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The Focal Plane Instruments

The HRC was produced at SAO; Dr. S. Murray is the Principal Investigator. The HRC-I is a large-format, 100-mm-square microchannel plate, coated with a cesium iodide photocathode to improve x-ray response. A conventional cross-grid charge detector reads out the photo-induced charge cloud and the electronics determine an arrival time to 16s, and the position with a resolution of about 18 m or 0.37 arcsec. The spectroscopy readout detector (HRC-S) is a 300-mm x 30-mm, 3-section microchannel plate. Sectioning allowed the 2 outside sections to be tilted in order to conform more closely to the Rowland circle that includes the low-energy gratings.

The ACIS has 2 charge coupled-device (CCD) detector arrays: ACIS-I is optimized for high-resolution spectrometric imaging; ACIS-S is optimized for readout of the high-energy transmission gratings, although these functions are not mutually exclusive. Prof. G. Garmire of the Pennsylvania State University is the Principal Investigator. The Massachusetts Institute of Technology's Center for Space Research, in collaboration with Lincoln Laboratories, developed the detector system and manufactured the CCDs; Lockheed-Martin integrated the instrument. Stray visible light is shielded by means of baffles and an optical blocking filter (about 1500- aluminum on 2000- polyimide). The ACIS-I is a 2x2 array of CCDs. The 4 CCDs tilt slightly toward the optics to conform more closely to the focal surface. Each CCD has 1024 x 1024 pixels of 24-m (0.5-arcsec) size. The ACIS-S is a 1x6 array with each chip tilted slightly to conform to the Rowland circle and includes two back-illuminated CCDs, one of which is at the best focus position. The back-illuminated devices cover a broader bandwidth than the front-illuminated chips and, under certain circumstances, may be the best choice for high-resolution, spectrometric imaging.

Sergei B. Popov
Tue Dec 7 18:45:32 MSK 1999