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TY - CONF AU - Roth, A. AU - Akcöltekin, E.M. AU - Boldt, O. AU - Klarner, F. AU - Röcken, H. AU - Stephani, T. AU - Wittschen, J.C. ED - Conradie, Lowry ED - De Villiers, John Garrett ED - Schaa, Volker RW TI - Energy Reduction of Varian’s ProBeam 250 MeV Cyclotron to 226 MeV J2 - Proc. of Cyclotrons2019, Cape Town, South Africa, 23-27 September 2019 CY - Cape Town, South Africa T2 - International Conference on Cyclotrons and their Applications T3 - 22 LA - english AB - With its superconducting 250 MeV isochronous proton cyclotron AC250, Varian uses a powerful accelerator for the ProBeam particle therapy systems. However, data from clinical operation has shown that the vast majority of treatments is only making use of proton ranges of less than 30 cm WET (water equivalent thickness), i.e. beam energy of 218 MeV at the patient. This led to a decision at Varian in Dec 2018 to conduct a redesign program with the goal to reduce extraction energy of the ProBeam cyclotron to 226 MeV. We present beam dynamics simulations for the AC226 beam acceleration and extraction. They actually show that only a reduced main coil current and adapted magnetic shimming process, as well as a slightly lower RF frequency is needed for re-tune. Furthermore, results indicate that a similar performance as compared to the AC250 can be expected. A first of its kind (FOIK) AC226 cyclotron is built by seamless integration into Varian’s production process. The magnetic field measurement and shimming is completed, in-house RF and beam commissioning is planned for autumn 2019. We report on the status of the FOIK machine. PB - JACoW Publishing CP - Geneva, Switzerland SP - 344 EP - 347 KW - cyclotron KW - extraction KW - proton KW - MMI KW - simulation DA - 2020/06 PY - 2020 SN - 978-3-95450-205-9 DO - doi:10.18429/JACoW-Cyclotrons2019-FRA03 UR - http://jacow.org/cyclotrons2019/papers/fra03.pdf ER -