Pinning down the 'Island of Stability': Stabilizing shell effects in heaviest elements directly measured

Aug 10, 2012
Enrique Minaya Ramirez and Michael Block are with the Shiptrap ion detector. Credit: G. Otto / GSI Helmholtzzentrum für Schwerionenforschung

(Phys.org) -- An international research team has succeeded in directly measuring the strength of shell effects in very heavy elements at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt. The results provide information on the nuclear structure of superheavy elements, thus promising to enable drastically improved predictions concerning the location and extension of the island of stability of superheavy elements.

So-called "superheavy" elements owe their very existence exclusively to shell effects within the atomic nucleus. Without this stabilization they would disintegrate in a split second due to the strong repulsion between their many protons. The constituents of an , the protons and neutrons, organize themselves in shells. Certain "magic" configurations with completely filled shells render the protons and neutrons to be more strongly bound together.

The SHIPTRAP Penning trap consist of several cylindrical gold-plated electrodes separated by ceramic insulators. Credit: Helmholtz Association of German Research Centres

Long-standing suggest that also in , filled proton and neutron shells will give rise to extraordinarily stable and hence long-lived nuclei: the "Island of stability". Still, after decades of research, its exact location on the chart of nuclei is a topic of intense discussions and no consensus has yet been reached. While some predict a magic proton number to be at , others prefer element 120 or even 126. Another burning question is whether nuclei situated on the island will live "only" hundreds or maybe thousands or even millions of years. Anyway, all presently known superheavy elements are short-lived and none have been found in nature yet.

Precise information on the strength of shell effects that enhance binding energies of protons and neutrons for filled shells is a key ingredient for more accurate theoretical predictions. As the is directly related to the mass via Einstein's famous equation E=mc2, the weighing of nuclei provides access to the nuclear binding energies and thus the strength of the shell effects. With the ion-trap facility SHIPTRAP, presently the most precise balance for weighing the heaviest elements, a series of very heavy atomic nuclei in the region of the magic neutron number N=152 have now been weighed with utmost precision for the first time. The studies at hand focused on nobelium (element 102) and lawrencium (element 103). These elements do not exist in nature, so the scientists produced them at the GSI's particle accelerator facility and captured them in the SHIPTRAP. The measurements had to be performed with just a handful of atoms: for the isotope lawrencium-256 just about 50 could be studied during a measurement time of about 93 hours.

This map shows presently known isotopes of the heaviest elements as squares. Blue: Calculated strength of shell effects. Red: nobelium and lawrencium isotopes studied. Green / yellow: Nuclides whose masses have been improved by the results. Orange: Location of closed shells. Courtesy of Science/AAAS

The new data will benchmark the best present models for the heaviest atomic nuclei and provide an important stepping stone to further refining the models. This will lead to more precise predictions on the location and extension of the "Island of stability" of superheavy elements.

Explore further: Neutrino trident production may offer powerful probe of new physics

More information: E. Minaya Ramirez et al. "Direct mapping of nuclear shell effects in the heaviest elements" von, Science 2012 DOI: 10.1126/science.1225636

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baudrunner
3 / 5 (2) Aug 10, 2012
Science is getting better in leaps and bounds all the time. I wonder if this kind of experiment would be better done in the microgravity of space, notwithstanding current theory concerning "negligible" effects of gravity at atomic scales.
axemaster
5 / 5 (4) Aug 10, 2012
Science is getting better in leaps and bounds all the time. I wonder if this kind of experiment would be better done in the microgravity of space, notwithstanding current theory concerning "negligible" effects of gravity at atomic scales.

Gravity is something like 10^20 times weaker than the other forces, so there's no difference if you're in orbit or not...
typicalguy
1 / 5 (1) Aug 11, 2012
Just think what kinds of bullets can be made of a new stable heavy element. It would make depleted uranium ammunition look like a child's toy. Wait, you thought this (when discovered) would be used for helping humanity?
Lurker2358
3 / 5 (2) Aug 11, 2012
Just think what kinds of bullets can be made of a new stable heavy element. It would make depleted uranium ammunition look like a child's toy. Wait, you thought this (when discovered) would be used for helping humanity?


Even if a stable element was found, do you have any idea how much it would cost to produce enough of it to make anything at all?

A bullet? You're talking about a couple GRAMS of the stuff. It would cost like 10 trillion dollars to make one bullet.

Element 120 would be highly reactive chemically, so no good as a bullet, and probably even more expensive to refine than anything imaginable.

Element 126 would be on a new row below Uranium, so maybe it would be good for bullets, in theory, or maybe it would be good for a breeder material for nuclear bombs.

As a fuel source it would be worthless, since it would cost so much more to make it than the energy available.

