Showers of particles

In the Roto-Louvre design of Figure 9.10(b) the gas enters at the wall, flows first through the bed of particles and subsequently through the shower of particles. Performance data are in Tables 9.10(b) and (c). 

Such tendencies may be reduced by growing crystals very slowly, for instance, by extremely slow cooling or evaporation. In fact, when it is desired to obtain perfect crystals for goniometric or X-ray work, the golden rule is to grow them as slowly as possible. Excessive nucleus formation in solutions can often be avoided by removing dust particles in the following way. A solution saturated at, say, 30° C is made up and allowed to cool without disturbance to room temperature it is then suddenly disturbed, so that a shower of small crystals is formed these... 

The primer cup contains a mixture of chemicals which sensitize each other to percussion and rapid burning, and consequently the primer burns rapidly producing a flame and a shower of hot particles that penetrates and ignites the propellant. 

The cosmic radiation incident on the earth is generated in our galaxy. It is effectively absorbed in the atmosphere, and the flux density is reduced from about 20 cm s to about 1 cm" s at the surface of the earth. By interaction with the atoms and the molecules in the atmosphere showers of elementary particles are produced, making up the secondary cosmic radiation. Positrons, muons, several kinds of mesons and baryons were first detected in the secondary cosmic radiation. Furthermore, nuclear reactions induced by secondary cosmic radiation lead to the production of cosmogenic radionuchdes, such as T and (section 1.2). 

These comprise, on the one hand, easily combustible substances such as charcoal, sulphur, antimony sulphide, resins, and tar and on the other hand, they include substances which readily give up oxygen and support combustion, such as saltpetre (potassium nitrate), and potassium chlorate or other chlorates. A third category includes those substances used for the various colour effects (barium strontium, copper, and other salts), and also finely divided metals, and coarse particles of charcoal to cause sparks and showers of fire ( golden rain and the like). Other substances are sometimes used to decrease the rate of burning and to increase brilliance (r.g. mercurous chloride and mercuric thiocyanate). 

The same set of cascade equations (see Eq. 19) governs air showers and uncorrelated fluxes of particles in the atmosphere. The boundary condition for an air shower initiated by a primary of mass A and total energy Eq is... 

At altitudes below a few kilometers, the number of particles in a shower attenuates with an attenuation length of about 200 g cm , ... 

When the primary cosmic particles enter the earth s atmosphere, they collide with the matter of the atmosphere and are annihilated. In this annihilation process a large number of new particles are formed whose total kinetic energy is less than that of the original primary radiation but whose total rest mass is larger than that of the primary particle. A 10 GeV cosmic helium ion may produce a shower of 50 - 100 new highly ionizing particles, cf. Fig. 10.2. The main reaction products are particles which are known as pions, designated ir. 

In Southeast Asia, most of the yellow rain attacks were delivered by aircraft or helicopter spray, bombs, and air-to-surface rockets. The attacks were described as a shower of sticky liquid, a yellow cloud of dust or powder, or a mist (like an insect spray).715 The delivery of the trichothecene mycotoxins was similar in many aspects to the spraying of pesticides on agricultural crops. This would result in a very low-efficiency respiratory aerosol (1-5 pm particles)34 but a highly effective droplet aerosol that could cause severe skin and eye irritation. 

The picture of the electron, the fundamental negative electric unit, as a minute mass, obeying the laws of particle dynamics seems so far to be very satisfactory, but matters are really much more complex. If a beam of electrons at a suitable angle of incidence is reflected from a crystal surface, the distribution of intensities is not at all what would be expected for a shower of projectiles, but is represented by a pattern with maxima and minima just like those occurring in the diflh-action of light. 

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