Download the lesson for the conversion of elementary particles. Three stages in the development of elementary particle physics - knowledge hypermarket. Introduction to theme lesson
\u003e\u003e Three stages in the development of elementary particle physics
Chapter 14. Elementary Particles
In this chapter, it will be about particles that cannot be divided and of which all matter is built.
§ 114. Three stages in the development of elementary particle physics
You are already more or less familiar with the electron, photomon, proton and neutron. But what is the elementary particle?
The first stage. From the electron to the positron: 1897-1932. (Elementary particles - "Democritoms" atoms at a deeper level.)
When the Greek physicist, Democritis named the simplest unintelligible particles of atoms (the word atom, we recall, means "indivisible"), then it was probably all presented in principle not very difficult. Various objects, plants, animals consist of indivisible, unchanged particles. The transformations observed in the world is a simple rearrangement of atoms. Everything in the world flows, everything changes, except for the atoms themselves, which remain unchanged.
But at the end of the XIX century. A complex structure of atoms was opened and an electron was isolated as an integral part of the atom. Then, already in the XX century, proton and neutron were discovered - particles, including the atomic nucleus. At first, they looked at all these particles exactly as democritus looked at atoms: they were considered indivisible and unchanged initial entities, the main bricks of the universe.
Stage second. From positron to quarks: 1932-1964(All elementary particles turn into each other.) The situation of an attractive clarity lasted not long. Everything turned out to be much more complicated: as it turned out, there is no constant particles at all. In the Word, the elementary is a dual sense. On the one hand, elementary is granted, as well as the Tears. On the other hand, under the elementary means something fucidative, underlying things (it is in this sense that the subatomic particles are now called elementary).
Elementary particles known now, the next unchanging atoms of democritus are prevented by the following simple fact. None of the particles is immortal. Most particles, called now elementary, can not live more than two millionth of a second, even in the absence of any exposure from the outside. Free neutron (neutron, located outside the atomic nucleus) lives on average 15 min.
Only photon particles, electron, proton and neutrino would preserve their immutability, if each of them was one in the whole world (the neutrino is deprived of an electric charge, and its peace weight, apparently, is zero).
But electrons and protons have the most dangerous fellow - positrons and antiprotons, when colliding with which the mutual destruction of these particles and the formation of new ones occurs.
Photon emitted with a desk lamp lives no more than 10 -8 s. This is the time he needs to reach the book page and absorb the paper.
Only neutrinos are almost immortal, since they are extremely weakly interact with other particles. However, neutrinos are dying in a collision with other particles, although such clashes happen extremely rarely.
So, in the eternal pursuit of finding the unchanging in our volatile world, scientists were not on the "granite basis", but at the "Private Sand".
All elementary particles turn into each other, and these mutual transformations are the main fact of their existence.
The conversion of elementary particles scientists was observed in collisions of high-energy particles. The ideas about the invariance of elementary particles were insolvent. But the idea of \u200b\u200btheir indecomposure has been preserved. Elementary particles are further indivisible, but they are inexhaustible in their properties. That's what makes it think so.
Let us have a natural desire to explore whether, for example, an electron from any other sub-elementary particles. What needs to be done in order to try to dispel the electron? You can come up with only one way. This is the same way to whom the child resorts if he wants to know what is inside the plastic toy, - a strong blow.
Of course, it is impossible to hit the electron by a hammer. To do this, you can use another electron flying at a huge speed, or any other elementary particle moving at high speed.
Modern accelerators are reported to charged velocity particles, very close to the speed of light.
What happens when a collision of particles of ultrahigh energy? They do not fail on something that it would be possible to call them components. No, they give birth to new particles from among those that are already featured in the list of elementary particles. The greater the energy of the colliding particles, the greater the number of particles is born. In this case, the appearance of particles with a greater mass than encountered particles. The main thing is that it should be noted, it is that the law of energy conservation is always performed.
In Figure 14.1, you see the result of the collision of the carbon kernel, which had an energy of 60 billion eV (oily top line), with a silver core of a photoemulsia. The core splits into fragments, flying out in different directions. At the same time, many new elementary particles are born - peonies. Such reactions in the collisions of relativistic nuclei, obtained in the accelerator, for the first time in the world were implemented in the High Energy Laboratory of the Joint Institute of Nuclear Research in Dubna under the leadership of Academician A. M. Baldin. The kernel devoid of electronic shells were obtained by ionizing carbon atoms with a laser beam.
Perhaps, of course, that in the collisions of particles with an inaccessible time for us will be born and some new, still unknown particles will be born. But the essence of the matter will not change. New particles born in collisions can not be considered as components of particles- "parents". After all, the "subsidiaries" particles, if they accelerate them, can, without changing their nature, generate, in turn, in collisions are immediately somewhat the same in the accuracy of the particles, which "parents" were, and there are also many other particles.
