Electron and proton beam testing of pixelated solid state detectors

Abstract

The biasing of guard rings in pixelated ion implanted silicon solid state detectors is often given little analysis as to the potential detrimental effects associated with capacitive coupling of the response of the pixel element to the guard ring and vise versa. This has been demonstrated and illustrates the importance of using beam testing to measure the angular response of particle instruments. We describe herein the development cycle of the Fixed Sensor Head (FSH) instrument, an imaging electron spectrometer that will be flown on the US Air Force's Demonstration and Science eXperiment (DSX) mission. During its construction, the FSH was tested using particle beams many times and each test yielded an important result that contributed to the design of the instrument before being delivered in August 2010.After several lower energy (<30keV) beam calibration tests at Hanscom Air Force Base demonstrated that the FSH was performing very well, a final, higher energy (150keV<E<1MeV) beam test at the Goddard Space Flight Center was almost skipped due to budget and scheduling constraints. This final test illuminated a major problem with the biasing of a detector guard ring that would have been difficult if not impossible to track down on orbit. The problem was easily fixed, but serves to highlight the importance of biasing of guard rings properly, and the necessity of testing instruments across the entire range of possible stimuli that they may encounter.