Accelerators – Split Beam Lines for Radionuclide Production
SPLIT BEAM LINES FOR RADIONUCLIDE PRODUCTION
The layout of the beam lines for operation with split beams is shown in the figure. A 800 mm long electrostatic channel, operating with a negative deflector voltage of 70 kV across a 30 mm gap, will be used to deflect about a third of the beam away from the existing beam line. Two thirds of the beam will then be used in the vertical beam line while the deflected beam will be diverted around the 90° vertical bending magnet before it is directed to the vault that is presently used for radionuclide production. The relatively low voltage and field strength of the electrostatic channel have been chosen because the electrodes are not situated in a strong magnetic field, as is usually the case in a cyclotron. To minimise beam losses in the septum it is important that the beam should be diverging at the entrance to the channel. The expected beam loss for a 400 µA total beam current is 2.2 µA. The quadrupole magnet, directly after the electrostatic channel, is planned for adjusting the beam height in the following septum magnet that deflects the beam through 20°. The entrance of the septum magnet is 2 m down stream from the entrance of the electrostatic channel and is similar to one of the magnetic extraction channels of the separated sector cyclotron. At the entrance of the septum magnet the beam separation is 35 mm. The deflected beam is focused by three quadrupole magnets to a double waist in the switcher magnet, with zero degree entrance and exit angles.
Final design of the septum magnet