Screening of materials with high purity germanium detectors at the Laboratori Nazionali del Gran Sasso

The Gran Sasso National Laboratories (LNGS) of the National Institute of Nuclear Physics (INFN) are equipped with an underground ultra-low background facility namely the SubTErranean Low Level Assay (STELLA), which is in first line dedicated to material screening for the fundamental physics experiments installed in the underground laboratories. The high level of performance of the ultra-low-level detector systems allows for detecting extremely low radioactivity levels in materials down to the itBq kg(-1) level. The installations and experimental setups using ultra-low background techniques will be described shortly, and an example of material screening will be discussed.