Reducing the ATHENA WFI background with the science products module: lessons from Chandra ACIS

The Wide Field Imager (WFI) on ESA’s Athena X-ray observatory will include the Science Products Module, a secondary CPU that can perform special processing on the science data stream. Our goal is to identify on-board processing algorithms that can reduce WFI charged particle background and improve knowledge of the background to reduce systematics. Telemetry limitations require discarding most pixels on-board, keeping just candidate X-ray events, but information in the discarded data may be helpful in identifying background events masquerading as X-ray events. We present full frame data from CCDs on-board Chandra, in high-Earth orbit, and the results of our search for phenomenological correlations between particle tracks and background events that would otherwise be categorized as X-rays. In addition to possibly reducing the Athena instrumental background, these results are applicable to understanding the particle component in any X-ray Silicon-based detector in space.