Measurement of the effect of Non Ionising Energy Losses on the leakage current of Silicon Drift Detector prototypes for the LOFT satellite

TL;DR

This study investigates how non-ionising energy losses from proton irradiation increase leakage current in silicon drift detectors, affecting their performance in space-based X-ray astronomy missions like LOFT.

Contribution

It provides the first experimental measurement of radiation-induced leakage current increase in silicon drift detectors for space applications.

Findings

Proton irradiation causes measurable leakage current increase.

Radiation damage impacts spectral resolution of detectors.

Results inform radiation hardness requirements for space detectors.

Abstract

The silicon drift detectors are at the basis of the instrumentation aboard the Large Observatory For x-ray Timing (LOFT) satellite mission, which underwent a three year assessment phase within the "Cosmic Vision 2015 - 2025" long-term science plan of the European Space Agency. Silicon detectors are especially sensitive to the displacement damage, produced by the non ionising energy losses of charged and neutral particles, leading to an increase of the device leakage current and thus worsening the spectral resolution. During the LOFT assessment phase, we irradiated two silicon drift detectors with a proton beam at the Proton Irradiation Facility in the accelerator of the Paul Scherrer Institute and we measured the increase in leakage current. In this paper we report the results of the irradiation and we discuss the impact of the radiation damage on the LOFT scientific performance.