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

TL;DR

This paper evaluates the effectiveness of a double-wall shield design for protecting the Wide Field Monitor's silicon detectors aboard the LOFT space mission from hyper-velocity dust impacts through simulations and laboratory testing.

Contribution

It introduces a novel double-wall shielding concept and demonstrates its successful testing for the first time in a space environment simulation.

Findings

Double-wall shield effectively reduces impact damage.

Laboratory tests confirm shield's protective capability.

Simulations support shield design for space applications.

Abstract

The space mission LOFT (Large Observatory For X-ray Timing) was selected in 2011 by ESA as one of the candidates for the M3 launch opportunity. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM), based on Silicon Drift Detectors (SDDs). In orbit, they would be exposed to hyper-velocity impacts by environmental dust particles, which might alter the surface properties of the SDDs. In order to assess the risk posed by these events, we performed simulations in ESABASE2 and laboratory tests. Tests on SDD prototypes aimed at verifying to what extent the structural damages produced by impacts affect the SDD functionality have been performed at the Van de Graaff dust accelerator at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. For the WFM, where we expect a rate of risky impacts notably higher than for the LAD, we designed, simulated and successfully tested at the plasma accelerator at the Technical University in Munich (TUM) a double-wall shielding configuration based on thin foils of Kapton and Polypropylene. In this paper we summarize all the assessment, focussing on the experimental test campaign at TUM.