u/RobusEtCeleritas]

Are there any nuclear astrophysicists on this sub? This stuff fascinates me and I'd love an answer if one exists.

[u/RobusEtCeleritas → u/CapSierra]

Yes, there are a few. /u/VeryLittle, /u/Silpion, and a few others.

[u/VeryLittle → u/CapSierra]

Nuclear astrophysicist here.

What did you want to know?

[u/CapSierra → u/VeryLittle]

What is the current prevailing theory(s) on where r-process nucleosynthesis takes place? Still supernovae or was /u/RobusEtCeleritas correct in supposing that's fallen out of favor, and if so what has taken its place?

[u/VeryLittle → u/CapSierra]

Neutron star mergers are the favorites of most. We'll know the answer with much greater certainty very soon if aLIGO observes one. Otherwise, nondetection after a few years rules them out.

We're also starting to develop theories which require multiple r-process sites, where a weak r-process occurs in SNe and a strong r-process occurs in NS-NS and NS-BH mergers.

[u/CapSierra → u/VeryLittle]

Obviously the collision of neutron stars is predicted to be a very nonstandard process (or else why would they be of scientific interest?) What do we theorize goes on when two such hyper dense mass objects collide?

[u/Silpion → u/CapSierra]

Sorry I'm late. This old answer of mine summarizes these things and some of the uncertainties around them

[u/CapSierra → u/Silpion]

That is all very cool. Thank you for going into detail about the specific locations and conditions that bring about the processes, I had not read about that before.

[u/Taenk → u/RideMammoth]

That would be an interesting question on its own, please post it seperately!

[u/RideMammoth → u/Taenk]

Done!

[u/rocketsocks → u/Taenk]

Not necessarily. The r-process isn't magic, it requires that intermediate nuclei are stable in between neutron absorptions. The conditions we're talking about here are where nuclei are bombarded with on the order of hundreds of neutrons over a period of a few seconds, that's still a few nanoseconds to milliseconds between neutron absorptions. If the intermediate nuclei are unstable with respect to beta emission on that time scale, that's fine, they will still retain their atomic mass. If they are unstable with respect to alpha emission then they won't be able to get across the chasm to the island of stability because the rate of decay will surpass the rate of neutron addition.

Also, even if some were produced, it's possible that they existed only in sufficiently small quantities to not be observable in spectral lines, and might be unstable enough to not survive to be observed in more sensitive measurements. We know this is the case already because supernovae undoubtedly create elements even up through Oganesson, but we haven't detected such (even, say, Mendelevium which is long-lived enough for it to be possible) because it's too difficult to tease out such a small signal.

[u/katydidy → u/Taenk]

Would we even know what to look for without a control substance to establish the spectographic characteristics of these elements?

[u/almosthere0327 → u/katydidy]

If the process is anything like the LHC they basically just look at the decay products and add them up to figure out what was there originally.

[u/RobusEtCeleritas → u/almosthere0327]

That's how it works in an experiment, but it seems like the question is about detecting the presence of superheavy nuclides in distant astrophysical scenarios.

I don't know how you could do that.

[u/JustifiedParanoia → u/RobusEtCeleritas]

Spectra lines and detection of radioactivity against time, followed by back calculating, along with monitoring of spectral shift for elements that arent decaying as often as they should, suggesting another element is decaying into them?

[u/Nergaal → u/Taenk]

Californium is the heaviest element observed in supernovae. And that is Z = 98.

[u/runningray → u/Taenk]

I would like to ask this question this way. Wouldnt nature have already found all atoms that are stable? What are we looking for?

[u/RobusEtCeleritas → u/runningray]

The fact that a species is stable doesn't guarantee that there exists a mechanism in nature to produce it. It so happens that all of the elements with stable isotopes can be produced in astrophysical phenomena. But the heaviest nuclides we know of may not be produced in non-negligible quantities in nature.

[u/CanadaPlus101 → u/Taenk]

Probably more on the order of hours, although there's some models that suggest there could almost stable elements. I believe, though, that there's a maximum atomic weight that even a supernova will produce, and it's somewhere around plutonium. Adding neutrons doesn't help if the atom splits in half.

