An international group of scientists, which included scientists from the University of Hong Kong, the RIKEN Institute (Japan) and the CEA Institute (France), showed that the number 34 is another of a series of “neutron magic numbers.” Using the RI Beam Factory accelerator (RIBF), these scientists showed that atoms with 34 neutrons have more stability than previously thought. Previous studies carried out in this direction gave scientists only hints of this fact, but its practical confirmation was received only recently.
In the experiments, scientists used calcium-54, whose core consists of 20 protons and 34 neutrons. The results of these experiments showed that the electron shells surrounding the calcium-54 nucleus form a strong “shell” around it, the same is found only in atoms with full electron shells, such as helium, neon, etc., resulting in these atoms are completely chemically passive.
It was previously believed that protons and neutrons are mixed within the nucleus in an erratic state, but now it is already known that they are ordered and form layers. In the case of complete filling of the upper layer, which is called the “magic number”, these isotope atoms have some properties that are different from the properties of the basic elements. For example, the energy for transferring an atom to the first energy level of an atom with a magic number may be greater than the energy required for the same for an ordinary atom.
Studies conducted in the direction of determining magic numbers gave scientists a number of meanings: 2, 8, 20, 28, 50, 82 and 126. And now this number has replenished with another number – 34.
The first experiments with calcium-54 were carried out on the RIBF accelerator in 2013, showed that the number 34 should be “magic”. And during the last experiment, scientists focused on measuring the stability of atoms with this number. In addition, scientists counted the number of neutrons in each layer of the calcium-54 nucleus, carefully knocking out these neutrons one by one.
In order to do all of the above, scientists used a beam containing calcium-54 ions, accelerated by the BigRIPS accelerator generator to a speed of 60 percent of the speed of light. This beam was focused on a target of liquid hydrogen, roughly speaking, protons cooled to a temperature of 20 Kelvin. The scattering angles and the energy of neutrons knocked out during collisions with protons allowed scientists to attach these neutrons to specific locations in the layers of atomic nuclei.
“For the first time, we were able to demonstrate that all layers in 54Ca nuclei are completely filled and 34 neutrons are indeed a” magic number, “the researchers write,” Already, we have other candidates for further magic numbers pointing to atoms with even more neutrons , 60Ca, for example. All of this is already within the capabilities of RIBF equipment, and in the near future a number of magic numbers can be replenished with one or more new members”.