Elements 142 and 143 might be interesting though...
Lurker2358
2.3 / 5 (6) Aug 11, 2012
We have Helium, Mercury, Uranium, Neptunium, and Plutonium.

Ahem, back when Plutonium was named, Pluto was considered a planet.

Now we need Venusium, Earthium(Terrium/Gaeium?), Marsium, Jupiterium, and Saturnium, not to mention Lunarium, etc. We can even do Cosmium and Galactium.

Lots of idiotic greek mythology names to mix in with scientific names which atheists on this site love the greek mythology names so much.
TheGhostofOtto1923
3.8 / 5 (17) Aug 11, 2012
Even if a stable element was found, do you have any idea how much it would cost to produce enough of it to make anything at all?
-You mean today, or when we devise the means to do so cheaply and in great abundance? Like antimatter, neutrinos, or plutonium...?
Lunarium
Lunaria is where you live isnt it QC?
Lots of idiotic greek mythology names to mix in with scientific names which atheists on this site love the greek mythology names so much.
Or why the catholics enjoyed erecting obelisks in front of their basilicas so much? Or for that matter, adopting the trinity concept from the original isis/osiris/horus construct? Maybe they were only iterations of the SAME THING.
Ober
3.7 / 5 (3) Aug 11, 2012
Just to add something ludicrous into the convo, didn't the so called Nazi Bell and Nazi UFO's run off element 115?? I think a person who claimed they worked at Area 51, said that captured UFO's also used element 115 for anti-gravity purposes. Not trying to be a nut-job here, just though I'd add that tad of information, as element 115 seems like it might be in the island of stability. (maybe thats why nut jobs use it in their UFO stories!!!) So Who knows!!!!!
antialias_physorg
4.2 / 5 (5) Aug 11, 2012
Just think what kinds of bullets can be made of a new stable heavy element

None at all. When we're talking about "islands of stability" we're not talking about long term stable atoms like iron or oxygen. We're talking about atoms that are still radioactive, but whose half lives are on the order of minuts/hours rather than micro/picoseconds for the ones immediately preceeding them on th etable of elements. (And after the island of stability half lives get shorter again)

So, no: we're not going to manufacture stuff out of these super heavy elements - even if we could produce them in bulk.
rwinners
Aug 11, 2012
This comment has been removed by a moderator.
Mike_Massen
1.7 / 5 (6) Aug 12, 2012
Gravity is something like 10^20 times weaker than the other forces, so there's no difference if you're in orbit or not...


Thats an assumption at best and not necessarily the full picture, we cant be sure of any complexities such as discontinuities, unknown interactions which can increase (or decrease) etc...
antialias_physorg
5 / 5 (2) Aug 12, 2012
Thats an assumption at best and not necessarily the full picture

This is not an assumption.
If it were otherwise all the other models (weak and strong nuclear force and electromagnetic force) wouldn't work. They give us very definite predictions at the atomic scale and these predictions have worked out time and again in experiment.

If gravity were to play and real part at those ranges then stuff would look quite different.

Electromagnetic forces are 36 orders of magnitude stronger than gravity (with strong nuclear forces being even 2 orders of magnitude stronger than that)
axemaster
5 / 5 (3) Aug 12, 2012
Thats an assumption at best and not necessarily the full picture, we cant be sure of any complexities such as discontinuities, unknown interactions which can increase (or decrease) etc...

This is not an assumption. If it were otherwise all the other models (weak and strong nuclear force and electromagnetic force) wouldn't work. They give us very definite predictions at the atomic scale and these predictions have worked out time and again in experiment.

You're both right. As AA said, if gravity were stronger at short distances, then we would easily detect it since it would change the nuclear energy levels and so on. However, that doesn't preclude gravity becoming weaker than expected - it may be that gravity disappears or changes at very small scales. This is sometimes predicted by models that say gravity is a statistical effect. Personally, I'm not entirely convinced that gravity is a true field force, so it'll be interesting to see what comes along.
axemaster
5 / 5 (4) Aug 12, 2012
Actually, I would point out to AA that to my knowledge, gravity is not detectable at the nuclear scale through any contemporary experimental techniques. It could probably vary up or down by a few orders of magnitude, and we wouldn't know it.
antialias_physorg
5 / 5 (2) Aug 12, 2012
It could probably vary up or down by a few orders of magnitude, and we wouldn't know it.

