A gas secondary electron detector

A new Secondary Electron gas Detector (SED) is under development to be used in conjunction with an emissive foil to detect low energy heavy ions as an alternative to micro-channel plates. It could measure position and time of flight. Secondary electrons are accelerated to 10 keV so that they can cross through the 0.9 μm Mylar entrance window. The electrons then are multiplied in the isobutane gas of the detector at 4–10 Torr. A time resolution of 150 ps and a spatial resolution of 3 mm have been obtained by using californium fission fragments on a prototype detector of 7×7 cm2. The advantage of the SED against MCP is that its size is not limited. Our final goal is to build a large size detector (15×40 cm2) that will operate at the focal plane of the VAMOS magnetic spectrometer at GANIL.