The central region of the SIN injector cyclotron

The SIN injector cyclotron accelerates: (1) protons in third harmonic mode to a fixed energy of 72 MeV (injector mode), and (2) light and medium heavy ions in a range of energies (variable energy mode). Ions are produced either by an internal ion source or by an axial injection system. The central region configuration is the same in the injector mode and in the variable energy mode. The internal ion source can be easily interchanged with the deflector of the axial injection system. The construction of this central region, including the ion source is described. The ion-optical design (based on trajectory calculations with field maps obtained by the magnetic analogue method) is discussed in detail. Some experimental data, obtained during operation of the cyclotron, are compared with the theoretical predictions. The equations of motion applied in the calculation are summarized in an appendix. (Auth.)