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Ion travel

Video: The ion's journey

 

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Video by CEA

 

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The ion source

 

The first step in the construction of a beam of accelerated ions is the ionization of the chosen atom. This occurs in the ion source, where a gas or solid (oxygen, carbon, ... ) is heated and ionized, that is, one or more electrons is or are removed or added to it. The resulting ion is then weakly accelerated in an initial, small compact cyclotron called C0, before being introduced into GANIL’s larger cyclotrons.

 

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The cyclotrons




At GANIL, nearly 1000 billion ions per second can be accelerated up to an energy chosen by the physicist who has designed the experiment. This beam of accelerated ions is obtained by means of two consecutive cyclotrons: CSS1 and CSS2,where ions travel along a curved spiral path. Within these two cyclotrons, the ions are accelerated and maintained in circular trajectories. 

 

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The fishbone and beam guidance



The fishbone is a component in the accelerator, which switches the beam's path between GANIL’s experimental rooms. 

The beam is transported and guided towards the rooms, along long pipes under vacuum, by means of magnetic elements: dipoles (magnets) used to rotate the beam, as well as quadrupoles, which keep it on-axis and focus it. Other pieces of equipment known as "beam diagnostic boxes" are used along the line to measure its energy, its flux, that is the number of particles per second, and its spatial and temporal dimensions.

 

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The experimental rooms




The experimental areas are rooms where the physicists carry out experiments using a target and detection systems. In these rooms, the beam is guided and focused by dipoles and quadrupoles. It takes the form of a regular succession of mostly radioactive ion clouds, travelling at a velocity of up to a third of the speed of light.

 

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The control room




The accelerator as a whole, that is the source, the cyclotrons, and the beam guidance and diagnostic components, is  controlled from a control room known as the CCP: the Central Control Station (PCP in French). Between 3 and 10 operators adjust all of the parameters (approximately 2000) involved in the beam transport line, and monitor each experimental room and accelerator component, paying particular attention to those aspects related to radioprotection and safety.

 

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