EbyE T0 for production_4p59GeV_fixedTarget_2019

Following up on my blog post from last year (Looking into event-by-event T0 in FXT), which looked at Run 19 3.85 GeV FXT, I calibrated here Run 19 4.59 GeV FXT. I again found that Irakli's method had the same flaws:
  • For roughly ~10% of events, the EPD west had a higher Max TAC than EPD east and was used for the T0
  • For another ~10% of events, the EPD east had a value of 0 that was considered valid and was used for the T0
So I calibrated my EbyE T0 using 20k events from run 20181004. Here are plots of the calibrations using the TPC prompt hit times from only the east side as "ptime":

  EPD east VPD east BBC east
of ptime vs.
for non-zero
ptime and
Spread profile
with fit

(errors on the
mean are
much smaller)
Fit of
ptime peak
Fit of
ptime peak
after slope

The EPD and VPD show the narrowest peaks after correction, while the BBC shows the most complete coverage of having a real signal in each event. So the BBC is used as the final fallback option after EPD and VPD are tried first:

Option 1: 0.01683 - 1.664e-05*epde (covers ~80% of events)
Option 2: 0.02853 - 1.711e-05*vpde (brings up to 92%)
Option 3: 0.02298 - 1.620e-05*bbce (brings up to 99.9%)