Accelerator Seminar - Ryan McFadden: SRF Materials Postdoctoral Researcher TRIUMF

Title: Insights into Nb SRF materials from implanted nuclear-decay spin-probes

Speaker: Ryan McFadden, SRF Materials Postdoctoral Researcher, TRIUMF

Abstract: In this talk, I will cover some recent insights on niobium-based SRF cavity materials gained from their interrogation by nuclear-decay spin-probe techniques. Such approaches [e.g., low-energy muon spin spectroscopy (μSR) and beta-radiation-detected nuclear magnetic resonance (β-NMR)] offer a unique combination of electromagnetic and spatial sensitivity, allowing for a depth-resolved characterization of subsurface magnetic fields within a material's topmost ~100 nm. Following an overview of these techniques, I will discuss their application to contemporary problems, such as how common surface treatments alter Nb's Meissner response and the identification of Nb's Meissner-state-breakdown at the nanoscale. Advances in understanding Nb's intrinsic properties will also be discussed.