CLUSTER: concept study and design of a low-medium β accelerating structure

A novel linear accelerating structure is proposed particularly suited for hadrontherapy applications. The main features are compactness, due to the high frequency and consequent large gradients, and good power efficiency, especially at low beam velocities, obtained by using coupled H-mode cavities. The structure is called CLUSTER which stands for 'Coupled cavity Linac USing Transverse Electric Radial field'. In order to compare the performances of this structure with other hadrontherapy linac designs operating at high frequencies, a conceptual study has been performed by choosing the frequency of 3 GHz. Moreover a proof of principle of the radiofrequency behaviour of the cavity has been obtained by RF measurements on a prototype running at 1 GHz