Option to randomize waveform sampling starting time

Author: kmtsui

cpp/include/HitDigitizer.h

@@ -61,4 +61,5 @@ class HitDigitizer_mPMT : public HitDigitizer
         float fDigiTimeOffset;
         int fHitInsensitivityPeriod;
         float fAmplitudeThreshold;
+        int fRandomSampleStartTime;
 };

cpp/src/HitDigitizer.cc

@@ -164,6 +164,7 @@ HitDigitizer_mPMT::HitDigitizer_mPMT(int seed) : HitDigitizer(seed)
     fAmplitudeSigma = 0.37;
     fADCMax = 999999;
     fADCOverflow = 0;
+    fRandomSampleStartTime = 0;
 
     Configuration *Conf = Configuration::GetInstance();
     Conf->GetValue<float>("SamplingInterval", fDt);
@@ -177,6 +178,7 @@ HitDigitizer_mPMT::HitDigitizer_mPMT(int seed) : HitDigitizer(seed)
     Conf->GetValue<int>("ChargeWindowBefore", fChargeWindowBefore);
     Conf->GetValue<int>("ChargeWindowAfter", fChargeWindowAfter);
     Conf->GetValue<int>("HitInsensitivityPeriod", fHitInsensitivityPeriod);
+    Conf->GetValue<int>("RandomSampleStartTime", fRandomSampleStartTime);
 
     this->LoadWaveform(Conf->GetValue<string>("WaveformFile"));
     Conf->GetValue<float>("AmplitudeSigma", fAmplitudeSigma);
@@ -349,6 +351,12 @@ TH1F HitDigitizer_mPMT::BuildWavetrain(const vector<TrueHit*> PEs, double wavefo
     double dt = fDt; 
     double tmin = floor((PEs.front()->GetTime())/dt)*dt;
     double tmax = ceil((PEs.back()->GetTime()+waveform_window)/dt)*dt; 
+    // Randomize waveform sample start time if necessary
+    if (fRandomSampleStartTime==1)
+    {
+        tmin = floor((PEs.front()->GetTime())/dt)*dt - dt*fRand->Uniform(0,1);
+        tmax = ceil((PEs.back()->GetTime()+waveform_window-tmin)/dt)*dt+tmin; 
+    }
     TH1F hWT("","",(int)(tmax-tmin)/dt,tmin,tmax);
 
     double waveform_offset = fWaveformOffset;

parameter/MDTParamenter_WCTE.txt

@@ -51,6 +51,7 @@
 < ADCMax = 61440 > # ADC dynamic range ~ 30PE
 < ADCOverflow = 0 > # Overflow causes ADC values to flip to negative
 < WaveformOffset = 0 > # ns
+< RandomSampleStartTime = 1 > # 1 = Waveform window start time is randomized with Uniform(0,SamplingInterval)
 < SamplingInterval = 8 > # ns
 < SamplingResolution = 0.1 >
 < AmplitudeThreshold = 683 > # self-trigger threshold (1/3 PE)