IPAC'23 - Student Poster Session Guide

IPAC’23 / STUDENT POSTER SESSION GUIDE 48 Student Poster Session SUPM090 Increased dose rate for a proton therapy eye treatment nozzle on a medical gantry system using a diamond degrader material Eustache Gnacadja (Universite libre de Bruxelles) . Cédric Hernalsteens (European Organization for Nuclear Research), Eliott Ramoisiaux, Marion Van- welde, Nicolas Pauly, Robin Tesse (Universite libre de Bruxelles). The IBA ProteusOne (P1) system is suitable to treat ocular tumors and achieves efficient dose conformality using state-of-the-art pencil beam scanning. Nevertheless, with the limited cyclo- tron current of the P1 system, clinically relevant (> 15 Gy/min) dose rates can barely be achieved in eye tumors treatment cases with the baseline configuration of the system due to the signifi- cantly high energy degradation required (from 230 to 70 MeV). One way to improve this dose rate is to modify the degrader to use a material causing a smaller emittance increase. In this work, we compare the performances of the P1 system in the context of eye tumors treatment when using Beryllium degrader on the one hand and Diamond degrader on the other. For the latter case, the optics is modified to reduce the losses along the beamline and ultimately in- crease the dose rate of the system while maintaining a symmetrical spot at the isocenter. Using Beam Delivery SIMulation, the dosimetric properties of the system are assessed and compared for the two configurations, and the differences in dose rate are quantified and discussed in detail. SUPM091 Origins of Quench in Buffered Chemical Polished and Low Temperature Baked SRF Cavities Hannah Hu (University of Chicago) . Daniel Bafia (Fermi National Accelerator Laboratory), Young-Kee Kim (University of Chicago). Electropolishing (EP) and buffered chemical polishing (BCP) are conventional surface prepara- tion techniques for superconducting radiofrequency (SRF) cavities that remove material and re- duce surface roughness. Both EP and BCP treated SRF cavities display high field Q-slope (HFQS), which degrades performance at high gradients. High gradient performance in EP cavities can be improved by applying a low temperature bake (LTB) of 120$^\circ$C by 48 hours to cure HFQS, but LTB does not consistently remove HFQS in BCP cavities. There is no consensus as to the why LTB is not effective on BCP prepared cavities, and the cause of HFQS in BCP cavities is not well understood. We examine the thermal and magnetic origins of quench in EP, BCP, EP+LTB, and BCP+LTB treated SRF cavities by studying the heating behavior with field using a temperature mapping (TMAP) system. We also show the effect of LTB on Q-disease, the onset of HFQS, and the concentration of free hydrogen near the surface of BCP treated cavities.