| Description: |
Based on a radiation tolerant, fully-depleted, high-resistivity CCD technology, a one billion pixel imager is envisioned for the Supernova Acceleration Probe (SNAP) satellite currently in early planning [SNAP 2000]. The imager is comprised of over one hundred large format CCD’s at the focal plane of a ~2-meter telescope. The diffraction-limited optics is achieved with a three-mirror anastigmat and provides a 1-square degree field of view. With a complimentary small near-IR imager and visible and near-IR spectrographs, the SNAP mission can discover over 2000 Type Ia supernovae in a year at redshifts between z=0.1 and 1.7, and follow their evolution with high-signal-to-noise light-curves and spectra. The resulting data set can determine the cosmological parameters with precision: mass density WM to ± 0.02, vacuum energy density WL to ± 0.05,and curvature Wk to ± 0.06. The data set can test the nature of the "dark energy " that is apparently accelerating the expansion of the universe. In particular, a cosmological constant can be differentiated from alternatives such as "quintessence " by measuring the ratio of the dark energy pressure and density to 0.05, and by studying this ratio's time dependence. A large field imager based on CCD technology fulfills the requirement for supernova detection and photometry. CCD's We have successfully developed a new type of large-format CCD's on n-type high-resistivity silicon. The |