Mosaics at the 4 m Blanco Telescope Prime Focus

2.2.1 SITe002A Detectors in Mosaic-2

The peak QE for SITe002As is 85% at 600 nm and the CCDs run at -95oC . Fringing is less than 5% in the I band. There is some low level crosstalk, which is successfully removed. There are no after-images. A Mosaic-2 image is shown in Fig. 3.

2.2.2 LBNL 2K x 4K CCDs for DECam

To achieve the requisite depth in the redder passbands within the available survey time, LBNL high-resistivity, back illuminated CCDs [4] with a QE >50% at 1000 nm will be used. Using a buried p-channel, these chips use clock and bias voltages that are reversed in sign from conventional CCDs. These CCDs use a backside bias voltage to fully deplete the substrate and to control the PSF. Fermilab will package the CCDs.

Monsoon will control the 62 science CCDs. The plan is to share the same clock rails between groups of 3 CCDs. The CCD temperature will be read for each CCD and used for QE corrections.

Figure 3. A Mosaic-2 image shown at the center of the DECam field. At the edges special CCDs for Guiding (G), Focus (F) and Wavefront Sensing (WF) are shown.

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