Physicists may have discovered an elusive cluster of four neutrons, called tetraneutrons, which could potentially help scientists understand more about nuclear forces.
The theory of the existence of tetraneutrons was first made by James Vary and his colleagues who predicted and first announced their hypothesis during a presentation in the summer of 2014. It was followed by a research paper in the fall of 2016.
Elusive Cluster of Four Neutrons
An Iowa State University professor of physics and astronomy, Vary said that whenever they present a theory, they are always saying that they are waiting for experimental confirmation. In the case of tetraneutrons, which are four neutrons briefly bound together in a temporary quantum state of resonance, the day of experiments showing results has finally come.
The recently announced experimental discovery of a tetraneutron by an international group led by researchers from Germany's Technical University of Darmstadt opens doors for new research. It could also lead to a better understanding of how the universe is put together on an atomic scale, as per Phys.org.
The new and exotic state of matter could also possess properties that are useful in existing or emerging technologies. Neutrons are subatomic particles with no charge that combine with positively-charged protons to make up the nucleus of an atom. Individual neutrons are not stable and after a few minutes convert into protons.
Combinations of double and triple neutrons also do not form what physicists call a resonance, which is a state of matter that is temporarily stable before it decays. However, tetraneutrons were found to have existed for less than a billionth of a billionth of a second.
According to Science News, it has been roughly six decades since researchers have started hunting for clusters of four neutrons. But despite the recent experimental trials, some scientists are doubtful that the claimed tetraneutrons are really what they seem.
Atomic Particles
The existence of neutrons is a fascinating point of discussion for physicists because if confirmed, the clusters would help them isolate and probe mysterious neutron-neutron forces and the inner workings of atomic nuclei. All atomic nuclei contain one or more protons, so scientists do not have a complete understanding of the forces at play within groups that are only composed of neutrons.
Nuclear physicist Meytal Duer of the Technical University of Darmstadt in Germany said that up to now, "there was no real observation of such a system that is composed only from neutrons." Duer and colleagues, in creating tetraneutrons, started with a beam of radioactive, neutron-rich type of helium called helium-8, which is created at RIKEN in Wako, Japan.
The group of researchers then slammed that beam into a target containing protons and found that when a helium-8 nucleus and proton collider, the proton knocked out a group of two protons and two neutrons, also known as an alpha particle. Due to each initial helium-8 nucleus having two protons and six neutrons, all that remained were four neutrons.
The researchers then measured the energy and momentum of all the particles pre- and post-collision. From past experiments and theoretical calculations, they learned how much energy should be "missing" after the collision if it was used in creating a tetraneutron, NewScientist reported.
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