[Xem2] calorimeter wiggles

[Dave Gaskell]

Hi all -

My memory was incorrect about the calorimeter wiggles.  Dave Mack did 
find/fix a "hardwired cut" issue, but it was in the time-of-flight 
calibration, not the calorimeter.

However, Dave also looked at the calorimeter issue with Carlos Yero a 
couple years ago (see these slides):

https://hallcweb.jlab.org/DocDB/0011/001122/003/HMS_CalWiggle_Studies_slides_Apr15.pdf

In summary, the FADC threshold of 10 mV is too high relative to the 
calorimeter PMT gain, so low amplitude pulses that should be included in 
the sum are dropped.  The only way to fix this is to increase the PMT 
gain, or decrease the FADC threshold.

At our momenta, it should not be a big effect.  If we're concerned about 
it, we could try to fit the wiggles and apply that as a correction to 
the calibration.

Cheers,
Dave