УРОК ОДИННАДЦАТЫЙ

Текст: The Nature and Origin of the Primary Cosmic Radiation. Грамматические основы перевода

Слова, словосочетания и обороты,- служащие для выражения отношения автора к высказываемой мысли и для ее уточнения (§ 75-8i). Перевод конструкции с двойным управлением (§ 105-i07>.

Лексические основы перевода

Перевод слов: borne, whereby, arise, rise, raise, capture, trap. Initiate, originate, agree, speculate.

Перевод глагола to depend с двумя предложными дополнениями. Перевод предлога over.

Перевод многозначного служебного слова Just и словосочетаний с ним (упр. 10).

Перевод слов с префиксами inter-, mal-, mis- (упр. 23).

ТЕКСТ

THE NATURE AND ORIGIN OF THE PRIMARY COSMIC

RADIATION

Once tfie existence of tfie cosmic radiation was establisfied work on its properties greatly intensified. Primary cosmic rays have been registered by balloon-borne * and rocket-borne cloud chambers *, Geiger and other tube counters, and in photographic emulsions called nuclear emulsions.

Of the various known types of particles only nuclei, protons, photons and electrons could be primary cosrtiic radiation. Mesons and neutrons are unstable, and would decay before they reached the earth. Electrons, positrons and photons were ruled out as possibilities by some experiments in 1950. It was found that these components, if present al all, comprise less than 0.5 per cent of the primary radiation of more than 1 Bev energy. When account was taken of the production of these particles in the upper atmo-

cloud chamber - камера Вильсона

sphere as secondaries to nuclear processes, it was possible to reduce the upper limit to 0,25 per cent.

With neutral particles, photons, positrons and electrons ruled out, and the primaries known to be stable and positively charged, the most likely conclusion is that they are protons (the nuclei of hydrogen atoms) and possibly the nuclei of heavier atoms. This is indeed * the case.

In the extreme relativistic range of velocities within which the primary radiation arrives in the atmosphere, it is not possible to measure directly the masses of particles passing through, or causing interactions* in, nuclear emulsions or counters, but, within certain limits, it was possible to determine their energies and charges.

The other very important field of cosmic ray research was the study of the intensity of the radiation and its variation with place and time of observation. Time variations in intensity were found to be small, (if any) leading to the conclusion that the immediate source of radiation is not within the solar* system. But the correlation* between certain large solar flares has led to the idea that the sun is I n fact responsible for a t 1 e a s t a part of the lower energy radiation.

That the whole of the primary radiation cannot originate from the sun, nor be accelerated in the rapidly varying magnetic fields associated with sunspots* and solar flares, is clear from energy considerations. For, even if one supposes that the whole of the low energy radiation originates from the sun, one is forced to assume some sort of suitable magnetic field around the solar system, which captures ** the radiation in such a way that it becomes more or less" uniformly distributed in direction. Even assuming a rather high value for such a field, it would be difficult to hold imprisoned particles with energies as high as IO" Bev known to exist in the cosmic radiation.

If one is going to give some account of the acceleration of the particles comprising the whole of the energy spectrum of the cosmic radiation, one must find some mechanism whereby )articles with energies of 10" BeV could be produced or, to put t In another way**, accelerated in interstellar space. Such a mechanism was suggested by Fermi in 1949. On his hypothesis the radiation arises* from the stellar ** magnetic disturbances", and is further accelerated by the interstellar magnetic fields, so that the whole of it is trapped " within the galaxy *. He showed that particles with initial ** energies of a few BeV could be accelerated in the interstellar magnetic fields to very much higher energies.

The Fermi process may be described shortly as follows: the particles of the cosmic radiation which have escaped from the

* galaxy - галактика

immediate neighbourhood of the stars in which they are produced move in spiral paths about the lines of force of the interstellar fields. These magnetic fields originate from, and are coupled") to, turbulent2> motions of the interstellar clouds of ionized gas. The particles are, so to say22, "locked" to particular lines of force and must follow the curvature of these in space, so that there is an interchange 23 of energy between the cosmic ray particles and the interstellar clouds. Now, Fermi could show that, if one assumes that the motion of the clouds is quite random 2* in all directions, the net25 result is that the cosmic ray particles gain energy exponentially *. On the other hand, a particle can lose its energy again if it is involved in a nuclear collision in interstellar spce, which will, on the average, happen about once in 6X10 years. The equilibrium 2» between these two effects results in an energy spectrum which falls off according to a power law with increasing energy, and by using reasonable quantities 2 for the various parameters which enter into the theory one may obtain a good agreement 2в with the experimental energy spectrum of the primary radiation.

However, it should be pointed out that there are few fields in physics or astrophysics, within which the accepted ideas change so quickly or so radically as that of the origin о the cosmic radiation. And nowadays there is much speculation 29 as to this problem. It is, therefore, necessary to treat any ideas on this subject with very considerable reserve.

УПРАЖНЕНИЯ

Грамматические упражнения

1. Переведите предложения, обращая виимаиие на перевод выделенных слов, словосочетаний н оборотов, выражающих уверенность («конечно», «само собой разумеется»). При переводе опирайтесь на значения слов, входящих в состав этих сочетаний (§ 76).

1. То be sure, these various methods may be combined, as we shall see later, to give a more complete analysis of the ionization phenomena occurring in matter.

2. Needless to say, both analog and digital equipment have their advantages and limitations.

3. True, the explosion of the bomb causes considerable air displacement.

4. To tell the truth, neither of these methods has been applied.

5. It is true that in the course of their descent cosmic rays are subjected to considerable disintegration.

6. There is every indication that the mass and weight of the air changes constantly with the seasons of the year, geographic locations, temperature and altitude variations.

* exponentially- лагеж. экспоненциально