Hyper-velocity impact test and simulation of a double-wall shield concept for the Wide Field Monitor aboard LOFT

摘要

The space mission LOFT (Large Observatory For X-ray Timing) was selected in2011 by ESA as one of the candidates for the M3 launch opportunity. LOFT isequipped with two instruments, the Large Area Detector (LAD) and the Wide FieldMonitor (WFM), based on Silicon Drift Detectors (SDDs). In orbit, they would beexposed to hyper-velocity impacts by environmental dust particles, which mightalter the surface properties of the SDDs. In order to assess the risk posed bythese events, we performed simulations in ESABASE2 and laboratory tests. Testson SDD prototypes aimed at verifying to what extent the structural damagesproduced by impacts affect the SDD functionality have been performed at the Vande Graaff dust accelerator at the Max Planck Institute for Nuclear Physics(MPIK) in Heidelberg. For the WFM, where we expect a rate of risky impactsnotably higher than for the LAD, we designed, simulated and successfully testedat the plasma accelerator at the Technical University in Munich (TUM) adouble-wall shielding configuration based on thin foils of Kapton andPolypropylene. In this paper we summarize all the assessment, focussing on theexperimental test campaign at TUM.