While the optimal detectors for the baseline concept require 25-40m pixels, most CCDs available today have 15 mpixels. Therefore, in order to image the full focal surface and provide a sufficient number of spectral resolution elements, we plan to use a mosaic array of 32 2Kx4K SITe (or equivalent) 15 m CCDs per spectrograph channel to yield an equivalent array of 16Kx16K. If arrays with larger pixels are available, the total number of arrays required is lower. The astronomer may wish to bin the CCDs in either the spectral or in the spatial dimensions to reduce the storage requirements for the data set. The detector system, therefore, is comparable in complexity to the NOAO Mosaic camera and similar arrays in common use today.
Since the pixel sizes of current IR detectors are m for HgCdTe and m for InSb, fewer pixels are required to cover the focal surface than in the case of CCDs. Assuming large format arrays with 27m pixels are available, we plan to use 16 arrays of 2Kx2K (mosaicked to 8Kx8K) for each spectrograph channel. The detector technology at near-IR wavelengths is technology driven at present, but the need for detectors for NGST and other ground-based facilities should result in usable detectors on the timescale of SWIFT.