In this article we will help you prepare for a lesson in physics (Grade 9). Experimental particle research methods are not a common topic, but a very interesting and exciting excursion into the world of molecular nuclear science. Civilization has been able to achieve such a level of progress recently, and scientists are still arguing, but does humanity need such knowledge? After all, if people can repeat the process of an atomic explosion, which led to the appearance of the Universe, then maybe not only our planet, but the whole Cosmos will be destroyed.
What particles are we talking about and why should they be investigated?
Partially answers to these questions are given by a physics course. Experimental particle research methods are a way to see what is inaccessible to humans, even when using the most powerful microscopes. But first things first.
An elementary particle is an aggregate term, which means such particles that can no longer be split into smaller pieces. In total, physicists have discovered more than 350 elementary particles. We are most used to hearing about protons, neurons, electrons, photons, quarks. These are the so-called fundamental particles.
Particle Characterization
All the smallest particles have the same property: they can interconvert under the influence of their own influence. Some have strong electromagnetic properties, others weak gravitational. But all elementary particles are characterized by the following parameters:
- Weight.
- Spin - own moment of momentum.
- Electric charge.
- Lifetime.
- Parity.
- Magnetic moment.
- Baryon charge.
- Leptonic charge.
A brief excursion into the theory of the structure of matter
Any substance consists of atoms, which in turn have a nucleus and electrons. Electrons, like planets in the solar system, move around a nucleus each in its own axis. The distance between them is very large, on an atomic scale. The nucleus consists of protons and neurons, the connection between them is so strong that it is impossible to separate them in any way known to science. This is the essence of experimental methods for studying particles (briefly).
Itβs hard for us to imagine, but nuclear communications exceed millions of times the forces known on earth. We know electromagnetic interaction, chemical, nuclear explosion. But what holds back protons and neurons in the aggregate is something else. Perhaps this is the key to unraveling the mystery of the origin of the universe. That is why it is so important to study experimental methods for studying particles.
Numerous experiments have led scientists to the idea that neurons are composed of even smaller units and called them quarks. What is inside them is not yet known. But quarks are indivisible units. That is, to select one does not work out in any way. If scientists use the experimental particle research method to isolate one quark, then no matter how many attempts they make, at least two quarks are always allocated. This once again confirms the indestructible strength of the nuclear potential.
What are the methods of particle research
We proceed directly to the experimental methods for the study of particles (table 1).
Method name | Process | Operating principle |
Geiger counter | Glow (luminescence) | A radioactive drug emits waves, due to which a collision of particles occurs and individual glows can be observed. |
Wilson's Chamber | Ionization of gas molecules by fast charged particles | Lowers the piston at high speed, which leads to strong cooling of the steam, which becomes oversaturated. Drops of condensate indicate the trajectory of the ion chain. |
Bubble chamber | Fluid ionization | The volume of the working space is filled with hot liquid hydrogen or propane, which are affected by pressure. Bring the state to overheated and sharply reduce the pressure. Charged particles, acting with even greater energy, cause hydrogen or propane to boil. On the trajectory along which the particle moved droplets of vapor are formed. |
Scintillation Method (Spintariscope) | Glow (luminescence) | The particle causes a flash of light in the phosphor, which is fixed by a photomultiplier. The current pulse is amplified. |
Thick emulsion method | Ionization of photoemulsion molecules | Nuclear emulsions are placed in the working area. Charged particles, falling into such a medium, cause ionization, leading to blackening of the molecules. After some chemical reactions, the particle motion track becomes visible. |
As can be seen, the experimental methods for studying particles (Table 1) have a very different nature of the interaction. Some of the theories are already outdated and have been improved by modern technology. Consider each of the methods in more detail.
Experimental methods for the study of particles. Geiger counter
This device was a real breakthrough in the early 20th century. But it helps to study only electrons.
It is a metal cylinder with a negative charge. A thin wire axis with a positive charge is stretched along its surface. The device is connected to a network with a very high voltage - about 1000 V, due to which a huge electric field is formed inside. Now this design needs to be placed in a sealed glass tube in which rarefied gas will be located .
When gas molecules ionize, a large number of electron-ion pairs occur. The greater the tension, the more free pairs arise until it reaches a peak and not a single free ion remains. At this point, the counter registers the particle.
Wilson's Chamber
This is one of the first experimental methods for studying charged particles, and was invented five years later than the Geiger counter in 1912.
The structure is simple: a glass cylinder, inside - a piston. A black cloth impregnated with water and alcohol is laid at the bottom, due to which the air in the chamber is saturated with their vapors.
The piston begins to lower and raise, creating pressure, as a result of which the gas cools. Condensation should form, but it does not exist, since there is no condensation center (ion or dust) in the chamber. After that, the flask is raised to hit particles - an ion or dust. The particle begins to move and condensate forms on its trajectory, which can be seen. The path that the particle travels is called the track.
The disadvantage of this method is too small particle mileage. This led to the emergence of a more advanced theory based on a device with a denser medium.
Bubble chamber
The following experimental particle research method, the Bubble Chamber , has a similar principle of operation of the Wilson chamber. Only instead of saturated gas, is there a liquid in the glass flask.
The basis of the theory is that under high pressure, the liquid cannot begin to boil above the boiling point. But as soon as a charged particle appears, along the track of its motion, the liquid begins to boil, passing into a vaporous state. The droplets of this process are captured by the camera.
Thick emulsion method
Let us return to the table on physics "Experimental methods for the study of particles." In it, along with the Wilson chamber and the bubble method, a method for registering particles using a thick-layer photoemulsion was considered. The experiment was first put forward by Soviet physicists L.V. Mysovsky and A.P. Zhdanov in 1928.
The idea is very simple. For experiments using a plate covered with a thick layer of emulsions. This emulsion consists of silver bromide crystals. When a charged particle penetrates a crystalline crystal, it separates electrons from the atom, which form a hidden chain. It can be seen by showing the film. The resulting image allows you to calculate the energy and mass of the particle.
In fact, the track turns out to be very short and microscopically small. But the method is good in that the developed image can be increased an infinite number of times, thereby studying it better.
Scintillation method
It was first conducted by Rutherford in 1911, although the idea arose a little earlier and another scientist - W. Krupe. Despite the fact that the difference was 8 years, during this time it was necessary to improve the device.
The basic principle is that on a screen coated with a luminescent substance, flashes of light will be displayed when a charged particle passes. Atoms of matter are excited when exposed to particles with powerful energy. At the moment of collision, a flash occurs, which is observed through a microscope.
This method is very unpopular among physicists. He has several drawbacks. First, the accuracy of the results depends very much on the visual acuity of a person. If you blink, you can skip a very important point.
The second - with prolonged observation, the eyes get tired very quickly, and therefore, the study of atoms becomes impossible.
conclusions
There are several experimental methods for studying charged particles. Since the atoms of substances are so small that it is difficult to see them even in the most powerful microscope, scientists have to put various experiments to understand what is in the middle of the center. At this stage of the development of civilization, a long way has been made and the most inaccessible to the eye elements have been studied. Perhaps it is in them that the secrets of the universe lie.