True. Which would change nothing as regarding the issue at hand (viz: whether gravity could cause changes in stability of superheavy atomic nuclei).
Whether gravity is dominated by 36 or 38 or 100 orders of magnitude by electrostatic or nuclear forces still comes out to the same thing: Superheavies aren't going to come out completely stable any which way.
axemaster
Aug 12, 2012
This comment has been removed by a moderator.
Mike_Massen
1 / 5 (3) Aug 12, 2012
antialias_physorg baulked
This is not an assumption.
Sorry to contradict you, it is a huge assumption & you claim it would affect other issues isnt necessarily true. Here is why:-

a. The model which makes the predictions you offer as 'proof' is incomplete, it's fine now within some experimental error for the atoms we know but cant necessarily be extrapolated with absolute certainty and especially so as we haven't clarified why gravity works the way it does...

b. Nucleon relativistic effects. As the nucleus grows in size there are oscillatory motions between the so called shells which reach relativistic speeds and can affect the interaction of forces which also has not been predicted or even observed.

c. For a large nucleus there will be a correspondingly larger electron cloud and the outer electrons will move at relativistic speeds also. It is known there are unusual interactions between nucleus and electrons as size grows.

Best not to assume certainty (yet)...
axemaster
5 / 5 (3) Aug 12, 2012
Sorry Mike, but you don't know what you're talking about here. Gravity just doesn't play any meaningful role in atomic physics. Quantum physics has successfully predicted nuclear energy levels to extraordinary precision for a wide variety of systems. YOU are the one making assumptions when you make entirely unfounded and frankly illogical claims that it won't continue to extend to larger atoms.
rwinners
not rated yet Aug 12, 2012
Certain "magic" configurations with completely filled shells render the protons and neutrons to be more strongly bound together.

Why?
Mike_Massen
1 / 5 (3) Aug 13, 2012
axemaster got defensive & doesnt understand the term 'illogical'
Quantum physics has successfully predicted nuclear energy levels to extraordinary precision for a wide variety of systems. YOU are the one making assumptions when you make entirely unfounded and frankly illogical claims..
Thats based upon interpretation, knowing why something works is not the same as being able to describe it.

We dont have 100% knowledge of any of the forces *and* their interaction this means we cannot be sure of how forces interact with gravity at the relativistic conditions likely in large atoms.

I know you crave certainty but, lets be mature, we dont have certainty, no where near it !

You can only claim to understand the logic of what goes on in the atom when you have a complete model, the model is not complete by a long shot.

Therefore my comments are not illogical per se but, bring up issues not addressed and not resolved Eg Re relativistic effects & combinatorial complexity & others !
antialias_physorg
5 / 5 (1) Aug 13, 2012
As the nucleus grows in size there are oscillatory motions between the so called shells which reach relativistic speeds and can affect the interaction of forces which also has not been predicted or even observed.

They are predicted and observed. Relativistic effects are the reason why gold is golden and not silver looking (like most other metals).

For a large nucleus there will be a correspondingly larger electron cloud and the outer electrons will move at relativistic speeds also

The real problem with stability isn't the electrons. It's the protons. Protons are positively charged and push against each other in every pair - so the stability decreases more rapidly as atomic weight increases. Island of stability is a geometric effect with 'magic numbers' of nucleons. Gravity plays no part in this.
kochevnik
not rated yet Aug 13, 2012
Certain "magic" configurations with completely filled shells render the protons and neutrons to be more strongly bound together.
They are tetrahedral vertex points that allow fractal nesting of the wave function vortex.
Mike_Massen
1 / 5 (2) Aug 13, 2012
As the nucleus grows in size there are oscillatory motions between the so called shells which reach relativistic speeds and can affect the interaction of forces which also has not been predicted or even observed.
They are predicted and observed.
Are you sure antialias_physorg ? The model is not complete and we havent had nucleons of that size for long enough and with enough purity to make the type of precise observations necessary to achieve certainty. See my previous post.

For a large nucleus there will be a correspondingly larger electron cloud and the outer electrons will move at relativistic speeds also

The real problem with stability isn't the electrons.
I was offering observation in different context. You've diverged.

See my last post, as it seems you posted without having the chance to read it, ie both your's and mine posted at ~ same time...
axemaster
not rated yet Aug 13, 2012
Are you sure antialias_physorg ?

He is. I got rather nostalgic when he brought up the thing about the color of gold, which I remember learning back in my quantum class.

The model is not complete and we havent had nucleons of that size for long enough

This is just wrong. You can generally group atomic nuclei into two camps - tightly bound and loosely bound.

Generally speaking tightly bound nuclei are those where the nucleons are close enough together to directly talk to each other, and the simpler ones can be solved pseudo-analytically (albeit with great effort).

Loosely bound nuclei are those where the nucleons can be thought of as clustering into separate groups, which then interact with each other. These are generally solved through horribly unpleasant computer methods, although analytic methods exist for getting relatively bad approximations.

