CMS-Ecal DPG Calibration HV system <br><br> CMS ECAL calibration of the HV system

Abstract: CMS ECAL calibration of the HV system.

Figure Caption
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In 2016 the ECAL Barrel HV system was calibrated with the old and new calibration apparatus. </br> The plot shows the relative difference of the laser monitoring signal in the ECAL Barrel crystals when the HV was calibrated with the new and with the old calibration system. The distribution is fitted with a gaussian function. </br> The sigma of the distribution is 0.1%. </br>The mean is slightly shifted from zero, due to the use of two different multimeters in the two HV calibration systems, whose calibration is compatible at the 30 mV level, which reflects in a 0.1% systematic error on the APD gain.</br>There are more than 99.4% channels within +- 0.5%. </br>The few channels with large shift are understood to be due to the fact that half of the channels were calibrated without load, because the resistor which had been employed was not suitable for high load. </br> In the next campaign a new resistor will be used, which allows better heat dissipation.

-- AndreaMassironi - 2016-10-07

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Topic revision: r1 - 2016-10-07 - AndreaMassironi
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