March 29, 2024

Tetra-Neutron Experiment: Understanding of Nuclear Forces Might Have To Be Significantly Changed

The tetra-neutron– experiment finds evidence for a long-sought particle comprising 4 neutrons.
While all atomic nuclei other than hydrogen are made up of neutrons and protons, physicists have actually been browsing for a particle including two, three, or 4 neutrons for over half a century. Experiments by a team of physicists of the Technical University of Munich (TUM) at the accelerator laboratory on the Garching research study campus now suggest that a particle consisting of four bound neutrons may well exist.

While nuclear physicists agree that there are no systems in the universe made from just protons, they have actually been browsing for particles consisting of 2, 3, or four neutrons for more than 50 years.
In the tandem Van de Graaff accelerator of the Maier-Leibnitz laboratory on the Garching research study school a team of physicists of the Technical University of Munich (TUM) bombarded a lithium-7 target with lithium-7 atomic nuclei which were accelerated to 12 percent of the speed of light. All measurement results show that their experiments produced carbon-10 and the popular tetra-neutron. Credit: Sonja Battenberg/ TUM
Should such a particle exist, parts of the theory of the strong interaction would need to be rethought. In addition, studying these particles in more detail might assist us better understand the properties of neutron stars.
” The strong interaction is literally the force that holds the world together at its core. Atoms heavier than hydrogen would be unimaginable without it,” states Dr. Thomas Faestermann, who directed the experiments.
Whatever now indicates the truth that specifically these kinds of particles were created in one of the last experiments performed at the now decommissioned tandem Van de Graaff particle accelerator on the Garching research campus.
In the tandem Van de Graaff accelerator of the Maier-Leibnitz laboratory on the Garching research study campus a group of physicists of the Technical University of Munich (TUM) bombarded a lithium-7 target with lithium-7 atomic nuclei, sped up to 12 percent of the speed of light. All measurement results suggest that their experiments produced carbon-10 and the popular tetra-neutron. Credit: Thomas Faestermann/ TUM
The long look for the tetra-neutron
As early as 20 years back, a French research study group published measurements that they interpreted as the signature of the sought-after tetra-neutron. However, later work by other groups revealed that the methodology utilized might not prove the existence of a tetra-neutron.
In 2016, a group in Japan tried to produce tetra-neutrons from helium-4 by bombarding it with a beam of radioactive helium-8 particles. From their measurement results, the scientists concluded that the tetra-neutron was unbound and quickly decomposed back into four neutrons.
Dr. Thomas Faestermann in the access hatch of the tandem Van de Graaff accelerator on the Garching research campus. Here, more than 10 million volts sped up lithium ions to about 12 percent the speed of light. Faestermann and his team bombarded a lithium-7 target with these lithium-ions. All measurement results show that their experiments produced carbon-10 and the popular tetra-neutron. Credit: Uli Benz/ TUM
In their experiments, Faestermann and his group bombarded a lithium-7 target with lithium-7 particles accelerated to about 12 percent of the speed of light. In addition to the tetra-neutron, this must produce carbon-10. And certainly, the physicists succeeded in detecting this species. A repeating validated the result.
Circumstantial proof
The teams measurement results matched the signature that would be anticipated from carbon-10 in its first fired up state and a tetra-neutron bound by 0.42 megaelectronvolts (MeV). According to the measurements the tetra-neutron would be roughly as stable as the neutron itself.
Dr. Roman Gernhäuser, researcher at the Departmernt of Physics of the Technical University of Munich (TUM), at the target chamber of the tandem Van de Graaff accelerator on the Garching research campus, where lithium ions, accelerated to about 12 percent of the speed of light, hit the lithium-7 target. All measurement results suggest that their experiments produced carbon-10 and the desired tetra-neutron. Credit: Uli Benz/ TUM
With their measurements, the group achieves a certainty of well over 99.7 percent, or 3 sigma. However in physics, the existence a particle is only considered conclusively proven when a certainty of 5 sigma is achieved. Hence, the scientists are now eagerly waiting for independent confirmation.
Referral: “Indications for a bound tetraneutron” by Thomas Faestermann, Andreas Bergmaier, Roman Gernhäuser, Dominik Koll and Mahmoud Mahgoub, 26 November 2021, Physics Letters B.DOI: 10.1016/ j.physletb.2021.136799.
The Maier-Leibnitz Laboratory, with its tandem Van de Graaf accelerator, was operated jointly by the Technical University of Munich and the Ludwig Maximillian University of Munich. The facility was shut down for structural reasons in early 2020. All five authors of the publication are graduates or employees of the Technical University of Munich.

All measurement results show that their experiments produced carbon-10 and the in-demand tetra-neutron. All measurement results show that their experiments produced carbon-10 and the sought-after tetra-neutron. In 2016, a group in Japan tried to produce tetra-neutrons from helium-4 by bombarding it with a beam of radioactive helium-8 particles. All measurement results indicate that their experiments produced carbon-10 and the sought-after tetra-neutron. All measurement results suggest that their experiments produced carbon-10 and the sought-after tetra-neutron.