The thing is, there are many many "standard" atoms in both camps, so there has been plenty of experiment already.
MaxwellsDemon
5 / 5 (1) Aug 15, 2012
@antialias_physorg
"When we're talking about "islands of stability" we're not talking about long term stable atoms like iron or oxygen. We're talking about atoms that are still radioactive, but whose half lives are on the order of minuts/hours rather than micro/picoseconds"

We don't know that yet. It's possible that some isotopes in the island of stability will last much longer:
they are expected to have radioactive decay half-lives of at least minutes or days as compared to seconds, with some expecting half-lives of millions of years.
[Scharff-Goldhaber & Swiatecki] calculated...an "Island of Stability" where their lifetimes could be measured in minutes or days - or even, some optimists think, in millions of years.
http://en.wikiped...tability

And from the article above:
Another burning question is whether nuclei situated on the island will live "only" hundreds or maybe thousands or even millions of years.
MaxwellsDemon
not rated yet Aug 15, 2012
Re: gravitational influence on nuclear stability
@antialias_physorg
"Which would change nothing as regarding the issue at hand (viz: whether gravity could cause changes in stability of superheavy atomic nuclei)."

and

@Axemaster
"Gravity just doesn't play any meaningful role in atomic physics."

Let's be mindful about context here, gents. Gravity may have a negligible effect on nuclear forces near the Earth, but strong gravitational fields can have an enormous impact on nuclear binding, viz, neutron stars (which have cores even denser than ordinary nuclear matter). Similar considerations would apply to the first instants of the Big Bang, when gravity was unified with the other forces (including the nuclear strong force).
antialias_physorg
not rated yet Aug 15, 2012
but strong gravitational fields can have an enormous impact on nuclear binding, viz, neutron stars

Well, if you want to deliver your heavy-element-bullet along with a complimentary neutron star, then be my guest. However, I don't think that will sell much.

Also note that the circumstances of a neutron star will not have a positive effect on the stability of individual atoms. It will only have an effect on how densely groups of atoms are packed (if anything atoms will get LESS stable before the neutron star stage is reached, since we're dealing with high temperatures and magnetic fields WAY beyond what is needed to tear atoms apart into plasma/fully ionized nuclei).

The original question was, whether we'll use these super-heavy elements to manufacture something macroscopic. And the answer is: No way.
MaxwellsDemon
5 / 5 (1) Aug 16, 2012
@antialias_physorg
Well, if you want to deliver your heavy-element-bullet along with a complimentary neutron star, then be my guest. However, I don't think that will sell much.

No need to get snippy. Just pointing out that, under extreme conditions, gravity can have an appreciable influence on nuclear stability: the core of a neutron star is essentially a single mammoth super-heavy nucleus stabilized entirely by gravitation. And I only mentioned it because you guys were starting to talk in absolutes, neglecting the all-important element of context.
MaxwellsDemon
not rated yet Aug 16, 2012
@antialias_physorg
The original question was, whether we'll use these super-heavy elements to manufacture something macroscopic. And the answer is: No way.

You're making two unsupported assumptions:
1.) that we won't find super-heavy isotopes with half-lives of many years or even eons, and
2.) that we won't find much more efficient means of manipulating nuclear chemistry than exists today (which is a brash assumption, given that we don't even have a fully empirical nuclear mass formula yet)

Personally, I never bet against future developments. You're free to do so (at your own peril), but it's wrong to state your *personal beliefs* as *established facts*.

I wouldn't be at all surprised if, in a few hundred years, spacecraft were fueled by a highly stable super-heavy element in pellet form, which could be converted to highly radioactive lighter elements by controlled thermal neutron bombardment to release energy on demand...much safer than antimatter.
antialias_physorg
not rated yet Aug 16, 2012
that we won't find super-heavy isotopes with half-lives of many years or even eons, and

The super heavy elements dont exist in nature. They have to be manufactured one atom at a time. The energy cost of making even one such atom is atrocious. To get macroscopic amounts would require energy on stupendous levels.

The stability is the result of these 'magic numbers'. If you go into the subject (topology) you will find that no matter how 'magic' these numbers get it doesn't work out to very stable configurations. The number of required protons (and neutrons) grows very fast. Atomic nuclei are held together via the strong nuclear force which, although 100 times as strong as the electromagnetic force, is also very short ranged.

With nuclei getting larger this range is quickly exceeded and the electromagnetic repulsion of the protons splits them apart.

This is why large atoms are already unstable in the first place. More protons just make it worse. Magic numbers can't reverse that.
antialias_physorg
not rated yet Aug 16, 2012
Personally, I never bet against future developments.

There's future developments and then there's fundamental laws of physics.

Even though we're sure to find new ones that doesn't mean the old ones suddenly don't apply anymore.

