| CMS Note | |
| Report number | CMS-CR-2017-281 |
| Title | High precision, low disturbance calibration of the High Voltage system of the CMS Barrel Electromagnetic Calorimeter |
| Author(s) | Marzocchi, Badder (INFN, Rome ; Rome U.) |
| Publication | 2017 |
| Collaboration | CMS Collaboration |
| Imprint | 22 Sep 2017 |
| Number of pages | 4 |
| Presented at | New Developments in Photodetection 2017, Tours, France, 3 - 7 Jul 2017 |
| Subject category | Detectors and Experimental Techniques |
| Accelerator/Facility, Experiment | CERN LHC ; CMS |
| Keywords | ECAL |
| Abstract | The CMS Electromagnetic Calorimeter is made of scintillating lead tungstate crystals, using avalanche photodiodes (APD) as photo-detectors in the barrel part. The high voltage system, consisting of 1224 channels, biases groups of 50 APD pairs, each at a voltage of about 380 V. The APD gain dependence on the voltage is 3pct/V. A stability of better than 60 mV is needed to have negligible impact on the calorimeter energy resolution. Until 2015 manual calibrations were performed yearly. A new calibration system was deployed recently, which satisfies the requirement of low disturbance and high precision. The system is discussed in detail and first operational experience is presented. |
| Copyright/License | Preprint: (License: CC-BY-4.0) |
Record creato 2017-10-02, modificato l'ultima volta il 2018-06-07
