Extra large carbon

Feb 09, 2010
Carbon-22 is now the heaviest observed Borromean nucleus. Borromean nuclei are named after the rings from the 15th century crest of the Borromeo family from Northern Italy. The rings are connected in such a way that the cutting of one ring results in the separation of all three. (Left) Marble representation of the Borromean rings, used as an emblem of Lorenzo de Medici in San Pancrazio, Florence. (Right) Schematic structure of 22C showing the two halo neutrons around a core. Removing any one element makes the entire structure unstable. Credit: APS Physics

An exotic form of carbon has been found to have an extra large nucleus, dwarfing even the nuclei of much heavier elements like copper and zinc, in experiments performed in a particle accelerator in Japan. The discovery is reported in the current issue of Physical Review Letters and highlighted with a Viewpoint by Kirby Kemper and Paul Cottle of Florida State University in the February 8 issue of Physics.

Carbon-22, which has a comprised of 16 neutrons and 6 protons, is the heaviest atom yet discovered to exhibit a "halo nucleus." In such , some of the particles that normally reside inside the nucleus move into orbits outside the nucleus, forming a halo of .

Because atoms like carbon-22 are packed with an excessive number of neutrons, they're unstable and rapidly break apart to form lighter atoms, but they are more stable than scientists had previously expected. The extra stability is a surprise because the three particles-- two neutrons and a nucleus-- that form a halo nucleus interact in a way that is difficult for physicists to model due to the complicated mathematics necessary to describe so-called "three body" problems.

The unexpected stability has led to such halo nucleus atoms being labeled Borromean atoms in reference to an ancient pattern depicting three rings interlocked such that the removal of any one ring would cause all three to be disconnected. Borromean rings were often used to symbolize a stable union of three parts in traditional carvings and family crests.

The detection and analysis of carbon-22 sets a new milestone in challenging nuclear physics, and hails a promising era in the investigation of heavier and even more exotic nuclei as new beam facilities and more sensitive detectors come on line over the next decade. The surprising discovery of carbon-22's halo suggests that nuclear physicists will have plenty of new ground to cover in coming years.

Explore further: Could 'Jedi Putter' be the force golfers need?

More information: Observation of a Large Reaction Cross Section in the Drip-Line Nucleus 22C, K. Tanaka et al. Phys. Rev. Lett. 104, 062701 (2010) - Published February 08, 2010. Download PDF (free)

Provided by American Physical Society

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chandram
5 / 5 (1) Feb 09, 2010
It is surprising to see the news item. It appears that even in a three body system the two body forces somehow get strengthened to provide more than the earlier estimates of overall stability. It adds mystery to the nature of 2 and many body nuclear force, as far known presently.
chandram
5 / 5 (1) Feb 09, 2010
It is a path breaking development that makes us rethink about the two body nuclear force that appears to change its nature as extra nucleons get added. The halo of C22 has a different 2-body force than the halo of C20 or C18!
NeilFarbstein
1 / 5 (1) Feb 09, 2010
I agree wholeheartedly. The C22 nucleus is something to keep in your search engine alerts.
physpuppy
5 / 5 (1) Feb 09, 2010
The article talks about how unexpectedly long lived the 22C nucleus is so that made me curious as to the actual value of the half life of 22C.

The paper doesn't state it directly, but it does give the reference to the value which was published in the paper's citation #11:
http://prc.aps.or.../e014316

where the value of the Beta decay is provided in the abstract, but I don't understand the notation:

6.1 subscript(-1.2) superscript (+1.4) ms

So I infer that the half life is on the order of milliseconds - maybe up to 10's of milliseconds (?) - but what are those subscripts and superscripts ?
Can anyone translate? Thanks!
NeilFarbstein
1 / 5 (3) Feb 09, 2010
its a mystery to me. Do you think laser light could stabilize a nucleus like C22?
frajo
3.7 / 5 (3) Feb 10, 2010
6.1 subscript(-1.2) superscript (+1.4) ms

So I infer that the half life is on the order of milliseconds - maybe up to 10's of milliseconds (?) - but what are those subscripts and superscripts ?
These are the error limits.
Bonkers
5 / 5 (2) Feb 10, 2010
i.e. 4.9 to 7.5 ms - and absolute age as far as nuclear physics is concerned
daywalk3r
3.7 / 5 (12) Feb 11, 2010
"Stable" is far too relative of a term. It all comes down to the "duration" part, which is a time component, which has infinite resolution (in my opinion), which in turn means it all comes down to the scale.

So basicaly, we could describe anything as stable, depending solely on the time scale used. But we don't. Mostly because we are humans, bound to our own scales - be it time, size, complexity, etc. - to which everything we perceive is "anchored".

So, (to be more on-topic) in case of the observed C22 stability, it all comes down to the conditions that were present at impact till approx. T+6ms when the nuclei decayed.

Pressure, temperature, density, strength of field (grav/mag), background radiation (interference), cosmic ray particle interference, and many more.. even the most relative parameter of them all, the scale and ratio of them all.

For example,if the collision was done at 1 mil. times greater ambient pressure,the results would quite differ.. :)
physpuppy
not rated yet Feb 12, 2010
Yes each field uses terms convenient to the object of study. Eg: Parsecs vs Millimeters. Stability is also a relative term.

From my understanding of currently accepted physics, a nuclei will decay in a time according to its half life probability, governed by the decay mode: the strong or weak force - the only way to cause it to decay any faster would be to provide sufficient energy for change - bombardment by particles or gamma radiation.

To keep it longer, that is done not by "stabilizing the nucleus" but by using relativity - circulate it near the speed of light and in the lab frame of reference the thing hasn't decayed - although in its own reference frame it still decays on time.

