Radiation tests of the Silicon Drift Detectors for LOFT

TL;DR

This paper reports on radiation testing of Silicon Drift Detectors for the LOFT mission, including proton irradiation and hypervelocity dust impacts, to assess damage and performance degradation.

Contribution

It provides new experimental data on the radiation tolerance of SDDs under conditions relevant to space missions.

Findings

Proton irradiation increases leakage current in SDDs.

Dust impacts cause measurable damage to detector surfaces.

Results inform the radiation hardness requirements for LOFT.

Abstract

During the three years long assessment phase of the LOFT mission, candidate to the M3 launch opportunity of the ESA Cosmic Vision programme, we estimated and measured the radiation damage of the silicon drift detectors (SDDs) of the satellite instrumentation. In particular, we irradiated the detectors with protons (of 0.8 and 11 MeV energy) to study the increment of leakage current and the variation of the charge collection efficiency produced by the displacement damage, and we "bombarded" the detectors with hypervelocity dust grains to measure the effect of the debris impacts. In this paper we describe the measurements and discuss the results in the context of the LOFT mission.