The world of ancient people was simple, understandable and consisted of four elements: water, earth, fire and air (in our modern understanding, these substances correspond to: liquid, solid, gaseous state and plasma). Greek philosophers went much further and found that all matter is divided into the smallest particles - atoms (from the Greek. "Indivisible"). Thanks to subsequent generations, it was possible to find out that the surrounding space is much more complicated than we initially thought. In this article we will talk about what a positron is and its amazing properties.
Discovery of the positron
Scientists have found that an atom (this supposedly whole and indivisible particle) consists of electrons (negatively charged elements), protons and neutrons. Since nuclear physicists learned how to disperse particles in special chambers, they have already found more than 200 different varieties of them that exist in space.
So what is a positron? In 1931, his appearance was theoretically predicted by the French physicist Paul Dirac. In the course of the solved relativistic problem, he came to the conclusion that in addition to the electron in nature there must exist exactly the same particle with identical mass, but only with a positive charge. Later it was called the "positron".
It has a charge (+1), in contrast to (-1) of an electron and a mass similar to it is about 9.103826 × 10 -31 kg.
Regardless of the source, the positron will always strive to "unite" with any nearest electron.
The only differences between them are the charge and the presence in the Universe, which is much lower than that of an electron. Being an antimatter, a particle coming into contact with an ordinary substance explodes with pure energy.
Having found out what a positron is, scientists went further in their experiments, allowing cosmic rays to pass through a Wilson chamber, shielded by lead and mounted in a magnetic field. There it was possible to observe pairs of electron-positrons, which were sometimes created, and after the appearance continued to move in opposite directions within the magnetic field.
Now it’s clear what a positron is. Like its negative double, the antiparticle responds to electromagnetic fields and can be stored in a confined space using confinement methods. In addition, it can combine with antiprotons and antineutrons to create antiatoms and antimolecules.
Positrons exist with low density in the entire space environment, so some enthusiasts have even proposed methods for collecting antimatter to use its energy.
Annihilation
If the positron and the electron meet each other on the way, then a phenomenon such as annihilation will occur. That is, both particles will destroy each other. However, in a collision, a certain amount of energy is released into space, which they had and is called gamma radiation. A sign of annihilation is the appearance of two gamma rays (photons) moving in different directions in order to maintain momentum.
There is a reverse process - when a photon under certain conditions can again turn into an electron-positron pair.
In order for this pair to be born, it is necessary for one gamma ray to pass through a substance, for example, through a lead plate. In this case, the metal absorbs momentum, but releases two oppositely charged particles in different directions.
Application area
We found out what happens when an electron interacts with a positron. The particle is currently most actively used in positron emission tomography, where a small amount of a radioisotope with a short half-life is introduced to the patient, and after a short waiting period, the radioisotope concentrates in the tissues of interest and begins to decay, releasing positrons. These particles move a few millimeters before they collide with the electron and release gamma rays that can be captured by the scanner. This method is used for various diagnostic purposes, including the study of the brain and the detection of cancer cells throughout the body.
So, in this article we learned about what a positron is, when and by whom it was discovered, its interaction with electrons, and also the area in which knowledge of it is of practical use.