Elementary particles and their interactions presentation. Presentation "Elementary particles" in physics - project, report

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Stage 1. From electron to positron: 1897-1932

Positroon Electron

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Stage 2. From positron to quarks

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Elementary particles

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Fundamental Interactions

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Particles and antiparticles

γ hν=2mc2 Electron Positron

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Stage 3. From the quark hypothesis to the present day

Almost the entire mass of any atom is concentrated in the nucleus, which is one hundred thousand times smaller than an atom. The nucleus is made up of protons and neutrons, which are made up of quarks. (Figure from www.star.bnl.gov)

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Structure of hadrons

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Gluons

The gluon forces that bind quarks in a proton do not weaken as one quark moves away from another. As a result, when trying to “pluck” a quark from a proton, the gluon field generates an additional quark-antiquark pair, and not a quark, but a pi-meson is separated from the proton. The pi meson can already fly as far as desired from the proton, because the forces between hadrons weaken with distance. (Figure from www.nature.com)

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Symmetry of elementary particles

modern theory In elementary particles, the concept of symmetry of laws regarding certain transformations is leading. Symmetry is considered as a factor determining the existence of various groups and families of elementary particles.

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This is what a typical “interesting” event looks like in the CDF detector at the Tevatron. The end view of the detector is shown. The beams collide in a direction perpendicular to the pattern, and the generated particles scatter in different directions, deflecting in the magnetic field. The greater the momentum of the particle, the weaker it is deflected. The histogram at the edges shows the energy release of the particles. (Figure from www-cdf.fnal.gov)

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"Physical labor

This figure illustrates the sometimes tedious and even menial work that physicists must do to isolate rare events from all the statistics. In fact, it is often impossible to reliably say whether the particle we are interested in was born or not in each specific event. Meaningful information can only be extracted from all statistics as a whole. (Artwork: CERN. Figure from www.exploratorium.edu))

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Homework

Write a story about elementary particles. Compose questions and answers “Jumble”

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Presentation for a physics lesson in 11th grade (profile level)

Completed by: Popova I.A., physics teacher Belovo, 2012

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Target:

• Introduction to the physics of elementary particles and systematization of knowledge on the topic.
• Development of abstract, ecological and scientific thinking of students based on ideas about elementary particles and their interactions

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How many elements are in the periodic table?

Only 92.

How? Is there more?

True, but all the rest are artificially obtained; they do not occur in nature.

So - 92 atoms. Molecules can also be made from them, i.e. substances!

But the fact that all substances consist of atoms was stated by Democritus (400 BC).

He was a great traveler, and his favorite saying was:

"Nothing exists except atoms and pure space, everything else is a view"

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Antiparticle - a particle that has the same mass and spin, but opposite values ​​of charges of all types;

Timeline of particle physics

Every elementary particle has its own antiparticle

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Timeline of particle physics

All these particles were unstable, i.e. decayed into particles with lower masses, eventually becoming stable protons, electrons, photons and neutrinos (and their antiparticles).

Theoretical physicists faced the most difficult task of ordering the entire discovered “zoo” of particles and trying to reduce the number of fundamental particles to a minimum, proving that other particles consist of fundamental particles

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Timeline of particle physics

This model has now turned into a coherent theory of all known types of particle interactions.

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How to detect an elementary particle?

Usually, traces (trajectories or tracks) left by particles are studied and analyzed using photographs.

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Classification of elementary particles

All particles are divided into two classes:

• Fermions, which make up matter;
• Bosons through which interaction occurs.

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Fermions are divided into

• leptons
• quarks.

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Quarks

• Gell-Mann and Georg Zweig proposed the quark model in 1964.
• The Pauli principle: in one system of interconnected particles there never exist at least two particles with identical parameters if these particles have half-integer spin.

M. Gell-Mann conference in 2007

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What is spin?

• Spin demonstrates that there is a state space that has nothing to do with the movement of a particle in ordinary space;
• Spin (from English to spin - to spin) is often compared to the angular momentum of a “rapidly rotating top” - this is not true!
• Spin is an internal quantum characteristic of a particle that has no analogue in classical mechanics;
• Spin (from the English spin - twirl, rotation) is the intrinsic angular momentum of elementary particles, which has a quantum nature and is not associated with the movement of the particle as a whole

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Spins of some microparticles

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Quarks

• Quarks participate in strong interactions, as well as weak and electromagnetic ones.
• The charges of quarks are fractional - from -1/3e to +2/3e (e is the charge of the electron).
• Quarks in today's Universe exist only in bound states - only as part of hadrons. For example, a proton is uud, a neutron is udd.

