<html><head><style type="text/css"></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt">Dear GATE users,<br><br>I'm simulating a TOF PET system using GATE in those days. I have a problem which confuses me very much.<br><br>I put a point source at center of system and didn't add any temporal resolution to the simulation. I expected that I can get a series of coincidences which time difference between two events were 0 (or close to 0) if GATE records the time information for each event when the gamma photon arrives the detector. <br>However, I got a Gaussian curve with 100ps (for LYSO) FWHM after plotting the histogram of time difference. This means the measured timing resolution is different from the given one. <br><br>Are there any explanations for this problem?  Or did I misunderstand the time information in GATE?<br><br>Thank you very much.<br><div> <span style="font-weight: bold;"><br></span>Hongwei<span style="font-weight: bold;"><br></span></div><span style="font-weight: bold;"></span><div><br></div></div><br> </body></html>