Example: Relativity replaced Newtonian gravity. However, a result gotten with Newtonian gravity that was -at the time- correct to within margins of error will therefore NOT suddenly be off by 500% if you do the same calculation with Relativity)

Or as Scotty so famously put it: "Captain, I canna change the laws of physics"

So while I think we will be able to make a lot of great (and by today's standards: incredible) developments I don't think well be able to change the laws of physics any time soon.
At least in a timeframe in which 'manufacturing stuff' is still of any importance.
antialias_physorg
2 / 5 (1) Aug 16, 2012
the core of a neutron star is essentially a single mammoth super-heavy nucleus

That's a metaphor. A neutron star is not an atom (it has no orbiting electrons) and it is also not an ion (it has no net charge).
We were talking about (super-heavy) atoms here - not nucleons.

The only way in which a neutron star is comparable to a nucleus is that nucleons (neutrons) in this case are very close together. That's about it. (and even that isn't true throughout the neutron star as the closer you get to the surface the more 'porous' it gets)
MaxwellsDemon
not rated yet Aug 17, 2012
There's future developments and then there's fundamental laws of physics.

Let's recap:

-You said that macroscopic quantities of super-heavy elements were unachievable. Your exact words were "No way."

-I said that your assertion isn't supported, because 1.) we don't yet know how stable they will be, and 2.) it's likely that we'll be able to produce them far more efficiently in the future.

-And now you're saying that my argument violates the laws of physics.

Which is wrong. The only *fundamental* quantity here is the mass defect. Which is only a tiny fraction of the energy that we now use/waste when we produce these elements in today's ultra-low-efficiency colliders. No physical law precludes much higher efficiency devices that would require little more than the energy necessary to produce these isotopes.

So this isn't a laws of physics challenge, it's a technical challenge. If you have citations to prove me wrong, then please do so. Thanks.
MaxwellsDemon
5 / 5 (1) Aug 17, 2012
the core of a neutron star is essentially a single mammoth super-heavy nucleus

That's a metaphor.

No it isn't. The primary distinction is that it's bound by gravity rather than the strong force, which was my point in the first place:

"A neutron star has some of the properties of an atomic nucleus, including density and being composed of nucleons. In popular scientific writing, neutron stars are therefore sometimes described as giant nuclei. However, in other respects, neutron stars and atomic nuclei are quite different. In particular, a nucleus is held together by the strong interaction, while a neutron star is held together by gravity."
http://en.wikiped...ron_star

A neutron star is not an atom (it has no orbiting electrons)

I never said it was an atom. I don't know why you keep bringing electrons into it.

We were talking about (super-heavy) atoms here - not nucleons.

That's all you; I've never mentioned atoms.
MaxwellsDemon
not rated yet Aug 17, 2012
The only way in which a neutron star is comparable to a nucleus is that nucleons (neutrons) in this case are very close together.

There may be protons too, we don't know yet. But it's hardly a specious comparison tightly bound nucleons that obey the Pauli exclusion principle is pretty much the definition of a nuclear matter, i.e., a nucleus.

(and even that isn't true throughout the neutron star as the closer you get to the surface the more 'porous' it gets)

I specified the core, so that's a straw man argument. My initial points remain unchallenged:

- gravity can bind nuclear matter under extreme conditions such as the core of a neutron star which is essentially a single gravitationally-bound nucleus of quark/gluon matter, and

- nothing in the laws of physics prohibits the production of macroscopic amounts of super-heavy elements (which might provide an excellent form of energy storage someday).
axemaster
2 / 5 (1) Aug 18, 2012
I would point out that if a "nucleus" is large enough to describe meaningfully using classical parameters, then it's really not a nucleus any more. Neutron stars are described using stuff like albedo, luminosity, flatness, etc. You can't apply any of those things to an atomic nucleus because they're quantum objects.

nothing in the laws of physics prohibits the production of macroscopic amounts of super-heavy elements (which might provide an excellent form of energy storage someday).

I'm sure even you can see the absurdity of this statement. And while the laws of physics don't literally say it's impossible, math and common sense (read visualizing) strongly point toward it being undoable. You have to collide many atoms to get one superheavy atom, and most of the energy that goes in will not be reuseable.

AA is quite correct to say "no way". You just need to understand that not everything is possible just because of "the future".
axemaster
2.3 / 5 (3) Aug 18, 2012
Also, Wikipedia is a crutch for people who don't know what they're talking about. I spend enough time having to correct my brother about stuff he misunderstands on Wikipedia. The trouble with Wikipedia is that while usually correct, it doesn't provide nearly enough context or background for newcomers to understand complex physics topics. It's written by scientists for scientists, so when they say a neutron star is like a nucleus, they don't really mean that. They're just pointing out the similarity because they find a gravity bound jumble of nucleons "amusing".
MaxwellsDemon
5 / 5 (2) Aug 18, 2012
@axemaster
For someone who offers no substance to debate, you certainly are patronizing about it.

