After the discovery of materials capable of spontaneous emission of elementary particles (radio emission as a result of decay), the study of their properties began. The curious spouses Curie, as well as E. Rutherford, took an active part in the search for new and systematization of existing knowledge in physics . It was he who first managed to discover gamma rays. The experiment he posed was simple and, at the same time, brilliant.
Radium was taken as a radiation source. A narrow hole was made in a thick-walled lead tank. Radium was placed at the bottom of the resulting channel. A small distance from the tank perpendicular to the axis of the hole was a photosensitive element - a plate. In the gap between it and the container with the radioactive substance, a special installation could generate a high-intensity magnetic field, the intensity lines of which were oriented parallel to the photosensitive plate. All elements, except the field generator, were in an airless medium to exclude the effect of air atoms on the result of the experiment. If Rutherford ignored this moment, then someone else could open gamma rays.
In the absence of magnetic action, a dark spot appeared on the plate, indicating a rectilinear propagation of radiation (all other directions were simply cut off by the walls of the lead capacitance). But as soon as the magnetic field appeared, three spots appeared at once on the photosensitive element of the system. This meant that certain particles emitted by radium were deflected by the field. Rutherford suggested that the beam consists of at least three components. The nature of the deviation indicated that the particles of two rays have an electric charge, and the third ray is electrically neutral. Moreover, the negative component of the initial radiation deviated much more pronounced than the positive. The electrically neutral component is gamma rays. The negative charge component is called beta rays, and the last, positive charge is called the alpha beam.
Besides the fact that they behaved differently in a magnetic field, the rays had various properties. Gamma rays are able to penetrate matter over fairly large distances. So, a lead plate with a thickness of 1 cm reduces their intensity by only half. An alpha beam can be stopped even by a thin sheet of paper. But beta radiation occupies an intermediate position: you can stop the flow of metal with a thickness of several millimeters.
Subsequently, it turned out that:
- beta ray is a stream of negatively charged particles (electrons) moving at high speed;
- alpha beam - these are helium nuclei, a very stable formation;
- gamma ray - one of the varieties of electromagnetic waves. The emission spectrum is completely linear, since the emitting core is characterized by discrete energy states. Represented in the form of energy distribution levels of emitted quanta. The term "gamma radiation" is increasingly used not only to describe the processes of radioactive decay, but also, in general, for any hard radiation of an electromagnetic nature in which each quantum corresponds to an energy of at least 10 keV. The source of this type of radiation are electrons in the structure of excited atoms. Excess energy transfers electrons to higher energy levels. From there, they return to their previous state, emitting radiation in the form of X-rays or light (electromagnetic waves). The spectrum of electromagnetic radiation in the case of gamma rays is extremely small and amounts to no more than 5 * 0.001 nm, which is why the properties of particles rather than waves are more clearly manifested.