Laboratory testing of the HEXIS Hard X-ray Imager balloon telescope

The High Energy X-ray Imager Survey (HEXIS) Coded Mask balloon instrument will test the performance of the electronics and the detector for the proposed MIRAX satellite mission, and measure the background in a near space environment. HEXIS is a Coded Mask Imager based upon a 100 x 100mm Tungsten MURA mask and a set of four Cadmium-Zinc-Telluride (CZT) crossed strip detectors assembled as one detector module with 40 cm(2) detector area and 0.5mm pitch strips creating an effective 126 x 126 grid of 0.5 x 0.5mm(2) pixels. Each detector strip can be read out individually using Readout Electronics for Nuclear Application (RENA)-ASICs developed by NOVA R&D. The system has an operating energy range of < 10 to 200 keV. The telescope has a passive shield as part of the instrument structure, which is surrounded by an active anti-coincidence shield of plastic scintillators with embedded wavelength shifting and-light transmitting fibers. The first HEXIS balloon flight is planned for Spring 2007. We present the lab performance for one module using RENA ASICs and for the scintillator shield. The MIRAX Hard X-ray Imager (HXI) will contain two cameras with 9 detector modules each.