Today we will talk about what alpha decay is and how it can be explained in terms of classical and alternative theories. The existence of the material world is possible only due to the fact that the structures of which any substance consists have sufficient stability. The forces that bind the particles in atoms together are the basis for the existence of the entire Universe. Modern models of the atomic device allow not only to formulate laws, but also to explain many of the observed phenomena of the microworld. Within the framework of the planetary model, in the center of each atom is a nucleus, which includes protons and neutrons in equal shares. The ratio of protons, neutrons and electrons is represented as 1: 1: 1. This only at first glance seems unbelievable, but in fact this dependence is a consequence of one of the key laws of the universe: the electric charge of an electron is -1, a proton +1, and neutrons, being the union of two smaller oppositely charged elements, are generally electrically neutral (by the way , hence the name).
Thanks to Coulomb forces, the protons in the nucleus repel each other, but the balancing strong interaction holds the particles together. What is alpha decay? The mechanism of its occurrence is very simple: if the protons move away from each other, then the electric repulsion force becomes greater than the strong interaction, which leads to the formation of a lighter nucleus and particle. The reasons for the initial distance are diverse - it can be both external influences and structural features of the nucleus (entropy factor).
Collapse of the worldview
Until 1896, it was believed that atoms are indivisible, and the structure of each is characteristic of any particular substance. But A. Becquerel (Rutherford is sometimes indicated), who studied uranium salts, discovered the phenomenon of radioactivity, which cast doubt on many of the postulates of the atomic theory of that time. Alpha decay is the emission of positively charged particles - helium-4 nuclei. It is noted that this process is characteristic primarily for nuclei of heavy elements. One of the features of an alpha particle is its double positive charge. This is due to the fact that two electrons are absent in the structure. The total charge in this case is equal to +2. Rutherford studied alpha decay. He determined that such a particle structure (2 neutrons + 2 protons) is extremely stable and, theoretically, most other nuclei would have to decay into similar particles and nuclei of lighter elements. However, this does not happen. Rutherford suggested that any nuclear change is possible only if a helium atom (alpha particles) or a high-energy electron (beta particles) enters it. Subsequently, this was confirmed, but it took dozens of years of research and the introduction of a new concept from the field of quantum mechanics - the tunnel junction.
Overcoming the barrier
As indicated above, the stable structure is an alpha particle. Its charge is from 2 to 10 MeV. In order for it to penetrate into the base of the atom, it is necessary to overcome the forces of electrical repulsion (because protons are present in the nucleus and particle). This is the very barrier, after passing through which the forces of intranuclear attraction begin to prevail. The laws of the microworld differ from those we are used to, therefore, in some cases, in order to pass through a wall, it is not necessary to destroy it. Through the tunnel crossing, it is possible to overcome the barrier. The smaller the difference between the energy of the particle and the cost of passage, the higher the probability of overcoming repulsion. For most nuclei, the possibility of a tunnel junction is so small that they can be considered stable formations. Others, under certain conditions, allow the penetration from the outside (and outflow from the inside) of alpha particles.