So, according to modern ideas, elementary particles are primary, extinct particles, of which all matter is built. However, the indivisibility of elementary particles does not mean that they do not have an internal structure.
Stage Third. From the hypothesis of quarks (1964) to the present day. (Most elementary particles have a complex structure.) In the 60s. There were doubts that all particles called now elementary, fully justify this name. The basis for doubt is simple: there are a lot of these particles.
The opening of the new elementary particle has always been and now constitutes an outstanding triumph of science. But for a long time for each next triumph, the share of concern began to mix. Triumps began to follow literally after each other.
A group of so-called strange particles was opened: k-mesons and hyperons with masses exceeding the mass of nucleons. In the 70s. They added a large group of particles with even greater masses called fascinated.
In addition, short-lived particles were opened with a life time of about 10 -22 -10 -23 s. These particles were called resonance, and their number exceeded for two hundred.
It was then that (in 1964) M. Gelle Mann and J. Collegone was proposed a model according to which all particles involved in strong (nuclear) interactions - hadron - built from more fundamental (or primary) particles - quarks .
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Signatures for slides:
The classification of elementary particles Elementary particles (particles that cannot be divided into composite) Fundamental (structuretural particles) hadron (particles having a complex structure) Leptons Quarks The reinforcements of reactors Barione Mesons E-, E +, MUON, Taon, three types of neutrinos (particles, from which consist of all Andron) U, C, T, D, S, B 1) of electromagnetic: photon 2) strong: gluons 3) weak: intermediate bosons W -, W + neutral boson Z 0 4) gravitational: gravelitit G (consist of Three quarks) P, N, hyperon (consist of two quarks, one of which is antique)
Preview:
Theme lesson : The world of elementary particles
Training Method: Lecture
Objectives lesson:
Educational:to introduce students with a concept - an elementary particle, with the classification of elementary particles, to summarize and consolidate knowledge of fundamental types of interactions,to form a scientific worldview.
Educational: To form cognitive interest in physics, the advent of love and respect for the achievements of science.
Developing: Development development, ability to analyze, independently formulate conclusions, the development of speech, thinking.
Equipment: interactive board (or projector with screen).
During the classes:
Organizational stage
Greeting, checking student readiness for lesson.
I. New topic In nature, there are 4 types of fundamental (basic) interactions: gravitational, electromagnetic, strong and weak. According to modern ideas, the interaction between bodies is carried out through the fields surrounding these bodies. The field itself in quantum theory is understood as a set of quanta. Each type of interaction has its own interaction carriers and is reduced to the absorption and emitting by particles of the corresponding light quanta.
Interaction can be long-absorbing (manifest in very large distances) and short-range (manifest and very small distances).
- Gravitational interaction is carried out by sharing graviton. Experimentally, they were not found. According to the law, open in 1687, the Great English scientist Isaac Newton, all the bodies independently of the form and sizes are attracted to each other with force, directly proportional to their mass and inversely proportional to the square of the distance between them. Gravitational interaction always leads to tel.
- Electromagnetic interaction is long-efficient. In contrast to gravitational interaction, electromagnetic interaction can lead both attraction and to repulsion. The carriers of the electromagnetic interaction are the quanta of the electromagnetic field - photons. As a result of the exchange of these particles and there is an electromagnetic interaction between charged bodies.
- Strong interaction is the most powerful of all interactions. It is short-scale, the corresponding forces decrease very quickly as the distance between them increases. Nuclear Force Radius 10-13 cm
- Weak interaction manifests itself at very low distances. The radius of action is about 1000 times less, the nuclear power in nuclear forces.
The opening of radioactivity and the results of the experiments of Rutinford convincingly showed that atoms consist of particles. As it was found, they consist of electrons, protons and neutrons. The first time of the particles from which atoms were constructed were considered indivisible. Therefore, they were called elementary particles. The idea of \u200b\u200bthe "simple" device of the world collapsed when an electron anti-particle was opened in 1932 - a particle that had a mastery as an electron, but differs from him an electric charge. This positively charged particle was named positron .. According to modern concepts, each particle has antiparticle. The particle and antiparticle have the same mass, but opposite signs of all charges. If the antiparticle coincides with the particle itself, then such particles are truly neutral, the charge of them is 0. For example, a photon. The particle and antiparticle in the collision is annihilated, that is, disappear, turning into other particles (often by these particles is photon).
Slide (in the course of the story on the slide, words appear).
All elementary particles (which cannot be divided into composite) are divided into 2 groups:fundamental (dramatic particles, all fundamental particles at this stage of physics development are considered structureless, that is, not consist of other particles) andhadron (particles having a complex structure).
