Title: TEM studies of niobium hydrides participants in superconducting niobium cavitiey cutouts
Author: Yulia Trenikhina
Abstract: Nanoscale near-surface investigation of cutouts from niobium cavities is the most direct way to understand the material features affecting the SRF performance. We will present temperature dependent TEM studies on cutouts from Q-disease free cavities prepared by EP, EP+120C baking, and N doping. We have found that several niobium hydride phases form upon cooldown to <100K in the penetration depth for EP and EP/120C cutouts with the difference in the density/size caused by 120C. No hydrides were found in the first few tens of nanometers of the N doped cutouts.These findings support the proposed involved of niobium nanohydrides in the high field Q slope, and the effect of N doping.