Tetraneutron

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A tetraneutron is a hypothetical particle made up of four neutrons . Although the existence of this nucleus contradicts accepted models of nuclear physics , there are some controversial experimental results intended to prove its existence.

Experiments

In an experiment, the results of which were published in 2002, Francisco-Miguel Marqués and his colleagues at GANIL in Caen encountered possible indications of such a particle during nuclear reactions with beryllium -14. In 2016, Japanese nuclear physicists also reported the discovery of a tetra neutron.

Marqués' group shot neutron-rich beryllium isotopes and other neutron-rich nuclei at a carbon target and analyzed the debris with proton scattering. The group identified six signals that they believe are highly likely to be due to clusters of four neutrons. According to Marqués and co-workers, other possible explanations of the observed events can account for a maximum of ten percent of the observed signal. A later analysis of the detection method used suggested that at least part of the original analysis was incorrect. Attempts to repeat the observations with other methods were unsuccessful and did not result in re-observation of such particles.

In 2016, a group led by Susumu Shimoura from the University of Tokyo and researchers from RIKEN reported on the generation of a tetra-neutron in experiments with beams of unstable helium-8 nuclei at the Radioactive Isotope Beam Factory (RIBF) in Saitama . According to the scientists, the significance level was 4.9σ.

Theoretical consequences

If the existence of stable tetraneutrons were ever to be independently proven, the current models of nuclear forces would have to be changed significantly. Bertulani and Zelevinsky suggested that the tetraneutron could consist of a bound state of two dineutrons . However, attempts to create a model that explains the formation of polyneutrons failed , and, according to Steven C. Pieper , it failed

“Does not seem possible to change modern nuclear Hamiltonians to bind a tetraneutron without destroying many other successful predictions of those Hamiltonians. This means that, a recent experimental claim of a bound tetraneutron should be confirmed, our understanding of nuclear forces will have to be significantly changed. "

“It does not seem to be possible to change modern nuclear physics Hamilton functions in such a way that a binding of tetraneutrons is possible without destroying many other successful predictions of these theories. This means that if a new attempt were to confirm tetraneutrons, our understanding of the nucleon-nucleon interaction would have to be significantly changed. "

See also

Web links

Individual evidence

  1. ^ F. Marques et al : The detection of neutron clusters . In: Phys. Rev. C , Volume 65, 2002, p. 044006, arxiv : nucl-ex / 0111001
  2. ↑ BM Sherrill, CA Bertulani: Proton-tetraneutron elastic scattering . In: Phys. Rev. C , 69, 2004, p. 027601
  3. ↑ DV Aleksandrov et al .: Search for Resonances in the Three- and Four-Neutron Systems in the 7Li (7Li, 11C) 3n and 7Li (7Li, 10C) 4n Reactions . In: JETP Letters , 81, 2005, p. 43
  4. ↑ K. Kisamori et al. a .: Candidate Resonant Tetraneutron State Populated by the He4 (He8, Be8) Reaction . In: Phys. Rev. Lett. , Volume 116, 2016, p. 052501, abstract
  5. ^ Tetraneutron Nucleus found, University of Tokyo 2016
  6. ↑ CA Bertulani, VG Zelevinsky: Tetraneutron as a dineutron-dineutron molecule . In: J. Phys. G , 29, 2003, p. 2431
  7. ↑ Rimantas Lazauskas, Jaume Carbonell: Three-neutron resonance trajectories for realistic interaction models . In: Phys. Rev. C , 71, 2005, p. 044004
  8. ↑ Koji Arai: Resonance states of 5H and 5Be in a microscopic three-cluster model . In: Phys. Rev. C , 68, 2003, p. 034303
  9. ↑ A. Hemmdan, W. Glöckle, H. Kamada: Indications for the nonexistence of three-neutron resonances near the physical region . In: Phys. Rev. C , 66, 2002, p. 054001
  10. ↑ Steven C. Pieper: Can Modern Nuclear Hamiltonians Tolerate a Bound Tetraneutron? In: Phys. Rev. Lett. , 90, 2003, p. 252501