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   PR # 22184
    We propose to begin the systematic study of the spectra of high      
    redshift clusters of galaxies.  Specifically we will make the first  
    determination 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 large scales.               
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