Студопедия — A STANDARD MODEL
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A STANDARD MODEL






UNIT ONE ATOM AND MATTER

“The creating element in the mind of man…

emerges in as mysterious a fashion as those elementary

particles which leap into momentary existence in great cyclotrons,

only to vanish again like infinitesimal ghosts”

Sir Arthur Eddington, 1928

Before you read

I. Discuss these questions with your partner.

1. What is an atom?

2. What is smaller than an atom?

3. What happens if you split an atom?

Vocabulary

II. 2. Match these words with their definitions.

1. subatomic a part of an atom which has no charge

2. electron b two or more particles

3. neutron c smaller than an atom

4. molecule d part of an atom that has a negative charge

5. proton e a theory developed by physicists to explain the atom

6. quantum mechanics f part of an atom which has a positive charge

7. carbon g pulled together

8. attracted h a chemical element

9. helium I a chemical element that is lighter than air

10. universe j the whole cosmos

III. 3. Read and complete the text using the words below.

STANDARD MODEL

All matter around us is made of elementary particles, the building blocks of matter. These particles occur in two basic types: quarks and leptons. Each group consists of six particles, which are related in pairs, or 1)…. The lightest and most stable particles make up the first generation, whereas the heavier and less stable particles belong to the second and third generations. All stable matter in the universe is made from particles that belong to the first generation, and heavier particles quickly decay to the next most stable level. The six quarks are paired in the three generations-the up quark and bottom (or beauty) quark. Quarks also come in three different “colors”: red, blue and green. Just as electrons and protons carry “color charge”, which is 2)… when quarks change from one type to another. Color charge is nothing to do with the visible colors of light- it is just an arbitrary way of naming the quantum properties of quarks. Just as electric charges produce a force, so color charges (quarks) can exert forces on one another. Color force gets 3)… the further the quarks are apart, so they stick together as if held by an invisible elastic band. Because the color force field tie is so strong, quarks cannot exist on their own and must always be locked together in combinations that are color neutral overall (exhibiting no color charge).

The second class of particles, the leptons, are related to and include 4)…. Again there are three generations with increasing masses: electrons, muons and taus. 5)… are 200 times heavier than an electron and taus 3700 times. Leptons all have single 6)… charge. They also have an associated particle called a neutrino that has no charge. Neutrinos have almost no mass and do not interact much with anything. They can travel right through the Earth without noticing, so are difficult to catch. All leptons have antiparticles.

Fundamental forces are mediated by the exchange of particles. There are four fundamental forces at work in universe: the strong force, the weak force, the electromagnetic force, the gravitation force. They work over different ranges and have different strengths. Gravity is the weakest but it has an infinite range. The electromagnetic force also has 7)… range but it is many times stronger than gravity. The weak and strong forces are effective only over a short range and dominate only at the level of 8)… particles. Despite its name, the weak force is much stronger than gravity but it is indeed the weakest of the other three. The strong force is the strongest of all four fundamental interactions.

Three of the fundamental forces result from the exchange of force-carrier particles, which belong to a broader group called 9)…. Particles of matter transfer discrete amounts of energy by exchanging bosons with each other. Each fundamental force has its own corresponding boson- the strong force is carried by the 10)…, the electromagnetic force is carried by the photon and the W and the Z bosons are responsible for the weak force.

The Standard model includes the electromagnetic, strong and weak forces and all their carrier particles, and explains well how these forces act on all of the matter particles. However, the most familiar force in our everyday lives, 11)…, is not part of the Standard model, as fitting gravity comfortably into this framework has proved to be a difficult challenge.

How do we know about these subatomic particles? Particle accelerators use giant magnets to accelerate particles to extremely high speeds and smash those particle beams either into a target or into another oppositely directed beam. At 12)… speeds, the particles break apart a little and the lightest generations of particles are released. Because mass means energy, you need a higher particle beam to release the heavier generations of particles.

The particles produced in the atom smashers then need to be identified and particle physicists do this by photographing their 13)… as they pass through a magnetic field. In the magnetic field, positive charged particles swerve one way and negative ones the other. The mass of the particle also dictates how fast it shoots through the detector and how much its path is curved by the magnetic field. So light particles barely curve and heavier particles may even spiral into loops. By mapping their characteristics in the detector, and comparing them with what they expect from their theories, particle physicists can tell what each particle is.

 

Tracks electrons muons subatomic stronger modest negative generations bosons

conserved gravity infinite gluon

 

IV. Read the text again and find the words that mean the same as the following definitions.

a) a property of something that dictates its potential for change;

b) a fundamental force through which masses attract one another;

c) a means of transmitting a force at a distance;

d) light manifesting as a particle;

e) physical substance in general that everything in the world consists of;

f) a property that is equivalent to the number of atoms or amount of energy that something contains;

g) to be destroyed gradually by natural processes;

h) to move in continuous circles, going upwards or downwards;

i) a lift, pull or push, causing the motion of something to change;

j) a fundamental particle, three of which combine to make up protons and neutrons.