Fundamental particles In turn, are divided intoleptons, quarks and interaction porters. Adrons are divided into Barione and Mesons. To Lepton The electron, positron, Muon, Taon, three types of neutrino are believed. Do not participate in strong interactions. TOquarks Called particles from which all hadrons consist. W.treat in strong interaction.According to modern ideas, each of the interactions arises as a result of particle exchanges, calledtransporters of this interaction: Photon (particle carryingelectromagnetic interaction), eight gluons (carrying particlesstrong interaction), three intermediate vector bosonsW +, W - and Z 0 carrying weak interaction, graviton (carrier gravitational interactioni). The existence of gravitons has not yet been proven experimentally.
Hadron participate in all kindsfundamental interactions. They consist of quarks And divided, in turn, on:barions consisting of three quarks andmesons consisting of twoquarks , one of which isantiquarian.
The strongest interaction is the interaction between quarks. The proton consists of 2 U quarks of one D quark, neutron from one C quark and 2 D quarks. It turned out that at very low distances, none of the quarks notices the neighbors, and they behave like free, non-consistent particles. When removing quarks from each other between them, an attraction occurs, which increases with increasing distance. To divide the hadrons on separate isolated quarks, it would be necessary to make a big energy. Since there is no such energy, the quarks are perpetual prisoners and forever remain locked inside the adronon. Quarks are held inside the adronon gluon field.
III. Fixing
- Name the main interactions that exist in nature
- What is the difference between particles and antiparticle? What do they have in common?
- What particles participate in gravitational, electromagnetic, strong and weak interactions?
The outcome of the lesson. At the lesson, they got acquainted by the micromyr particles, found out which particles are called elementary.
D / s § 28
Municipal budgetary educational institution -
secondary school № 7 Belgorod
Open lesson in physics
Grade 11
"Elementary particles"
Prepared and spent:
physics teacher
Pokakovova A.N.
Belgorod 2015.
Subject: Elementary particles.
Type of lesson: lesson study and primary consolidation of new knowledge
Training method: lecture
Form of students: frontal, collective, individual
The purpose of the lesson: expand the representation of students on the structure of the substance; consider the main stages of the development of elementary particle physics; To give the concept of elementary particles and their properties.
Tasks lesson:
Education : To introduce students with a concept - an elementary particle, with the typology of elementary particles, as well as with the methods of studying the properties of elementary particles;
Developing: to develop cognitive interest to students, providing landing their involvement in active cognitive activities;
Educational: The upbringing of universal qualities - the awareness of the perception of scientific achievements in the world; Development of curiosity, excerpt.
Equipment for lesson:
Didactic materials: tutorial material, tests with tests and tables
Visual manuals: Presentation
During the classes
(Presentation)
1. Organization of the beginning of the lesson.
Teacher's activities: mutual greetings of teachers and students, fixation of students, checking the readiness of students to the lesson. Organization of attention and inclusion of students in business rhythm.
Predicted student's activities: Organization of attention and inclusion in business rhythm of work.
2. Preparation for the main stage of the classes.
Teacher's activities: today we will proceed to the study of the new section of "quantum physics" - "elementary particles". This chapter will discuss the primary, indecomposable particles, from which all matter is constructed, about elementary particles.
The existence of elementary particles of physics was found in the study of nuclear processes, therefore, until the middle of the XX century, the physics of elementary particles was a section of nuclear physics. Currently, physics of elementary particles and nuclear physics are close, but independent sections of physics, combined communities of many problems under consideration and applied research methods.
The main task of the physics of elementary particles is the study of nature, properties and mutual transformations of elementary particles.
It will be our main task in the study of the physics of elementary particles.
3. The assimilation of new knowledge and ways of action.
Teacher's activities: The subject of the lesson: "Stages of the development of elementary particle physics". At the lesson, we will consider the following questions:
The history of the development of ideas that the world consists of elementary particles
What is elementary particles?
What way can you get a separate elementary particle and is it possible?
Tipology of particles.
The idea that the world consists of fundamental particles has a long history. To date, three stages of the development of elementary particle physics are distinguished.
Let's open a tutorial. We will get acquainted with the names of the stages and the temporary framework.
Stage 1. From an electron to Positron: 1897 - 1932.
Stage 2. From Positron to quarks: 1932 - 1964.
Stage 3. From the quark hypothesis (1964) to our days.
Teacher's activities:
Stage 1.
