Solid-State Imaging Spectrometer Research Articles

Statistical uncertainties in temperature diagnostics for hot coronal plasma using the ASCA SIS

Statistical uncertainties in determining the temperatures of hot (0.5 keV to 10 keV) coronal plasmas are investigated. The statistical precision of various spectral temperature diagnostics is established by analyzing synthetic ASCA Solid-state Imaging Spectrometer (SIS) CCD spectra. The diagnostics considered are the ratio of hydrogen-like to helium-like line complexes of $Z\ge14$ elements, line-free portions of the continuum, and the entire spectrum. While fits to the entire spectrum yield the highest statistical precision, it is argued that fits to the line-free continuum are less susceptible to atomic data uncertainties but lead to a modest increase in statistical uncertainty over full spectral fits. Temperatures deduced from line ratios can have similar accuracy but only over a narrow range of temperatures. Convenient estimates of statistical accuracies for the various temperature diagnostics are provided which may be used in planning ASCA SIS observations.

Proton damage in X-ray CCDs for space applications: ground evaluation techniques and effects on flight performance

We report measurements of effects of 2.1 and 40 MeV protons on charge coupled device X-ray detectors of a type soon to be launched on several astronomical research satellites. We discuss ground performance characterization techniques and compare our measurements to simple models of the detector damage mechanism. We predict detector performance degradation rates in low-earth orbit. We plan to compare these predictions to early flight data obtained from the solid state imaging spectrometer (SIS) focal plane instrument mounted on the Japan/US X-ray astronomy satellite Asuka launched on February 20, 1993.