Analysis of the DELPHI RICH data at LEP II

The DELPHI RICH has been operated successfully at LEP I energies. With the increase of the centre of mass energy at LEP II the changed running conditions set new challenges: a very short period at the Z0 pole to provide calibration data and a long data taking period at high energy with the low event rate typical for operation away from the pole. These conditions require to revise the strategy for calibration and alignment of the DELPHI RICH. The most relevant improvement was the development of a new alignment program. In addition, the detector stability had to be monitored more carefully due to the long data-taking periods. As a result it will be shown that a similar data quality has been obtained as during LEP I operation. The new procedures also decrease dramatically the time necessary to perform the detector analysis.