| Irfu-09-236
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| Involvement of hydrogen-vacancy complexes in the baking effect of niobium cavities |
| B. Visentin, M.F. Barthe, V. Moineau, P. Desgardin |
| Baking is necessary to improve high accelerating gradient performances of superconducting niobium cavities. Ten years after this discovery in 1998, the understanding of this effect still resists a lot of theoretical explanations. For the first time, Positron Annihilation Spectroscopy performed on niobium samples reveals the increase after baking of positrons trapped under the Nb surface. Presence of hydrogen-vacancy complexes and their dissociation by baking could both explain rf losses observed at high fields (Q-drop) and its cure (baking effect). |