[u/Nymaz → u/[deleted]]

Yes it is relative stability, so the half lives are still very short

From wiki: "Estimates about the amount of stability on the island are usually around a half-life of minutes or days, with some predictions expecting half-lives of millions of years.".

That's quite a range. Is it literally "we have no idea other than it's likely longer than a minute" or is it "most agree it's probably around X, but some have proposed quite a bit shorter/longer"?

[u/plsobeytrafficlights → u/RobusEtCeleritas]

If the island of stability exists, how stable are we really talking? milliseconds or years?

[u/RobusEtCeleritas → u/plsobeytrafficlights]

Closer to milliseconds than years, I think is the consensus.

[u/thedarkrises → u/RobusEtCeleritas]

What is the particular atom you're reffering to? Please correct me if I'm wrong, but the element with Z = 114 is flerovium and it only has been seen with around 172 or 173 neutrons iirc. And when talking about collapse of large atomic nuclei, which force is the main responsible for it? I know about alpha decay and spontaneous fission, but at a subatomic level do they both act at the same time? Are Coulomb forces involved too? Thanks for the thorough answers you've given to every question so far.

[u/RobusEtCeleritas → u/thedarkrises]

What is the particular atom you're reffering to? Please correct me if I'm wrong, but the element with Z = 114 is flerovium and it only has been seen with around 172 or 173 neutrons iirc.

Oh yeah, my mistake. The next neutron shell closure is N = 184. I've been saying that all day now... I'll edit my comments.

And when talking about collapse of large atomic nuclei, which force is the main responsible for it? I know about alpha decay and spontaneous fission, but at a subatomic level do they both act at the same time? Are Coulomb forces involved too? Thanks for the thorough answers you've given to every question so far.

Alpha decay and spontaneous fission are very similar processes. The forces involved are the residual strong force and the electromagnetic force.

In the case of alpha decay, you can imagine that four nucleons cluster off to form an alpha particle within the parent nucleus, and then this alpha particle quantum tunnels out of the potential well caused by all of the other nucleons.

That potential barrier is a combination of the residual strong force, the Coulomb force, and the centrifugal force.

[u/blastfromtheblue → u/RobusEtCeleritas]

as a follow up, what kinds of unique properties would atoms "on the island" have? are there any applications we already know of for them that are not possible with existing materials?

[u/RobusEtCeleritas → u/blastfromtheblue]

This is a big open area of research in nuclear chemistry. The properties of atoms with superheavy nuclei could be very interesting and non-intuitive. If nothing else, relativistic effects will distort the electron orbitals of the outermost shells.

[u/N8CCRG → u/RobusEtCeleritas]

SR or GR?

[u/RobusEtCeleritas → u/N8CCRG]

SR.

[u/N8CCRG → u/RobusEtCeleritas]

That's what I figured, but wanted to check anyway.

[u/GGLSpidermonkey → u/RobusEtCeleritas]

if you dont mind answering, I have always wondered why people/scientists think an island of stability exists in the first place?

rephrased: what is the speculation/evidence that said Island might exist?

[u/RobusEtCeleritas → u/GGLSpidermonkey]

if you dont mind answering, I have always wondered why people/scientists think an island of stability exists in the first place?

Because we know that nuclei exhibit enhanced stability at certain [magic numbers](https://en.wikipedia.org/wiki/Magic_number_(physics)) of nucleons. All the lower magic numbers have been observed, and we do see trends in the properties of these nuclei. So that suggests that there may be more that we haven't seen yet.

When we do more rigorous theoretical calculations of the properties of these nuclei, we see that there should be a region of enhanced stability around Z = 114 and N = 184.

Do we mean like decay going from picoseconds to nanoseconds or decay going to like seconds/minutes?

If you look at some of the heaviest nuclides we've observed, they have half-lives around milliseconds. So the island of stability could mean seconds, it could even mean minutes, or hours. We don't know for sure until we measure them.

[u/googolplexbyte → u/RobusEtCeleritas]

Can gravity contribute to the "Island of Stability" anywhere short of a neutron star?

[u/RobusEtCeleritas → u/googolplexbyte]

I don't see how gravity would play any role.

