Abstract
The ATLAS Insertable B-Layer (IBL) is the innermost layer of pixel detectors, and was installed in May 2014 at a radius of 3.3 cm from the beam axis, between the existing Pixel detector and a new smaller radius beam-pipe. The new detector, built to cope with high radiation and occupancy, is the first large scale application of 3D sensors and CMOS 130 nm technology. The IBL detector construction was completed within about two years (2012 – 2014), and the key features and challenges met during the IBL project are presented, as well as its commissioning and operational experience at the LHC.
Highlights
The stave loading phase lasted one year with two interruptions, for the investigations of the bump-bonding failure, and the wire-bond corrosion. Both issues were solved during the production and 0.1% of pixels were dead on the 14 staves used in the Insertable B-Layer (IBL) [8]
The temperature dependence of the distortion was investigated during 2015 cosmic runs at various temperatures; track-based alignment corrections determined the position of IBL modules, as well as their displacement relative to the nominal geometry
Based on the data collected from the temperature sensors of the IBL detector during the stable cosmic runs, the size of the peak-to-peak temperature variation of the IBL staves was measured to be less than 0.2 K
Summary
In May 2014 the IBL detector was successfully installed inside ATLAS and the commissioning started. Detailed comparisons between QA results and commissioning test results confirmed that the module operation were identical before and after the integration. The temperature dependence of the distortion was investigated during 2015 cosmic runs at various temperatures; track-based alignment corrections determined the position of IBL modules, as well as their displacement relative to the nominal geometry. Based on the data collected from the temperature sensors of the IBL detector during the stable cosmic runs, the size of the peak-to-peak temperature variation of the IBL staves was measured to be less than 0.2 K. The effect of the distortion due to temperature variation of 0.2 K was estimated, and the expected bias to the transverse impact parameter (d0) of charged tracks is about 1 μm, which is small in comparison to the expected d0 resolution, O(10 μm) [10]
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