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Four types of physical interactions

• gravitational,
• electromagnetic,
• weak,
• strong.

Weak interaction - changes the internal nature of particles.

Strong interactions determine various nuclear reactions, as well as the emergence of forces that bind neutrons and protons in nuclei.

The mechanism of interactions is the same: due to the exchange of other particles - carriers of interaction.

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• Electromagnetic interaction: carrier - photon.
• Gravitational interaction: carriers - gravitational field quanta - gravitons.
• Weak interactions: carriers - vector bosons.
• Carriers of strong interactions: gluons (from English word glue - glue), with rest mass equal to zero.
• Both photons and gravitons have no mass (rest mass) and always move at the speed of light.
• A significant difference between weak interaction carriers and photons and gravitons is their massiveness.

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Properties of quarks

Quark supermultiplets (triad and antitriad ) ,d,s>,d,s>

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Properties of quarks: color

Quarks have a property called color charge.

There are three types of color charge, conventionally designated as

• blue,
• green
• Red.

Each color has a complement in the form of its own anti-color - anti-blue, anti-green and anti-red.

Unlike quarks, antiquarks do not have color, but anticolor, that is, the opposite color charge.

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Properties of quarks: mass

Quarks have two main types of masses, which differ in size:

current quark mass, estimated in processes with significant transfer of squared 4-momentum, and

structural mass (block, constituent mass); also includes the mass of the gluon field around the quark and is estimated from the mass of hadrons and their quark composition.

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Properties of quarks: flavor

Each flavor (type) of a quark is characterized by such quantum numbers as

• isospin Iz,
• strangeness S,
• charm C,
• charm (bottomness, beauty) B′,
• truth (topness) T.

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Characteristics of quarks

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Let's consider the tasks

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What energy is released during the annihilation of an electron and a positron?

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What energy is released during the annihilation of a proton and antiproton?

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What nuclear processes produce neutrinos?

A. During α - decay.

B. During β - decay.

B. When γ - quanta are emitted.

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What nuclear processes produce antineutrinos?

A. During α - decay.

B. During β - decay.

B. When γ - quanta are emitted.

D. During any nuclear transformations

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A proton is made up of...

A. . . .neutron, positron and neutrino. Slide 33

1.What physical systems are formed from elementary particles as a result of electromagnetic interaction?

A. Electrons, protons. B. Atomic nuclei. B. Atoms, molecules of matter and antiparticles.

2. From the point of view of interaction, all particles are divided into three types: A. Mesons, photons and leptons. B. Photons, leptons and baryons. B. Photons, leptons and hadrons.

3. What is the main factor in the existence of elementary particles? A. Mutual transformation. B. Stability. B. The interaction of particles with each other.

4. What interactions determine the stability of nuclei in atoms? A. Gravitational. B. Electromagnetic. B. Nuclear. D. Weak.

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6. The reality of the transformation of matter into an electromagnetic field: A. Confirmed by the experience of annihilation of an electron and a positron. B. Confirmed by the experiment of annihilation of an electron and a proton.

7. Reaction of transformation of matter into a field: A. e + 2γ→e+B. e + 2γ→e- B.e+ +e- =2γ.

8. What interaction is responsible for the transformation of elementary particles into each other? A. Strong interaction. B. Gravitational. B. Weak interaction D. Strong, weak, electromagnetic.

Answers: B; IN; A; IN; B; A; IN; G.

5. Are there unchanging particles in nature?

A. There are. B. They don’t exist.

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Literature

Periodic table elementary particles

Ishkhanov B.S. , Kabin E.I. Physics of nucleus and particles, XX century /

table of elementary particles

Particles and antiparticles

Elementary particles. directory > chemical encyclopedia /

Particle physics

Quark /sila.narod.ru/physics/physics_atom_04.htm

Quark. Material from Wikipedia - the free encyclopedia /

2.About quarks.

