A HIGH-SENSITIVITY PAYLOAD FOR BALLOON-BORNE HARD X-RAY ASTRONOMY

A new balloon-borne Large Area Scintillation counter Experiment (LASE) has been built to detect ultrafast variations in the flux of X-ray so urces in hard X-ray band upto 200 keV. Presently, the instrument consi sts of three modules, each made of a 3 mm and a 30 mm NaI(Tl) crystals . arranged in a back-to-back geometry and having an effective area of 400 cm(2). In final configuration, the payload will have an area of 24 00 cm(2). The data is spectrum analyzed in 128 channels between 20 and 200 keV and each event is time-tagged to an accuracy of 25 mu s. The estimated sensitivity of the telescope is similar to 10(-6) cm(-2) s(- 1) keV(-1) for 3 h of source observation. The detector design, backgro und rejection, on-board trigger system, attitude control parameters an d the flight performance are described briefly. (C) 1998 Elsevier Scie nce B.V. All rights reserved.