View source for PMT timing offsets

The goal here is to set time offsets for all PMT's such that t=0 corresponds as closely as possible to the moment photons imping on the target.

First, I used the clean photon peak from a CF252 run to synchronize all the detectors. Here is what the timing spectra look like after these offsets are applied:

Next, I take the difference between per-pulse-normalized TDC spectra of empty target and Al target. 

Finally, a single offset is applied to all PMTs in order to center the photon peak around 4 ns, since 4 ns is the time it takes light to travel the distance from target to detector.


Below is Al target minus MT target after calibration offsets are applied:


[[File:TimeCalibratedPhotonPeak.png|700px]]



Below is the most recent CF252 run with the same offsets:

[[File:CF252TimingCalibration.png|650 px]]


Here are the offsets used, in ns (there are 10 TDC channels per ns): 

float D30T_offset = -17.2;

float D30B_offset = -30.4;

float D54T_offset = -13.9;

float D54B_offset = -24.9;

float D78T_offset = -18.5;

float D78B_offset = -33.2;

float D102T_offset = -29.6;

float D102B_offset = -28.0;

float D126T_offset = -14.9;

float D126B_offset = -25.2;

float D150T_offset = -18.0;

float D150B_offset = -25.9;

float D210T_offset = -17.7;

float D210B_offset = -27.9;

float D234T_offset = -14.5;

float D234B_offset = -27.8;

float D258T_offset = -1.2;

float D258B_offset = -22.8;

float D282T_offset = -13.9;

float D282B_offset = -28.2;

float D306T_offset = -15.4;

float D306B_offset = -27.9;

float D330T_offset = -17.0;

float D330B_offset = -33.0;