Characterization of ultra-thin silicon strip detectors for hadrontherapy beam monitoring

For precise treatment purposes in hadrontherapy, the particle beam has to be monitored in real time without being degraded. For the first time, silicon strip detectors have been fabricated over an area as large as 4.5cm x 4.5cm with ultra low thickness of 20 microns in order to reduce the beam scattering. In this work, we briefly describe the fabrication process and characterize this novel detector consisting of 81 4cm-long strips. Fabrication was carried out in the cleanroom facilities of Université catholique de Louvain starting from p-type thick-SOI wafers. A 62MeV proton beam similar to the ones in clinical treatments has been used to irradiate the sensor at Cyclotron Research Center, Louvain-la-Neuve. The considered parameters were dark current and signal strip repeatability, linearity versus dose rate, and response uniformity through the wafer. The fabrication process was successful and characterization gave satisfactory results. These novel fabricated devices constitute a very promising technology for future in-vivo, non-invasive verification of the actual treatment delivery in hadrontherapy.