Chemical purification of lanthanides for low-background experiments

There are many potentially active isotopes among the lanthanide elements which are possible to use for low-background experiments to search for double β decay, dark matter, to investigate rare α and β decays. These kind of experiments require very low level of radioactive contamination, but commercially available compounds of lanthanides are always contamined by uranium, thorium, radium, potassium, etc. A simple chemical method based on liquid–liquid extraction has been applied for the purification of CeO2, Nd2O3 and Gd˙2O˙3 from radioactive traces. Detailed schemes of purification procedure are described. Measurements by using HPGe spectrometry demonstrate high efficiency in K, Ra, Th, U contaminations reduction on at least one order of magnitude.