Btw, according to the leading model, the core of neutrons stars is composed of superfluid (re: correlated) degenerate matter, which means that it's a quantum object with a corresponding de Broglie wavelength:
http://allrite.ne...ars7.htm

Which you might've known, if you'd read the wiki more carefully:
"One model describes the core as superfluid neutron-degenerate matter"
http://en.wikiped...ron_star
axemaster
1 / 5 (1) Aug 19, 2012
I did know it... what I'm saying is that your claim that it can be meaningfully described as a nucleus is wrong. And there is a difference between some properties being explainable using quantum mechanics and the thing being a quantum object. And in any case I'm simply refuting your claims which are:

-Neutron Stars are comparable to atomic nuclei.
-Mass production of island-of-stability elements is feasible.
-The laws of physics as currently understood are going to be replaced with something that makes the previous statement true.

It should be fairly apparent that these statements are all wrong. You say I'm not contributing to this conversation, but hey, at least I'm not making a bunch of ridiculous claims and then crying about it when people point out my mistakes. And at least I've bothered to educate myself enough that I don't need to waste time reading shoddy Wikipedia articles about it.
Mike_Massen
1 / 5 (1) Aug 19, 2012
axemaster mumbled he did it himself - dont we all ? And when is it 'enough' ?
And at least I've bothered to educate myself enough that I don't need to waste time reading shoddy Wikipedia articles about it.
Top 5 current examples of these shoddy examples re Wikipedia and topics more or less directly related to the discussion here ?

btw: axemaster, Your vague 'scientists for scientists' remark doesn't quite cut it, link please ?

"Details Matter" tm

MaxwellsDemon
not rated yet Aug 19, 2012
@axemaster
You seem to be more interested in trying to convince people that you're a Ph.D. in QM, than debating rationally.

I'm simply refuting your claims which are: -Neutron Stars are comparable to atomic nuclei

Here's a Physical Rev. Letters paper by Horowitz and Piekarewicz that refutes your refutation:
The original paper for Ph.D.'s, "Neutron Star Structure and the Neutron Radius of 208Pb"
http://prl.aps.or.../p5647_1
MaxwellsDemon
5 / 5 (1) Aug 19, 2012
Further References

Hendrik van Hees, "Neutron Stars: Giant atomic nuclei in the sky"
http://cyclotron....hees.pdf

"The remnant of the core has become essentially one giant atomic nucleus made up of neutrons."
Penn State, Dept. of Astronomy and Astrophysics, Astronomy 801
https://www.e-edu..._p7.html
MaxwellsDemon
not rated yet Aug 19, 2012
@axemaster
And there is a difference between some properties being explainable using quantum mechanics and the thing being a quantum object.

That's just silly.

the laws of physics...(etc., etc.)

And as I've already pointed out to antialias_physorg, "the laws of physics" don't preclude large-scale super-heavy nuclei production, because the fundamental factor of concern is the conservation of energy, which actually supports my argument: energy in - efficiency losses = energy out. So it's physically possible, by today's laws of physics, to produce super-heavy nuclei with far greater efficiency than we now achieve with our current technology. If you have *any citations whatsoever* that describe any law of physics which refutes this statement, then I challenge you to provide it right now (and please spare us the blustering this time, thanks).
antialias_physorg
2 / 5 (1) Aug 20, 2012
the laws of physics" don't preclude large-scale super-heavy nuclei production

Of course they don't - because we have produced them (and if we can produce them you can bet that they get produced in the occasional supernova or similar high energy event in the cosmos).

BUT the laws of physics also say that super heavy elements are unstable - so any such element won't be around for long. Magic numbers do give them a higher halflife than for other high atomic mass elements - but there's a VAST difference between "half life of minutes" and "totally stable". And the latter is just not in the cards - no matter how ultra-magic the numbers become.
MaxwellsDemon
4.5 / 5 (2) Aug 21, 2012
@antialias_physorg
Yes shell effects play the key role in nuclear stability, but we don't yet know what all the magic numbers are, so we don't yet know the precise location of the "Island of stability." From this very article:
While some theoretical models predict a magic proton number to be at element 114, others prefer element 120 or even 126

So your appeal to "the laws of physics" means *nothing*. We don't have a complete model yet.

Also from this article:
Another burning question is whether nuclei situated on the island will live "only" hundreds or maybe thousands or even millions of years.

That statement concurs with all of the literature I've read on this subject.

So when you say that "the laws of physics" preclude super-heavy elements with half-lives of thousands or even millions of years, you're making an assertion that leading nuclear physicists aren't ready to make, i.e. you're misrepresenting the state of knowledge on this subject.

