Tetraneutron
Encyclopedia
A tetraneutron is a hypothesised stable cluster of four neutron
s. This cluster of particles is not supported by current models of nuclear
forces. There is some empirical
evidence which suggests this particle does exist, based on an experiment by Francisco-Miguel Marqués and co-workers at the Ganil
accelerator in Caen
using a novel detection method in observations of the disintegration of beryllium
and lithium
nuclei. However, subsequent attempts to replicate this observation have failed.
experiments, Marques' team fired atomic nuclei at carbon targets and observed the 'spray' of particles from the resulting collisions. In this case the experiment involved firing beryllium-14, beryllium-15 and lithium-11 nuclei at a small carbon
target, the most successful being beryllium-14. This isotope of beryllium has a nuclear halo
that consists of four clustered neutrons; this allows it to be easily separated intact in the high speed collision with the carbon target. Their approach to the production and detection of bound neutron clusters was new and novel. Current nuclear models suggest that four separate neutrons should result when beryllium-10
is produced, but the single signal detected in the production of beryllium-10 suggested a multineutron cluster in the breakup products; most likely a beryllium-10 nucleus and four neutrons fused together into a tetraneutron.
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
s. This cluster of particles is not supported by current models of nuclear
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...
forces. There is some empirical
Empirical
The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....
evidence which suggests this particle does exist, based on an experiment by Francisco-Miguel Marqués and co-workers at the Ganil
GANIL
The Grand Accélérateur National d’Ions Lourds , or Large Heavy Ion National Accelerator, is a French national nuclear physics research center in Caen. The facility consists primarily of two serialised synchrocyclotrons.- See also :Similar facilities:...
accelerator in Caen
Caen
Caen is a commune in northwestern France. It is the prefecture of the Calvados department and the capital of the Basse-Normandie region. It is located inland from the English Channel....
using a novel detection method in observations of the disintegration of beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...
and lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
nuclei. However, subsequent attempts to replicate this observation have failed.
Marqués' experiment
As with many particle acceleratorParticle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
experiments, Marques' team fired atomic nuclei at carbon targets and observed the 'spray' of particles from the resulting collisions. In this case the experiment involved firing beryllium-14, beryllium-15 and lithium-11 nuclei at a small carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
target, the most successful being beryllium-14. This isotope of beryllium has a nuclear halo
Nuclear halo
In nuclear physics, an atomic nucleus is called a halo nucleus or is said to have a nuclear halo if its radius is appreciably larger than that predicted by the liquid drop model, wherein the nucleus is assumed to be a sphere of constant density....
that consists of four clustered neutrons; this allows it to be easily separated intact in the high speed collision with the carbon target. Their approach to the production and detection of bound neutron clusters was new and novel. Current nuclear models suggest that four separate neutrons should result when beryllium-10
Beryllium-10
Beryllium-10 is a radioactive isotope of beryllium. It is formed mainly by cosmic ray spallation. Be-10 has a half-life of 1.36 × 106 years, and decays by beta decay to stable Boron-10 with a maximum energy of 556.2 keV....
is produced, but the single signal detected in the production of beryllium-10 suggested a multineutron cluster in the breakup products; most likely a beryllium-10 nucleus and four neutrons fused together into a tetraneutron.