A low-background He-3 bolometer array test facility and its use in evaluating prototype arrays for FIRST-SPIRE

We report on the imaging detector array test and evaluation program for the Spectral and Photometric Imaging REceiver (SPIRE) instrument for the Far I nfraRed and Submillimetre Telescope (FIRST) satellite. Three candidate dete ctor array technologies are under evaluation: (i) hexagonally close-packed arrays of 2 F lambda feedhorns with NTD germanium sensors; (Ii) filled abso rber arrays with 0.5 F lambda square pixels with ion-implanted silicon sens ors; and (iii) 0.5 F lambda filled arrays with transition-edge superconduct ing (TES) sensors. Detector arrays are required for SPIRE bands covering th e 200-700 mu m range. To meet the SPIRE performance requirements, the detec tors must be background limited by the thermal emission from the 80 K low-e missivity FIRST telescope, achieve a speed of response of 20 Hz, and be fab ricated in sizes up to 32 x 32. A novel cryogenic array test facility has b een built to enable a range of experiments to be carried out under low back ground to enable a comprehensive evaluation and calibration programme on pr ototype detector arrays with a minimum of disruptive warm-up/cool-down cycl es. The facility will be used to compare the performance of the different a rray types prior to array technology selection for SPIRE. (C) 2000 Elsevier Science B.V. All rights reserved.