Set Energy Range

I am trying so set the Energy Threshold to below the Default 1KeV by having the following code in in my file: Setting the cuts seems to work fine, but I need to be able to generate lower energy gammas (in the range of 200-1000eV).

UPDATE: I should have mentioned that I am using a Reference Physics List, not a UserPhysicsList, so I am not even sure if I can use SetEnergyRange

But I cannot seem to get the Energy Threshold below 1KeV (see the gamma below as an example)