Elementary, i.e. The simplest, indivisible, so imagined an atom known ancient Greek scientist democritus. Let me remind you that the word "atom" means "indivisible". For the first time, the idea of \u200b\u200bthe existence of the smallest, invisible particles, of which all the surrounding items consist, was expressed by a democritium for 400 years before our era. The science began to use an idea of \u200b\u200batoms only at the beginning of the XIX century, when on this basis it was possible to explain a number of chemical phenomena. And at the end of this century, the complex structure of the atom was opened. In 1911, an atomic nucleus was opened (E. Rutherford) and finally proved that atoms have a complex structure.
Recall the guys: what particles are part of the atom and briefly characterize them?
Predicted student's activities:
Teacher's activities: guys, maybe someone remembers from you: by whom and what years an electron, proton and neutron have been opened?
Predicted student's activities:
Electron. In 1898, J. Thomson proved the reality of the existence of electrons. In 1909, R. Milliken first measured the electron charge.
Proton. In 1919, E. Rutherford, with nitrogen bombardment, the particles found a particle, the charge of which is equal to the charge of an electron, and the mass of 1836 times the mass of the electron. Called the proton particle.
Neutron. Rutherford also suggested the existence of a particle that does not have a charge, the mass of which is equal to the mass of the proton.
In 1932, D. Changer opened a particle that Refordford assumed, and called it a neutron.
Teacher's activities: after the discovery of the proton and the neutron, it became clear that the nuclei of atoms, like themselves atoms, have a complex structure. The proton-neutron theory of the structure of the nuclei (D. D. Ivanenko and V. Heisenberg).
In the 30s of the XIX century in the theory of electrolysis, developed by M. Faraday, the concept of -Ion appeared and the elementary charge was measured. The end of the XIX century - in addition to the opening of the electron, was marked by the discovery of the phenomenon of radioactivity (A. Becquer, 1896). In 1905, the physics had an idea of \u200b\u200bthe quanta of the electromagnetic field - photons (A. Einstein).
Recall: What is called photon?
Predicted student's activities: Photon (or kvant of electromagnetic radiation) - elementary light particle, electrically neutral, deprived of the masses of rest, but with energy and pulse.
Teacher's activities: open particles considered indivisible and unchanged initial entities, the main bricks of the universe. However, such an opinion existed not long.
Stage 2.
In the 1930s, mutual transformations of protons and neutrons were found and investigated, and it became clear that these particles were also not constant elementary "bricks" of nature.
Currently, about 400 subit-sized particles are known (particles of which are atoms that are called elementary). The overwhelming majority of these particles are unstable (elementary particles turn into each other).
The exception is only a photon, electron, proton and neutrino.
Photon, electron, proton and neutrinos are stable particles (particles that can exist in a free state unlimited time), but each of them when interacting with other particles can turn into other particles.
All other particles after certain intervals are experienced by spontaneous transformation into other particles and this is the main fact of their existence.
I mentioned another particle - neutrino. What are the main characteristics of this particle? Who and when she was open?
The predictable activity of the student: neutrinos - particle, deprived of electric charge and the mass of rest it is 0. The existence of this particle predicted in 1931. V. Pauli, and in 1955, the particle was experimentally registered. Manifests itself as a result of the decay of the neutron:
Teacher's activities: unstable elementary particles are very different from each other at the time of life.
The most long-lived particle is neutron. Neutron's life of about 15 min.
Other particles "live" a much smaller time.
There are several dozen particles over time of life, exceeding 10 -17 from. The scale of the micromyr is a considerable time. Such particles are calledrelatively stable .
Most short-lived elementary particles have times of life of about 10 -22 -10 -23 s.
The ability to mutual transformations is the most important property of all elementary particles.
Elementary particles are able to be born and destroyed (emit and absorb). This also applies to stable particles with the only difference that the conversion of stable particles occurs not spontaneously, and when interacting with other particles.
An example can serveannihilation (i.e. disappearance ) Electron and positron, accompanied by the birth of high energy photons.
Positron - (electron anti-particle) is a positively charged particle having the same mass and the same (module) charge as an electron. We will talk about its characteristics in more detail in the next lesson. Let's just say that the existence of the positron was predicted by P. Dirak in 1928, and opened it in 1932 in the space rays K. Anderson.
In 1937, particles with a mass of 207 electronic masses were discovered in the cosmic rays.muona ( -Mesons ). Average lifetime- Season equals 2.2 * 10 -6 s.
Then in 1947-1950 were openpeonies (i.e. - Seasons). Average neutral life- Season - 0.87 · 10 -16 p.
In subsequent years, the number of newly opened particles began to grow rapidly. This was facilitated by the study of cosmic rays, the development of accelerator equipment and the study of nuclear reactions.
