IPAC'23 - Student Poster Session Guide

IPAC’23 / STUDENT POSTER SESSION GUIDE 37 Student Poster Session velocity map imaging. This paper focuses on measurements of the ion imaging performance, as well as the dependence of Ion intensity on gas density and incident beam current for low-ener- gy electron beams (<10 MeV). SUPM066 A 5 MeV Compton transmission polarimeter designed for a SRF photogun Greg Blume (Thomas Jefferson National Accelerator Facility) . B. Moffit, Chris Cuevas, Hai Dong, Joseph Grames, Matt Poelker, Max Bruker, Probir Ghoshal, Riad Su- leiman, Sandesh Gopinath, Shukui Zhang (Thomas Jefferson National Accelerator Facility), Benjamin Fernandes Neres, Christine Le Galliard, Eric Voutier, Thi Nguyen Trung (Université Paris-Saclay, CNRS/ IN2P3, IJCLab), Sylvain Marsillac (Old Dominion University). SUPM067 Fundamental R&D for high-Q0 in ~650 MHz superconducting RF cavities for hadron linacs Kellen McGee (Fermi National Accelerator Laboratory) . Alexandr Netepenko, Grigory Eremeev, Martina Martinello, Oleksandr Melnychuk (Fermi National Accelerator Laboratory), Peter Ostroumov, Sang-Hoon Kim (Facility for Rare Isotope Beams, Michigan State University). Upcoming projects requiring ~650 MHz medium-to-high-beta elliptical cavities such as Michi- gan State University’s Facility for Rare Isotope Beams’ energy upgrade and Fermilab’s Proton Improvement Project-II drive a need to understand magnetic RF loss mechanisms in greater de- tail. It remains to be seen whether fux trapping mitigation techniques used in 1.3 GHz cavities are as effective at ~650 MHz, given differences in cavity geometry, material of manufacture ven- dor, and frequency-dependent superconducting RF dynamics. We explore the fast-cooldown method, and high-temperature annealing (900°C), which promote fux-expulsion efficiency, but are more difficult to implement in ~650 MHz cavities. In high-power RF testing, we measure the cool-down temperature gradient vs fux expulsion efficiency, the cavity’s residual resistance sensitivity to trapped fux as a function of cavity treatment. We further used the Physical Prop- erty Measurement System available at Fermilab to directly measure the fux pinning force in bulk niobium samples, and correlate changes in the fux pinning force with different niobium vendors, heat treatments, and cavity fux expulsion performance. Finally, to investigate the ef- fect of 900°C baking on the structural integrity of these large cavities, we heat-treated and tensile-tested a variety of dog-bone samples cut from different parts of a cavity half-cell to mea- sure changes in the yield strength as a function of high-temperature annealing. SUPM068