Hi Gate-Users I have one problem to store in the simulation the annihilation point. I simulate one cylindrical scanner PET, where I place one sphere source of F18, inside one phantom of water; I want to plot the annihilation point but I do not know how to store this type of data in the Root output. I saw in the example_ROOT_Analyse, there is a root output file named data_PET.root; inside this file, there are some folder and in one of this, named Gate, is stored the annihilation point. I want to know how I can obtain the same folder in my simulation, using the Root output file, because there is not a Gate-macro correlated to the output file data_PET.root. I post below the part of my Gate-macro where I set the type of the output file. ROOT Output format # /gate/output/root/enable # /gate/output/root/setFileName MyWork_2 # /gate/output/root/setRootNtupleFlag 1 # /gate/output/root/setRootHitFlag 1 # /gate/output/root/setRootSinglesFlag 1 # /gate/output/root/setRootCoincidencesFlag 1 # /gate/output/root/setSaveRndmFlag 1 # #/gate/output/verbose 2 Help me please. Best Regards Manuele Calussi