Modern accelerators are needed to implement the process of birth of new particles and study the properties of elementary particles. The source particles accelerate in an accelerator to high energies "on counter courses" and in a certain place are faced with each other. If the particle energy is large, then in the process of the collision, many new particles are born, usually unstable. These particles flying out of the collision point are disintegrated into more stable particles, which are recorded by detectors. For each such act of collision (physics, they say: for each event) - and they are registered by thousands per second! - Experiments as a result determine the kinematic variables: the values \u200b\u200bof pulses and the energies of "caught" particles, as well as their trajectories (see Fig. In the textbook). Having gained many events of the same type and having studied the distribution of these kinematic values, physics restore how the interaction proceeds and to which type of particles include the obtained particles.
Stage 3.
Elementary particles are combined into three groups: photons , leptons and hadron (Appendix 2).
Guys list me the particles belonging to the photons group.
Predicted student's activities: To group photons true is the only particle - photon
Teacher's activities: the following group consists of light particleslepton .
: This group includes two varieties of neutrino (electronic and muon), electron and? -sezon
Teacher's activities: leptons include another series of particles not specified in the table.
The third large group is heavy particles called adronomes. This group is divided into two subgroups. Lighter particles make up a subgroup mesons .
Predicted student's activities: The easiest of them is positive and negatively charged, as well as neutral-seasons. Peonies are quanta nuclear field.
Teacher's activities: the second subgroup -barions - Includes heavier particles. She is the most extensive.
Predicted student's activities: the lightest of bariones are nucleons - protons and neutrons.
Teacher's activities: they follow the so-called hyperons. Closes the table Omega-minus-hyperon, opened in 1964
The abundance of open and newly opened hadrons brought scientists to the idea that they are all built from some other more fundamental particles.
In 1964, a hypothesis confirmed by subsequent studies was nominated by American physicist, confirmed by subsequent studies that all severe fundamental particles - hadrons were built from more fundamental particles calledquarks.
From a structural point of view, elementary particles from which atomic nuclei (nucleons) consist, and in general, all heavy particles - hadron (barions and mesons) - consist of even simpler particles that are called fundamental. In this role, quarks, electric charge of which are +2/3 or -1/3 of a single positive proton charge protrocate in this role in this role.
The most common and light quarks are called the upper and lower and denote, respectively, U (from English UP) and D (DOWN). Sometimes they are called proton and neutron quark due to the fact that the proton consists of a combination of UUD, and neutron - UDD. The upper quark has a +2/3 charge; Nizhny - Negative charge -1/3. Since the proton consists of two upper and one lower, and the neutron is from one top and two lower quarks, you can independently make sure that the proton and neutron total charge is obtained strictly equal to 1 and 0.
Two other quark pairs are included in more exotic particles. Quarks from the second pair are called fascinated - C (from Charmed) and strange - S (from Strange).
The third pair is true - T (from Truth, or in the English. Top traditions) and beautiful - B (from Beauty, or in English. Traditions of Bottom) quarks.
Almost all particles consisting of various combinations of quarks are already open experimentally.
With the adoption of the quark hypothesis, it was possible to create a slim system of elementary particles. Numerous search for quarks in free state, produced at high-energy accelerators and in the space rays, turned out to be unsuccessful. Scientists believe that one of the reasons for no observability of free quarks is perhaps their very large masses. This prevents the birth of quarks with the energies that are achieved on modern accelerators.
However, in December 2006, a strange message about the opening of "free top quarks" was passed on the tapes of scientific news agencies and the media.
4. Primary testing of understanding.
Teacher's activities: so guys, we looked at you:
the main stages of the development of elementary particle physics
found out which particle is called elementary
got acquainted with the particle typiology.
In the next lesson, we will look at:
more detailed classification of elementary particles
types of interactions of elementary particles
anticascies.
And now I suggest you to perform a test to revive the main points of the material we studied. (Appendix 3).
5. Summing up the lessons.
Teacher's activities: Estimates the most active students.
6. Homework
Teacher's activities:
1. § 114 - 115
2. Abstract.
Atomic and nuclear physics
Lesson 11/60
Subject. Elementary particles
The purpose of the lesson: to give the concept of elementary particles and their properties.
Type of lesson: Combined lesson.
Lesson plan
Studying a new material
· The first stage. From the electron to the positron: 1897-1932 pp. We consider the particles that, from a modern point of view, do not consist of simpler.
As the Italian physicist Enrico Fermi noted, the concept of "elementary" relates rather to the level of our knowledge than the nature of the particles. According to the fact that science developed, many elementary particles passed into the discharge of the neelentar.
· The second stage. From positron to quarks: 1932-1964
All elementary particles turn into each other, and these mutual transformations are the main fact of their existence.
