DEVELOPMENT OF THE BEAM POSITION MONITORS FOR THE SPIRAL2 LINAC

The SPIRAL 2 facility will deliver stable heavy ion beams and deuteron beams at very high intensity, producing and accelerating light and heavy rare ion beams. The driver will accelerate between 0.15mA and 5 mA deuteron beam up to 20 MeV/u and also q/A=1/3 heavy ions up to 14.5 MeV/u. The accurate tuning of the Linac is essential for the operation of SPIRAL2 and requires from the Beam Position Monitor (BPM) system the measurements of the beam transverse position, the phase of the beam with respect to the radiofrequency voltage and the beam energy. This paper addresses all aspects of the design, realization, and calibration of these BPM, while emphasizing the determination of the beam position and shape. The measurements on the BPM are carried out on a test bench in the laboratory: the position mapping with a resolution of 50 µm is performed and the sensitivity to the beam displacement is about 1.36dB/mm at the centre of the BPM. The characterization of the beam shape is performed by means of a special test bench configuration. An overview of the electronics under realization for the BPM of the SPIRAL2 Linac is given.