Measurement Results for 4kX2k Frontside Illuminated CCD

2 Summary CCD is an engineering grade 4kX2k device mounted front illuminated (FI) on ‘picture frame’ circuit board. It was taken from a ‘control’ wafer and was not thinned so is 650 um thick. The picture frame board is identical to the one which we will use for BI devices, but because it is FI the 37-pin Airborn connectors point outward rather than inward with respect to the imaging surface. The CCD was found to work adequately as shown in the images in the following pages. However it has a breakdown problem at substrate voltages (Vsub) greater than ~30v. As a result we did not test it at voltages greater than 35v. The serial and parallel clock phasing to operate the device is described in the operating documents. The pinout of the Airborn connectors on the picture frame board is also described. Technical questions with regard to operation of the CCD can be addressed to Bill Kolbe ) or Armin Karcher

3 Operational Parameters The CCD was operated with the following clock and bias values: —V1,2,3 = [-3v,5v], FS1,2,3 = [-3v,5v], TG = [-3v,5v] —H1,2,3 = [-4v,6v], SW = [-5v,5v], RG = [0v,-6v] —Vdd = -22.0v, Vr = -12.5v, Vog = 2.3v —Vsub = 30v (maximum Vsub applied during testing was 35v) —Operating temperature, T = -135 C To obtain the best results the CCD should be ‘erased’ and ‘e-purged’ as described in the documentation.

4 55Fe X-ray Image 4-Corner Readout Example 55Fe x-ray image taken with exposure time of 80 seconds. Because of 4-corner readout, baselines for each quadrant are slightly different. Operating parameters were as described above.

5 55Fe X-ray Image UL Quadrant UL quadrant of the image from previous slide is shown here together with x-ray histogram. Measured gain was 1.22 adu/e- for our system (approx. 3  V/e-). Measured parallel CTE was worse than expected possibly related to the defects found in the device. Quad. Gain Ser. CTE Par. CTE LL LR UL UR

6 Dark Current Image Half-hour dark image at operating temperature, T = -135 C. Tracks in image are due to muons and residual radioactivity in the environment. Note that the number and length of the tracks for the same exposure would be reduced by a factor of ~3 for a thinned CCD of thickness  m.

7 Dark Current Image Expanded view showing UL quadrant of same 30 minute dark image. The fuzzy tails on the muon tracks are a result of the partial depletion obtained at Vsub = 30v. Measured dark current from this image was 1.3 e-/px-hour.

8 Flat-field Image Uncorrected flat-field image taken at 500 nm wavelength shows that the CCD has no blocked columns. The rounded edges in the image are due to vignetting caused by the dewar windows. The variations in brightness are largely due to the slightly different gains of the 4 channels. (baseline, span = [40000, 5000] adu)

9 Breakdown at Elevated Vsub Illustration of breakdown occurring at Vsub = 35V in this device. 30 sec. exposure with sky, span = [1000, 3000].