Dear Gate Users, I have upgraded to Gate V.6.2 and my previously developed simulation that used to run and complete at a speed ~160,000 particles per minute on Gate V6.1, now no longer completes after any amount of time (even when the total number of primaries is set to 1). The simulation remains at: "[Acquisition-0] Slice 0 from 0 to 1 s [slice=1 s], final stop at 1 s.". The only change I made to the code was the following: I changed all UHadronElastic instances to HadronElastic in the physics file as such: /gate/physics/addProcess HadronElastic /gate/physics/processes/HadronElastic/setModel G4HadronElastic /gate/physics/processes/HadronElastic/setDataSet G4HadronElasticDataSet My simulation imports an image as ImageNestedParametrisedVolume, uses the GPS, and the outputs are dose actors. I have performed the PET benchmark on Gate V6.2 and it completes as expected in ~6 hours. Any help is appreciated, Matt -- Matthew Belley Doctoral Student Medical Physics Graduate Program, Duke University Duke Radiation Dosimetry Laboratory, Duke University Medical Center Durham, North Carolina 27705