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TY - CONF AU - Srinivasan, S. AU - Duperrex, P.-A. AU - Schippers, J.M. ED - Tavares, Daniel ED - Picoreti, Renan ED - Bruno, Gustavo ED - Marques, Sergio ED - Schaa, Volker R.W. TI - Experiments With a Quadrated Dielectric-Filled Reentrant Cavity Resonator as a Beam Position Monitor (BPM) for a Medical Cyclotron Facility J2 - Proc. of IBIC2020, Santos, Brazil, 14-18 September 2020 CY - Santos, Brazil T2 - International Beam Instrumentation Conference T3 - 9 LA - english AB - Low beam currents (0.1-10 nA) are used for tumour treatment in the proton radiation therapy facility at PSI. The facility houses a superconducting cyclotron with extraction energy of 250 MeV pulsed at 72.85 MHz. Online measurement of the beam position is traditionally performed with the help of ionisation chambers (ICs), however, at the expense of reduced beam quality and scattering issues. There is a strong demand to have this measurement performed with minimal beam disturbance since the beam position is directly associated with the dose-rate applied. A cavity resonator, working on the principle of an electric dipole mode resonance, whose frequency is coupled to the second harmonic of the pulse rate, has been built to measure beam position in a purely non-invasive manner. Followed by a reasonable agreement between the test-bench and the simulation results, the cavity is installed in one of the beamlines. Here, we report on the measurement of the cavity BPM as a function of beam current and position and its shortcomings. The cavity BPM can deliver position information within the accuracy and resolution demands of 0.50 mm, when measured with a spectrum analyzer. PB - JACoW Publishing CP - Geneva, Switzerland SP - 128 EP - 131 KW - cavity KW - proton KW - cyclotron KW - dipole KW - polarization DA - 2020/10 PY - 2020 SN - 2673-5350 SN - 978-3-95450-222-6 DO - doi:10.18429/JACoW-IBIC2020-WEPP15 UR - https://www.jacow.org/ibic2020/papers/wepp15.pdf ER -