NaI moves to 4850 Level

Physics experiments are installed deep underground to shield them from the noise of cosmic radiation, but even 4,850 feet underground the occasional uninvited muon shows up. Gamma radiation also is emitted from traces of uranium and thorium in the rock.

Researchers running sensitive underground experiments, including the LUX dark-matter detector and the Majorana Demonstrator experiment, need to know background radiation levels to properly calibrate their detectors.

Enter the Background Characterization Group, an umbrella designation for a variety of experiments involving researchers from the University of South Dakota, Notre Dame University and Regis University. For example, the group just moved a sodium-iodide based detector from the 2000 Level to the 4850 Level to measure gamma radiation, including muon-induced gamma radiation. 

Members of the group already have published papers. To read an example, go to http://arxiv.org/abs/0912.0211