Dear maire!
Thank you very much for your response. I tried like you said. It worked like this. But i am using MaGe simulation framework for my work. I am trying to incident Cs137 from detector holder to detectors and finding its activity of 662 keV gamma line.
In my case, it seems that it’s not producing daughter nucleus properly so i decided to do something like this. I did one simulation using Cs137 at energy 0 keV and ran other simulation using Excited state of Ba-137 with energy of 662 keV so that i can also get 662 keV gamma line . And then i tried to add energy spectrum of both. But in this case Branching ratio i get for 284 keV(5.30%) and 662 keV(94.7%) are not the way it should be. Figure is attached below.
Looking forward to your opinion, if you could hep me here.
Thank you!