Electronics for HARPO: Design, development and validation of electronics for a high performance polarised-Gamma-ray detector

We designed and built an experimental apparatus based on a time projection chamber, a novel scheme for high performance γ-ray astronomy and polarimetry in the γ → e
⁺
e
^-
regime. This presentation focuses on the electronics aspect of the detector and, in particular, on the versatile dedicated trigger system that we have developed which allowed us to take data on beam with a high γ-conversion signal efficiency and a high rejection factor for single tracks and upstream conversion background events. Our scheme allows for the selective collection of γ conversions in a high-background-rate environment, such as that which is present in orbit, with a fine 3D imaging of the events and very low (in particular electronics) background, at a mild cost in terms of the number of electronics channels and therefore of electrical power consumption.