The source and C0
For each one of the experiments it performs, GANIL produces ion beams from atoms ranging from Helium to Uranium.
Creating the source of ions is the first step of an experiment.
Starting from a jar containing any particular gas such as oxygen, we transform these atoms into ions so they can be subsequently accelerated.
Since atoms are neutral particles, they have no electric charge, which makes them highly stable and therefore difficult to accelerate.
In order to ionize these atoms, we generate an electromagnetic field using magnets so as to excite the electrons orbiting the atoms. Thus loaded with energy, the electrons are released from the nucleus. A second method consists in placing the atoms within some kind of an oven, at a temperature of approximately 1500°C. Thus heated, the electrons increase their energy and can escape in a similar fashion.
We thus obtain a plasma, which is a collection of more or less charged ions. It should be recalled that the more electrons an ion has lost, the more strongly charged and therefore unstable it is. Whilst travelling along the guide pipes, this plasma is focused by magnets, and sorted so as to keep only those ions with a given charge, defined by the needs of the experiment. The beam of ions thus selected is forwarded to the cyclotrons where it is accelerated.
At the source output, the plasma undergoes an initial acceleration within a cyclotron known as C0. The energy thus exchanged provides the beam with an initial impulse, which allows it to travel with a rather high velocity in the first section of the line.