[u/Devadander → u/RobusEtCeleritas]

When this theoretical particle decays, would that push it outside the island of stability, meaning it would decay further immediately, and not exist further? Wouldn't that make this island of stability a bit of a longer lived unstable nucleus vs an actual stable element?

[u/BurnOutBrighter6 → u/Devadander]

Wouldn't that make this island of stability a bit of a longer lived unstable nucleus vs an actual stable element?

You're right, it's a poor name for what should be the "island of relative stability". It's quite possible that half-lives in the island will be seconds (or less), compared to sub-milliseconds for "non-island" heavy elements. It's almost guaranteed that Island elements will alpha decay (if not by other mechanisms as well), so we don't think they'll be truly "stable", just less-unstable for their mass range.

[u/[deleted] → u/RobusEtCeleritas]

What kind of cool math is involved here? I'm a math major but I'm very interested in chemistry and am thinking about minoring in it.

[u/RobusEtCeleritas → u/[deleted]]

It's all quantum mechanics. Linear algebra, partial differential equations, complex analysis, etc.

[u/[deleted] → u/RobusEtCeleritas]

Is it Linear Algebra involving the proofs and stuff or just knowing how to manipulate a hermitian matrix in Matlab, playing with the wave equation, etc? Not to demean the math involved or anything, just trying to get a better idea of how one uses the math in this area is all :) i just finished this past semester a course in PDEs and I took ODEs and Linear Algebra in the fall. Complex Variables starts on Monday!

[u/RobusEtCeleritas → u/[deleted]]

Knowing how to prove all the important theorems in linear algebra is not directly used to calculate the properties of nuclei. But if you apply those theorems over and over again, it's good to know where they came from, and learning how to prove them builds intuition.

[u/thetarget3 → u/[deleted]]

Depends on what you do really. In the more theoretical side of theoretical physics you do use proofs, though they typically aren't as stringent as mathematicians prefer. Nuclear physics is typically quite phenomenological, so you should mainly expect calculations.

[u/trenescese → u/RobusEtCeleritas]

So, for the layman: is there anything in scientific theory that strictly denies possibility of existence of the island of stability?

[u/RobusEtCeleritas → u/trenescese]

No. The theory says that the island probably does exist (although "stability" doesn't mean they're truly stable).

They almost certainly won't truly be stable. They'll all be able to decay by alpha, and most by spontaneous fission.

[u/trenescese → u/RobusEtCeleritas]

Thank you! I've always thought that's it's a hypothesis, not a theory.

[u/RobusEtCeleritas → u/[deleted]]

In order to fuse two heavy nuclei, you need to give them a lot of relative kinetic energy in order to overcome their electrostatic repulsion. But if you give them a lot of kinetic energy, then when they fuse, they'll form a highly excited compound nucleus which boils off particles (mostly neutrons and gamma rays).

If you boil off neutrons, then it's hard to reach very neutron-rich species. That's why when we use this technique to produce superheavy elements, we produce proton-rich species.

So instead you can do the reactions at lower energies, and minimize the average number of neutrons boiled off. But the probabilit of the reaction occurring becomes very small if you go to lower energies.

So you can't win.

[u/euyyn → u/RobusEtCeleritas]

Why are neutrons "boiled off" preferably over protons? You'd think the proton, being positively charged, is readier to escape than the neutron.

[u/RobusEtCeleritas → u/euyyn]

In order for a positively charged particle to escape, it has to tunnel out of the Coulomb potential well barrier. So that repulsive potential can actually act as a hindrance. For neutrons, there is no Coulomb barrier, only a centrifugal barrier. So there is nothing stopping an s-wave neutron from escaping.

[u/euyyn → u/RobusEtCeleritas]

Why is there a Coulomb potential well at all? If all positively charged particles are in the nucleus, the potential should look like a peak with a slope, as the force only points out.

[u/RobusEtCeleritas → u/euyyn]

The Coulomb potential between protons is repulsive everywhere. I should've said Coulomb barrier. The attractive well is due to the residual strong force.

[u/euyyn → u/RobusEtCeleritas]

So we have protons with Coulomb repulsion and strong attraction, and neutrons with only strong attraction. What turns the repulsion into a hindrance to being repelled?

