Physicists demonstrate existence of new subatomic structure

November 3, 2016
James Vary, right, and coauthor Andrey Shirokov with an illustration of a tetraneutron. Credit: Christopher Gannon/Iowa State University

Iowa State University researchers have helped demonstrate the existence of a subatomic structure once thought unlikely to exist.

James Vary, a professor of physics and astronomy, and Andrey Shirokov, a visiting scientist, together with an international team, used sophisticated supercomputer simulations to show the quasi-stable existence of a tetraneutron, a structure comprised of four (subatomic particles with no charge).

The new finding was published in Physical Review Letters, a publication of the American Physical Society, on October 28.

On their own, neutrons are very unstable and will convert into protons—positively charged subatomic particles—after ten minutes. Groups of two or three neutrons do not form a stable structure, but the new simulations in this research demonstrate that four neutrons together can form a resonance, a structure stable for a period of time before decaying.

For the tetraneutron, this lifetime is only 5×10^(-22) seconds (a tiny fraction of a billionth of a nanosecond). Though this time seems very short, it is long enough to study, and provides a new avenue for exploring the strong forces between neutrons.

"This opens up a whole new line of research," Vary said. "Studying the tetraneutron will help us understand interneutron forces including previously unexplored features of the unstable two-neutron and three-neutron systems."

The advanced simulations demonstrating the tetraneutron corroborate the first observational evidence of the tetraneutron earlier this year in an experiment performed at the RIKEN Radioactive Ion Beam Factory (RIBF), in Saitama, Japan. The tetraneutron structure has been sought for 40 years with little evidence supporting its existence, until now. The properties predicted by the calculations in the simulations were consistent with the observed properties from the experiment in Japan.

The research in Japan used a beam of Helium-8, Helium with 4 extra neutrons, colliding with a regular Helium-4 atom. The collision breaks up the Helium-8 into another Helium-4 and a tetraneutron in its brief resonance state, before it, too, breaks apart, forming four lone neutrons.

"We know that additional experiments with state-of-the-art facilities are in preparation with the goal to get precise characteristics of the tetraneutron," Vary said. "We are providing our state-of-the-art predictions to help guide these experiments."

The existence of the tetraneutron, once confirmed and refined, will add an interesting new entry and gap to the chart of nuclides, a graph representing all known nuclei and their isotopes, or nuclei with a different number of neutrons. Similar to the periodic table, which organizes the chemical behavior of elements, the nuclide chart represents the radioactive behavior of elements and their isotopes. While most nuclei add or subtract neutrons one at a time, this research shows that a neutron itself will have a gap between a single neutron and a tetraneutron.

The only other known neutron structure is a neutron star, small but dense stars thought to be made almost entirely of neutrons. These stars may be only about seven miles in radius but have a mass similar to that of our sun. Neutron stars have neutrons on the order 10^57. Further research may explore if there are other numbers of neutrons that form a stable resonance along the path to reaching the size of a neutron star.

Explore further: Nickel-78 is a 'doubly magic' isotope, supercomputing calculations confirm

More information: A. M. Shirokov et al, Prediction for a Four-Neutron Resonance, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.117.182502

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20 comments

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ursiny33
1 / 5 (3) Nov 03, 2016
Gravity is not the only force to hold a neutron stars neutrons together the multiplied repulsion forces would pervent that density from maintaing stability, a positive charged plasma of positively charged particles is of equal quantum mass is present. To counter those repulsion forces
Chris_Reeve
1.6 / 5 (7) Nov 04, 2016
Mainstream thinkers love their subatomic particles, but tell them that we can explain both gravity and quantum mechanics with electron sub-particles that simply travel really, really fast, and suddenly they get very hostile.
Gigel
4.4 / 5 (7) Nov 04, 2016
Mainstream thinkers love their subatomic particles, but tell them that we can explain both gravity and quantum mechanics with electron sub-particles that simply travel really, really fast, and suddenly they get very hostile.

Measure the electron sub-particles and then come back to us.
Hyperfuzzy
1 / 5 (2) Nov 04, 2016
You only need pairs, electron and proton, i.e. diametrical spherical fields. The neutron is a containment of a proton and an electron. Compute the relative velocities when near each other. Compute the force of attraction near zero. Define what field, static or changing that will cause breakup or combination. Anyway, you may place as many neutrons together as you wish. Keeping parity you may build all sorts of quasi particles. Note: every particle contains at least 1 proton and 1 electron. The fields of each of these is physically transparent, field, not substance. Repulsion defines most surfaces. Don't start calling neutrinos, etc. particles, there are no particles.