· Third stage. From the hypothesis of quarks (1964) to the present day. Most elementary particles have a complex structure.
in 1964, M. Gel-Mann and J. Tsweig proposed a model according to which all particles involved in strong (nuclear) interactions are built of more fundamental particles - quarks.
The world of elementary particles turned out to be very complex and confusing. But it was still possible to figure it out. And although the final theory of elementary particles, which explains the variety of their properties, has not yet been developed, much more turned out. Since molecules, atoms and nuclei can be cleaved, they do not belong to elementary particles. This, however, does not mean that elementary particles cannot consist of some other, even more "small" formations. In addition, most of them have the most difficult structure. But the components of these particles hold such forces that to break the appropriate bonds, taking into account modern ideas, are fundamentally insolvent.
Accordingly, before that, all elementary particles are divided into two large classes (see Figure): hadron (particles having a complex structure) and fundamental (or truly elementary) particles, which today relate to abstructures and therefore claim to be really primary elements of matter.
A distinctive feature of all hadrons is their composition and the ability to strong interaction than, in fact, their name is due (the Greek word "hadros" means "big", "strong"). No other particles can participate in strong interaction. The classroom class is the most numerous (more than 300 particles). Depending on the quark composition, all of them are divided into two groups - Barionees and Mesons.
True elementary particles today consider carriers of fundamental interactions - leptons and quarks.
Ø According to quantum field theory, all the fundamental interactions (strong, electromagnetic, weak and gravitational) are shared.
This means that as elementary acts of each of the listed interactions are processes in which the particles are emitted and absorb certain quanta. These quanta are called relevant interactions. Exchange by them, particles interact with each other.
The English physicist P. Dirac in 1928 created a relativistic theory of electron movement. Of this theory, it was necessary that the electron could have a negative and positive charge.
in 1932, American physicist K. Anderson, photographing the traces of space particles in the Wilson chamber, found on one of the photos it follows that it belongs to the electron, but ... with a positive charge. A particle that gave a strange trail, Anderson called the positron. In 1933, the phenomenon of the formation of a positron and an electron was opened in the interaction of γ-quanta with a substance:
1934 It was found that positrons produce some radioactive nuclei (this is due to the transformation of the nuclear proton to the neutron):
For example, the radioactive core of the phosphorus isotope decomposes onto the silicon core, positron and neutrino:
P. Dirac assumed that when meeting a positron with an electron, a reverse process should occur: the conversion of these particles into two photons. Shortly after experimental positron detection, such a reverse process was established. This process was called annihilation.
It is important to draw the attention of students to the fact that the electron and positron, which have a lot of peace turn into two photons, do not have the masses of peace. It follows that:
Ø At the level of elementary particles disappears the difference between the substance and the field.
Annihilation is the cause of the lack of positron on Earth: the positron immediately after its appearance occurs with an electron, and both of them turn into two photons.
At one time, the opening of birth and annihilation of electron-positron pairs was really sensation in science. Subsequently, twins - antiparticles - were found in all particles.
1931 V. Paula envisaged, and in 1955 neutrinos N and antineutrino were experimentally registered. Neutrinos appears during the decay of 1 0 n. In 1955, antiproton was experimentally obtained during the collision of fast protons with the kernel of thember. In 1956, an antineutron was opened in the reaction 
Those. The collision of the proton and antiproton leads to the appearance of neutron and an antineutron.
Anticastics may differ from particles by an electrical charge sign, the direction of the magnetic moment or another characteristic. But their main feature is as follows:
Ø An anti-particle meeting with a particle always leads to their mutual annihilation.
Atoms whose kernels consist of antinoclonv, and the shell is from positrons form antimatter. In 1969, antigels were obtained for the first time.
With annihilation of antimatter with a substance, the energy of rest turns into the kinetic energy of gamma quanta formed.
The energy of rest is the most ambitious and concentrated reservoir of energy in the universe. And only during the annihilation, it is completely released, turning into other types of energy. Therefore, antimatter is the most advanced source of energy, the very calorie "fuel". Does humanity be able to be "fuel" someday, it is difficult to say now.
Question to students during the presentation of a new material
First level
1. What particles are called elementary?
2. Name the particles that are currently considered truly elementary.
3. What is explained by very rare cases of observation of the positron?
4. Which antiparticles do you know?
5. What do you understand under antimatter?
Second level
1. What are fundamental particles?
2. What types of fundamental interactions do you know? Which of them are the strongest? Most weak?
3. What are the basic properties of quarks?
4. Are there quarks in a free state?
Fixing the material studied
· Elementary we consider those particles that from a modern point of view are not consistent with simpler.
· At the level of elementary particles disappears the difference between the substance and the field.
· Meeting of antiparticles with a particle always leads to their mutual annihilation.
