Characterization of a photon counting detector and Development of an attitude sensor for high altitude balloon experiments

Abstract

The information contained in an optical image can be expressed as the spatial and temporal variation in number of photons at very low light level. The high gain Micro Channel Plate (MCP) image intensifier that constitutes the input device of a Photon Counting detector, converts each incoming photon that interacts photo electrically at its input face, into a luminous spot on a phosphor screen that preserves the x, y location of the event. A CMOS camera subsequently detects electronically the location of each event, whose centroid coordinates can be determined with sub pixel accuracy. The unique capability of micro channel plates to convert a single photon into a charge of 10 4 – 107 electrons localized within 4-12 μm from the event position is widely used in photon counting imaging detectors. Micro channel plate based photon counting detectors remain the primary choice for most current and future planned UV imaging and spectroscopic missions, include, HST-STIS, FUSE, GALEX. In this work we present different measured characteristics of a Micro Channel Plate (MCP340 from Photek) based photon counting detector.

For any astronomical payload it is important to have information about its pointing direction. An attitude sensor will tell us where we are pointing in the sky. We will also discuss about the development of such an attitude sensor, in which we combined data from gyroscope, accelerometer, magnetometer and a GPS unit to calculate the RA, DEC coordinates of the pointing direction.