<html><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><META name="Author" content="Novell GroupWise WebAccess"></head><body style='font-family: Tahoma, sans-serif; font-size: 13px; '>Hello gate users, I am simulating a PET system with two plates. I would like to use the takeEnergyCentroid option for the digitizer's readout. However, I need to attach a volume to a 'crystal' of a system (according to the error message I keep getting). Thus a PETscanner system cannot work since it uses level1-4 and layers for system attachment. The I tried a cylindricalPET system with a ring repeater of 2, and that also didn't work. Interestingly, cylindricalPET works for a 4+ plate ring system, but no singles or coincidences in the output for 2-3 plates (with only the ring repeat number changed). Can anyone offer any insight as to what I should do? Regards, Devin Van Elburg ------------------------ Physics w/ c/ Biomedical Physics Lakehead University </body></html>