Installation and Commissioning of the CMS Hadron Forward Calorimeters Phase I Upgrade

The final phase of the CMS Hadron Forward Calorimeters Phase I upgrade was performed during the Extended Year End Technical Stop of 2016-2017. In the framework of the upgrade, the PMT boxes were reworked to implement two channel readout in order to exploit the benefits of the multi-anode PMTs in background tagging and signal recovery. The front-end electronics was also being upgraded to QIE10-based electronics which will implement larger dynamic range and a 6-bit TDC to provide additional handles to eliminate the background. Following this major upgrade, the Hadron Forward Calorimeters are being commissioned for operation readiness in 2017. Here we describe the details and the components of the upgrade, and discuss the operational experience and results obtained during the upgrade and commissioning.