Shame on you.
Mike_Massen
2 / 5 (5) Aug 21, 2012
Damn right MaxwellsDemon re antialias_physorg with this
So your appeal to "the laws of physics" means *nothing*. We don't have a complete model yet..
Shame on you
Ditto, & antialias_physorg & others have deterministic habits out of mere hope & desire like some religious adherents, take note here:-

http://en.wikiped...r_isomer

And especially so in reference to Para 2
Occasionally the...
Yes I know, its wikipedia & yes occasionally in transition & 'off the money' but rarely if ever downright false.

Besides all good scientists take the probabilistic view & that also means mostly attending to the references offered by wikipedia & others to arrive at the 'critical mass' or rather the gestalt...

btw: There is nothing to say miniscule amounts of high no. elements dont have long lived nuclear isomers not discovered yet !

Thanks MaxwellsDemon you put it well and addressed my potentially transitional isomeric impatience with antialias_physorg tut tut

*grin*
antialias_physorg
not rated yet Aug 21, 2012
Yes shell effects play the key role in nuclear stability, but we don't yet know what all the magic numbers are

We do. They are just a matter of topology. The first island of stability will be the most 'stable' of them. Other islands of stability further up the sequence will be less stable (albeit more stable than the atoms on either side - otherwise it wouldn't be an 'island of stability')

The effect of of proton-proton interaction outgunning the strong nuclear force increases faster than increasing magic numbers decrease it.

Besides all good scientists take the probabilistic view & that also means mostly attending to the references offered by wikipedia & others to arrive at the 'critical mass' or rather the gestalt...

Whut? I call "pseudo-hippy mumo-jumbo" on this one.

i.e. you're misrepresenting the state of knowledge on this subject.

No. I represent the state of knowledge on this. YOU represent "might be" knowledge - which is NOT state of knowledge.
MaxwellsDemon
not rated yet Aug 21, 2012
@antialias_physorg
I see you've chosen to ignore my references for a third time. That's not very sporting of you. Let's try some new ones then.

Here are some excerpts from the world's leading superheavy element researchers at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia (these are the guys who invented the requisite nuclear synthesis process, and then created elements 112-118):

Nuclei in the "Island of Stability" of Superheavy Elements
Oganessian, 2012
"In the region where the liquid-drop model predicted that the nuclei should decay within 10-19 sec, now the half-lives of «long-lived» nuclei at the peak of the island of stability are expected to reach thousands and even millions of years! (see, for example, review [5])."
http://iopscience...2005.pdf

Ref.[5] Description of Structure and Properties of Superheavy Nuclei
Sobiczewskia and Pomorskib, 2007
http://kft.umcs.l...-292.pdf

(cont.)
MaxwellsDemon
not rated yet Aug 21, 2012
Decay Properties and Stability of Heaviest Elements
Karpov, Zagrebaev, et al., 2012
"Our calculations yield that the -stable isotopes 291Cn and 293Cn with a half-life of about 100 years are the longest-living superheavy nuclei located at the island of stability."
http://www.worlds...de=ijmpe

But here Dr. Valery Zagrebaev estimates that element 112/291 will have a half-life of 1200 years:

Path to Island of Stability
Zagrebaev, 2012
"A macroscopic amount of the long-living SH nuclei located at the island of stability may be produced with the use of pulsed nuclear reactors of the next generation (factor 1000 is needed)."
cyclotron.tamu.edu/nn2012/Slides/Plenary/NNC_2012_Zagrebaev.ppt

Time to face the music, antialias_physorg: either A.) admit that you're wrong (finally), or B.) claim that your expertise on SHN stability exceeds that of the world's top researchers in the field (which would discredit you completely).

Which is it?
MaxwellsDemon
1 / 5 (1) Aug 21, 2012
For the record - until now I've had nothing but the utmost respect for your contributions here, antialias_physorg: you have consistently augmented the articles with links and info that I value.

But this total unwillingness to recognize the limitations of your knowledge on -any - subject, exemplifies a level of egoism totally unworthy of your legacy, and leads you to say outrageously self-deifying things like:
I represent the state of knowledge on this.

You're better than that. Take a bite of humble pie, and relax. We're all here to expand our understanding, not to proclaim our own omniscience.
axemaster
not rated yet Aug 21, 2012
I would like to point out for the record that everything AA has said has been correct.

but we don't yet know what all the magic numbers are, so we don't yet know the precise location of the "Island of stability." - MaxwellsDemon

The conversation should have ended right here, because this statement reveals a complete lack of understanding of the topic, and the physics and maths underlying the topic. The "magic numbers" have been known for a long time, it's just the precise atomic states (energies, lifetimes) at these numbers that are hard to calculate.

