ATLAS experiment is preparing an upgrade of its detector for High-Luminosity LHC (HL-LHC) operation. The upgrade involves installation of the new all-silicon Inner Tracker (ITk). In the context of the ITk preparations, more than 80 strip modules were built with prototype barrel sensors. They were tested with electrical readout on a per-channel basis. In general, an excellent performance was observed, consistent with previous ASIC-level and sensor-level tests. However, the lessons learned included two phenomena important for the future phases of the project. First was the need to store and test the modules in a dry environment due to humidity sensitivity of the sensors. The second was an observation of high noise regions for 2 modules. The high noise regions were tested further in several ways, including monitoring the performance as a function of time and bias voltage. Additionally, direct sensor-level tests were performed on the affected channels. The inter-strip resistance and bias resistance tests showed low values, indicating a temporary loss of the inter-strip isolation. A subsequent recovery of the noise performance was observed. We present the test details, an analysis of how the inter-strip isolation affects the module noise, and the relationship with sensor-level quality control tests.

Inter-strip isolation, Readout noise, Silicon strip sensors, Strip module
dx.doi.org/10.1016/j.nima.2020.164402
Nuclear Inst. and Methods in Physics Research, A
Department of Physics

Helling, C. (C.), Allport, P. (P.), Affolder, A.A. (A. A.), Bernabeu, J. (J.), Fadeyev, V. (V.), Galloway, Z. (Z.), … Yarwick, J. (J.). (2020). Strip sensor performance in prototype modules built for ATLAS ITk. Nuclear Inst. and Methods in Physics Research, A, 978. doi:10.1016/j.nima.2020.164402