A Detailed Study of Two Optically-Selected comma High-Redshift Clusters of Galaxies

We propose to obtain detailed Xray spectral and structural data for two distant, opticallyselected clusters of galaxies which are known Xray emitters, CL1324+3011 at z 0.76 and CL1604+4304 at z 0.90. These observations will, for the first time ever, allow us to place accurate constraints on the temperature, surfacebrightness profile, and mass fraction of the intracluster medium in rich, opticallyselected clusters at very high redshift. The two target clusters are the most wellstudied systems at z > 0.7 in the optical and infrared regimes; therefore, the addition of the XMM data will enable us to probe the specifics of the relationship between the Xray and optical properties and their implications for galaxy and cluster evolution. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]