Abstract
The CMS pixel detector was repaired successfully, calibrated and commissioned for the second run of Large Hadron Collider during the first long shutdown between 2013 and 2015. The replaced pixel modules were calibrated separately and show the expected behavior of an un-irradiated detector. In 2015, the system performed very well with an even improved spatial resolution compared to 2012. During this time, the operational team faced various challenges including the loss of a sector in one half shell which was only partially recovered. In 2016, the detector is expected to withstand instantaneous luminosities beyond the design limits and will need a combined effort of both online and offline teams in order to provide the high quality data that is required to reach the physics goals of CMS. We present the operational experience gained during the second run of the LHC and show the latest performance results of the CMS pixel detector.
Highlights
The CMS pixel detector was repaired successfully, calibrated and commissioned for the second run of Large Hadron Collider during the first long shutdown between 2013 and 2015
The operational team faced various challenges including the loss of a sector in one half shell which was only partially recovered
We present the operational experience gained during the second run of the LHC and show the latest performance results of the CMS pixel detector
Summary
All modules were repaired during LS1, but in the commissioning eight modules showed faulty behavior (Figure 2). During the operation in nominal magnetic field of 3.8 T, a sector (a power and a read-out group) in a half-shell of the barrel signaled an under-voltage problem (Figure 2b)). There was no solution found to recover all modules but a stable configuration was found that allowed to keep layer 1 and 3 modules functional. The good detector fraction during stable operation is 98.3% for the barrel and 99.98% for the forward pixels where only a single readout chip (ROC) is not operational (Figure 3)
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