Speaker
Description
Silicon strip detectors in the Inner Tracker (ITk) of the upgraded ATLAS experiment at HL-LHC will have to operate in high radiation environment. The tracker is designed to withstand irradiation with 1 MeV neutron equivalent fluence of 1.6e15 n$_{\mathrm{eq}}$/cm$^2$ in the strip sensor region. To achieve such radiation hardness, extensive irradiation studies were performed during development of sensors. These included irradiations with reactor neutrons as well as low (25 MeV and 70 MeV) and high (24 GeV) energy protons.
During four years of production of over 20000 sensors for the ITk, regular irradiations of test structures with neutrons and low energy protons are a part of production quality assurance (QA) procedures. Because of less frequent availability, irradiations with high energy protons are not part of QA, but irradiation campaigns with 24 GeV/c protons at CERN PS were carried out to check the effect of high energy hadrons on samples from production wafers. This is important because the balance of ionizing dose and bulk damage of protons at this energy is the closest to the one expected in the experiment from all sources.
After irradiation with 24 GeV/c protons few issues were observed: collected charge (CC) measured with miniature strip sensors was lower than expected in certain fluence range; unusual dependence of CC on annealing time at 60°C was observed. These effects initiated extensive investigations and initial results show that they could be caused by different radiation effects of 24 GeV/c protons compared to irradiations with lower energy protons or neutrons, by secondary particles generated by the passage of primary protons through material of the irradiation support and detectors and non-uniformities due to irradiation with narrow proton beam.
Results of studies of these effects based on CV-IV, CC and Edge-TCT measurements will be presented in this contribution.
| Collaboration | ATLAS ITk Strip Sensor Community |
|---|---|
| Role of Submitter | I am the presenter |