Rainbow Harmony

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Examples of phenomena that cast doubt on the immutability of atoms Electrification of bodies Line spectra of emission and absorption of atoms Radioactivity Electrolysis Photoelectric effect Thermionic emission Electric discharge in gases Conclusion: atoms are complex internal structure and are not the simplest indestructible and unchangeable particles

Elementary particles (from the Latin elementarius - original, simplest, basic) The particles from which atoms are built were considered incapable of any transformations. Electrons, protons and neutrons began to be considered elementary. Later, photons were included in the number of elementary particles. It was discovered that the free neutron is unstable and lives on average 15 minutes But it cannot be said that the neutron consists of these particles; they are born at the moment of decay

Elementary particles are particles that, at the current level of development of physics, cannot be considered a combination of other, more “simple” particles that exist in a free state. An elementary particle, in the process of interaction with other particles or fields, must behave as a single whole. All elementary particles transform into each other, and these mutual transformations are the main fact of their existence. The indivisibility of elementary particles does not mean that they lack an internal structure

ANTI-PARTICLES In 1928, Paul Dirac developed a theory of electron motion in an atom, taking into account relativistic effects. From the equation it turned out that the electron must have a “double” - a particle of the same mass, but with a positive elementary charge. In 1932, K. Anderson experimentally discovered positrons in cosmic radiation

ANTIPARTICLES All elementary particles have antiparticles. Charged particles exist in pairs. In 1955, an antiproton was discovered. In 1956, an antineutron. There are truly neutral particles - photon, pi-zero meson, etameson. They completely coincide with their antiparticles

ANNIHILATION Antiparticles turned out to be capable of a special type of interaction (proved by the experiment of F. Joliot-Curie in 1933). Two antiparticles annihilate when meeting (from the Latin nihil - nothing), turning into two, rarely three photons. Two antiparticles annihilate when meeting (from Lat nihil - nothing), turning into two, rarely three photons

Elementary particles are divided into groups according to their ability to various types fundamental interactions 1. Gravitational interaction - - is described by the law universal gravity- - acts between any bodies of the Universe - - plays a major role only for macroscopic bodies of large masses - - carriers - gravitons?

2. Electromagnetic interaction - acts between any electrically charged particles and bodies, as well as photons - quanta electromagnetic field- provides the possibility of the existence of atoms and molecules; determines the properties of solids, liquids, gases and plasma - causes the fission of heavy nuclei; emission and absorption of photons by matter - carriers - photons

3. The strong interaction - this is the interaction between nucleons and other heavy particles - manifests itself at very short distances~ m - an example is the interaction of nucleons by nuclear forces - particles capable of this interaction are called hadrons - carriers - gluons and mesons

4. Weak interaction - any elementary particles except photons participate in it - manifests itself only at very small distances ~ m - an example of weak interaction is the process of beta decay of a neutron, the decay of a charged pion - carriers - intermediate bosons

QUARKS main idea, first expressed by M. Gell-Mann and J. Zweig, is that all particles participating in strong interactions are built from more fundamental particles - quarks. Apart from leptons, photons and intermediate bosons, all already discovered particles are composite. Quarks in today's Universe exist only in bound states - only as part of hadrons. For example, a proton is uud, a neutron is udd.

Quark composition of elementary particles All particles are divided into two classes: Fermions, which make up matter; Bosons through which interaction occurs. Fermions are divided into leptons and quarks. Currently, 6 leptons and 6 quarks claim to be true elementary particles

Summary During the study of atoms and elementary particles, phenomena were discovered that did not obey the laws of classical physics at all, and this led to the creation of quantum physics as the physics of microworld phenomena. What is the relationship between classical and quantum physics? Do they exist as two independent theories or has quantum physics refuted and canceled the classical one?

Summary Neither the first nor the second happened. The laws of quantum physics turned out to be universal laws, applicable not only to systems of elementary particles, but also to any bodies of the macrocosm. In accordance with the correspondence principle, classical physics turned out to be a special case of quantum physics, applicable only in a limited range of distances and sizes of bodies in the macroworld.

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Elementary particles

Municipal budgetary non-standard educational institution "Gymnasium No. 1 named after G. Kh. Tasirov of the city of Belovo"

Presentation for a physics lesson in 11th grade (profile level)

Completed by: Popova I.A., physics teacher

Belovo, 2012

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Introduction to the physics of elementary particles and systematization of knowledge on the topic. Development of abstract, ecological and scientific thinking of students based on ideas about elementary particles and their interactions

Slide 3

How many elements are in the periodic table?