There's little use arguing with someone who does even know this small fact, so I'll retire from this "debate" now.
TheGhostofOtto1923
4.2 / 5 (11) Aug 21, 2012
Just think what kinds of bullets can be made of a new stable heavy element

None at all. When we're talking about "islands of stability" we're not talking about long term stable atoms like iron or oxygen. We're talking about atoms that are still radioactive, but whose half lives are on the order of minuts/hours rather than micro/picoseconds for the ones immediately preceeding them on th etable of elements. (And after the island of stability half lives get shorter again)

So, no: we're not going to manufacture stuff out of these super heavy elements - even if we could produce them in bulk.
It could be an advantage to have bullets which decay into something more benign after they are used. Look at the problems that DU causes on the battlefield.
MaxwellsDemon
not rated yet Aug 21, 2012
@axemaster
I see you ignored my challenge. Pity.
The "magic numbers" have been known for a long time

It's kinda funny to hear you talk about this burgeoning area of on-going theoretical and experimental research as if it's already mapped and understood, when in fact we have several competing models that make various predictions about the shell structures of nuclei that haven't been observed yet.

There are several factors that contribute to different models making different predictions about the magic numbers and semi-magic numbers of superheavy nuclei, but deformation and the prospect of "bubble nuclei" are among the top factors. If you had bothered to read my links you'd already know this.

You'd also know that the world's leading team on this subject predicts that the island of stability is a region too neutron-rich to be accessed with current technology, but they have a plan to get there so they can test the current models.
MaxwellsDemon
not rated yet Aug 21, 2012
(cont.)
Source: http://kft.umcs.l...-292.pdf

"Theoretical studies indicated that reasonable candidates for magic numbers (closed shells), next to the experimentally known Z = 82 and N = 126, could be Z = 114 and N = 184 [3537]."

"Fig. 14 [110] illustrates a comparison between the qualities of descriptions of mass of heaviest (transfermium) nuclei obtained in four different approaches: Semi-empirical (SE), two macromicro (HN and TF) and purely microscopic (HF) approaches. The SE description [102] uses a shell model with 15 adjustable parameters, specially adapted to describe masses of nuclei with proton number contained between known magic number Z = 82 and assumed one Z = 126 and with neutron number contained between known magic number N = 126 and assumed one N = 184."

"Skyrme HartreeFock models predict Z = 126 as the magic number, while the RMF theory prefers Z = 120 independently from the parameters used (NL3, NL-Z, NL-Z2, NL-VT1)."
MaxwellsDemon
not rated yet Aug 21, 2012
"Bubble nuclei":
"A number of candidates for magic numbers in such nuclei has been found. Fig. 47 shows single-particle levels for protons (l.h.s.) and neutrons (r.h.s.) plotted as functions of the inner to outer radius ratio. One can see that candidates for the lowest magic numbers, within this approach, are for protons Z = 80, 104, 120 and for neutrons N = 146, 172, 182."

"Due to this effect the subsequent magic numbers corresponding to the bubble geometry differ by 2 (2l + 1)."

"For protons, the lowest magic number, where the semi-bubble exists is Z = 120. The proton numbers Z = 114 and Z = 126, which are the magic ones in ordinary superheavy nuclei, are observed at smaller radii and correspond to the solutions with no central depression of the nucleon density. The lowest shell closure for the neutron levels, where a semi-bubble is found, is N = 172. Here again the magic neutron number N = 184 occurs for the normal solutions, i.e., without the central depression."
MaxwellsDemon
1 / 5 (1) Aug 21, 2012
@axemaster
So if you know all the magic numbers for all the nuclei that we haven't made in the lab yet, I suggest that you call the Joint Institute for Nuclear Research and tell them which ones are correct. And while you're at it, tell them the size and the precise location of the island of stability, and the half-lives they'll find there.

I'm sure they'd love to hear from the man who already has all the answers, lol.

(btw, I'm PMing you so I know you read all of this. Help yourself to a piece of pie ;)
MaxwellsDemon
1 / 5 (1) Aug 22, 2012
@axemaster
Here it is more succinctly:

"In fact, the predicted magic numbers, especially for protons, are quite different within different theoretical approaches."
Decay Properties and Stability of Heaviest Elements
Karpov and Zagrebaev, 2012
http://nrv.jinr.r...JMPE.pdf

A larger excerpt offers additional clarity:

"However, the most stable superheavies are predicted to be located along the beta-stability line in the region of more neutron-rich nuclei, which is unreachable by fusion reactions with stable beams. In fact, the predicted magic numbers, especially for protons, are quite different within different theoretical approaches. The magic number Z = 114 was predicted in earliest macro-microscopic calculations and confirmed later in Refs. 12, 13. The fully microscopic approaches predict the proton shell closure at Z = 120, Z = 126, or Z = 114, 120, 126 (see Ref. 16) depending on the chosen nucleon-nucleon interaction in meson field theory."