Van de Graaff

There are seven types of electron accelerator available for industrial uses [41] (1) Van de Graaff generator (2) Cockcroft-Walton generator (3) insulated core transformer (4) parallel coupling, cascading rectifier accelerator (5) resonant beam transformer (6) Rhodetron (7) linear accelerator (LINAC). 

The Cockroft-Walton and Van de Graaff accelerators are linear that is, they accelerate particles in a straight line. A short time later Ernest Lawrence got the idea to build a circular accelerator, called a cyclotron, and with the help of M. Stanley Livingston he constructed it in 1932. This first cyclotron accelerated protons to about 4 MeV. Since then, many other cyclotrons have been built, and they have been used to accelerate particles to more than 50 times as much kinetic energy as the original one. Also, other kinds of circular accelerators, such as synchrotrons, have been constructed. 

Westinghouse constructs its Atom Smasher in Forest Hills, Pennsylvania. The five million volt van de Graaff generator represents the first large-scale program in nuclear physics established in industry, makes possible precise measurements of nuclear reactions, and provides valuable research experience for the company s pioneering work in nuclear power. 

The five million-volt van de Graaff generator, Westinghouse Atom Smasher, 1937, represents the first large-scale program in nuclear physics established by industry. 

The development of mass spectrometric techniques for nuclide identification using a tandem Van de Graaff accelerator at the University of Rochester Nuclear Structure Laboratory by H. Gove, K. Purser, A. Litherland, and numerous associates has provided an excellent means for the precise measurement of 36C1 concentrations in natural water [43]. Thus far, about 40 groundwater related samples which have been collected and purified chemically by H. Bentley have been analyzed for 36C1 by D. Elmore, H. Bentley, and others using the University of Rochester machine. Some of these samples are listed in Table 2. 

In anticipation of the development to operational status of the ion or direct counting systems, it would be helpful if we could compare these values with projected counting errors for the two types of direct counting systems being developed. Table 4 lists projections for the Rochester Van de Graaff facility [49] and the University of California Lawrence Berkeley cyclotron system employing an external ion source [31,50]. Table 4 also lists the sample sizes and approximate measurement periods for both systems. This data illustrates the potential extention in dating... 

Protons can also be used instead of X-rays or electrons to create the initial vacancies in the inner electron shells, giving rise to a method known as proton induced X-ray emission (PIXE). In these instruments a high intensity, highly focused beam of protons is produced by a van de Graaff accelerator,... 

Van de Graaff/Rhees HUMAN ANATOMY AND PHYSIOLOGY order code 066884-i/ 12.95... 

Much of the pioneering research on nitrosoalkane dimers is based on reactions involving the formation of free radicals. Most of the reactions are of little value from the preparative standpoint, either because a highly specialized apparatus (e.g., photolysis equipment, high-vacuum trains, even a Van de Graaff generator) is used or because complex mixtures of products are produced. However, this work is of such importance in the historical development of aliphatic nitroso chemistry that it merits a brief review here rather than relegation to Section 5. 

A radiation dose of 1 kw. could irradiate about 795 pounds per hour of any material to a dose level of 1 Mrad at 100% efficiency. The power efficiency of the different machines varies from a low of 15% for a Van de Graaff accelerator or resonant transformer to 90% for an insulating core transformer. On the other hand, the Van de Graaff accelerator, being a d.c. machine, can be precisely controlled and adjusted, which is important for research and development. The resonant transformer, Dynamitron, and ICT are less precise, but they have lower operating costs and higher output power, making them more suitable for production purposes. 

The first few tests were carried out using an 8-m.e.v. linear electron accelerator at Berkeley, Calif. In subsequent tests, a 3-m.e.v. Van de Graaff generator at MIT was used. 

---