Pressure, temperature, density,E&M and gravitational fields, at least the levels in our common experience, should have no effect on the nucleus and not effect on decay time.

Unless there is something different - the neutron halo structure or perhaps something new discovered since I studied physics?
daywalk3r
3.5 / 5 (11) Feb 13, 2010
Pressure, temperature, density,E&M and gravitational fields, at least the levels in our common experience, should have no effect on the nucleus and not effect on decay time.
Yes, you are partialy right, except the gravity part. The position in a gravity well, or "how deep" you are inside, will have an effect (relativistic) on the decay time, no matter what - at least to an observer situated at a "different depth".

With all the other mentioned parameters (mag field, etc.) it is a bit more tricky.. Every atom (and nucleus aswell) has its own "sphere of effect" which "shields" it from direct outside influence - simmilar, in principle, to the Heliosphere of our Sun. So yeah - to get some influence past this natural "shield", it would require intensities, levels, frequencies well past "the levels in our common experience" (as you wrote) - but that does not mean it is completely "immune" to them in every case.

So basicaly, we are back at the "scale" point, I mentioned earlier ;-)
daywalk3r
3.5 / 5 (11) Feb 13, 2010
In regard to the describeb C22 nucleus:
So we have 1 tightly packed nucleus comprising of 14 neutrons and 6 protons, with 2 off-set neutrons orbiting it. And as no orbit is perfect or "eternal", those two neutrons are either closing-in or receding as time goes by, with the ultimate outcome being either a collision or decoupling from the nucleus - which in both cases is resulting in a destabilization of the whole construct (C22) and a further decay into new particles.. up until a formation is made that our lovely scientists could call "stable" ;)

This is a very over-simplified view. There could be many sub-phases involved of course, but we just don't have enough data avaliable to determine those - at least not yet.
Jarek
not rated yet Feb 13, 2010
So what holds these neutrons? Gravity?? Gluons(7fm!)??
Or maybe it's another argument that spin is not pointlike, but rather curvelike property...
Quantum_Conundrum
1 / 5 (1) Feb 13, 2010
Perhaps the neutrons somehow obtained a fractional charge, and were thus repelled from the "real" nucleus?

Or perhaps they are observing the cumulative effects of some previously un-described third nuclear force, or perhaps even anti-gravity...

In any case...

God did it!
Jarek
not rated yet Feb 14, 2010
Repelling?:) I was rather asking about attracting force to compensate centrifugal one ...
If we take seriously how quantum mechanics describes spin, there is no problem about these neutrons - they would just create only one type of connection from the scheme on page 15 of http://arxiv.org/abs/0910.2724
seneca
1 / 5 (1) Feb 17, 2010
Recent theories and experimental results are indicating, Higgs particle should have character of unparticle due the supersymmetry.

http://www.physor...225.html

It would mean (between others), the dark matter phenomena are scale invariant and we can observe them like dark matter and Pioneer anomaly deceleration at large scale, fifth force at meter scale, Casimir force at nanometer scale, anomalous attractive force at attometer scale and so on. The finding of sparse, but stable halo nuclei could fit into this conceptual image well.
seneca
1 / 5 (1) Feb 17, 2010
what holds these neutrons? Gravity?? Gluons(7fm!)
It could be low distance analogy of Casimir force. The idea of fractional charge of neutrons is similar to R. Mills hydrino theory, in which formation of fractional quantum energy states of hydrogen were observed reportedly at surface (cavities) of Raney nickel. He reported evolution of anomalous heat in similar way, like Arata during absorbtion of deuterium on surface of Raney nickel and palladium. The unusually high yield of "cold fusion" could be explained, if deuterions would form halo nuclei inside of cavities. Arata's experiments were confirmed and published recently in peer reviewed journal Physical Letters.

http://tinyurl.com/ykmh5mn
NeilFarbstein
1 / 5 (1) Feb 17, 2010
what holds these neutrons? Gravity?? Gluons(7fm!)
It could be low distance analogy of Casimir force. The idea of fractional charge of neutrons is similar to R. Mills hydrino theory, in which formation of fractional quantum energy states of hydrogen were observed reportedly at surface (cavities) of Raney nickel. He reported evolution of anomalous heat in similar way, like Arata during absorbtion of deuterium on surface of Raney nickel and palladium. The unusually high yield of "cold fusion" could be explained, if deuterions would form halo nuclei inside of cavities. Arata's experiments were confirmed and published recently in peer reviewed journal Physical Letters.

http://tinyurl.com/ykmh5mn
interesting. That is a respected Journal. Its on my reading list. Can you talk about the hydrino model at length?
NeilFarbstein
1 / 5 (1) Feb 17, 2010
Laser have been used to increase the stability of borormean carbon. I forgot that and thought it was merely a theory instead of a real experiment. Maybe they can add neutrons to the C22 system and create other stable carbon atoms.
broglia
1 / 5 (1) Feb 18, 2010
hydrino model at length
Currently hydrino model is considered a fringe science. But the physics of vacuum at Casimir force distance scope could differ from those at bulk. My intuitive insight is, particles of matter are surrounded by sea of virtual photons, which are forming vacuum more dense here, analogously to clouds of dark matter which surround larger objects at cosmic scale. Inside of such dense vacuum the stability of particles is lower and forces, which are keeping them together are weaker - especially inside of surface cavities.

The same phenomena occurs at atomic nuclei scale, because nucleons are surrounded by coat of virtual quark-antiquarks, which shields gluon charge (compare the tetraneutron evidence).

http://en.wikiped...aneutron

And it would work even at smaller scale (compare the recent pentaquark observation at Tevatron), because it's quite general scale invariant supersymmetry phenomena.

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