This is a plot from HLT onlineQA. Looks like we are triggering a tail of the distribution.

Detail can be find at http://online.star.bnl.gov/HLT/

please see the QA file for day 153. And this plot shows in page 9 plot 3.

Below is the same plot from HLT online QA for this year Cu+Au run, it is from day 140 run 13140050

Below is the same plot from HLT online QA for this year U+U run, it is from day 123 run 13123038 

Below is the same plot from run 13156078 taken after the tof group reverted the firmware.