V. In pairs, discuss and write definitions for the following terms from the text. Use a dictionary to help you.

Stable charge infinitesimal dominate discrete magnet release beam curve (n)

VI. Read the sentences and mark T (true) or F (false).

1. The strong force causes nuclear reaction that has let the sun shine for billions of years.

2. Photons mediate the electromagnetic force between electrically charged particles.

3. Neutrinos are very light and hardly ever interact with ordinary matter.

4. Protons and neutrons are both made from quarks.

5. The weak force binds atomic nuclei together, making them stable.

6. The neutron consists of two up and one down quarks.

VII. Complete each sentence by matching it with the appropriate ending.

1. The Standard model of particle physics is a theory which describes

2. Each quark carries

3. Leptons do not carry

4. The down-type leptons participate in

5. The up-type leptons carry

6. Particles of matter exchange

7. The weak and strong forces are effective only

a) no electric charge;

b) at the level of subatomic particles;

c) any of the three color charges;

d) bosons with each other;

e) any color charge- they are color neutral;

f) electromagnetic interactions;

g) three of the four known fundamental interactions between elementary particles that make up all matter.

 

VIII. Choose the correct answer A, B, or C from the list below.

In the early 20th century physicists knew that matter was 1)… of protons, neutrons and electrons. 2)… had described how, due to quantum theory, electrons arranged themselves in a series of 3)… around nucleus, like the orbits of planets around the Sun. The 4)… of the nucleus were even stranger. Despite their repelling positive charges, nuclei could host tens of protons alongside neutrons 5)… into a tiny hard kernel, bound by the precise strong nuclear force. But as more was learned from radioactivity about how nuclei broke apart or joined together, it became clear that more 6)… needed to be explained.

First, the burning of hydrogen into 7)… in the Sun, via fusion, implicates another particle, neutrino, which transforms 8)… into neutrons. In 1930, the neutrino’s existence was inferred to explain the decay of a neutron into a proton and electron-9)… radioactive decay. The neutrino itself was not discovered until 1956, having virtually no 10)…. So, even in the 1930s there were many loose ends. But in the 1940s and 50s other particles were sought and the collection grew.

1. A discovered B consisted C made up

2. A Newton B Niels Bohr C Dalton

3. A groups B shells C grid

4. A properties B composition C mass

5. A squeezed B pushed C compressed

6. A phenomena B events C facts

7. A oxygen B helium C deuterium

8. A protons B electrons C taus

9. A alpha B beta C gamma

10. A mass B electric charge C color charge

SPEAKING

IX. Answer the following questions.

1. What is the Standard model?

2. What groups does it consist of? Can you describe them?

3. How do the fundamental forces differ from each other?

4. What ways did the scientists use to detect subatomic particles?

5. Why isn’t gravity included in Standard model?

 

X. Complete these sentences with information that reflects your personal views.

1. The Standard model is a successful theory of particle physics…

2. The biggest success of the Standard model is…

3. The biggest failure of the Standard model is…

XI. In pairs, role-play conversations in which a physicist explains the main ideas of the Standard model to a layperson.

XII. In pairs or small groups, look for information on one of the topics from the list below and prepare an oral report.

1) How will the discovery of Higgs boson affect the Standard model?

2) Do all the scientists support the Standard model?

3) Is it possible to create a Unified theory?

 

XIII.Listen to ‘CERN the Standard Model of Particle Physics’ and complete the notes. Check and compare your answers.

1) The objective of particle physicists is …

2) You can build a very simple universe with…

3) At the beginning of the 20th century the scientists found …

4) The birth of the Standard model is connected with discovery of…

5) First there were discovered only…

6) Then another set of fundamental building blocks of matter…

7) Strong nuclear force is carried by…

8) Beyond the Standard model there are many questions to be answered…

Funny Science Jokes.

1. What’s the difference between a quantum mechanic and an auto mechanic? The quantum mechanic can get inside without opening the door.

2. Who solves mysteries involving electricity? Sherlock Ohms.

 

XIV. Look at the table and describe it.

To understand and describe graphs and tables you should understand the following details:

1) What is the information or data in the graph or table about?

2) What are the units of measurement used?

3) What are the area (place) involved?

4) What is the purpose of the graph or table?

5) What is the time-scale involved?

This is the list of some introductory expressions which can be useful to begin the description of the graph or table with:

The graph/ table shows / indicates/illustrates/ reveals/represents;

It is clear from the graph/table;

It can be seen from the graph/table;

As the graph/table shows;







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