Homework
РІВ1 № 18.3; 18.4; 18.6; 18.10.
RІV2 No. 18.11; 18.13; 18.14; 18.15.
РІВ3 № 18.16, 18.17; 18.18; 18.19.
World of elementary particles
Lesson in grade 11
The purpose of the lesson:
Educational:
Introduce students with the structure of elementary particles, with the peculiarities of forces and interaction inside the core; To teach to summarize and analyze the knowledge gained, correctly state your thoughts; promote the development of thinking, the ability to structure information; educate emotional and value relations to the world
Developing:
Continue the development of thinking, the ability to analyze, compare, make logical conclusions.
Develop curiousness, ability to apply knowledge and experience in various situations.
Educational:
Development of intellectual team skills; Education of the basics of moral self-consciousness (thought: the responsibility of the scientist, the discoverer for the fruits of his discoveries);
Awaken in students interest in scientifically popular literature, to the study of the prerequisites for the opening of concrete phenomena.
The purpose of the lesson:
Create conditions for the development of intellectual and communicative competencies in which the student will be able to:
Call the main types of elementary particles;
Comprehend the multivalousness of the modern standard model of the world;
Formulate their ideas about the history of the development of elementary particles;
Analyze the role of the development of elementary physics;
Classify elementary particles by their composition;
Think about the need to have their own position, tolerantly refer to another point of view;
Show confinitive communication when working in the group.
Type of lesson: Studying a new material.
Form of the lesson: Combined lesson.
Lesson Methods: Valid, visual, practical.
Equipment: Computer presentation, multimedia projector, student's workbook, personal computer.
| Stages lesson | Time, min. | Methods and techniques |
| 1. Organization administration. Staging a learning problem. | Record the lesson theme. Teacher's story. |
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| 2. Actualization of Knowledge (Presentation of the student) | Student story about knowledge existing, new backgrounds. |
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| 3. Studying a new material (teacher presentation) | Teacher's story using slides. Observation. Conversation. Student's story using slides. |
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| 4. Development of the material studied. Fastening. | Consolidation by the reference abstract and working with a textbook. Answers to check questions. |
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| 5. Summing up. Homework | Allocation of the main teacher, students. |
During the classes
Organizational moment of lesson (Greeting, checking the readiness of students to the lesson)
Today, at the lesson, we will look at various views on the device of the world, from which particles everything is what surrounds us. The lesson will be similar to the lecture, and from you, basically, attention is required.
At the beginning of the lesson, I want to offer to your attention the story of the exercise of particles.
2. Actualization of knowledge. (Presentation of Aleksakhina V. "The history of the development of knowledge about particles")
Slide 2.. Antique atomism - It is ideas about the structure of the world by scientists of antiquity. According to democritus, the atoms were eternal, unchanged, indivisible, characterized in the form and dimensions of particles, which, connecting and disconnecting, formed various bodies.
Slide 3. Thanks to the discovery of scientists, Dirac, Galileem and Newton, the principle of relativity, the laws of dynamics, the laws of conservation, the law of the world, in the 17th century, the atomistic of the ancients has undergone significant changes and established in science. mechanical picture of the world, which was based on gravitational interaction - all the bodies and particles are subject to it, regardless of charge.
Slide 4. Knowledge accumulated in the study of electrical, magnetic and optical phenomena, led to the need to supplement and develop the picture of the world. Thus, in the 19th century and before the beginning of the 20th century, it became dominated electrodynamic picture of the world. It addressed two types of interaction - gravitational and electromagnetic. But they could not explain only thermal radiation, the stability of the atom, radioactivity, photoeff, a stripped spectrum.
Slide 5. At the beginning of the 20th century, the idea of \u200b\u200bquantization of the energy was appeared, which was supported by Planck, Einstein, Bor, Counters, as well as corpuscular wave dualism Louis de Broglie. These discoveries marked the appearance quantum Field Paintings of the Worldin which strong interaction has also been added. The active development of the physics of elementary particles began.
3. Studying a new material
Until the thirties, the 20th century, the device of the world seemed to scientists in the simplest form. They believed that the "complete set" of particles from which the substance consists is a proton, neutron and an electron. Therefore, they were called elementary. These particles include photon - the carrier of electromagnetic interactions.
Slide 6. Modern standard world model:
Matter consists of quarks, leptons and particles - interaction carriers.
For all elementary particles there is a possibility to detect antiparticles.
Corpuscular wave dualism. Principles of uncertainty and quantization.
Strong, electromagnetic and weak interactions are described by the theories of the Great Association. There remains unindicted gravity.
Slide 7. The atom core consists of hadrons, which consist of quarks. Adrics - particles involved in strong interaction.
