A cross-type imaging electron spectrometer

Energetic electron measurement is of great significance to theoretical space physics research and space weather applications. Current energetic electron detectors must cooperate with a spin-stabilized satellite platform to achieve high angular resolution in pitch angle distribution and three-dimensional (3D) imaging measurement of energetic electrons. This article introduces a crosstype quasi-3D imaging electron spectrometer (IES) based on pinhole imaging technology developed in the laboratory. The imager is composed of five imaging units, including a nine-pixel area array Si-PIN detector imaging unit in the middle and four three-pixel linear array Si-PIN detector imaging units placed in a cross-shape around it. The combination of five imaging units forms two orthogonal nine-pixel linear array detectors (with a common pixel in the middle). There are four pixels with a view angle of 20° × 20° in the 45° oblique directions of the cross-type detection array. There are 21 imaging pixels in the entire cross-type sensor head, corresponding to 21 directions. Two multichannel integrated preamplifier ASICs are integrated in the sensor head to realize particle signal readout from 21 pixels. With a back-end electronics system, each pixel can achieve high energy resolution detection of 50–600 keV electrons. Radioactive sources and electron accelerators are used to calibrate the cross-type imaging sensor head, and the results demonstrate its good energy and directional detection characteristics (the energy resolution reaches 6.9 keV for the incident 200 keV electron beam). We performed simulations on the imaging sensor head’s ability to measure the electron pitch angle distribution on the three-axis stabilized platform, and the results show that the sensor head can perform quasi-three-dimensional detection of electrons incident within 2π solid angles on the three-axis stabilized satellite platform, with an average angular resolution of the electron pitch angle distribution of less than 6°.