Matter and antimatter and its annihilation

in #steemstem • 7 years ago

Greetings friends of Steemit!

In this publication I will speak qualitatively and descriptively about matter and antimatter, which is currently a subject of studies and in which the very explanation of our origins and existence is in the foreground.

There is a great variety of particles and antiparticles, I will make special emphasis on the pairs electron-positron and the proton-antiproton , which motivated me to write this little article.

The phenomena that underlie the atom that make up matter is undoubtedly a complex and abstract universe, but equally fascinating. At first the atom was considered as indivisible and became our elementary particle.

Nothing is further from reality. The path we have traveled has been much, great scientists laid the foundations that allowed us to have the compression that we now have of the structure of the atom.

The discovery of the electron made by Thomson (1897), the model of the nuclear atom of Bohr (1913) and the discovery of James Chaadwick (1932) of neutron and many other models, changed the structure that was had of the atom.

Thanks to particle accelerators, significant advances have been made that have allowed us to identify a large number of them. In this universe of particles we now know that each of them has an associated anti-particle.

The first to predict these antiparticles was the physicist Dirac (1928), in his work on the relativistic generalization of Schodinger's equation. His model required the existence of an identical particle to the electron but with a positive charge.

It was later in 1932, when the physicist Carl Anderson while studying the cosmic rays in a fog chamber, confirmed the existence of these particles which were called positrons (e+).

The theoretical and experimental models showed that the masses of the electron and the positron are equal with charges of equal magnitude and opposite sign.

Other properties have been verified. In the positron its spin S and magnetic moment μ are parallel. In the electron these are opposite.


Figure 1 - Spin Electron - Positron
Source

No positrons are found in matter. These antiparticles are generated in electron-positron pairs when charged particles of high energy or gamma (γ) rays colisionate against matter.

When a particle and its antiparticle are combined they annihilate and reappear as photons "γ" (radiated energy). In this aniliquilacion the principles of conservation of energy and momentum must be fulfilled.

Conversely, electron-positron pairs are generated, see Figure 2:

Figure 2 - Electron-positron pair formation process
Source

The threshold energy required for the generation of electron -positron pairs and their annihilation is given by:

In this first presentation of annihilation of particles we ask ourselves: Is there enough anti-particles in the space that incline the balance to the destruction of matter?

After the verification of the existence of positrons, in 1955 the researchers Emilio Segre and 0wen Chamberlain observed antiprotons using a beam of accelerated protons.


Figure 4 - Atomic Model Matter and Antimatter
Source

These interactions are more complex since in the process of annihilation a greater number of new particles are formed and the threshold of energy required is greater.

The pion is a subatomic particle with zero spin discovered in 1947.

Conversely, the formation of the proton-antiproton pair is of the form:

In these collisions other processes have been observed.

The threshold energy required for the generation of proton -antiproton pairs and their annihilation is given by:

(in a mass center system) (in this case the protons approach each other with equal and opposite moments).

If one of the protons is at rest, the minimum energy required is:

These differences in threshold energies are due to the fact that electrons and positrons have smaller masses at rest.

Recently a group of physicists from CERN using a Penning trap determined that the magnetic moment of an antiproton is the same as that of the proton, but with a negative sign .


Figure 5 - Pennig trap
Source

After the creation of high-energy particle accelerators and more sophisticated and accurate detectors, many particles have been discovered and classified.

Some models used classify these particles according to their mass and others according to the type of interaction (Figure 6).


Figure 6 - Standard model of fundamental Particles
Source

From the above we can see how in our universe there is the presence of matter and antimatter. The reason for our existence and our environment as we know it, makes clear in my opinion, that the proportions of matter must be giganticly greater than those of antimatter, at least in our near space. Otherwise the annihilation would be the winner in this universe of particles and would exist in a space invaded by gamma radiation.

There is evidence of the presence of antiprotons in the Van Allen Belt (Figure 7). These are originated by the high energy radiations coming from the sun that impact on the atmosphere.


Figure 7 - Van Allen Belt
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It will only be a matter of time for the scientists, who are hard at work explaining this apparent imbalance between matter and antimatter, to elucidate the origin and evolution of our universe.


Figura 8 – History of the universe
Source

Future research points to the use of antimatter for treatments against cancer, as well as for its use as a possible source of fuel due to the amount of energy released in the annihilation process, as shown in the previous calculations.

References:

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7 years ago in #steemstem by
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