ASIM Instruments

1. ASIM Instruments MXGS - Modular X-ray and Gamma-ray Sensor. MXGS consist of multiple units, structures and thermal systems. The sensor is made up of a Low Energy Detector (LED) and a High Energy Detector (HED). Low Energy Detector (LED). . .The detector plane consists of an array of 1064 CZT detector crystals operating in the photon energy band from 15 to 400 keV. A collimator defines the 80X80˚ field of view for the LED. A coded mask is mounted on the collimator to provide the imaging capability of the LED. High Energy Detector (HED). . . The HED, mounted below the LED, comprises 12 BGO detector bars, each with their own photomultiplier. HED will operate in the 200keV to 20 MeV photon energy band. X and soft  -rays, which enter through the opening of the collimator and the coded mask, interact in CZT crystals of the LED. The energy of the incoming photon is thereby converted to electrical charges. These are drifted to the detector readout electrodes by an electric field, produced in the detector by the LED HVPS. The detector signals are amplified by the preamplifiers - ASICs - and subsequently digitized and time stamped by the FPGA of the LED DAU. A large fraction of the  -rays with energies above 300 keV will pass through LED; but will be absorbed in the BGO crystals of HED. The light produced in this process is read out by the HED PMTs, digitized and processed by the FPGA of the HED DAU. Data Processing Unit (DPU). . . The DPU is mounted in its own compartment. It is based on the Xilinx Virtex 5 high performance FPGA. Both the data from LED and HED are passed on to the DPU for processing. The DPU will also monitor the instrument and interface the Payload Data Handling and Power Unit (DHPU). Mass = 140 Kg. Max. power incl. heaters = 129 W. FOV = 80 deg. Nadir pointing • MMIA - Modular Multi-spectral Imaging Array MMIA consist of two separate units: Sensor Unit. . . The MMIA instrument consists of 3 PHOTs and 2 CHUs interfaced to the MMIA Optical Bench. The Optical Bench is interfaced to the MMIA support structure, which again is mounted on the ASIM CEPA platform. The two MMIA CHUs are designed for 337 nm (CHU1) and 777.4 nm (CHU2) wavelength, respectively, and thus both requiring different optic and baffle design. The housing is identical for both configurations. The three MMIA PHOTs are designed for 337 nm (PHOT1), 180-230 nm (PHOT2) and 777.4 nm (PHOT3). The 337 nm and 777.4 nm configuration share the same optics and baffle design. The broadband photometer (180-230 nm) does not include any optics. The photometer housing is the same for all configurations. Data Processing Unit. . . The MMIA DPU, also a part of the MMIA instrument, is mounted directly onto the ASIM CEPA platform. The MMIA DPU is interconnected to the instruments on the optical bench via the electrical harness. The MMIA DPU Is based on the Xilinx Virtex 5 FPGA, which today is the most powerful FPGA developed for Space. The DPU Handles the readout and monitoring of the 5 optical instruments as well as the interface to the Payload Data and Power Unit (DHPU). Mass = 25 Kg. Max. power incl. heaters = 75 W. FOV = 80 deg. Nadir pointing