Non-Invasive Beam Monitoring Using LHCb VELO With 40 MeV Protons

In proton beam therapy, knowledge of the detailed beam properties is essential to ensure effective dose delivery to the patient. In clinical practice, currently used interceptive ionisation chambers require daily calibration and suffer from slow response time. This contribution presents a new non-invasive method for dose online monitoring. It is based on the silicon multi-strip sensor LHCb VELO (VErtex LOcator), developed originally for the LHCb experiment at CERN. The semi-circular detector geometry offers the possibility to measure beam intensity through halo measurements without interfering with the beam core. Results from initial tests using this monitor in the 40 MeV proton beamline at the University of Birmingham, UK are shown. Synchronised with an ionisation chamber and the RF cyclotron frequency, VELO was used as online monitor by measuring the intensity in the proton beam halo and using this information as basis for 3D beam profiles. Experimental results are discussed.