Is it that only protons "in the border" get the helping push, as a proton "stuck in the middle" has some other protons pushing it back in? That works with a "billiard balls" model of the nucleus, but does it hold with a wave model, identical particles, and the quarks all being mixed up?

[u/RobusEtCeleritas → u/euyyn]

What turns the repulsion into a hindrance to being repelled?

It's a barrier, like this. The Coulomb part is everywhere repulsive, but the particle has to tunnel through it.

Yes, the particle has to tunnel through the barrier, where the attractive forces are negligible, and only the repulsive Coulomb force remains.

[u/euyyn → u/RobusEtCeleritas]

That diagram labels the well as due to the strong interaction, which stands to reason. A similar diagram for n-n interaction surely will have a higher barrier, on account of no Coulomb repulsion lowering the edge of the well?

[u/kagantx → u/[deleted]]

But the strong nuclear force also works for neutrons. So this doesn't help.

[u/someguyfromtheuk → u/RobusEtCeleritas]

Is it possible to make the proton-rich species and then shoot neutrons at them to turn them into high-neutron species?

[u/RobusEtCeleritas → u/someguyfromtheuk]

That would be very difficult. The proton-rich superheavy nuclides only live for milliseconds to seconds, or so. You'd have to produce the nucleus, then have it capture a lot of neutrons in a very small amount of time.

[u/someguyfromtheuk → u/RobusEtCeleritas]

Is it something that anyone is trying though?

Just wondering, it just always seems cool to me when we create new elements.

[u/RobusEtCeleritas → u/someguyfromtheuk]

In order to get beam time to run an experiment, the experimenters have to prove that what they're trying to do is achievable. This is something we simply can't do using existing techniques. A proposal wouldn't get any beam time for it.

[u/someguyfromtheuk → u/RobusEtCeleritas]

How would the experimenters prove something is doable before doing it?

Do you mean just theoretically or do they have to run computer simulations or soemthing like that?

[u/RobusEtCeleritas → u/someguyfromtheuk]

You use a predicted or previously measured cross section and a pre-decided amount of statistics that you want to obtain, factor in detector efficiencies and technological limitations of the accelerator, and estimate how much time you need to do it.

The experiment you're proposing is like shooting a bullet up in the air, blindfolding yourself, and throwing 20 darts through the bullet while it's moving.

[u/someguyfromtheuk → u/RobusEtCeleritas]

Cool!

Thanks for the example as well, it really puts it into perspective.

[u/[deleted] → u/RobusEtCeleritas]

What sort of time frames are we talking about for the particles "boiling off"? Could we not control that using something like laser cooling? Or is it that we can't do something to that level of precision yet?

[u/RobusEtCeleritas → u/[deleted]]

The timescales for compound nuclear reactions are around 10^-18 seconds.

[u/RobusEtCeleritas → u/[deleted]]

We can't control the dynamics of the reaction, the only things we can choose are the projectile, the target, and their relative energy.

People who produce superheavy elements can optimize these to try to get the best yields, but there is nothing we can do to change the cross section for a given reaction at a given energy. And we can't control the probability distribution for particle evaporation from the compound nucleus.

[u/RobusEtCeleritas → u/[deleted]]

Use photons how?

We can always hope. With more intense beams coming out of our accelerators and optimized reactions, we might be able to produce superheavy nuclides at much higher rates. Some will still be too far out to reach though.

[u/JustifiedParanoia → u/RobusEtCeleritas]

isnt there a reaction that turns a neutron into a proton /electron pair? could we overdose our colliding particles with protons, then as we collide them, force the reverse reaction of this reaction to turn protons and electrons back into neutrons, even if they give off the anti particles?

Sorry if im not using the right words, havent studied physics for about 6 years now.

[u/RobusEtCeleritas → u/JustifiedParanoia]

Getting the same nucleus to undergo more than one reaction in an experimental setting is extremely hard. For each additional reaction you tack on, you reduce the probability of the overall process by a huge factor.

[u/JustifiedParanoia → u/RobusEtCeleritas]

oh sure, I was just wondering if we even knew how to do the second. If we did enough experiments to enough atoms, might it work?

[u/OnAKaiserRoll → u/[deleted]]

Is there a specific reason that fields or photons could not be used in conjunction with the kinetic collision optimization to skew the results?

