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ISOTOPIC TRACERS AND NUCLEAR RADIATIONS [Chap. 21 



Alternative schemes have been proposed which may prove more successful 

 in extracting very high-energy beams (> 100 mev) where simple electrostatic 

 deflection is impracticable. For instance, if the magnetic field is locally 

 weakened by shims along a spiral path leading outward from the maximum 

 radius, ions of the proper energy entering this region can be led out to the 



MAGNET 

 UPPER COIL 

 DEE 



OSCILLATOR HOUSING 



ROTARY CONDENSER 

 HOUSING 



DEE TRUCK 



VACUUM TANK 



VACUUM 

 MANIFOLD 



DIFFUSION PUMPS 

 TO MECHANICAL PUMPS 



LOWER COIL TANK 



DEUTERON SOURCE 

 Fig. 127. Cut-away diagram showing the main structural features of the 184-in. frequency- 



modulated cyclotron of the Radiation Laboratory, University of California. 

 permission of the Radiation Laboratory.] 



[Reprinted by 



periphery of the field [2]. Magnetic deflection of this kind combined with 

 appropriate electric fields may ultimately provide the most satisfactory 

 deflector system in such cases. 



The general structural features of the cyclotron are illustrated by the 

 diagrams of the 184-in. cyclotron at the Radiation Laboratory of the Uni- 

 versity of California shown in Figs. 127 and 128. 



21.2. Ion Paths. The ultimate fate of an ion depends largely on its 

 trajectory during the first few cycles after it leaves the source. Less than 

 10 -4 of the ions produced at the source ever reach the target. The majority 

 of ions are lost immediately by neutralization in collisions with parts of the 



