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   PR # 42193
   We propose to begin the systematic study of the spctra of high
   redshift clusters of galaxies. Specifically, we will make the first
   determinations of the cluster temperature function at a redshift
   other than zero. This measurement will discriminate among various
   models of the evolution of the X-ray gas in clusters and will also
   determine the mass density fluctuation spectrum on cluster scales.
   This proposal requests observations of the last four clusters in our
   complete sample.
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