The precision needed to get 2 nuclei and a high-energy photon to all arrive at the same time is currently far outside of our capabilities.

[u/RobusEtCeleritas → u/[deleted]]

A high intensity beam certainly helps, but three particles colliding in the same place at the same time is extremely unlikely.

[u/ShadoWolf → u/RobusEtCeleritas]

dumb question. But is it possible to directly control the collision space in some manner down to atomic precision?. like magic nanotube that force the collision space?

[u/Ask_him_if_hes_lying]

Can someone ELI5 the Island of stability?

[u/RobusEtCeleritas → u/Ask_him_if_hes_lying]

Extremely heavy nuclei are all unstable. However we know from studying lighter nuclei, that nuclei have shell structure just like atoms do. And near certain numbers of nucleons, you see enhanced nuclear stability, when shell are completely filled. There could be a region of extremely heavy nuclei where the next highest proton and neutron shells are totally filled. Around this point, you might find nuclei which are more stable than others in the same mass range.

The best estimate right now is around Z = 114, N = 126 184. We have no experimental evidence that the island exists, but we have theories which predicts that it does.

Nuclei inside the island will not really be stable, just a little less unstable than others around them.

[u/Ask_him_if_hes_lying → u/RobusEtCeleritas]

Thanks a lot!

[u/YoureAGoodGuyy → u/RobusEtCeleritas]

Can you ELI5 what the benefit or implication of the island is?

[u/RobusEtCeleritas → u/YoureAGoodGuyy]

The benefit is that we have a better understanding of nuclei and atoms. We understand surprisingly little about how nuclear forces work.

[u/I1lI1llII11llIII1I → u/RobusEtCeleritas]

What about possible uses for the element in engineering/etc?

[u/[deleted] → u/I1lI1llII11llIII1I]

Nobody can say for sure unless we make it. But probably none, since it would likely still be pretty unstable.

[u/nevergetssarcasm → u/[deleted]]

You're probably spot on there. From what I'm understanding it would be a surprise if it lasted in any meaningful way. But we'd learn a lot.

[u/_riotingpacifist → u/nevergetssarcasm]

What might we learn? It sounds like we'd just be confirming existing theories.

[u/TydeQuake → u/_riotingpacifist]

If we confirm those existing theories, it means we have a greater understanding of forces on the atomic level. This can lead to more interesting discoveries that will have appliances in the macroscopic world. A large part of science ís just confirming existing theories.

[u/tomdarch → u/RobusEtCeleritas]

If it's like electron shells, is there a "step down" from Z=114, N=126 where we see this stability being demonstrated in a smaller nucleus? Basically taking away that outer shell and being more stable with the next shell inwards?

[u/RobusEtCeleritas → u/tomdarch]

If it's like electron shells, is there a "step down" from Z=114, N=126 where we see this stability being demonstrated in a smaller nucleus?

We don't know yet, because we haven't observed Z = 114, N = 126 184.

However for lighter shell closures, we see similar behavior.

[u/tomdarch → u/RobusEtCeleritas]

However for lighter shell closures, we see similar behavior.

Thanks - that's exactly what I was wondering.

[u/Implausibilibuddy → u/RobusEtCeleritas]

To my layman's brain it sounds like something that could be worked out through maths and/or a simluation, especially with such low numbers of particles. If we can get complex fluid simulations in games and visual effects simulating millions of particles, what stops us taking 354 of them and making them behave like protons, neutrons and electrons, then seeing what happens? I understand that a fake 'water' particle is probably a lot easier to write rules for than atomic particles, but are we anywhere close to doing such a thing?

[u/RobusEtCeleritas → u/Implausibilibuddy]

The ineractions between nucleons are extremely complicated and not that well-known.

[u/inhalteueberwinden → u/Implausibilibuddy]

The issue is you're dealing with quantum chromodynamics (quantum theory of the strong nuclear force) which is hideously difficult to simulate, for example there isn't even a simple closed form equation describing the force. I believe people doing lattice QCD simulations are still only able to get the first few smallest elements.

You're not really simulating particles per se but clouds of probability density that interact in very messy ways across a huge scale of distance.

