CEA, Gif-sur-Yvette
CNRS Orléans, Orléans Cedex 2
A decade after the ‘baking effect” discovery [*], the quest to understand this effect and its correlated question about the High Field Q-slope origin, goes on at Saclay. SIMS analyses and “fast baking” experiments in Oxygen free atmosphere [**] have shown since then that interstitial oxygen diffusion is not involved in baking phenomenon. In this paper we will describe preliminary experiments performed on niobium samples by means of positron annihilation radiation Doppler broadening spectroscopy. Experimental results reveal many vacancy sites and help us to give a new interpretation of the “baking effect”.
[*] “Improvement of Superconducting Cavity Performances”, 6th EPAC (1998): TUP07B
[**] “Optimization of Baking Parameters for Electropolished Cavities”, 13th SRF Workshop(2007): TUP69
