Yang Zaihong, a member of the research team and an assistant professor at the School of Physics at Peking University, explained to Science and Technology Daily that while all matter contains neutrons, only neutron stars contain matter that is almost entirely made up of neutrons, which are bound together by nuclear force. Evidence is mounting for the existence of a peculiar and elusive form of matter called a “tetraneutron”, which is formed by the brief bonding of four neutrons.
Twenty years ago, scientists first obtained “trails” of the existence of “four neutron states” – they found evidence that “four neutron states” may be formed after the collision of beryllium and carbon atoms, but the experimental error was very large at that time, scientists Other possibilities have been proposed, such as the formation of different types of particles in so-called “quaternary neutron states”.
In the latest study, Roman Gernhaus of the Technical University of Munich and colleagues created helium atoms with four more neutrons than ordinary helium atoms, and then collided them with protons. These helium atoms leave behind only four neutrons after the collision, and these four neutrons can combine to form a “quaternary state.” Subsequently, the research team measured the energy and momentum of all particles before and after the collision, thereby calculating the energy lost after the collision formed the “quadron state”, and deduced from this energy that the “lifetime” of the “quaternion state” is only For 10-22 seconds.
The Gernhaus team is currently developing a special detector that records a clear signal when a “quaternary neutron state” enters it, which will help to study the matter more directly, obtaining its more precise details.
According to Yang Zaihong, the research team of Peking University is also developing new detection equipment, which can directly capture the four neutrons released by the “four-neutron state” at the “dead end”, take high-precision “photographs” of its internal structure, and conduct further research Heavier “neutron matter” (such as “six neutron state” and “eight neutron state”), to deeply explore this novel form of matter that is currently known to exist only in the interior of neutron stars.
