Arrival time distribution of optical photon

[shapeandsymmetry]

I have coupled my scintillator detector with PMT. I included all optical property correctly. I am simulating with mono energetic gamma ray .
Now I want to find the arrival time distribution of optical photon to the PMT. I attached PMT as my sensitive detector.
I am getting the time distribution with exponential tail. But How can I be sure that I am getting the arrival time distribution of optical photon?

[dsawkey]

This question is asked and discussed in a different thread:

How to record time of arrival?

Hello! I am relatively new to Geant4. I have simulated a scintillation detector and want to record the arrival times of optical photons arriving at the photocathode of a photomultiplier tube. So I want to end up with a plot of amplitude against time. Can anyone give me some guidance on how I would do this? I have assigned the photodetector as a sensitive detector to record ‘hits’ - Do I use GlobalTime() to get time of arrival? And how can I get a histogram of amplitude against time for this? T…