Classification of hadrons: Mesons consist of one quark and one antiquarian Barione consist of three quarks - nucleons (protons and neutrons) and
hyperons.
Slide 8. Quarks are fundamental particles from which the hadrons consist. Currently, 6 different varieties are known (more often they say fragrances) quarks. Quark keeps strong interaction, involved in strong, weak and electromagnetic. Exchange gluons among themselves, particles with zero mass and zero charge. For all quarks there are antiquarka . They cannot be observed in free form. They have a fractional electric charge: + 2 / 3e - called u-quarks (top) and -1 / 3e - d-quark (bottom).
Electron Quark Composition - UUD, Quark Composition Proton - UDD
Slide 9. Particles not included in the kernel - leptons. Leptons are fundamental particles that are not involved in strong interaction. Today 6 leptons and 6 of their anti-patse are known.
All particles have anti-graders. Leptons and their antiparticles: electron and positron with them electron neutrino and antineutrino. Muon and Antimuon with them muon neutrino and antineutrino. Taon and anti-anti-ton neutrino and antineutrino.
Slide 10.All interactions in nature are manifestations of four types. fundamental interactions Between fundamental particles - lepton and quarks.
Strong interaction Sounded quarks, and gluons are its carriers. It binds them together, forming protons, neutrons and other particles. Indirectly, it affects the connection of protons in atomic nuclei.
Electromagnetic interaction Capped particles are subject to. In this case, under the influence of electromagnetic forces, the particles themselves do not change, but only acquire the property to repel in the case of the charges of the same name.
Weak interaction Sounds are subject to quarks and leptons. The most famous effect of weak interaction is the transformation of the lower quark to the upper one, which in turn causes the neutron to break into the proton, electron and antineutrino.
One of the most significant varieties of weak interaction is higgs interaction. According to assumptions, the Higgs field (gray background) fills the entire liquid space, limiting the range of weak interactions. Also, Higgs Boson interacts with quarks and leptons, ensuring the existence of their mass.
Gravitational interaction. It is the weakest of those known. It involves everything without exception particles and carriers of all types of interaction. It is carried out due to the exchange of graviton - the only, not yet open on the experimental particles. Gravitational interaction is always attraction.
Slide 11. Many physicists hope that, just as they managed to combine electromagnetic and weak interactions into electro-weak, eventually it will be possible to build the theory that unites all known types of interactions, the name of which "Great Association".
4 . Consolidation of knowledge.
Primary fixing (Presentation Gordienko J. "Large Hadron Collider". Modern scientists try to improve the process of studying particles, in order to achieve new discoveries for scientific and technological progress. For this, grandiose research centers and accelerators are being built. One of these grand structures is a big hadron collider.
Final consolidation (Work in groups: answers to questions on the textbook)
You are divided into two groups: 1 row and 2 row. You have a task on the leaves: you need to answer questions, and you will find the answers in the textbook in paragraph 28 (p. 196 - 198).
Tasks of the first group:
How many fundamental particles? (48)
Quarter composition of the electron? (UUD)
List the two most powerful interactions (strong and electromagnetic)
Complete number of gluons? (eight)
Tasks of the second group:
How many particles underlies the universe? (61)
Quarcar composition of proton? (UDD)
List the two weakest interactions (weak and gravitational)
What particles do electromagnetic interaction? (photon)
Jumping out the leaders of the answers to questions and exchange cards.
The outcome of the lesson.
You met some aspects of the development of modern physics and now have elementary ideas about how our science develops and why we need it.
6. Homework. Paragraph 28.
Tasks of the first group:
1. How many fundamental particles? ______________
2. Quark composition of the electron? ____________
3. List the two most powerful interactions ______
4. Complete number of gluons? _______
___________________________________________________________________
Tasks of the second group:
1. How many particles underlies the universe? ________
2. Quarter composition proton? ___________
___________________________________________________________________
Tasks of the first group:
1. How many fundamental particles? __________
2. Quark composition of the electron? __________
3. List the two most powerful interactions __________________________________________________________________________
4. Complete number of gluons? _________
___________________________________________________________________
Tasks of the second group:
1. How many particles underlies the universe? ____________
2. Quarter composition proton? _____________
3. List the two weakest interactions ______________________
4. What particles carry out electromagnetic interaction? ______
___________________________________________________________________
Tasks of the first group:
1. How many fundamental particles? _____________
2. Quark composition of the electron? ______________
3. List the two most powerful interactions ________________________________________________________________________
4. Complete number of gluons? _____
___________________________________________________________________
Tasks of the second group:
1. How many particles underlies the universe? ______
2. Quarter composition proton? _________
3. List the two weakest interactions _______________________
4. What particles carry out electromagnetic interaction? _______
