SLIM (SEM for Low Interception Monitoring): An Innovative Non-Destructive Beam Monitor for the Extraction Lines of a Hadrontherapy Centre

Real time monitoring of hadrontherapy beam intensity and profile is a critical issue for the optimisation of the dose delivery to the patient carcinogenic tissue, the patient safety and the operation of the accelerator complex. For this purpose an innovative beam monitor, based on the secondary emission of electrons by a nonperturbative, sub-micron thick Al target placed directly in the extracted beam path, is being proposed. The secondary electrons, accelerated by an electrostatics focusing system, are detected by a monolithic silicon position sensitive sensor, which provides the beam intensity and its position with a precision of 1 mm at 10 kHz frame rate. The conceptual design and the engineering study optimised for hadrontherapy, together with the results of the preliminary tests of the first system prototype, will be presented.