BEAMS
In the literature: contested
Why low-temperature baking at about 120 C removes the Q-slope
In plain words
Heating a niobium cavity at about 120 degrees Celsius for two days removes the high-field loss rise. What this mild bake changes in the metal is not fully known.
Precise statement
A 120 C bake of 24 to 48 h in vacuum eliminates the high-field Q-slope in electropolished Nb. Determine which change in the near-surface region (oxygen diffusion from the native oxide, suppression of hydride nucleation by vacancy-hydrogen complexes, or change in mean free path) is necessary and sufficient, and predict the required bake time and temperature.
What would settle it
Depth-resolved composition and defect measurements on samples baked in parallel with cavities, reproducing the cure and its absence for varied bake parameters.
Related problems
- Special case of Mechanism of the high-field Q-slope and its cure by baking · Baking cure is the bake-dependence part of the high-field Q-slope problem