Dynamical and content evolution of a sample of clusters from z similar to 0 to z similar to 0.5

In this paper, we present an analysis of the dynamics and segregation of ga laxies in rich clusters from z similar to0.32 to z similar to0.48 taken fro m the CFHT Optical PDCS (COP) survey and from the CNOC survey (Carlberg et al. 1997). Our results from the COP survey are based upon the recent observ ational work of Adami et al. (2000a) and Holden et al. (2000) and use new s pectroscopic and photometric data on six clusters selected from the Palomar Distant Cluster Survey (PDCS; Postman et al. 1996). We have compared the C OP and CNOC samples to the ESO Nearby Abell Cluster Survey (ENACS: z simila r to0.07). Our sample shows that the z less than or equal to 0.4 clusters have the sam e velocity dispersion versus magnitude, morphological type and radius relat ionships as nearby (similar to 0.07) Abell clusters. The z similar to0.48 c lusters exhibit, however, departures from these relations. Furthermore, the re appears to be a higher fraction of late-type (or bluer, e.g. Butcher Br Oemler, 1984) galaxies in the distant clusters compared to the nearby ones. The classical scenario in which massive galaxies virialize before they evol ve from late into early type explain our observations. In such a scenario, the clusters of our sample began to form before a redshift of approximately 0.8 and the late-type galaxy population had a continuous infall into the c lusters.