Only 92. How? Is there more? True, but all the rest are artificially obtained; they do not occur in nature. So - 92 atoms. Molecules can also be made from them, i.e. substances! But the fact that all substances consist of atoms was stated by Democritus (400 BC). He was a great traveler, and his favorite saying was:

"Nothing exists except atoms and pure space, everything else is a view"

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Antiparticle - a particle that has the same mass and spin, but opposite values ​​of charges of all types;

Timeline of particle physics

Every elementary particle has its own antiparticle

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All these particles were unstable, i.e. decayed into particles with lower masses, eventually becoming stable protons, electrons, photons and neutrinos (and their antiparticles).

Theoretical physicists faced the most difficult task of ordering the entire discovered “zoo” of particles and trying to reduce the number of fundamental particles to a minimum, proving that other particles consist of fundamental particles

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How to detect an elementary particle?

Usually, traces (trajectories or tracks) left by particles are studied and analyzed using photographs.

Slide 8

Classification of elementary particles

All particles are divided into two classes: Fermions, which make up matter; Bosons through which interaction occurs.

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Fermions are divided into leptons and quarks.

Quarks participate in strong interactions, as well as weak and electromagnetic ones.

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Gell-Mann and Georg Zweig proposed the quark model in 1964. The Pauli principle: in one system of interconnected particles there never exist at least two particles with identical parameters if these particles have half-integer spin.

M. Gell-Mann at a conference in 2007

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What is spin?

Spin demonstrates that there is a state space that has nothing to do with the movement of a particle in ordinary space; Spin (from English to spin - to spin) is often compared to the angular momentum of a “rapidly rotating top” - this is not true! Spin is an internal quantum characteristic of a particle that has no analogue in classical mechanics;

Spin (from the English spin - twirl, rotation) is the intrinsic angular momentum of elementary particles, which has a quantum nature and is not associated with the movement of the particle as a whole

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Four types of physical interactions

gravitational, electromagnetic, weak, strong.

Weak interaction - changes the internal nature of particles. Strong interactions determine various nuclear reactions, as well as the emergence of forces that bind neutrons and protons in nuclei.

The mechanism of interactions is the same: due to the exchange of other particles - carriers of interaction.

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Electromagnetic interaction: carrier - photon. Gravitational interaction: carriers - gravitational field quanta - gravitons. Weak interactions: carriers - vector bosons. Carriers of strong interactions: gluons (from the English word glue), with a rest mass equal to zero.

Both photons and gravitons have no mass (rest mass) and always move at the speed of light.

A significant difference between weak interaction carriers and photons and gravitons is their massiveness.

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Properties of quarks

Quark supermultiplets (triad and antitriad )

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Quarks have a property called color charge. There are three types of color charge, conventionally designated as blue, green, and red. Each color has a complement in the form of its own anti-color - anti-blue, anti-green and anti-red. Unlike quarks, antiquarks do not have color, but anticolor, that is, the opposite color charge.

Properties of quarks: color

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Quarks have two main types of masses that do not coincide in magnitude: the current quark mass, estimated in processes with significant transfer of squared 4-momentum, and structural mass (block, constituent mass); also includes the mass of the gluon field around the quark and is estimated from the mass of hadrons and their quark composition.

Properties of quarks: mass

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Each flavor (type) of a quark is characterized by such quantum numbers as isospin Iz, strangeness S, charm C, charm (bottomness, beauty) B′, truth (topness) T.

Properties of quarks: flavor

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What nuclear processes produce neutrinos?

A. During α - decay. B. During β - decay. B. When γ - quanta are emitted. D. During any nuclear transformations

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A proton is made up of...

A. . . .neutron, positron and neutrino. B. . . .mesons. IN. . . .quarks. D. A proton has no constituent parts.

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A neutron is made up of...

A. . . .proton, electron and neutrino. B. . . .mesons. IN. . . . quarks. D. The neutron has no constituent parts.

2. From the point of view of interaction, all particles are divided into three types: A. Mesons, photons and leptons. B. Photons, leptons and baryons. B. Photons, leptons and hadrons.

3. What is the main factor in the existence of elementary particles? A. Mutual transformation. B. Stability. B. The interaction of particles with each other.

4. What interactions determine the stability of nuclei in atoms? A. Gravitational. B. Electromagnetic. B. Nuclear. D. Weak.

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6. The reality of the transformation of matter into an electromagnetic field: A. Confirmed by the experience of annihilation of an electron and a positron. B. Confirmed by the experiment of annihilation of an electron and a proton.

