ELENA MCP detector: absolute detection efficiency for low-energy neutral atoms

摘要

Microchannel Plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiationand particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensorELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling andEmitted Natural Abundances) on board the BepiColombo mission of ESA to Mercury to be launched in 2015. ELENA isa Time of Flight (TOF) sensor, based on a novel concept using an ultra-sonic oscillating shutter (Start section), which isoperated at frequencies up to 50 kHz; a MCP detector is used as a Stop detector. The scientific objective of ELENA is todetect energetic neutral atoms in the range 10 eV – 5 keV, within 76° FOV, perpendicular to the S/C orbital plane.ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion.The major scientific objectives are the interaction between the plasma environment and the planet’s surface, the globalparticle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigatedby identifying particles released from the surface, via solar wind-induced ion sputtering (& 1eV – & 100 eV) as well asHydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E &30 eV) is a crucial point for this investigation. At the MEFISTO facility of the Physical Institute of the University ofBern (CH), measurements on three different types of MCP (with and without coating) have been performed providingthe detection efficiencies in the energy range 10eV – 1keV. Outcomes from such measurements are discussed here.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.