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.
Measurement of the Current Related Damage Rate at ${-}50^\circ$C and Consequences on Macropixel Detector Operation in Space Experiments
A diode irradiation with 10-MeV protons was performed to measure the silicon current related damage rate at a temperature of -50°C. This measurement was fundamental to predict the performance of the detectors which will be used in the X-ray spectrometers of the Simbol-X and BepiColombo space missions. These detectors consist of arrays of large area silicon drift chambers with integrated depleted p-channel field effect transistors. The leakage current increase due to radiation damage and its consequent energy resolution degradation can be critical for these missions, specially for BepiColombo. These effects cannot be predicted because, during the whole missions, the sensors will be kept at temperatures below -40°C, and the existing models are based on measurements on structures which underwent annealing at higher temperatures. An irradiation experiment was performed to measure the current related damage rate at - 50°C, and the obtained value was (11.1 ± 0.2) X 10-17 A/cm. This result implies that it will be possible to achieve the Simbol-X energy resolution, whereas some annealing strategies will be needed for the BepiColombo mission. The annealing behaviour at 60°C was studied as well and the results are in agreement with the already available measurements.
The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF
At TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN’s capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.