Accelerators, Van de Graaf

The basis of the method is shown in Fig. 3.8. Pulsed radiation is usually generated by linear electron accelerators (Linacs) or by Van de Graaf accelerators, each having certain advantages. Both give nan-... 

Since ERDA is complementary to RBS analysis, this method should be a part of every MeV ion-beam analysis system. When it is employed on small Van de Graaf accelerators, ERDA can be used for determining concentration depth profiles or areal densities of hydrogen and of deuterium. Using larger Van de Graaf accelerators with the ability to accelerate heavy ions, this technique can be used for concentration depth profiling of heavier elements up to fluorine. 

Electrons with adequate energies were provided by a Van de Graaf accelerator at the solid-state physics laboratories of Groningen University. According to the expected doses in Table 4.4, 1.3 x 10 Gy is the nominal dose for one year at mean sun activity. The realistic dose of 10 Gy produces only faint damages, if any. To investigate time dependence and the types of defects, 1, 5, 10, 10, and 10" years in space (10 -10 Gy) were simulated. 

B. van de Graaf and E. de Vos Burchart, Comput. Chem., 17, 81 (1993). Simplification and Acceleration of Crystal Energy Calculations Under Constant Pressure. 

Curing can be carried out by mixing 100 parts of a polymeric allylic diene with 10 parts of tetrathiol, adding 0.05 parts of a subjecting hindered phenol antioxidant, and subjecting the mixture to radiation beam curing (2 MeV electrons, Van de Graaf electron accelerator). 

Rutherford s experiments opened the door to nuclear transmutations of all kinds. Atoms were bombarded by alpha particles, neutrons, protons, deuterons (iH), electrons, and so forth. Massive instruments were developed for accelerating these particles to very high speeds and energies to aid their penetration of the nucleus. The famous cyclotron was developed by E. O. Lawrence (1901-1958) at the University of California later instruments include the Van de Graaf electrostatic generator, the betatron, and the electron and proton synchrotrons. With these instruments many nuclear transmutations became possible. Equations for a few of these are as follows ... 

Canada, Visiting Scientist, CSIR, National Accelerator Centre, Van de Graaf Group Faure, South Africa, Bell Laboratories, Murray Hill, NJ, USA, GTE Laboratories, Waltham, MA, USA. His current research interests are diffusion in solids, thin film deposition and properties (mostly by sputtering) and characterization of thin films, among them various silicides. 

An interesting technical idea has been advanced by Cheifetz et al. who allowed fission fragments produced by a Cf source to be accelerated by a Van de Graaf machine. They estimate that it would not be difiiciilt to obtain the heavy fragments at 900 MeV which would be sufficient to overcome coulomb barriers in a target, but the important point is that with such a system, irradiations could be carried out with neutron-rich particles. 

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