Operational Experience with Radioactive Source Calibration of the CMS Hadron Endcap Calorimeter Wedges with Phase I Upgrade Electronics

The Phase I Upgrade of the CMS Hadron Endcap Calorimeters consist of new photodetectors (Silicon Photomultipliers in place of Hybrid Photo-Diodes) and front-end electronics (QIE11). The upgrade will allow the elimination of the high amplitude noise and drifting response of the Hybrid Photo-Diodes, at the same time enabling the mitigation of the radiation damage of the scintillators and the wavelength shifting fibers with a larger spectral acceptance of the Silicon Photomultipliers. The upgrade will also allow to increase the longitudinal segmentation of the readout to be beneficial for pile-up mitigation and recalibration due to depth-dependent radiation damage.As a realistic operational exercise, the responses of the Hadron Endcap Calorimeter wedges are being calibrated with a $^{60}$Co radioactive source both with current and upgrade electronics. The exercise will provide a manifestation of the benefits of the upgrade. Here we describe the instrumentation details and the operational experiences related to the sourcing exercise.