Overview of the loss cone imager fixed sensor head instrument

The Loss Cone Imager (LCI) instrument is part of the US Air Force Demonstration and Science Experiments (DSX) satellite and is comprised of three components: the Fixed Sensor Head (FSH), the High Sensitivity Telescope (HST), and the Central Electronics Unit (CEU). The emphasis of this paper is on the FSH, which is comprised of three Si solid state detectors (SSD) each comprised of six pixels capable of measuring incident particle energies (~ 30 keV - 500 keV) and their respective pitch angles. The FSH is mounted onto the exterior of the DSX Payload Module and covers a 180° by 10° view of the sky. Each pixel has a 10° by 10° field of view. Due to a small geometric factor, the FSH is able to operate in the high particle flux areas of the Earth's magnetosphere. The Readout Electronics for Nuclear Application 3 (RENA3) chip, developed by NOVA R&D, contains 36 analog channels used for detection of nuclear events. Each of the 18 Si pixels is connected to a corresponding RENA3 channel for event detection and analog energy readout. The output of the chip is digitized and the digital value of each event, along with its corresponding RENA channel, is recorded by the Data Processing Unit housed in the CEU.