Radiation tolerance studies of the double sided silicon strip sensor

Sumitted to PubDB: 2023-01-26

Category: Master Thesis, Visibility: Public

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Authors Takeo Higuchi, Fumiaki Otani
Date Jan. 1, 2023
Belle II Number BELLE2-MTHESIS-2023-002
Abstract The B meson decays can be studied precisely and compared with the standard model (SM) to search for new physics of elementary particles. The Belle II experiment, which has an accelerator and detector in Tsukuba, Ibaraki, Japan, is also called the “B factory” experiment, and produces many B mesons and can precisely measure their decays. Currently, efforts are underway to bring the beam luminosity of the SuperKEKB collider to 6 × 10^35 cm^2/s for the Belle II experiment. While an increase in beam luminosity increases the number of B produced and allows for more precise measurements, the beam background also increases with beam luminosity. Therefore, radiation damage to the detector is also expected to worsen. In particular, the innermost layer of the Silicon Vertex Detector (SVD), which plays an important role in the search for new physics, is simulated to receive 20 kGy of radiation after 10 years of target luminosity operation. We decided to investigate whether there would be any problems with the operation of the SVD after receiving this radiation dose through the electron beam irradiation test. In order to evaluate the radiation hardness of the SVD sensor, a measurement system was developed that allowed for the remote measurement of the leakage current-voltage characteristics (IV), capacitancevoltage (CV), and interstrip capacitance-voltage (cint) of the sensor. The system was used to focus on the stepwise changes in IV, CV, and Cint with a radiation dose up to 100 kGy for the TID and 3 × 10^13 neq/cm2 for the NIEL. Additionally, changes in noise and charge collection efficiency were measured before and after irradiation of the sensor by utilizing a signal readout module equipped with a readout ASIC that was attached to the sensor. The evaluation results confirm that our SVD has no operational problems even after 10 years of cumulative radiation dose under beam luminosity 6 × 1035 cm2/s.
Conference Tokyo, Japan

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