Steve Kissel has been testing a readout mode known as squeegee mode which shows great promise at reducing the effects of radiation damage. (See Steve's page for more about squeegee mode). Here are some examples of the improvement in instrument performance seen in the lab.
NEW! FWHM vs. row at -120 C. Gain calculated locally.
Above is a comparison of the center pixel pulseheight for all events in two data sets. The top plot shows nominal readout and the bottom plot shows 48 row squeegee readout. Both the amount of charge lost to traps (the centroid of the spectral line) and the noise introduced by the charge trapping (the width of the spectral line) are greatly improved by the squeegee mode.
The next two plots show results from binning the data by row, 64 rows per bin, and fitting a Gaussian to the Mn-Ka line.
Shown above is the fitted peak of the spectral line versus row number with and without a 48 row squeegee.
Above is the FWHM of the Mn-Ka line in eV with and without a 48 row squeegee. The gain (ADU to eV conversion) was calculated locally for each bin.