DESIGN OF THE DIPOLE VACUUM CHAMBER FOR THE CNAO SYNCHROTRON (Based on the PIMM Study)

The thin walled vacuum chamber of the CNAO synchrotron dipole has been studied in the framework of the Proton Ion Medical Machine Study (PIMMS). Sixteen curved chambers, one for each dipole, about 1.9 m long and with inner aperture 130 mm x 64 mm are needed. The rapidly changing magnetic field in the dipole (maximum field rate of 3 T/s) imposes a stainless steel wall of thickness not bigger than 0.4 mm. Different construction schemes of the chamber have been investigated and two prototypes have been simulated, realised and measured.