You can define any energy set you want (you don’t even have to have a REC defined to run calculations). Please pay attention that, when you use a REC for calculations, all energies you are interested in must fall inside the regions defined in that REC (that’s if you defined them, i.e. if you are not using discrete curve).
There is a simple way to do that. Select the data in your document, copy them, go to Angle and press “Paste from Clipboard”.
Angle support energies from as low as 0.1 keV to 100 GeV (108 keV). However, in low gamma-energy region (say below 50 keV), attenuation becomes so intense that detector geometrical and compositional data cannot be specified accurately enough to enable the same quality of results as for higher energies. Above 2000 keV reliable calibration points are scarce, so in this region RECs are generally poor, limiting Angle’s practical applicability. Using Angle (like any other software based on absolute or semi-empirical efficiency calculation method) in very low and very high energy regions should thus be carried out with this in mind and with the utmost care.
“Discrete REC” option, though, enables this limitation to be greatly overcome, thus Angle energy region of practical applicability considerably expanded, thanks to ET error-compensation effect.
Open the “Energies” dialog and click on the “Load saved energies” button. Choose the file with the name under which you saved the energies and click OK.
Another, more flexible way to select the previously saved energies is by using the pop-up menu, which you can open by clicking the “Energies” label in the “Additional parameters” group of the main window. Choose the option “Saved energies” and select the previously saved energy set from the sub-menu.