1. This is possible provided the reactor under consideration is not too small.
2. Provided one knows the rate of the emission, one can determine the range of the particles.
3. These terms may have arbitrary values providing equation (17) is satisfied.
4. Diode D2 provides a reference voltage against which the regulated output voltage is compared.
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READING (20A)
• Read the passage. Search for the arguments to prove that a worldwide collaboration could minimize the world expenditures for scientific research into the structure of matter.
THE NEXT GENERATION OF PARTICLE ACCELERATORS
For some 60 years the effort to understand the ultimate structure of matter has proceeded almost entirely through a single experimental technique. A particle of matter is brought to high speed and made to strike another particle. From an examination ofthe debris released in the aftermath of the collision, information isgained about the nature of the particles and about the forces that act between them. To carry out a program of such experiments it is necessary to have a source of energetic particles. Cosmic rays provide a natural source, but the flux of particles is diffuse and is beyond the control ofthe experimenter. A more practical source is a particle accelerator, the device for increasing the speed of a particle and hence also its energy.
One of the first particle accelerators, built by Ernest O. Lawrence in 1928, was made of laboratory glassware a few inches in diameter. Most of the accelerators in service today are linear descendants of Lawrence's device, but they have grown enormously in size and complexity, the largest extending over many square kilometers. The particle accelerator is no longer an instrument installed in a laboratory; instead the laboratory is assembled around the accelerator. Building such a machine costs hundreds of millions of dollars; operating it requires a staff of about 1,000 people and dozens of digital computers.
A new generation of particle accelerators is now in prospect. The first few are just coming into operation; several more are under construction; others are still being planned, and their characteristics arc not yet fixed. For both, the physicist and the layman, the principal interest inspired by these new machines is in the results of the experiments they will make possible, but the accelerators themselves also merit notice. In the physics of elementary particles the highest available energy represents a frontier marking one of the boundaries of experimentally verifiable knowledge. Several ofthe new accelerators will be capable of attaining higher energies than any existing machine, and so they will push the frontier into unexplored territory. In order to reach those energies the accelerators will of necessity be larger, more complicated and more expensive than their predecessors.
Largely because ofthe cost, the construction of an accelerator today requires the resolution not only of technical problems but also of political, economic and managerial ones. Money for scientific research is a scarce resource, and it is imperative that it be used as efficiently as possible. Technical innovations have brought a substantial reduction in the cost per unit energy of accelerating a particle. It is encouraging to note that another means for minimizing the total world expenditure is now emerging: through international cooperation the unnecessary duplication of facilities can be avoided, and projects too large for any one nation can be undertaken by regional groups of nations and perhaps eventually through a worldwide collaboration such as * CERN, the European Organization for Nuclear Research, which has its headquarters in Geneva. At present, its Member States arc Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland, the United Kingdom, Israel, Japan, the Russian Federation, the United States of America and Turkey.
• Re-read the passage carefully and explain how you understand the italicized words.
• Look through the passage and supply answers to the following questions.
1. By means of what experimental techniques is information gained about the structure of matter?