High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia progenitor survey

Context.We present a detailed spectroscopic analysis of the stars with helium-dominated spectra in the ESO Supernova Ia Progenitor Survey (SPY). Aims.Atmospheric parameters, masses, and abundances of trace hydrogen are determined and discussed in the context of spectral evolution of white dwarfs. Methods.The spectra are compared with theoretical model atmospheres using a $\chi^2$ fitting technique, leading to determinations of effective temperature, surface gravity, and hydrogen abundance. Results.Our final sample contains 71 objects, of which 6 are new detections and 14 are reclassified from DB to DBA because of the presence of H lines. One is a cool DO with weak He i