A Study of Anomalous Events in CMS-HF PMTs

In the 2004 HF test beam data, signals corresponding to unusually high energies compared to the beam energy were observed and later confirmed in the subsequent test beam study in 2007. These high energy signals most likely result from particles directly hitting the PMTs instead of passing through the fibers to produce Cherenkov radiation, which is the basis of the HF calorimeter. We studied these events using the 2004 HF test beam data confirming the previous results.