"Magic" numbers remain magic

[C1ay]

Nuclear physicists have created an isotope of silicon that contains twice as many neutrons as protons. Measurements made with silicon-42 - which contains 14 protons and 28 neutrons - will shed new light on the concept of "magic numbers" in nuclei (Nature 435 922).

 

lefthttp://hypography.com/gallery/files/9/9/8/atomic.jpg[/img]Most nuclei contain similar numbers of neutrons and protons, or more neutrons than protons. However, if an isotope of a given element contains too few or too many neutrons it will not be stable. The nuclear shell model, which was first proposed in 1949, explains that nuclei with certain magic numbers of neutrons and/or protons are especially stable because the neutrons and/or protons form closed shells. Nuclei that contain magic numbers of both protons and neutrons are even more stable and are said to be "doubly magic". The magic numbers are 2, 8, 20, 28, 50 and 82.

 

However, it had been thought that highly unstable nuclei would have magic numbers that were different from those found in their more stable counterparts. To investigate this, Paul Cottle and colleagues at Florida State University, Michigan State University, the Lawrence Berkeley National Laboratory and Surrey University in the UK decided to study the silicon-42 nucleus, which has 12 neutrons more than silicon-30, the heaviest stable isotope of the element, and six protons fewer than calcium-48, the lightest stable nucleus to contain 28 neutrons.

 

"The surprise for us was that the magic number for protons in silicon-42, and also the full shell structure, are the same as in calcium-48," Cottle told PhysicsWeb. "Silicon-42 is very close to the limit of nuclear existence - the heaviest silicon isotope ever observed is silicon-43 - and we anticipated significant changes in proton shell structure from calcium-48."

 

Cottle and colleagues produced the silicon-42 nuclei by crashing sulphur-44 nuclei into a beryllium target at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University. The experiment was made possible by the Coupled Cyclotrons Facility at Michigan, which produces the most intense beams of short-lived nuclei, like sulphur-44, that are available anywhere. The experiments also relied on the use of fast-beam "knockout" reactions, pioneered by Gregers Hansen of the NSCL and Jeffrey Tostevin of Surrey, to eject two protons from the sulphur-44 nuclei to produce silicon-42.

 

The results show that the silicon-42 nucleus remains stable despite containing a large excess of neutrons. The data also suggest that the proton number 14 is semi-magic because it corresponds to a closed subshell, which means that the nucleus is also spherical.

 

Source: Physics Web

[nkt]

Now this stuff is voodoo!

 

I used to have a wall chart with all the natural and unnatural isotopes and "stuffed" nuclei on the wall near the labs. I'd sit and ponder it for hours.

 

What this article doesn't say is that the constructed nuclei aren't very stable at all, in most cases, and "drip" the extra neutrons away, often in milliseconds, leading to some more interesting physics.

 

One could posit a weapon made of this stuff. Make a load up, and have it suddenly decompose to order, releasing a mass of neutrons from each atom, killing nearby organic targets in much the same way as a neutron bomb. Of course, it is hard to make the neuclei stable, and just as hard to make them fall apart on command...

[Dannel Roberts]

Wow! Is it possible the Bohr's atom is wrong? Is it possible the construction of the atom isn't a minature solar system? Is it possible the charts on the wall in the science rooms are wrong? Is it possible the protons and the neutrons idea is wrong?

 

It sure is? It sure is? It sure is? It sure is?

 

Thank you for posting this article. You have absolutly made my day beyond belief.

[nkt]

Wow! Is it possible the Bohr's atom is wrong? Is it possible the construction of the atom isn't a minature solar system? Is it possible the charts on the wall in the science rooms are wrong? Is it possible the protons and the neutrons idea is wrong?

 

It sure is? It sure is? It sure is? It sure is?

 

Thank you for posting this article. You have absolutly made my day beyond belief.

Not quite. Not quite. Not quite. Certainly not. The charts on the wall aren't wrong, exactly, they are just incomplete.

 

To cover the extra neutrons that can be added, you would need three dimensions, for the standard Mendlev table to work. However, since the number of neutrons has no effect on the chemical or biological properties, there is no reason to add this complexity to most chemical element tables.

 

If playing with particle accelerators, however, the chemistry matters not, but the physical structures under the electron shells do, and so the chemical side goes out, and a two dimensional chart of the protons and neutron count goes in.

[Turtle]

Nuclear physicists have created an isotope of silicon that contains twice as many neutrons as protons. Measurements made with silicon-42 - which contains 14 protons and 28 neutrons - will shed new light on the concept of "magic numbers" in nuclei (Nature 435 922).

 

Again a Perfect Number in a physics construct! Here, it is 28, the next Perfect Number after 6. The sum of its parts. 28 divides by 1, 2, 4, 7, 14, & itself. In defining a Perfect Number, the "itself isn't counted in the sum of the parts. Therefore, 1+2+4+7+14= 28.

[Racoon]

Turtle, Turtle , Turtle....

I Know your HOT on the Math Key Trail, :cup: BUT, with my limited Chemistry knowledge, It's the number of electrons that are most important. YES, protons, neutrons important as well, BUT neutrons are just that, NEUTRAL; and serve by giving heft to atoms. GRAVITY, the 4th dimension; You are , I am , it is,.... weighing heavily!!!:confused: :confused: :confused: :confused:

[Tormod]

Wow! Is it possible the Bohr's atom is wrong?

 

Bohr's model is...a MODEL. Atoms are not solar systems. If a model doesn't fit the explanation, or our understanding improves, we find new models. Simple as that. It doesn't mean the model is *wrong*.