Just count the different methods to stabilize diametrical pairs; best, think of them as diametrical field objects, updated by relative motion with reference to the center at the speed of light. Simpler if you ignore the standard model.
Gigel
not rated yet Nov 05, 2016
@Hyperfuzzy: You also need good knowledge on the force between the proton and electron (the weak force I think) in order to model the neutron that way. Doing it with the electrostatic force will give the H atom with an average size 100 000 times larger than the neutron. I'm not at all sure the fields will have spherical symmetry, except maybe in the ground state.
Hyperfuzzy
1 / 5 (1) Nov 05, 2016
@Hyperfuzzy: You also need good knowledge on the force between the proton and electron (the weak force I think) in order to model the neutron that way. Doing it with the electrostatic force will give the H atom with an average size 100 000 times larger than the neutron. I'm not at all sure the fields will have spherical symmetry, except maybe in the ground state.

You are stuck in the 20th century, there are no other forces. I'm trying to tell you that! There is no source for these spherical fields. the fields are the object. Where do you get your non spherical fields, the big bang?
Fleetfoot
not rated yet Nov 06, 2016
The neutron is a containment of a proton and an electron.

If that were the case, the neutron would have a dipole moment but it doesn't.
Phys1
not rated yet Nov 06, 2016
@Fleetfoot
If it were true the neutron would have integer spin, but
not necessarily an electric dipole moment, like the H atom.
Note that, like the H atom, the neutron _does_have a magnetic dipole moment.
However the neutron also involves an electron anti-neutrino.
Hyperfuzzy
1 / 5 (1) Nov 06, 2016
@Fleetfoot
If it were true the neutron would have integer spin, but
not necessarily an electric dipole moment, like the H atom.
Note that, like the H atom, the neutron _does_have a magnetic dipole moment.
However the neutron also involves an electron anti-neutrino.

First think of the field, we can only see the effect of charge motion if it is in ranges of frequencies we can observe. So charge is at the center of the field. There are only 2 diametrical fields. Can't have anymore. The static field, the dynamic field, it's only the field. i.e charge is the actual field updated at the speed of light relative to its center. All your other "names" will comply. Know what you are talking about axiomatically!
Hyperfuzzy
1 / 5 (1) Nov 06, 2016
Just because we can't measure it does not mean it does not exist; however, if existence is impossible, it does not exist. Think what axiom was used to describe particle physics?

There are no anti- anything. We know the axiomatic structure of everything; however, we cannot account for imagination and nonsense, like gluons, etc.

Neutrinos have a frequency, duh!
Hyperfuzzy
1 / 5 (1) Nov 06, 2016
Discover the electron and the proton! From here, describe the universe and everything in it. See the special places we might exist? See the nonsense we created, looking for things like the stuff we touch see and here. Repulsion gives you a surface, motion of the center of the field gives us vision, nothing else!

Everything else we named and imagined. Only 1 set of axioms, the diametrical spherical fields, never created or destroyed, transparent, obey Maxwell, nothing else!
Gigel
5 / 5 (1) Nov 07, 2016
You are stuck in the 20th century, there are no other forces. I'm trying to tell you that! There is no source for these spherical fields. the fields are the object. Where do you get your non spherical fields, the big bang?
QM
Hyperfuzzy
not rated yet Nov 07, 2016
QM, guessing with probability, the wave equation and cat torture metaphors? Ever wonder why we are still doing this?

Gigel
not rated yet Nov 10, 2016
QM, guessing with probability, the wave equation and cat torture metaphors? Ever wonder why we are still doing this?


Because it works.
Hyperfuzzy
not rated yet Nov 10, 2016
QM, guessing with probability, the wave equation and cat torture metaphors? Ever wonder why we are still doing this?


Because it works.

Why
Gigel
not rated yet Nov 10, 2016
Well, semiconductors are modeled using QM and they work. That is just one small example.
Phys1
not rated yet Nov 10, 2016
@hf
Why

Good question.
Hyperfuzzy
not rated yet Nov 10, 2016
@hf
Why

Good question.

It works because everything is made of the diametrical spherical fields. The problem with QM is it has no axiomatic structure and is therefore noncausal. Make this assumption: There exist Diametrical Spherical Fields(DSF) we call the proton and the electron, apparently never created or destroyed. There is no fractional field, or 1/2 or 1/3 charge! So with logic, redefine modern physics. Always bet on logic. If it doesn't make sense, it's illogical!
Phys1
not rated yet Nov 10, 2016
@hf
Bad answer.
Hyperfuzzy
not rated yet Nov 11, 2016
@hf
Bad answer.

OK, these fields are certain; the particles are theorized. So in your world, there are no answers.

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