Difference between revisions of "PMT timing offsets"

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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:
 
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]]
 
[[File:CF252TimingCalibration.png|650 px]]
  
  
Next, I take the difference between per pulse normalized TDC spectra of empty target runs and Al runs. Next, a single offset is applied to all detectors so that the photon peak lies at 4 ns - or the time it takes light to travel the distance from target to detector.
+
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;
  
These are the resulting offsets:
+
float D330T_offset = -17.0;
  
D30T_offset = -17.2
+
float D330B_offset = -33.0;
D30B_offset = -30.4
 
D54T_offset = -13.9
 
D54B_offset = -24.9
 
D78T_offset = -18.5
 
D78B_offset = -33.2
 
D102T_offset = -29.6
 
D102B_offset = -28.0
 
D126T_offset = -14.9
 
D126B_offset = -25.2
 
D150T_offset = -18.0
 
D150B_offset = -25.9
 
D210T_offset = -17.7
 
D210B_offset = -27.9
 
D234T_offset = -14.5
 
D234B_offset = -27.8
 
D258T_offset = -1.2
 
D258B_offset = -22.8
 
D282T_offset = -13.9
 
D282B_offset = -28.2
 
D306T_offset = -15.4
 
D306B_offset = -27.9
 
D330T_offset = -17.0
 
D330B_offset = -33.0
 

Latest revision as of 23:49, 3 September 2017

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:


TimeCalibratedPhotonPeak.png


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

CF252TimingCalibration.png


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;