Ge, G.M. Eichhorn, R.G. Furuta, F. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-MOPB083 English 324-327 MOPB083 cavity SRF experiment electronics linac Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-MOPB083 http://srf2015.vrws.de/papers/mopb083.pdf Cooling speed significantly affects flux trapping of a SRF cavity, which will determine the residual resistance and the quality factor of the cavity. We measured the temperature distribution of a 9-cell cavity at different cooling speeds by the multi-cell T-map system of Cornell University. This paper proposed a method to evaluate the formation of a normal conducting island at different cooling speed. The fast cool-down and slow cool-down has been compared. We conclude that the slow cool-down freezes less normal conducting islands.