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   PR # 41284
   The origin of the Cosmic X-ray Background(CXB) is still now an open
   question in the X-ray astronomy. Previous observations in soft X-ray
   band have resolved more than half of the CXB flux to known classes of
   objects such as AGNs and QSOs, while there sill remains a significant
   part of the CXB flux unresolved whose constituents may be unknown
   X-ray sources. We propose short exposure observations of deep optical
   survey fields where we have well calibrated optical catalogs, and to
   take cross-correlations of measured X-ray flux distributions to
   various color-selected subsets of optical objects. Our Monte-Carlo
   simulation indicate that with 20ksec effective exposure we can detect
   a correlation signal with high confidence(>99%) if selected subset is
   contributing to the CXB flux significantly.
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