Kavli Affiliate: T. Higuchi
| First 5 Authors: K. Adamczyk, K. Adamczyk, , ,
| Summary:
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 $3.0times 10^13~rm n_rm eq/rm cm^2$. 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 $6.0times 10^12~rm
n_rm eq/rm cm^2$. The leakage current increases proportionally to the
radiation dose. We determine a damage constant of $3.9 times 10^-17$ A/cm at
17 C$^circ$ 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 $3.0times 10^13~rm n_rm eq/rm cm^2$. Noise increases by
approximately 44% after irradiation, while signal charge does not change
significantly when a sufficiently high bias voltage is applied.
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