All particles other than photons can be classified into two broad categories, hadrons and leptons, according to their interactions. Particles that interact through the strong force are called hadrons. There are two classes of hadrons, known as mesons and baryons, distinguished by their masses and spins. All mesons are known to decay finally into electrons, positrons, neutrinos, and photons. Leptons (from the Greek leptos, meaning "small" or "light") are a group of particles that participate in the weak interaction. All leptons have a spin of 1/2. Included in this group are electrons, muons, and neutrinos, which are less massive than the lightest hadron.
Many particles discovered in the 1950s were produced by the nuclear interaction of pions with protons and neutrons in the atmosphere. A group of these particles was found to exhibit unusual properties in their production and decay and hence were called strange particles. To explain these unusual properties of strange particles, a law called conservation of strangeness was introduced, together with a new quantum number S called strangeness.
Scientists are convinced that because of the limited energy available in conventional accelerators using fixed targets, it is necessary to build collid- ing-beam accelerators called colliders. The concept of a collider is straightforward. In such a device, particles with equal masses and kinetic energies, traveling in opposite directions in an accelerator ring, collide head-on to produce the required reaction and the formation of new particles.
Our understanding of physics at short and long distances is far from complete. Particle physics is faced with many questions. The questions go on and on. Because of the rapid advances and new discoveries in the related fields of particle physics and cosmology, by the time you read this book some of these questions may have been resolved and others may have emerged.
1.What are the two ways of getting energy from nuclear reactions?
2.When does nuclear fission occur?
3.Why do reactor fuels must be artificially enriched?
4.What’s the main problem of getting energy from nuclear fusion?
5.Why did physicists regard protons, neutrons and electrons as elementary particles before 1932?
6.What subatomic particles do you know?
7.What’s the concept of collider?
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Exercises
1. Rearrange the letters in the anagrams to form equivalents for the Russian words:
Замедлитель |
deratormo |
|
|
Кварки |
arksqu |
|
|
Адроны |
dronsha |
|
|
Лептоны |
tonslep |
|
|
Странность |
nessstrange |
|
|
2. Match the words in A with the words in B to form word combinations:
A |
B |
Nuclear |
chain reaction |
Fission |
fission |
Self-sustained |
fragments |
Runaway |
nuclei |
Light |
accelerators |
Colliding-beam |
reaction |
3. Fill in the gaps with the missing words from the list:
fusion reactions, fission fragments, quark, strangeness, moderator
1.The _____, barium and krypton, and the released neutrons have a great deal of kinetic energy following the fission event.
2.The slowing down of the neutrons by the _____ serves the dual purpose of making them available for reaction with 235U and decreasing their chances of being captured by 238U.
3.When _____ occur at the core of a star, the energy that is liberated eventually becomes sufficient to prevent further collapse of the star under its own gravity.
4.The _____ model has reduced the bewildering array of particles to a manageable number and has predicted new quark combinations that were subsequently found in many experiments.
5.The law of conservation of _____ states that whenever a nuclear reaction or decay occurs, the sum of the strangeness numbers before the process must equal the sum of the strangeness numbers after the process.
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Список использованной литературы
1.Толстой Д.М. Англо-русский физический словарь. Ок. 60000 терминов. М.: Сов. энциклопедия, 1972. 848 с.
2.INIS: THESAURUS. International Atomic Energy Agency, Vienna, http://www.iaea.org/INIS
3.Jerry S. Faughn, Raymond A. Serway, Chris Vuille, Charles A. Bennett. Serway’s College Physics. Seventh edition. USA, 2006. 1008 p.
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ПРИЛОЖЕНИЕ. Англо-русский терминологический словарь
179
Absolute zero – абсолютный нуль Absorption spectrum – спектр поглощения
AC (Alternating-current) circuits – цепи переменного тока
Acceleration at the Highest point – ускорение в наивысшей точке
Acceleration of gravity – ускорение силы тяжести, ускорение свободного падения
Acceptor atoms – атомы акцепторы Accommodation – аккомодация
Action potentials – действующий потенциал Action-at-a-distance – действие на расстоянии Adding vectors – суммирование векторов Addition laws – дополнительные законы Adiabatic process – адиабатический процесс Adjustable bellows – регулируемый сильфон Adjustment – регулирование
AFM (atomic force microscope) – атомный микроскоп
Allowed states – разрешённые состояния Alpha particles – альфа частицы Aluminum – алюминий
Amber – янтарь Ammeter – амперметр
Amorphous solid – аморфное тело Ampere (A) – ампер
Amplitude – амплитуда Analyzer – анализатор
Angle subtended – стягиваемый угол Angular momentum – момент импульса Antineutrino – антинейтрино Antiparticle – античастица
Aperture – диафрагма
Approximate values – приблизительные значения Archimedes’s principle – принцип Архимеда Artificial radioactivity – искусственная радиоак-
тивность Assumptions – предположения
Atmospheric refraction – атмосферная рефракция Atomic number – атомное число
Atomic transitions – атомные перемещения Audible wave – звуковая волна
Average power – средняя мощность Axis – ось
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Back emf – обратная ЭДС
Band gap – ширина запрещённой зоны Bar magnet – стержневой магнит Baryons – барионы
Base – база (в транзисторе) Battery – батарея Becquerel(Bq) – беккерель Beta decay – бета-распад Binding energy – энергия связи Black hole – чёрная дыра
Blackbody radiation – излучение абсолютно чёрного тела
Blades of a turbine – лопасти турбины Blurred images – смазанное изображение Bohr radius – боровский радиус
Bohr's Correspondence principle – боровский принцип соответствия
Boiling point – точка кипения
Boltzman’s constant – постоянная Больцмана Breaking point – точка разрушения Bremsstrahlung – тормозное излучение Brightness – яркость
British thermal unit (Btu) – британская тепловая единица
Bulb – колба (лампы)
Bulk modulus – объёмный модуль Buoyant force – выталкивающая сила Calculations – вычисления
Calorie – калория Calorimeter – калориметрия
Camera – фотоаппарат (оптика) Capacitance – ёмкость
Capacitors in series – последовательно соединённые конденсаторы
Carnot engine – двигатель Карно Case ground – заземление
Celsius temperature scale – температурная шкала Цельсия
Centimeter – сантиметр
Centripetal force – центростремительная сила Charge carriers – носитель заряда
Charging by friction – заряд трением Chemical energy – химическая энергия Chip – чип (в микроэлектронике)
Chromatic aberration – хроматическая аберрация (отклонение)
Circuit breaker – прерыватель цепи Circular motion – круговое движение Clockwise – по часовой стрелке Closed loop – замкнутый контур