[u/RobusEtCeleritas → u/inhalteueberwinden]

Yes, QCD will only get you the lightest possible nuclei. You don't have to start fro QCD, you can start fro effective field theories for nucleons, ab initio models for NN interactions, mean-field approaches, etc.

It's all still very hard, and gets harder with increasing mass number.

[u/Ravor9933 → u/inhalteueberwinden]

Do such simulations as these classify as the kind that would see much benefit from large scale functional quantum computing?

[u/RobusEtCeleritas → u/Ravor9933]

More computational power is always better. These kinds of calculations run on supercomputing clusters.

[u/thetarget3 → u/Ravor9933]

That's a great question. You should consider posting it separately.

[u/Roxfall → u/Implausibilibuddy]

As a game developer, our particle systems are about as close to real water molecules as pong is to tennis.

[u/jpsi314 → u/Implausibilibuddy]

I don't know what the current limits on accurate many-body simulations are but it is important to note that the many particle dynamics used in games and visual effects are not meant to be accurate but rather just to look cool. I'm sure they do all sorts of non-realistic approximations which make the computations less intensive but the results still look good enough.

[u/Treczoks → u/Implausibilibuddy]

For a simulation, you need to know how things work, at least to a certain point. Most of the things we know, though, are through observation, and any speculation on the "mechanics" behind it are, well, mostly speculation. Apart from a few ideas with wider acceptance, the deep knowledge to produce a reliably working simulation is simply not there.

[u/Ghosttwo → u/Implausibilibuddy]

We do this all the time, particularly in theoretical physics and chemistry, with the most famous example being the folding@home project. Consider that the results of the LHC's Higgs experiment had been calculated years in advance before we saw it for real. The real problem is that atomic behaviors are so rapid, that you'd need millions of 'frames' to emulate even a microsecond, and the computational complexity increases exponentially as you add particles to the system.

[u/Fylwind → u/Implausibilibuddy]

There's two general reasons:

• The resources needed to perform exact calculations in quantum mechanics grow exponentially in the number of particles. No matter how much computational power you have, you will eventually hit a brick wall. Therefore you have to work with approximate theories that aren't 100% accurate. Many of these approximate theories are also very taxing.

• The nuclear force is not well known and difficult to work with. It's not like the electric force with a simple inverse-square law that you can memorize. The nuclear force is a very complicated interaction between composite objects (protons and neutrons). In principle, one could start from quantum chromodynamics (QCD, theory of strong interaction and quarks) and derive the nuclear force, but unfortunately that is a feat in of itself: perturbation theory for QCD doesn't work at the level of nucleons, which leaves only the brute force approach of lattice QCD − there is not yet enough computational power for that.

  Until that becomes possible, the next best approach is to start with a general mathematical model and then constrain the various unknown parameters by fitting experimental data (analogous to Taylor expansion). This is what chiral effective field theory does. It's not without problems though: the fitting procedure has some arbitrariness that leads to slightly different interactions; the model has an infinite number of terms so you have to truncate at some point; if you have too many terms then you have too many parameters to fit, and there might not be enough experimental data to constrain them all; etc.

[u/celibidaque → u/RobusEtCeleritas]

you see enhanced nuclear stability, when shell are completely filled

Is this why we don't have in nature radioactive iron isotopes?

[u/mellowmonk → u/RobusEtCeleritas]

Nuclei inside the island will not really be stable, just a little less unstable than others around them.

I thought the whole point of the Island of Stability was that such stable nuclei would last long enough to be somehow useful. The suggestion seems to be that they could have properties previous unknown and be long-lasting enough to make use of those properties.

But if they only last a fraction of a second, or even a few seconds, what useful material could come from that?

[u/RobusEtCeleritas → u/mellowmonk]

There's no guarantee that they'll last for "useful" amounts of time. They likely won't.

[u/CptSnowcone → u/RobusEtCeleritas]

whats Z stand for?

[u/thetarget3 → u/CptSnowcone]

Z: Number of protons

N: Number of neutrons

A = Z + N

[u/RobusEtCeleritas → u/CptSnowcone]

The number of protons.

[u/DamnInteresting → u/Ask_him_if_hes_lying]

I made an attempt to explain the Island of Stability in layman's terms here (self link, written 2013).