7. Reaction of transformation of matter into a field: A. e + 2γ→e+ B. e + 2γ→e- C. e+ +e- =2γ.

8. What interaction is responsible for the transformation of elementary particles into each other? A. Strong interaction. B. Gravitational. B. Weak interaction D. Strong, weak, electromagnetic.

Answers: B; IN; A; IN; B; A; IN; G.

5. Are there unchanging particles in nature? A. There are. B. They don’t exist.

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Literature

Periodic system of elementary particles / http://www.organizmica.ru/archive/508/pic-011.gif; Ishkhanov B.S. , Kabin E.I. Physics of nuclei and particles, XX century / http://nuclphys.sinp.msu.ru/introduction/index.html table of elementary particles / http://lib.kemtipp.ru/lib/27/48.htm Particles and antiparticles / http://www.pppa.ru/additional/02phy/07/phy23.php Elementary particles. reference book > chemical encyclopedia / http://www.chemport.ru/chemical_encyclopedia_article_4519.html Physics of elementary particles / http://www.leforio.narod.ru/particles_physics.htm Quark / http://www.wikiznanie.ru/ru -wz/index.php/%D0%9A%D0%B2%D0%B0%D1%80%D0%BA Physics of the nucleus and elementary particles. Knowledge is power. / http://znaniya-sila.narod.ru/physics/physics_atom_04.htm Quark. Material from Wikipedia - the free encyclopedia / http://ru.wikipedia.org/wiki/%CA%E2%E0%F0%EA 2. About quarks. / http://www.milogiya.narod.ru/kvarki1.htm Harmony of the rainbow / http://www.milogiya2008.ru/uzakon5.htm

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What are elementary particles?

The particles that make up the atoms of various substances - electron, proton and neutron - are called elementary. The word "elementary" implied that these particles are primary, simplest, further indivisible and unchangeable.

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How to detect an elementary particle?

Typically, traces (trajectories or tracks) left by particles are studied and analyzed.

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History of the discovery of elementary particles

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Discovery of the electron

Based on experiments on electrolysis, M. Faraday established that there are charges in the atoms of all chemical elements.

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In 1899, J. Thomson proved the reality of the existence of electrons.

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In 1909, R. Millikan first measured the electron charge: q e = 1.602·10-19 C

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Discovery of the proton

In 1919, E. Rutherford, while bombarding nitrogen with alpha particles, discovered a proton: 147N + 42He→ → 178O + 11 p

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Discovery of the neutron

In 1932, D. Chadwick discovered a new particle and called it a neutron, which does not have electric charge. In a free state, a neutron lives for about 1000 s, then decays into a proton, electron and neutrino: n → p + 0-1e + ν

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Rutherford's experiments and the phenomenon of radioactivity showed that atoms are not the simplest indivisible particles. It was found that atoms consist of electrons, protons and neutrons, which were considered incapable of any changes and transformations, i.e. elementary or simplest.

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But it soon became clear that these particles are not immutable at all...

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Discovery of the positron

In 1928, P. Dirac predicted, and in 1932, G. Anderson discovered the positron (e+), photographing traces of cosmic particles in a cloud chamber.

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Discovery of other elementary particles

In 1931, W. Pauli predicted, and in 1955, experimentally detected neutrinos and antineutrinos. The antiproton was discovered in 1955, and the antineutron in 1959. In 1947, H. Yukatawa discovered the π meson.

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Further studies of the particles showed that they cannot be considered elementary. Each of these particles, when interacting with other particles and atomic nuclei, can turn into other particles. Therefore, the term “elementary particle” is conditional. Today, about 400 elementary particles have been discovered.

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Gravitational – interaction between all particles (gravitons).

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Large linear accelerator

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Linear accelerator

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Particle accelerator

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Elementary particles can travel through time

Research using a unique instrument - the Large Hadron Collider - will allow scientists to send elementary particles into the past. This follows from a theory that is planned to be tested in the near future at this largest accelerator in the world, located in Geneva.

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Hadron Collider

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For the first time, physicists have managed to hold antimatter atoms in a special trap for a relatively long time. Antimatter is the “double” of ordinary matter with the difference that all antimatter particles have the opposite sign of charge. When particles of matter and antimatter interact, their mutual destruction occurs.

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American physicists working with the Tevatron particle accelerator at the National Laboratory. Enrico Fermi, are ready to announce a sensational discovery. Perhaps they were able to discover a new elementary particle or even the new kind physical interaction

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