The "Energy Spectrum" tab allows you to define the energies of the x-ray source. The table will define a probability density function of the energy. Each entry will contain an energy in eV and a probability. You can use the "Add Row" and "Delete Row" buttons to add or remove values from the table, and each value can be edited by clicking on the appropriate cell. Note that the last entry MUST have a probability of -1 to tell penEasy that the end of the list has arrived. The energy associated with the -1 probability will not be used.

Since this might not be the most convenient method of input, you may also click the "Import..." button to load an x-ray source (*.xrs) file.An x-ray source file is a simple plain-text file that contains the values you would see in the energy spectrum table, seperated by tabs.