Space radiation induced displacement damage effects on the performance of the silicon drift detector onboard chandrayaan-2 mission
The space radiation induced displacement damage effects on the performance of the Silicon Drift Detector (SDD) based X-ray spectrometer has been studied using X-ray (Fe-55) and gamma ray (Co-60) radiations. The spectroscopic performance of the SDD based spectrometer degrades due to radiation damage during the transit and in-orbit operations. Silicon detectors are sensitive to displacement damage which is due to the non ionizing energy loss of the incident radiation. The displacement damage increases the leakage current of the SDD and hence the energy resolution. The X-ray irradiation is to quantify the X-ray fluence level up to which the SDD provides stable energy resolution. After X-ray irradiation tests, it is observed that there is no change in the leakage current and the energy resolution for dose up to 64 krad. The gamma ray irradiation test is to quantify the space radiation damage effects on the SDD and shown that the energy resolution degrades from ~160 eV at 5.9 keV to ~210 eV for the detector operating temperature of ~-40°C for the gamma ray dose of ~10 Krad. It is observed that the increase in the leakage current due to displacement damage is ~0.15 pA and its contribution to the degradation in the energy resolution is insignificant. The degradation in the energy resolution is attributed to the radiation damage of the electronic components inside the SDD module and meets the Chandrayaan-2 requirement of <; 250 eV for the mission life of 2 years.
The effect of the displacement damage on the Charge Collection Efficiency in Silicon Drift Detectors for the LOFT satellite
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.
Frontal cognitive dysfunction in juvenile myoclonic epilepsy
Purpose: The aim of the present study was to investigate the possible frontal cognitive dysfunction in patients with juvenile myoclonic epilepsy (JME) and to compare the results with those of patients with frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE), as well as with controls.