Upgrade of the LHCb ECAL monitoring system

During the LHCb running in 2011 and 2012 it was found that the precision of PMT gain monitoring with LED system is affected by radiation damage of the long light guides transporting LED light to calorimeter cells. It was decided to replace in 2014 the present light guides to new ones that should be made of radiation tolerant quartz fibers. After the replacement, the system requires full tuning. It includes adjustment of the LED flash agnitudes and delays, and, after that, adjustment of the PIN diode system. My work was the following: to adjust the PIN signal amplitudes. This included a rough equalization of the amplitudes of signal from the 4 or 2 LEDs served by each PIN diode (achieved by mechanical adjustment of positions of corresponding fibers with respect to the PIN), and then reducing the PIN signal amplitude to the middle of the ADC range when necessary (total of 40 resistive attenuators were produced for this); to find timing corrections for ADCs digitizing the PIN signals; perform a PMT gain measurements using photo statistics. The procedure of determination of timing correction from ECAL step runs was implemented. Finally, it was shown that the ECAL sensitivity degradation can be explained by the degradation of ECAL cells more than PMTs'.