I have just done an efficiency calibration measurement for the HPGe detector of a whole-body counter. Ba-133 and Eu-152 were the calibration nuclides. For a calibration at low energies I thought of using the X-ray emissions of both nuclides as well. However, the result looks quite bad - see the attachment. The peak at 45.6 keV originating from Eu-152 is far too small compared to the X-ray peaks at 30.8 and 35.2 (Ba-133) and at 39.9 (Eu-152). A difference between the emissions of Eu-152 and Ba-133 is possible because of a slightly different distribution of the sources within the phantom. (I used a brick phantom with rod sources.) However, what might be the reason for the difference between the two emissions of Eu-152? The problem occurs also in repeated calibrations so the small number of counts at 45.6 keV is not a random event. The abundance of the X-ray emissions at 45 keV was entered as 14.82%, that at 39.9 keV as 58.5% - values that I found both on nucleide.org and on nucleonica.net. Thank you for your help!