Check the pronunciation of these words.

C

In a celebrated experiment by James Chadwick (1891-1974) at the Cavendish Laboratory in 1932, the neutron was discovered. Chadwick at first believed that what he had discovered was Rutherford’s neutron, that is, a proton-electron composite. More than a year after this experiment most physicists shared this view and hesitated to include the neutron among the true elementary particles: indeed, the atomic nucleus was usually considered to consist of protons, neutrons, and electrons. The claim that the neutron was a new elementary particle, a third fundamental constituent of ordinary matter, was first made by the Russian physicist Dmitri Ivanenko in 1932 and was soon adopted by Werner Heisenberg in his theory of atomic nucleus. The convergence of theory and experiment led in 1934 to the general acceptance of the neutron as an elementary particle; thus the electron was finally expelled from the nucleus after twenty years. In the mid-1930s it was realized that the proton and the neutron can be regarded as states of the same kind of particle for which the name “nucleon” was coined.

(from Companion to the History of Modern Science)

D

This was just the beginning of a great increase in the roster of so-called elementary particles. Muons were added to the list in 1937 (though their nature was not understood until later), and pions and strange particles in the 1940s. Neutrinos had been proposed by Wolfgang Pauli in 1930, and made part of beta-decay theory by Enrico Fermi [ˊfǝ:mɪ] in 1933, but were not detected until the Reines-Cowan experiment of 1955. Then in the late 1950s the use of particle accelerators and bubble chambers revealed a great number of new particles, including mesons and baryons.

(from What Is an Elementary Particle by Steven Weinberg)

E

Shortly after the discovery of the pion, evidence was reported for the existence of new, unexpected particles. In 1947 George Rochester Butler from Manchester produced cloud chamber photographs of what were then called ‘V-particles’, recognized in the following years as heavy mesons. In 1951 some 15 elementary particles were identified, including new mesons known as the τ meson, the Λ meson and the θ meson. With the diversity of new particles the scene of particle physics seemed at the same time confusing and challenging. And yet the explosion of elementary particles had hardly begun.

(from Companion to the History of Modern Science)

F

In 1964 Murray Gell-Mann [ˊmʌrɪ dʒel mæn] and George Zweig of the California Institute of Technology independently proposed that all particles subject to the strong nuclear force are made up of more elementary constituents: the particles Gell-Mann named quarks. Particles subject to the strong force are called hadrons, and the so-called quark model was introduced in order to classify the proliferating new hadrons being generated in experiments with accelerators. According to this model each quark carries a fractional electric charge (2/3 and 1/3 of the electron’s charge). Just as Mendeleev’s periodic system and Borh’s atomic model had brought order and unity to the chaos of the chemical elements so the quark model had reinstated order in the crowded world of elementary particles. The proton, the neutron, the mesons and all the other hadrons could now be considered manifestations of just a few fundamental quarks.

The original quark scheme includes three flavors, or kinds, of quarks, called up (u), down (d) and strange (s). The proton, for example, is made up of two u quarks and a d quark, whereas the neutron is made up of a u quark and two d quarks. Three more quark flavors have since been discovered; they are called charm (c), bottom or beauty (b) and top or truth (t).

(from Companion to the History of Modern Science)

Note: for that matter – если уж на то пошло

bubble chamber – пузырьковая камера

cloud chamber – камера Вильсона

3. What do the following dates refer to?

1897, 1911, 1930, 1932, 1934, 1937, 1947, 1951, 1955, 1964

4. Translate text C into Russian with the help of a dictionary (in writing).

5. Make up a list of 10–12 questions to all the texts and discuss them in groups.

6. Today’s elementary particles, the leptons (ν_e,e), (ν_μ,μ), (ν_τ,τ), and the quarks (u,d), (c,s), (t,b), form one of the pillars of our understanding of matter and energy. The quarks are colour triplets that experience the strong interactions. The leptons, which have no colour charge, do not.

Here is a chart with 12 elementary particles that are considered to be the “building blocks” of matter. Read it carefully and complete the analogous chart in your notebooks in English.

Фундаментальные фермионы (fermions)		Лептоны	Кварки
Электрич. заряд		-1		+2/3	-1/3
Частицы окружающего мира принадлежат этой группе.	Первое семейство	Электрон переносит электрический ток.	Электронное нейтрино играет фундамен­тальную роль при горении Солнца, каждую секунду сквозь нас пролетают миллиарды этих частиц.	U-кварк (up-верхний) входит в состав протонов и нейтронов.	d-кварк (down – нижний) входит в состав протонов и нейтронов, M=6 МэВ/с2, открыт в 1964 г.
Эти частицы существовали в первый момент после Большого Взрыва (Big Bang). Теперь их можно обнаружить в космосе и на ускорителях частиц.	Второе семейство	Мюон – аналог электрона, время жизни – 2 микросекунды М= 106МэВ/с2	Мюонное нейтрино – обра­зует­ся при рождении и распаде мюонов М<0,2 МэВ/с2	c-кварк (charm – очарованный) открыт в 1974 г. М=1300 МэВ/с2	s-кварк (strange – странный) открыт в 1964 г. М=100 МэВ/с2
Третье семейство	Тау – аналог электрона, время жизни 3·10-13с, М=1777МэВ/с2	Тау-нейтрино – образуется при рождении и распаде тау-лептонов, открыто в 1975 г. М<20 МэВ/с2	t-кварк (top – самый верхний или truth – истинный) открыт в 1995 г. М=175000 МэВ/с2	b-кварк (beauty – прелестный) открыт в 1977 г. М=4300 МэВ/с2

7. Write a brief description of the information contained in the chart. Begin your description like this:

There are two types of elementary particles: leptons and quarks. Both leptons and quarks can be sub-divided according to … into ….

While classifying you may use the following words and phrases.