The effect of the displacement damage on the Charge Collection Efficiency in Silicon Drift Detectors for the LOFT satellite

TL;DR

This paper investigates how displacement damage from protons affects the charge collection efficiency of Silicon Drift Detectors used in the LOFT space mission, providing experimental measurements and comparisons with expected in-orbit damage.

Contribution

It presents the first measurement of charge collection efficiency variation due to proton-induced displacement damage in SDDs for space applications.

Findings

Displacement damage reduces charge collection efficiency in SDDs.

Measured damage aligns with predictions for in-orbit proton exposure.

Results inform the reliability assessment of SDDs in space missions.

Abstract

The technology of Silicon Drift Detectors (SDDs) has been selected for the two instruments aboard the Large Observatory For X-ray Timing (LOFT) space mission. LOFT underwent a three year long assessment phase as candidate for the M3 launch opportunity within the "Cosmic Vision 2015 -- 2025" long-term science plan of the European Space Agency. During the LOFT assessment phase, we studied the displacement damage produced in the SDDs by the protons trapped in the Earth's magnetosphere. In a previous paper we discussed the effects of the Non Ionising Energy Losses from protons on the SDD leakage current. In this paper we report the measurement of the variation of Charge Collection Efficiency produced by displacement damage caused by protons and the comparison with the expected damage in orbit.