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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 - Reentrant Cavity Resonator as a Beam Current Monitor (BCM) 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 - At PSI, a dedicated proton therapy facility, with a superconducting cyclotron, delivers 250 MeV beam energy, pulsed at 72.85 MHz. The measurement of beam currents (0.1-10 nA) is generally performed by ionisation chambers (ICs), but at the expense of reduced beam quality, and scattering issues. There is a strong demand to have an accurate signal with a minimal beam disturbance. A cavity resonator, on fundamental resonance mode, has been built for this purpose. The cavity, coupled to the second harmonic of the pulse rate, provides signals proportional to the beam current. It is installed in a beamline to measure for the energy range 238-70 MeV. Good agreement is reached between the expected and measured sensitivity of the cavity. The cavity delivers information for currents down to 0.15 nA with a resolution of 0.05 nA when integrated over one second. Its application is limited to a machine-safety monitor to trigger inter-locks, within the existing domain of the proton therapy due to the low beam current limits. With new advancements in proton therapy, especially FLASH, the cavity resonator’s application as an online beam-monitoring device is feasible. PB - JACoW Publishing CP - Geneva, Switzerland SP - 107 EP - 109 KW - cavity KW - proton KW - cyclotron KW - monitoring KW - resonance DA - 2020/10 PY - 2020 SN - 2673-5350 SN - 978-3-95450-222-6 DO - doi:10.18429/JACoW-IBIC2020-WEPP05 UR - https://www.jacow.org/ibic2020/papers/wepp05.pdf ER -