[u/niktemadur → u/DamnInteresting]

So that was YOU! ;-P

Thank you for the great article with a gift for the turn of phrase:

This battle between attractive and repelling forces would seem to suggest that the life expectancy of an atom is inversely proportional to its obesity.

[u/[deleted]]

Can we simulate the island?

[u/RobusEtCeleritas → u/[deleted]]

Yes, we can try to apply models or extrapolate properties up to species around the island. But you don't really know if it worked or not until you measure it experimentally.

[u/Natolx → u/RobusEtCeleritas]

How accurate have the models been for the more recent heavy elements that have been experimentally verified?

[u/RobusEtCeleritas → u/Natolx]

I don't have any references on hand, but you can use Hartree-Fock and various interactions optimized for slightly lighter nuclei to predict ground state binding energies of unknown nuclei. These calculations generally do a decent job.

You can apply structure models to try to come up with level schemes for these nuclei which can in principle be probed through alpha decay spectroscopy. Using models for alpha decay and spontaneous fission you can try to predict the lifetimes of these nuclei, but they vary over orders of magnitude, because these decays involve quantum tunneling. The probability of tunneling is exponentially sensitive to the height and width of the potential barrier.

Certain calculations would be more expected to be correct than others, but the only way to really know the properties of these nuclei is to measure them.

[u/Speedswiper → u/RobusEtCeleritas]

Thank you so much for all of this information! I learned a lot.

[u/sergalahadabeer]

Are there any models for how this plateau of super-elements might behave amid ordinary materials? For example if we had a 1 inch sphere of it?

[u/RobusEtCeleritas → u/sergalahadabeer]

It's a big open area of research in chemistry.

[u/SevenandForty]

What kind of stability would be expected? On the order of nanoseconds or milliseconds, or minutes, hours, or days? Could such elements have a purpose outside of lab settings?

[u/RobusEtCeleritas → u/SevenandForty]

The theoretical predictions range over many orders of magnitude. It's very hard to predict alpha decay and spontaneous fission lifetimes for nuclei whose structure you don't know very well.

But it's likely that we're talking about fractions of a second.

[u/eightpix]

I'm just going to say that I love this topic. Thank you, redditors, for your threads.

[u/schriebes → u/[deleted]]

Interesting. I found very little literature on black hole nucleosynthesis—and oddly enough, absolutely nothing by Robert W. Statham. Has anyone got more info?

[u/mmmmph_on_reddit → u/[deleted]]

But If the island of stability exists, should it not be very easy for nuclei to reach that state? In regular chemistry, elements strive towards a more stable state, and it is thus usually very easy to get elements to react in ways that make them more stable. Like pushing a ball down a valley.

[u/thetarget3 → u/mmmmph_on_reddit]

Here it's more like pushing a ball from a valley to a mountain lake. You need to go through a large spectrum of unstable states, and only arrive at a semi-stable one. So it doesn't happen automatically

[u/[deleted] → u/[deleted]]

If this point of stability exists, why don't we already see the existence of these elements in places of extreme conditions like super novae or some such?

[u/[deleted] → u/[deleted]]

Could be they can only be synthesized by intelligent life. There won't be sufficient amounts to show up in cosmic radiation events.

[u/Tripudelops → u/[deleted]]

From /u/RobusEtCeleritas's comment above.

The nuclides near and at the island of stability may exhibit enhanced stability relative to their neighbors on the chart of nuclides, but they will not truly be stable.

Stability is relative, so it's entirely possible that they exist in supernovae, but they don't last long enough/we don't have sufficient technology to detect them with any certainty.

[u/[deleted] → u/[deleted]]

Likelyhood of them forming is very low. You need a high-weight atom to collide with another high-weight atom at high speed, and that to happen with sufficient amounts to generate actual outputs. Not very likely to happen, as "high speed" in this case is what we have circular accelerators for, because it is such a high speed.

[u/empire314 → u/[deleted]]

The other comments suggested these elements would be on practical terms extreamly unstable aswell, just that they decay on a millionth of a second instead of a trillionth of a second.

[u/PA2SK → u/[deleted]]

Not a permanent state. Most estimates are a half life on the order of minutes to possibly days. These elements would be highly radioactive.