Abstract:
The original CMS HF Photomultiplier tubes (PMT) that were used by the CMS experiment during Run I were Hamamatsu R7525 single anode PMTs. These PMTs had a known issue of producing anomalous events due to the Cherenkov radiation produced by the muons passing through their thick front windows. In the rst part of the phase 1 upgrade of the HF detector, these PMTs were replaced with Hamamatsu R7600U-200-M4, which was a 4-anode PMT with a thinner front window, to deal with this problem. This model was selected, because its thinner front window would reduce the amount of Cherenkov radiation and having multiple anodes would provide one more distinction between normal events and window events. The new thinner window signi cantly reduced the amount of Cherenkov radiation, but did not eliminate it completely. However, due to the lack of enough input channels on the frontend DAQ system of the HF, the new PMTs were connected as if they were single anode PMTs. The second part of this upgrade is the replacement of the frontend DAQ system with the new one that has more input channels, in order to make it possible to connect these new PMTs as if they were 2-anode PMTs. After the second part of the phase 1 upgrade, it will be possible to eliminate more of these window events via additional information coming from two pairs of anodes of these new PMTs. The new DAQ system will also have a time-to-digital converter (TDC) functionality to track the timing of the events, which will help this elimination further. As part of this thesis, 180 DAQ cards were tested.
