2025/09/22 by Adamczyk, K., Aihara, H., Amos, K. +58
#FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det)
paper · doi:10.48550/arxiv.2509.17373
The silicon strip sensors of the Belle II silicon vertex detector were irradiated with 90 MeV electron beams up to an equivalent 1-MeV-neutron fluence of 3.0× 1013~\rm n\rm eq/\rm cm2. We measure changes in sensor properties induced by radiation damage in the semiconductor bulk. Electrons around this energy are a major source of beam-induced background during Belle II operation. We discuss observed changes in full depletion voltage, sensor leakage current, noise, and charge collection. The sensor bulk type inverts at an equivalent 1-MeV-neutron fluence of 6.0× 1012~\rm n\rm eq/\rm cm2. The leakage current increases proportionally to the radiation dose. We determine a damage constant of 3.9 × 10-17 A/cm at 17 C^∘ immediately after irradiation, which drops significantly to approximately 40% of the initial value in 200 hours, then stabilizes to approximately 30% of the initial value in 1000 hours. We measure sensor noise and signal charge for a sensor irradiated with the equivalent 1-MeV-neutron fluence of 3.0× 1013~\rm n\rm eq/\rm cm2. Noise increases by approximately 44% after irradiation, while signal charge does not change significantly when a sufficiently high bias voltage is applied.