Installation of an underground laboratory for measuring low radioactivities and usage in context of transmutation research

Measuring of lowest specific activities of extremely long-lived isotopes has crucial importance for fundamental questions in nuclear and particle physics. These measurements can only take place underground because reduced natural background radiation is necessary.

Felsenkeller, Einfahrt LKW-Tunnel

Figure: Felsenkeller Dresden (© D.Bemmerer)

The underground laboratory "Felsenkeller" established by VKTA Rossendorf represents a unique low background facility in Dresden for low background experiments.

Within this project the measuring conditions in this laboratory should be improved. It can be used for precision γ-spectroscopy of materials activated at the neutron facility (DT generator) of TU Dresden at HZDR. Furthermore a measuring setup for α-spectroscopy of extremely long-lived α-emitters and a setup for measuring isotopes decaying via electron capture (detecting x-rays) shall be installed.

The measurements can be used to predict the neutron induced background because of activation or (α,n) reactions in low background experiments (e.g. neutrinoless double beta decay). α-particles are produced in the decay chains of thorium or uranium which is contained in materials (e.g. concrete) in small fractions.

The long-lived α-emitter 144Nd should be measured in this project. Nd which contains 150Nd (a candidate for neutrinoless double beta deday) and  144Nd is used in the SNO+ experiment in a liquid scintillator. The background radiation produced by 144Nd has to be well understood for this high precision low background experiment.